Análisis de los factores determinantes de la repetición del proceso de compra en el comercio electrónico entre empresas y consumidores finales. Aplicación al mercado español

Las Tecnologías de la Información y la Comunicación en general e Internet en particular han supuesto una revolución en nuestra forma de comunicarnos, relacionarnos, producir, comprar y vender acortando tiempo y distancias entre proveedores y consumidores. A la paulatina penetración del ordenador, los teléfonos inteligentes y la banda ancha fija y/o móvil ha seguido un mayor uso de estas tecnologías entre ciudadanos y empresas. El comercio electrónico empresa–consumidor (B2C) alcanzó en 2010 en España un volumen de 9.114 millones de euros, con un incremento del 17,4% respecto al dato registrado en 2009. Este crecimiento se ha producido por distintos hechos: un incremento en el porcentaje de internautas hasta el 65,1% en 2010 de los cuales han adquirido productos o servicios a través de la Red un 43,1% –1,6 puntos porcentuales más respecto a 2010–. Por otra parte, el gasto medio por comprador ha ascendido a 831€ en 2010, lo que supone un incremento del 10,9% respecto al año anterior. Si segmentamos a los compradores según por su experiencia anterior de compra podemos encontrar dos categorías: el comprador novel –que adquirió por primera vez productos o servicios en 2010– y el comprador constante –aquel que había adquirido productos o servicios en 2010 y al menos una vez en años anteriores–. El 85,8% de los compradores se pueden considerar como compradores constantes: habían comprado en la Red en 2010, pero también lo habían hecho anteriormente. El comprador novel tiene un perfil sociodemográfico de persona joven de entre 15–24 años, con estudios secundarios, de clase social media y media–baja, estudiante no universitario, residente en poblaciones pequeñas y sigue utilizando fórmulas de pago como el contra–reembolso (23,9%). Su gasto medio anual ascendió en 2010 a 449€. El comprador constante, o comprador que ya había comprado en Internet anteriormente, tiene un perfil demográfico distinto: estudios superiores, clase alta, trabajador y residente en grandes ciudades, con un comportamiento maduro en la compra electrónica dada su mayor experiencia –utiliza con mayor intensidad canales exclusivos en Internet que no disponen de tienda presencial–. Su gasto medio duplica al observado en compradores noveles (con una media de 930€ anuales). Por tanto, los compradores constantes suponen una mayoría de los compradores con un gasto medio que dobla al comprador que ha adoptado el medio recientemente. Por consiguiente es de interés estudiar los factores que predicen que un internauta vuelva a adquirir un producto o servicio en la Red. La respuesta a esta pregunta no se ha revelado sencilla. En España, la mayoría de productos y servicios aún se adquieren de manera presencial, con una baja incidencia de las ventas a distancia como la teletienda, la venta por catálogo o la venta a través de Internet. Para dar respuesta a las preguntas planteadas se ha investigado desde distintos puntos de vista: se comenzará con un estudio descriptivo desde el punto de vista de la demanda que trata de caracterizar la situación del comercio electrónico B2C en España, poniendo el foco en las diferencias entre los compradores constantes y los nuevos compradores. Posteriormente, la investigación de modelos de adopción y continuidad en el uso de las tecnologías y de los factores que inciden en dicha continuidad –con especial interés en el comercio electrónico B2C–, permiten afrontar el problema desde la perspectiva de las ecuaciones estructurales pudiendo también extraer conclusiones de tipo práctico. Este trabajo sigue una estructura clásica de investigación científica: en el capítulo 1 se introduce el tema de investigación, continuando con una descripción del estado de situación del comercio electrónico B2C en España utilizando fuentes oficiales (capítulo 2). Posteriormente se desarrolla el marco teórico y el estado del arte de modelos de adopción y de utilización de las tecnologías (capítulo 3) y de los factores principales que inciden en la adopción y continuidad en el uso de las tecnologías (capítulo 4). El capítulo 5 desarrolla las hipótesis de la investigación y plantea los modelos teóricos. Las técnicas estadísticas a utilizar se describen en el capítulo 6, donde también se analizan los resultados empíricos sobre los modelos desarrollados en el capítulo 5. El capítulo 7 expone las principales conclusiones de la investigación, sus limitaciones y propone nuevas líneas de investigación. La primera parte corresponde al capítulo 1, que introduce la investigación justificándola desde un punto de vista teórico y práctico. También se realiza una breve introducción a la teoría del comportamiento del consumidor desde una perspectiva clásica. Se presentan los