University of Cienfuegos

www.ucf.edu.cu/
Havana, Cuba

The University of Cienfuegos "Carlos Rafael Rodríguez" is a university located in Cienfuegos, Cuba. Wikipedia.


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Alvarez-Betancourt Y.,University of Cienfuegos | Garcia-Silvente M.,University of Granada
Scientometrics | Year: 2014

Person identification based on iris recognition is getting more and more attention among the modalities used for biometric recognition. This fact is due to the immutable and unique characteristics of the iris. Therefore it is of utmost importance for researchers interested in this discipline to know who and what is relevant in this area. This paper presents a comprehensive overview of the field of iris recognition research using a bibliometric approach. Besides, this article provides historical records, basic concepts, current progress and trends in the field. With this purpose in mind, our bibliometric study is based on 1,354 documents written in English, published between 2000 and 2012. Scopus was used to perform the information retrieval. In the course of this study, we synthesized significant bibliometric indicators on iris recognition research in order to evaluate to what extent this particular field has been explored. Thereby, we focus on foundations, temporal evolution, leading authors, most cited papers, significant conventions, leading journals, outstanding research topics and enterprises and patents. Research topics are classified into three main categories: ongoing, emerging, and decreasing according to their corresponding number of publications over the period under study. An analysis of these indicators suggests there has been major advances in iris recognition research and also reveals promising new avenues worthy of investigation in the future. This study will be useful to future investigators in the field. © 2014, Akadémiai Kiadó, Budapest, Hungary.


Piedra O.P.F.,University of Cienfuegos | De Oliveira J.,University of Sao Paulo
International Journal of Modern Physics D | Year: 2010

We investigate the influence of vacuum polarization of quantum massive fields on the scalar sector of quasinormal modes in spherically symmetric black holes. We consider the evolution of a massless scalar field on the spacetime corresponding to a charged semiclassical black hole, consisting of the quantum-corrected geometry of a ReissnerNordström black hole dressed by a quantum massive scalar field in the large mass limit. Using a sixth order WKB approach we find a shift in the quasinormal mode frequencies due to vacuum polarization. © 2010 World Scientific Publishing Company.


Caridade P.J.S.B.,University of Coimbra | Horta J.-Z.J.,University of Coimbra | Horta J.-Z.J.,University of Cienfuegos | Varandas A.J.C.,University of Coimbra
Atmospheric Chemistry and Physics | Year: 2013

The hydroxyl nightglow has been examined anew using calculated rate constants for the key reactive and inelastic O + OH(v') quenching processes. These constants have been obtained from quasiclassical trajectories run on the adiabatic ab initio-based double many-body expansion-IV potential energy surface for the ground state of the hydroperoxil radical. Significant differences in the vertical profiles of vibrationally excited hydroxyl radicals are obtained relative to the ones predicted by Adler-Golden (1997) when employing an O + OH(v') effective rate constant chosen to be twice the experimental value for quenching of OH(v' Combining double low line 1). At an altitude of 90 km, such deviations range from ∼ 80% for v' Combining double low line 1 to only a few percent for v' Combining double low line 9. Other mechanisms reported in the literature have also been utilized, in particular those that loosely yield lower and upper limits in the results, namely sudden-death and collisional cascade. Finally, the validity of the steady-state hypothesis is analysed through comparison with results obtained via numerical integration of the master equations. © Author(s) 2013.


Leon G.,Pontifical Catholic University of Valparaíso | Roque A.A.,University of Cienfuegos
Journal of Cosmology and Astroparticle Physics | Year: 2014

In this paper we investigate, from the dynamical systems perspective, the evolution of a Kantowski-Sachs metric in a generic class of f(R) models. We present conditions (i.e., differentiability conditions, existence of minima, monotony intervals, etc.) for a free input function related to the f(R), that guarantee the asymptotic stability of well-motivated physical solutions, specially, self-accelerated solutions, allowing to describe both inflationary- and late-time acceleration stages of the cosmic evolution. We discuss which f(R) theories allows for a cosmic evolution with an acceptable matter era, in correspondence to the modern cosmological paradigm. We find a very rich behavior, and amongst others the universe can result in isotropized solutions with observables in agreement with observations, such as de Sitter, quintessence-like, or phantom solutions. Additionally, we find that a cosmological bounce and turnaround are realized in a part of the parameter-space as a consequence of the metric choice. © 2014 IOP Publishing Ltd and Sissa Medialab srl.


BACKGROUND:: A new vaccine candidate against pneumococcus is being developed in Cuba, and it is a priority of the national health system. There is limited information on nasopharyngeal colonization burden, though it is essential for monitoring the impact of the vaccine. The study aims to estimate the prevalence of nasopharyngeal colonization in 2-18 month old toddlers, identify circulating serotypes, antimicrobial resistance, and its association with selected risk factors. METHODS:: A cross-sectional study was conducted between October and December 2013 in Cienfuegos municipality. Inclusion criteria were evaluated and informed consent was obtained from the parents. Clinical and epidemiologic data were collected through a semi-structured questionnaire. Nasopharyngeal swabs according to established protocols were taken. Data analysis included frequency distributions and comparison of proportions. The association between colonization and selected risk factors was assessed by multivariate analysis. RESULTS:: 984 children (87.2% living in urban areas) were included. The overall prevalence of colonization was 21.6%. The most frequent serotypes isolated were: 6A (23.1%), 23F (10.8%), 6B (10.3%), 19F (8.5%) and 14 (3.3%). We found no resistance to beta-lactamases in circulating serotypes. Living with sibling younger than 5 years, previous respiratory infections, previous hospitalization, and day-care attendance were determinants of NP carriage. CONCLUSIONS:: The findings suggest that the burden of pneumococcal disease and colonization in Cuba could be significantly impacted after vaccine introduction. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.


