Diversity in mobile communications for blind detection of block-coded modulations

Spatial, temporal, and frequency diversity structures are analyzed to address the blind equalization problem in the presence of time-variant frequency selective channels. The aim of the paper is to present equalization schemes useful in front of fast changing channel responses. The best solution is a deterministic blind criterion that allows direct channel equalization and symbol detection. The main contribution of this paper is to present deterministic blind equalization schemes in CDMA systems (frequency diversity) to reduce the impact of the time-variant frequency selective channel.Peer ReviewedPostprint (published version

ADC Quantization Requirements

In this document, we analyze the impact of the quantization at the input of the demultiplexer. The required number of bits of the Analog-to-Digital-Converter (ADC) is obtained, along with the corresponding quantization losses.Preprin

Conducting Polymers Films Deposited on Carbon Steel and Their Interaction with Crude Oil

The formation of scale/solids deposits inside the pipelines is a frequent problem in the petrochemical industry. These scales can be organic as the asphaltenes and inorganic as the accumulations of salts, which apart from blocking the inside of the pipes can also cause a change in the integrity of the steel. Therefore, it is necessary to avoid the conditions where deposition occurs, together with chemical and mechanical methods of remediation to mitigate the deposition. In this work we intend to use conductive polymers in order to inhibit the deposition of asphaltenes on carbon steel surfaces, by using polypyrrole (PPy) as material capable of conducting electrical current. The electrodeposition of PPy on carbon steel were performed by cyclic voltammetry (CV) and chronoamperometry (CA). The results showed that under certain experimental conditions it is possible to make a PPy film with adequate characteristics. Important factors were the grip and electrochemical stability of the formed film on steel, which depends on the electrosynthesis technique and in some cases favoured by a pre-treatment with a 10% HNO3 solution applied to the steel prior to electropolymerization. The PPy films deposited with pre-treatment completely covered the steel surface and showed better stability, adherence and generated a hydrophobic material

A rain and scintillation Ka-band channel simulator

This paper describes the implementation of a Ka-band satellite channel simulator with emphasis on the synthesis of scintillation processes. The problem becomes one of generating a given probability density function, the Moulsley-Vilar distribution, with a specified power spectral density using aWiener model based on orthogonal Hermite polynomials for the nonlinearity. A numerical procedure is devised to calculate the filter and non-linearity coefficients of the Wiener model. The generation of rain processes conforms to the Maseng-Bakken model.Postprint (published version

Citrinina como inhibidor de corrosión en medio dulce para un acero API 5L X52

Los problemas de la corrosión son frecuentes en la industria del petróleo donde la extracción de los crudos suele estar contaminado hasta con 26 mil ppm de cloruros provenientes de agua de mar. Los inhibidores de corrosión son ampliamente utilizados en el control y prevención de este fenómeno, sin embargo, la mayoría de los compuestos usados para este fin resultan demasiado tóxicos, costosos y dañinos tanto para el medio ambiente como para el ser humano. Esta situación ha creado la necesidad de encontrar inhibidores de corrosión que sean ambientalmente amigables y de bajo costo. Para simular las condiciones de basicidad en los ductos, se empleó cloruro de sodio saturado con dióxido de carbono. Por lo que, en este proyecto se evalúa a un inhibidor (citrinina) en condiciones de medio dulce para observar la influencia que tiene bajo diferentes velocidades de rotación y temperatura, así como un análisis cinético. Finalmente, la citrinina muestra protección contra la corrosión en condiciones estáticas alcanzando un 87% a 20 ppm.Corrosion problems are frequent in the oil industry where crude extraction is usually contaminated with up to 26 thousand ppm of chlorides from seawater. Corrosion inhibitors are widely used in the control and prevention of this phenomenon, however, most of the compounds used for this purpose are too toxic, expensive and harmful both for the environment and for the human being. This situation has created the need to find low cost and environmentally friendly corrosion inhibitors. To simulate the basicity conditions in the pipelines, sodium chloride saturated with carbon dioxide was used. Therefore, in this project an inhibitor (citrinin) is evaluated under sweet medium conditions to observe the influence it has under different rotation rates and temperature, as well as a kinetic analysis. Finally, citrinin shows protection against corrosion under static conditions reaching 87% at 20 ppm

Gamonales y alcaldes: poder institucional y parainstitucional en la Primera Violencia (Colombia, 1930-1934)

By consulting and collating periodical and documentary sources –of both a civil and ecclesiastical nature– this article analyses the relationship that local political leaders (gamonales) and civil authorities established with armed institutional and illegal non-institutional groups. By exerting coercion and persecution, both leaders and civilian authorities served as a means for their political party to achieve electoral victory. This relationship made them key architects of the first stage of the Liberal-Conservative Violence, initiated under the government of Colombian President Enrique Olaya Herrera (1930-34).A partir de la consulta y el cotejo de fuentes documentales y hemerográficas, civiles y eclesiásticas, el presente artículo analiza la relación de los gamonales y las autoridades civiles locales con grupos armados institucionales y parainstitucionales, los cuales, mediante el ejercicio de la coacción y la persecución, sirvieron como instrumentos para lograr el triunfo electoral de sus partidos políticos. Esta relación convirtió a dichos actores en artífices de primer orden de la fase inicial de la violencia liberal-conservadora, que empezó bajo el gobierno del presidente colombiano Enrique Olaya Herrera (1930-34)

