José-Francisco Vicent

José-Francisco Vicent
University of Alicante | UA · Computer Sciences and Artificial Intelligence

Ph.D

About

55
Publications
14,659
Reads
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412
Citations
Additional affiliations
January 2000 - present
University of Alicante
Position
  • Professor (Associate)
January 1990 - November 1994
Telefónica, S.A
Position
  • Analyst
Education
January 2005 - July 2007
University of Alicante
Field of study
  • Computer Science

Publications

Publications (55)
Article
Many scholars have tried to address the identification of critical nodes in complex networks from different perspectives. For instance, by means of the betweenness methods based on shortest paths and random walk, it is possible to measure the global importance of a node as an intermediate node. All these metrics have the common characteristic of no...
Article
Taking into account that accessibility is one of the most strategic and determining factors in economic models and that accessibility and tourism affect each other, we can say that the study and improvement of one of them involved the development of the other. Using network analysis, this study presents an algorithm for labeling the difficulty of t...
Article
In this work we look for characteristics and mobility patterns in the cities of Rome and London, from a dataset of private vehicle movements in those cities. Based on mobility data and other data related to the urban public transport network, commercial activity and tourist information, a multiplex network with three layers is constructed for each...
Article
Complex networks provide a framework for modelling real-world systems. Based on a set of data on mobility by car between different urban areas of the city of Rome, we represent and analyze these mobility data coupled with urban public transport networks, augmenting the network nodes with data on commercial, economic, service and tourist activity in...
Poster
Full-text available
This Special Issue is dedicated to collecting original research contributions focused on the application of artificial intelligence (AI) methods for acquisition, filtering, management, analysis, discovery, and visualization of geo-information systems from multiple sources. We aim to take an integrated approach to AI solutions that fosters a robust...
Article
A new algorithm for attributed multiplex networks is proposed and analysed with the main objective to compute the centrality of the nodes based on the original PageRank model used to establish a ranking in the Web pages network. Taking as a basis the Adapted PageRank Algorithm for monoplex networks with data and the two-layer PageRank ap- proach, a...
Article
Full-text available
Drawing on the recent advances in complex network theory, urban mobility flow patterns, typically encoded as origin-destination (OD) matrices, can be represented as weighted directed graphs, with nodes denoting city locations and weighted edges the number of trips between them. Such a graph can further be augmented by node attributes denoting the v...
Article
Full-text available
For a considerable time, researchers have focused on defining different measures capable to characterizing the importance of vertices in networks. One type of these networks, the cities, are complex systems that generate large quantity of information. These data are an important part of the characteristics of the urban network itself. Because of th...
Research Proposal
Full-text available
Special Issue "The Application of AI Techniques on Geo-Information Systems" A special issue of International Journal of Geo-Information Deadline for manuscript submissions: 31 Dec 2020 https://www.mdpi.com/journal/ijgi/special_issues/GIS_AI Dear Colleagues, This Special Issue is dedicated to collecting original research contributions focused on t...
Article
Full-text available
Networks are useful to describe the structure of many complex systems. Often, 1 understanding these systems implies the analysis of multiple interconnected networks simultaneously, 2 since the system may be modeled by more than one type of interaction. Multiplex networks are 3 structures capable of describing networks in which the same set of nodes...
Article
Full-text available
Cities can be represented by spatial networks, and the mathematical structure that defines a spatial network is a graph. Taking into account this premise, this paper is focused on analysing information on an urban scale by combining a new ray-casting visibility index with a data set of the urban street network. The visibility index provides informa...
Article
Full-text available
The current flow betweenness centrality is a useful tool to estimate traffic status in spatial networks and, in general, to measure the intermediation of nodes in networks where the transition between them takes place in a random way. The main drawback of this centrality is its high computational cost, especially for very large networks, as it is t...
Article
Full-text available
Usually, the nodes’ interactions in many complex networks need a more accurate mapping than simple links. For instance, in social networks, it may be possible to consider different relationships between people. This implies the use of different layers where the nodes are preserved and the relationships are diverse, that is, multiplex networks or bi...