Gutierrez A.S.,University of Cienfuegos | Vandecasteele C.,Catholic University of Leuven
Energy | Year: 2011

A new way to evaluate the energetic performance of lime shaft kilns is proposed. Two new exergy-based indicators are introduced for the evaluation, one to assess the exergy efficiency of limekilns and the other indicator to assess the effectiveness of the exergy consumption of the dissociation reaction. The combination of both indicators provides a clear picture of the energetic performance of the process, highlighting the main potentialities for fuel saving (fuel consumption represents about 50% of total production costs).The validity of the proposed assessment is examined using some operating data measured in a commercial lime factory. Results show that introduction of exergy-based indicators in the assessment improves the evaluation of the energy consumption of the calcination process. In this way the impact of the process losses in the fuel consumption is better addressed. © 2011 Elsevier Ltd.


Sagastume Gutierrez A.,University of Cienfuegos | Van Caneghem J.,Catholic University of Leuven | Cogollos Martinez J.B.,University of Cienfuegos | Vandecasteele C.,Catholic University of Leuven
Journal of Cleaner Production | Year: 2012

Lime production is characterized by large emissions of CO2 and by other environmental impacts. In Cuba this industry operates with outdated technology, resulting in low energy and material efficiency and in high environmental impacts. In order to improve the environmental performance of the lime industry in Cuba it is necessary to have an overview of the environmental impacts associated with the production process. This paper quantifies the environmental impacts of lime production in Cuba by means of LCA methodology in a cradle-to-gate evaluation. It also aims at establishing a benchmark for improvement by comparing the environmental impact of this industry in Cuba with a plant in an industrialized country. For the inventory evaluation the process of lime production was divided in five production stages. When necessary, the data was completed with literature sources. For the impact assessment the impacts in the following categories were considered: energy consumption, global warming, human toxicity, photoxidant formation and acidification. Results show that the calcination stage and the consumption of fuel, electricity and limestone are the main contributors to environmental impact of the production process. The economic assessment shows possibilities to improve the environmental performance while achieving cost reductions in the production process. The larger improvements in the environmental performance and cost saving can be achieved by improving the energy efficiency of the calcination stage. This can partially be accomplished with moderate investments. © 2012 Elsevier Ltd. All rights reserved.


Lara B.G.V.,University of Cienfuegos | Molina L.M.C.,University of Cienfuegos | Yanes J.P.M.,University of Cienfuegos
Energy and Buildings | Year: 2015

Minimizing energy consumption of heating, ventilation and air conditioning (HVAC) systems in buildings has experienced an increasing attention recently. Mainly motivated by the exploitation of building automation systems (BAS), as well as simulation tools, innovative practices and methodologies have been introduced to reduce the costs of energy required for heating and air conditioning of buildings. Outstanding has been the establishment of model predictive control (MPC) as a control strategy for the optimal operation of HVAC systems. The basis for MPC is a dynamic model, which is objectively challenging and time-consuming to obtain. This paper presents two modeling approaches of the return water temperature of a central chiller plant based on data of the real operation of a building, weather disturbances, and the temperature of a reference thermal zone. It integrates building's real measurements with a room simulator model. In this work, an original method for accurately describing the cooling dynamics of a case study hotel on a tropical island is proposed. © 2015 Elsevier B.V. All rights reserved.


Sagastume Gutierrez A.,University of Cienfuegos | Cogollos Martinez J.B.,University of Cienfuegos | Vandecasteele C.,Catholic University of Leuven
Applied Thermal Engineering | Year: 2013

Calcium oxide (CaO), commonly known as lime or quicklime, is an energy intensive product. In order to produce lime, vertical shaft kilns are widely used in the lime industry. The objective of this work is to analyze the energy and exergy consumption of the calcination process in vertical shaft kilns, in order to identify the factors affecting fuel consumption. Data on energy and exergy consumption and losses throughout the calcination process are given for two shaft kilns. In the process, the energy efficiency is found to be higher than the exergy efficiency, e.g. 71.6% and 40.8% for the energy and exergy efficiency of one of the kilns. Results also showed that the most irreversible processes taking place in the kiln are the exergy destruction due to fuel combustion and the exergy destruction due to internal heat and momentum transfer both accounting for about 40% of the efficiency loss. Moreover, the main exergy loss through the boundaries of the kiln is the exergy loss with the exhaust gases contributing with more than 10% of the efficiency loss. Improvements on both the energy and the exergy efficiencies can be achieved through a better control of the operational parameters of the kiln (ratio limestone/fuel supply, excess of combustion air, size and size distribution of the limestone fed to the kiln and exit temperature of quicklime flow). The present study proposes a tool for the analysis of energy and exergy utilization of the calcination process in limekilns, and also provides some energy conservation measures. © 2012 Elsevier Ltd. All rights reserved.


Martinez Y.H.,University of Cienfuegos
Revista de Economia e Sociologia Rural | Year: 2015

The reproduction of the peasantry, as a family-economic unit and social class, has become a global concern. The food emergency and the need for sustainable forms of production have pushed up the family farming as an alternative solution; for this reason, the scientific activity invests in studying the diversity of family forms and changes in livelihood strategies and social reproduction. The article presented is a review about the factors involved in the reproduction of the peasantry in Cuba, result of theoretical reconstruction achieved from the sociology of knowledge. This theoretical and methodological perspective establishes the dialectical relationship between scientific knowledge that has occurred, and the social context of reference; also describes the context of implementation of economic policies and social transformations that reflects the science about the countryside. The main result lies in determining the forms of manifestation of economic, cultural and social capital, which is the result of data's interpretation using content analysis and that support from a socio-historical perspective, understanding the peasantry and their reproduction, as a case study for science in Cuba.

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