Virtualización de la tutoría académica en alumnos de nuevo ingreso de magisterio

Se presenta un estudio evaluativo que trata de optimizar la tutoría académica centrada en la evaluación auténtica que se orienta hacia la construcción transversal de un proyecto profesional del estudiante de nuevo ingreso en el grado en magisterio. Se aborda un proceso hacia la virtualización de las tutorías académicas analizando las necesidades del estudiante, los requisitos competenciales de estudiantes y docentes universitarios y las buenas prácticas. An evaluative study is presented that tries to optimize the academic tutoring focused on the authentic evaluation that is oriented towards the transversal construction of a professional project of the new student of degree in primary education teaching. A process towards the virtualization of the academic tutorials is approached, analyzing the needs of the student, the competence requirements of students and university professors and the good practices

Atlas de las praderas marinas de España

Knowledge of the distribution and extent of seagrass habitats is currently the basis of management and conservation policies of the coastal zones in most European countries. This basic information is being requested through European directives for the establishment of monitoring programmes and the implementation of specific actions to preserve the marine environment. In addition, this information is crucial for the quantification of the ecological importance usually attributed to seagrass habitats due to, for instance, their involvement in biogeochemical cycles, marine biodiversity and quality of coastal waters or global carbon budgets. The seagrass atlas of Spain represents a huge collective effort performed by 84 authors across 30 Spanish institutions largely involved in the scientific research, management and conservation of seagrass habitats during the last three decades. They have contributed to the availability of the most precise and realistic seagrass maps for each region of the Spanish coast which have been integrated in a GIS to obtain the distribution and area of each seagrass species. Most of this information has independently originated at a regional level by regional governments, universities and public research organisations, which explain the elevated heterogeneity in criteria, scales, methods and objectives of the available information. On this basis, seagrass habitats in Spain occupy a total surface of 1,541,63 km2, 89% of which is concentrated in the Mediterranean regions; the rest is present in sheltered estuarine areas of the Atlantic peninsular regions and in the open coastal waters of the Canary Islands, which represents 50% of the Atlantic meadows. Of this surface, 71.5% corresponds to Posidonia oceanica, 19.5% to Cymodocea nodosa, 3.1% to Zostera noltii (=Nanozostera noltii), 0.3% to Zostera marina and 1.2% to Halophila decipiens. Species distribution maps are presented (including Ruppia spp.), together with maps of the main impacts and pressures that has affected or threatened their conservation status, as well as the management tools established for their protection and conservation. Despite this considerable effort, and the fact that Spain has mapped wide shelf areas, the information available is still incomplete and with weak precision in many regions, which will require an investment of major effort in the near future to complete the whole picture and respond to demands of EU directives

Atlas de las praderas marinas de España

Knowledge of the distribution and extent of seagrass habitats is currently the basis of management and conservation policies of the coastal zones in most European countries. This basic information is being requested through European directives for the establishment of monitoring programmes and the implementation of specific actions to preserve the marine environment. In addition, this information is crucial for the quantification of the ecological importance usually attributed to seagrass habitats due to, for instance, their involvement in biogeochemical cycles, marine biodiversity and quality of coastal waters or global carbon budgets. The seagrass atlas of Spain represents a huge collective effort performed by 84 authors across 30 Spanish institutions largely involved in the scientific research, management and conservation of seagrass habitats during the last three decades. They have contributed to the availability of the most precise and realistic seagrass maps for each region of the Spanish coast which have been integrated in a GIS to obtain the distribution and area of each seagrass species. Most of this information has independently originated at a regional level by regional governments, universities and public research organisations, which explain the elevated heterogeneity in criteria, scales, methods and objectives of the available information. On this basis, seagrass habitats in Spain occupy a total surface of 1,541,63 km2, 89% of which is concentrated in the Mediterranean regions; the rest is present in sheltered estuarine areas of the Atlantic peninsular regions and in the open coastal waters of the Canary Islands, which represents 50% of the Atlantic meadows. Of this surface, 71.5% corresponds to Posidonia oceanica, 19.5% to Cymodocea nodosa, 3.1% to Zostera noltii (=Nanozostera noltii), 0.3% to Zostera marina and 1.2% to Halophila decipiens. Species distribution maps are presented (including Ruppia spp.), together with maps of the main impacts and pressures that has affected or threatened their conservation status, as well as the management tools established for their protection and conservation. Despite this considerable effort, and the fact that Spain has mapped wide shelf areas, the information available is still incomplete and with weak precision in many regions, which will require an investment of major effort in the near future to complete the whole picture and respond to demands of EU directives.Versión del edito