Subsede Yucatán

Laboratorio Nacional de Geointeligencia

Artículos Científicos

Evolutionary approach for detection of buried remains using hyperspectral images

  • León Dozal, José L. Silván Cárdenas, Daniela Moctezuma, Oscar S. Siordia, and Enrique Naredo.

Programming technique called Brain Programming (BP) for automating the design of Hyperspectral Visual Attention Models (H-VAM.), which is proposed as a new method for the detection of buried remains. Four graves were simulated and monitored during six months by taking in situ spectral measurements of the ground. Two experiments were implemented using Kappa and weighted Kappa coefficients as classification accuracy measures for guiding the BP search of the...


Medic-Us an Intelligent Social Network for Medical Services

  • Gandhi Hernández Cham, Oscar S. Siordia, Alejandro Molina-Villegas, Mario Chirinos-Colunga, y Jorge Canto-Esquivel

Health services are on the top priorities for society, but up to now we have fail in make it universal all around the world. Nowadays information technologies, specially social networks have demonstrated its usefulness in different areas. This article describes the design and development of a social network platform focused on the physician-patient and physician-physician interactions, in order to achieve better and faster diagnosis. Like other social networks or social media tools, it focus...


Multi-Scale Extraction of Regular Activity Patterns in Spatio-Temporal Events Databases: A Study Using Geolocated Tweets from Central Mexico

  • Pablo López-Ramírez, Alejandro Molina-Villegas, Oscar S. Siordia, Mario Chirinos and Gandhi Hernandez Chan

This paper proposes a new technique for the extraction of regular activity patterns at different scales (resolution levels), mined from the microblogging platform Twitter. The approach is based on the recursive application of the DBSCAN clustering algorithm to the geolocated Twitter feed. The proposed technique includes a novel way to obtain ’averaged’ regular activity zones based on the rasterization and aggregation of the Concave Hull of the clusters identified at each...


A simple approach to multilingual polarity classification in twitter

  • Eric S. Tellez, Sabino Miranda-Jiménez, Mario Graff, Daniela Moctezuma, Ranyart R. Suárez, and Oscar S. Siordia

Recently, sentiment analysis has received a lot of attention due to the interest in mining opinions of social media users. Sentiment analysis consists in determining the polarity of a given text, i.e., its degree of positiveness or negativeness. Traditionally, Sentiment Analysis algorithms have been tailored to a specific language given the complexity of having a number of lexical variations and errors introduced by the people generating content. In this contribution, our aim is to provide a...


A case study of spanish text transformations for twitter sentiment analysis

  • Eric S. Tellez, Sabino Miranda-Jiménez, Mario Graff, Daniela Moctezuma, Oscar S. Siordia, and Elio A. Villaseñor.

Sentiment analysis is a text mining task that determines the polarity of a given text, i.e., its positiveness or negativeness. Recently, it has received a lot of attention given the interest in opinion mining in micro-blogging platforms. These new forms of textual expressions present new challenges to analyze text because of the use of slang, orthographic and grammatical errors, among others. Along with these challenges, a practical sentiment classifier should be able to handle efficiently...


Who participates in conservation initiatives? Case studies in six rural communities in Mexico

  • Méndez-López, M.E., E. García-Frapolli, I. Ruiz-Mallén, L. Porter-Bolland, C. Sánchez- González y V. Reyes-García

Previous studies attempting to explain the factors that determine local participation in conservation initiatives have concluded that socio-political exclusion is the main barrier to being involved in such initiatives. Such studies have not differentiated between different types of conservation initiatives. In this paper, we contribute to the literature analyzing the socio-cultural correlates of participation, by differentiating between participation in three types of conservation schemes:...


Determinants of livelihood diversification: The case wildlife tourism in four coastal communities in Oaxaca, Mexico

  • Véronique SophieAvila-Foucat, Karla Juliana Rodríguez-Robayo

Diversification is a process by which households increase the number of economic activities in different sectors to improve their well-being and chance of survival. The aim of this research is to study the determinants of livelihood diversification with a specific emphasis on wildlife watching in the coastal communities of Oaxaca, Mexico. Based on household surveys, two econometric models were used to examine the differences regarding the asset determinants for those households increasing the...


Preserve and produce: Experience in implementing payments for environmental services in two indigenous communities in the northern and southern ranges

  • Rodríguez-Robayo, K., Merino-Pérez, L. Journal of Sustainable Forestry, 2018.

Payments for environmental services (PES) are conservation instruments in place in various Latin American countries. They are generally undergoing adjustment and implementation changes, and they are widely implemented in indigenous communities. This article aims to suggest a relevant group of context variables in PES implementation. Characterizing the local context of two indigenous communities located in Oaxaca, Mexico, and analyzing the relationship between the local context and PES...


Variational phase recovering without phase unwrapping in phase-shifting interferometry

  • R. Legarda-Sáenz, A. Téllez-Quiñones, C. Brito-Loeza, and A. Espinosa-Romero.

We present a variational method for recovering the phase term from the information obtained from phase-shifting methods. First we introduce the new method based on a variational approach and then describe the numerical solution of the proposed cost function, which results in a simple algorithm. Numerical experiments with both synthetic and real fringe patterns show the accuracy and simplicity of the resulting algorithm.


Dual-plane slightly off-axis digital holography based on a single cube beam splitter

  • M. León-Rodríguez, J.A. Rayas, R.R. Cordero, A. Martínez-García, A. Martínez-Gonzalez, A. Téllez-Quiñones, P. Yañez-Contreras, and O. Medina-Cázares

In order to recover the holographic object information, a method based on the recording of two digital holograms, not only at different planes but also in a slightly off-axis scheme, is presented. By introducing a π-phase shift in the reference wave, the zero-order diffracted term and the twin image are removed in the frequency domain during the processing of the recorded holograms. We show that the zero-order elimination by the phase-shifted holograms is better than working with...


Comparison of multihardware parallel implementations for a phase unwrapping algorithm

  • Francisco Javier Hernandez-Lopez, Mariano Rivera, Adan Salazar-Garibay, Ricardo Legarda-Sáenz

Phase unwrapping is an important problem in the areas of optical metrology, synthetic aperture radar (SAR) image analysis, and magnetic resonance imaging (MRI) analysis. These images are becoming larger in size and, particularly, the availability and need for processing of SAR and MRI data have increased significantly with the acquisition of remote sensing data and the popularization of magnetic resonators in clinical diagnosis. Therefore, it is important to develop faster and accurate phase...


Built-up index methods and their applications for urban extraction from Sentinel 2A satellite data: discussion

  • J. C. Valdiviezo-Navarro, A. Téllez-Quiñones, A. Salazar-Garibay, A. López-Caloca.

Several built-up indices have been proposed in the literature in order to extract the urban sprawl from satellite data. Given their relative simplicity and easy implementation, such methods have been widely adopted for urban growth monitoring. Previous research has shown that built-up indices are sensitive to different factors related to image resolution, seasonality, and study area location. Also, most of them confuse urban surfaces with bare soil and barren land covers. By gathering the...


The retarded potential of a non-homogeneous wave equation: introductory analysis through Green functions

  • A. Téllez-Quiñones, J. C. Valdiviezo-Navarro, A. Salazar-Garibay, A. López-Caloca

The retarded potential, a solution of the non-homogeneous wave equation, is a subject of particular interest in many physics and engineering applications. Examples of such applications may be the problem of solving the wave equation involved in the emission and reception of a signal in a synthetic aperture radar (SAR), scattering and backscattering, and general electrodynamics for media free of magnetic charges. However, the construction of this potential solution is based on the theory of...