Article
Full-text available
Identifying the influential nodes in complex networks is a fundamental and practical topic at the moment. In this paper, a new centrality measure for complex networks is proposed based on two contrasting models that have their common origin in the well-known PageRank centrality. On the one hand, the essence of the model proposed is taken from the A...
Article
Diversity is an important measure that according to the context, can describe different concepts of general interest: competition, evolutionary process, immigration, emigration and production among others. It has been extensively studied in different areas, as ecology, political science, economy, sociology and others. The quality of spatial context...
Article
Full-text available
A massive amount of information as geo-referenced data is now emerging from the digitization of contemporary cities. Urban streets networks are characterized by a fairly uniform degree distribution and a low degree range. Therefore, the analysis of the graph constructed from the topology of the urban layout does not provide significant information...
Article
Full-text available
Quito's urban planning department contemplated the creation of a new suburb called Villaflora following the \textit{garden city} model: homes in connection with nature but also near services. In Villaflora we do not find monumental elements that characterize patrimonial architecture; the~value of Villaflora's patrimony is in its urban model charact...
Conference Paper
This paper focuses on the process of quantification and visualization of a heritage conservation study in a neighbourhood of Quito (Ecuador). The first part of the paper consists of collecting real information about different features of every building in the urban network of the mentioned neighbourhood. The information collected is then quantified...
Article
The Adapted PageRank Algorithm (APA) proposed by Agryzkov et al. provides us a method to establish a ranking of nodes in an urban network. We can say that it constitutes a centrality measure in urban networks, with the main characteristic that is able to consider the importance of data obtained from the urban networks in the process of computing th...
Article
Full-text available
This paper analyzes success public spaces (specifically plazas) in the urban fabric of the city of Murcia, Spain. Two approaches were adopted. Firstly, the city was visualized as a complex network whose nodes represent plazas. A centrality algorithm was applied to determine the importance of each node. Secondly, data sets were used from social netw...
Article
Full-text available
Among social networks, Foursquare is a useful reference for identifying recommendations about local stores, restaurants, malls or other activities in the city. In this article, we consider the question of whether there is a relationship between the data provided by Foursquare regarding users’ tastes and preferences and fieldwork carried out in citi...
Conference Paper
In this paper we study the success of public spaces (exactly, plazas) existing in the urban fabric of the city of Murcia, Spain, from two points of view. On the one hand, we apply an algorithm to classify the nodes of a graph in order of importance, from the data obtained through a fieldwork developed on the city itself. On the other hand, we use t...
Chapter
In this paper we study the success of public spaces (exactly, plazas) existing in the urban fabric of the city of Murcia, Spain, from two points of view. On the one hand, we apply an algorithm to classify the nodes of a graph in order of importance, from the data obtained through a fieldwork developed on the city itself. On the other hand, we use t...
Conference Paper
Full-text available
Three different models for visualisation of geolo-cated social networks data are presented in this paper. One is based on the concept of grid computing; another uses the nearest neighbour query location and the third adopts the urban network structure itself. The models follow two different approaches. They all consider the geographic location of d...
Article
Full-text available
This paper aims to represent the commercial activity of a city taking as source data the social network Foursquare. The city of Murcia is selected as case study, and the location-based social network Foursquare is the main source of information. After carrying out a reorganisation of the user-generated data extracted from Foursquare, it is possible...
Article
We propose and discuss a new centrality index for urban street patterns represented as networks in geographical space. This centrality measure, that we call ranking-betweenness centrality, combines the idea behind the random-walk betweenness centrality measure and the idea of ranking the nodes of a network produced by an adapted PageRank algorithm....
Conference Paper
Full-text available
In this paper, we present a way for analyzing and visualizing extensions or enhancements of an existing urban network, as well as the effects that cause these extensions on commercial activity taking place in the network itself. This analysis is based on an algorithm for classifying the nodes of the network, depending on the type and number of faci...
Conference Paper
Full-text available
Given a set of points S in the plane, we propose a triangulation process to construct a triangulation for the set S. Triangulating scattered point-sets is a a very important problem in computational geometry; hence the importance to develop new efficient algorithms and models to triangulate point-sets. This process presents two well distinguished p...
Article
Urban researchers and planners are often interested in understanding how economic activities are distributed in urban regions, what forces influence their special pattern and how urban structure and functions are mutually dependent. In this paper we want to show how an algorithm for ranking the nodes in a network can be used to understand and visua...
Article
This paper presents a new method to establish a ranking of nodes in an urban network. In the original PageRank algorithm, a single PageRank vector is computed to determine the relative importance of Web pages, independent of any particular search query. We follow a similar reasoning, adapting the concept of PageRank vector to urban networks. We tra...
Article
Block upper triangular matrices with elements in ZpZp have very interesting properties for many applications. Some of them involve powers of this type of matrices with very large exponents requiring specific exponentiation algorithms to compute them efficiently. In this paper, we analyze quick exponentiation in block upper triangular matrices of si...
Conference Paper
Full-text available
In this paper we describe a special group of block upper triangular matrices with 3 ×3 blocks and elements in a finite field. We also verify that, with properly chosen parameters, the cardinality of the subgroup generated by one matrix of this group can be as large as required. Then we introduce two examples of this group of matrices employed in cr...
Article
The main idea of this work is to present a tool which may be useful to generate a mesh of points where urban actions may be taken after analysing and understanding complex urban situations. By the word complex we mean urban concentrations without precise limits and without a recognizable geometry pattern. In these situations, it is very hard for th...
Conference Paper
Full-text available
In this paper we propose a neural network model to simplify and 2D meshes. This model is based on the Growing Neural Gas model and is able to simplify any mesh with different topologies and sizes. A triangulation process is included with the objective to reconstruct the mesh. This model is applied to some problems related to urban networks.
Article
A 2D triangle mesh simplification model is described in this paper, with the main objective of preserving the shape of the original mesh. The proposed model consists of a self-organizing algorithm whose objective is to generate the positions of the nodes of the simplified mesh; afterwards, a triangulation algorithm is performed to reconstruct the t...
Conference Paper
Tangle is an iterative one-way hash function based on the Merkle-Damgard scheme strengthened by a message dependent round function. It was submitted to the NIST SHA-3 competition, being accepted for first round evaluation. We propose an alternative message expansion scheme for Tangle in order to thwart the collision attacks found during such evalua...
Conference Paper
The urban world of the 21st century is composed of numerous nodes, streams and webs, which create a new landscape of globalization and impose different logic of space and time perception. Therefore, the urban infrastructure is updated and its networks are continuously multiplied. A method known as urban acupuncture on the one hand tests the local e...
Article
We present a 2D triangle mesh simplification model which is able to produce high quality approximations of any original planar mesh, regardless of the shape of the original mesh. This method consists of two phases: a self-organizing algorithm and a triangulation algorithm. The self-organizing algorithm is an unsupervised incremental clustering algo...
Conference Paper
We present a 2D triangle mesh simplification model, which is able to produce high quality approximations of any original planar mesh, regardless of the shape of the original mesh. This model is applied to reduce the urban concentration of a real geographical area, with the property to maintain the original shape of the urban area. We consider the r...
Conference Paper
The aim of this article is twofold. In the first place, we describe a special non-abelian group of block upper triangular matrices, and verify that choosing properly certain parameters, the order of the subgroup generated by one of these matrices can be as large as needed. Secondly, we propose and implement a new key exchange scheme based on these...
Article
We propose a new key exchange scheme where the secret key is obtained by multiplying the powers of block upper triangular matrices. After studying the cryptographic properties of these block matrices, the theoretical aspects of this scheme are analyzed, concluding that common ciphertext attacks are not applicable to this cryptosystem. Moreover, our...
Conference Paper
The primary objective of this paper is to carry out a performance comparison of two models to generate simplified meshes representing 3D objects, the GNG3D modei and the Quadric Error Metrics (QEM) modei. The QEM modei constitutes a well-known classical algorithm based on interactive contraction of vertex pairs and represents perhaps the best balan...
Conference Paper
Full-text available
We propose an original method to geoposition an audio/video stream with multiple emitters that are at the same time receivers of the mixed signal. The achieved method is suitable for those comes where a list of positions within a designated area is encoded with a degree of precision adjusted to the visualization capabilities; and is also easily ext...
Article
In this paper we present different error measurements with the aim to evaluate the quality of the approximations generated by the GNG3D model for mesh simplification. The first phase of this method consists on the execution of the GNG3D algorithm, described in the paper. The primary goal of this phase is to obtain a simplified set of vertices repre...
Article
Full-text available
We describe a new public key cryptosystem using block upper triangular matrices with elements in Zp, based on a generalization of the discrete logarithm problem over a finite group. The proposed cryptosystem is very efficient, requiring very few operations and also allows an ElGamal based digital signature scheme. The main benefit is that the secur...
Article
Full-text available
In this paper we present different error measurements with the aim to evaluate the quality of the approx-imations generated by the GNG3D method for mesh simplification. The first phase of this method consists on the execution of the GNG3D algorithm, described in the paper. The primary goal of this phase is to obtain a simpli-fied set of vertices re...
Article
The best method for exponentiation is highly dependant on the algebraic set employed. Block upper triangular matrices defined in Zp, have very interesting properties for multiple applications, in which exponentiation is very important in order to achieve adequate performance. We analyze the usage of quick exponentiation methods with these matrices...
Article
We propose a new mathematical problem that is applicable to public key cryptography. Based on the Discrete Logarithm Problem (DLP), it uses certain elements formed by two matrices with elements in a finite field and a matrix whose elements are points of an elliptic curve. With this system, we get a larger key space without increasing the underlying...
Article
Over the last few years, it has been proven that GSM is insecure. In order to improve the standard GSM protection mechanisms, we propose a new secure communication system relying on well known recognized cryptographic standards. This system is capable of securely transmitting voice, text or any other kind of data and has been implemented on Symbian...
Article
This paper describes a new method for authentication and integrity using block upper triangular matrices in which the discrete logarithm problem (DLP) defined over a finite group is used. In the proposed public key cryptosystem, the encryption requires very few operations and decryption is equivalent to the DLP and, finally, the signature scheme pr...
Article
Full-text available
As standard GSM protection methods are now well-known to be insecure, we have designed a new secure communication system over GSM network which is developed using the Symbian OS platform. It uses standard cryptographic methods such as key generators, key exchange protocols and public and private key cipher algorithms. This system allows communicati...
Article
Full-text available
We propose a public key cryptosystem based on block upper triangular matrices. This system is a variant of the Discrete Logarithm Problem with elements in a finite group, capable of increasing the difficulty of the problem while maintaining the key size. We also propose a key exchange protocol that guarantees that both parties share a secret elemen...
Article
Full-text available
As the user base of the Internet has grown tremendously, the need for secure services has increased accordingly. Most secure protocols, in digital business and other fields, use a combination of symmetric and asymmetric cryptography, random generators and hash functions in order to achieve confidentiality, integrity, and authentication. Our proposa...

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Projects

Projects (2)
Project
The main objective of the project is the selection, analysis and display of information in a complex network, with particular attention to urban networks.
Project
The main objective of the project is the selection, analysis and display of information in a complex network, with particular attention to urban networks. On one hand, it raises the need to propose theoretical models of analysis of complex networks; on the other hand, it is necessary the creation of a software tool for visualizing the information studied as well as the theoretical analysis carried out by means of the design and implementation of new measures of centrality and density. Particularize this analysis in urban networks, studying their own characteristics, in order to establish new theoretical and practical models that allows us to quantify and process the information we can extract from the city.