principales modelos de adopción y se introducen los modelos de continuidad de utilización que se estudiarán más detalladamente en el capítulo 3. En este capítulo se desarrollan los objetivos principales y los objetivos secundarios, se propone el mapa mental de la investigación y se planifican en un cronograma los principales hitos del trabajo. La segunda parte corresponde a los capítulos dos, tres y cuatro. En el capítulo 2 se describe el comercio electrónico B2C en España utilizando fuentes secundarias. Se aborda un diagnóstico del sector de comercio electrónico y su estado de madurez en España. Posteriormente, se analizan las diferencias entre los compradores constantes, principal interés de este trabajo, frente a los compradores noveles, destacando las diferencias de perfiles y usos. Para los dos segmentos se estudian aspectos como el lugar de acceso a la compra, la frecuencia de compra, los medios de pago utilizados o las actitudes hacia la compra. El capítulo 3 comienza desarrollando los principales conceptos sobre la teoría del comportamiento del consumidor, para continuar estudiando los principales modelos de adopción de tecnología existentes, analizando con especial atención su aplicación en comercio electrónico. Posteriormente se analizan los modelos de continuidad en el uso de tecnologías (Teoría de la Confirmación de Expectativas; Teoría de la Justicia), con especial atención de nuevo a su aplicación en el comercio electrónico. Una vez estudiados los principales modelos de adopción y continuidad en el uso de tecnologías, el capítulo 4 analiza los principales factores que se utilizan en los modelos: calidad, valor, factores basados en la confirmación de expectativas –satisfacción, utilidad percibida– y factores específicos en situaciones especiales –por ejemplo, tras una queja– como pueden ser la justicia, las emociones o la confianza. La tercera parte –que corresponde al capítulo 5– desarrolla el diseño de la investigación y la selección muestral de los modelos. En la primera parte del capítulo se enuncian las hipótesis –que van desde lo general a lo particular, utilizando los factores específicos analizados en el capítulo 4– para su posterior estudio y validación en el capítulo 6 utilizando las técnicas estadísticas apropiadas. A partir de las hipótesis, y de los modelos y factores estudiados en los capítulos 3 y 4, se definen y vertebran dos modelos teóricos originales que den respuesta a los retos de investigación planteados en el capítulo 1. En la segunda parte del capítulo se diseña el trabajo empírico de investigación definiendo los siguientes aspectos: alcance geográfico–temporal, tipología de la investigación, carácter y ambiente de la investigación, fuentes primarias y secundarias utilizadas, técnicas de recolección de datos, instrumentos de medida utilizados y características de la muestra utilizada. Los resultados del trabajo de investigación constituyen la cuarta parte de la investigación y se desarrollan en el capítulo 6, que comienza analizando las técnicas estadísticas basadas en Modelos de Ecuaciones Estructurales. Se plantean dos alternativas, modelos confirmatorios correspondientes a Métodos Basados en Covarianzas (MBC) y modelos predictivos. De forma razonada se eligen las técnicas predictivas dada la naturaleza exploratoria de la investigación planteada. La segunda parte del capítulo 6 desarrolla el análisis de los resultados de los modelos de medida y modelos estructurales construidos con indicadores formativos y reflectivos y definidos en el capítulo 4. Para ello se validan, sucesivamente, los modelos de medida y los modelos estructurales teniendo en cuenta los valores umbrales de los parámetros estadísticos necesarios para la validación. La quinta parte corresponde al capítulo 7, que desarrolla las conclusiones basándose en los resultados del capítulo 6, analizando los resultados desde el punto de vista de las aportaciones teóricas y prácticas, obteniendo conclusiones para la gestión de las empresas. A continuación, se describen las limitaciones de la investigación y se proponen nuevas líneas de estudio sobre distintos temas que han ido surgiendo a lo largo del trabajo. Finalmente, la bibliografía recoge todas las referencias utilizadas a lo largo de este trabajo. Palabras clave: comprador constante, modelos de continuidad de uso, continuidad en el uso de tecnologías, comercio electrónico, B2C, adopción de tecnologías, modelos de adopción tecnológica, TAM, TPB, IDT, UTAUT, ECT, intención de continuidad, satisfacción, confianza percibida, justicia, emociones, confirmación de expectativas, calidad, valor, PLS. ABSTRACT Information and Communication Technologies in general, but more specifically those related to the Internet in particular, have changed the way in which we communicate, relate to one another, produce, and buy and sell products, reducing the time and shortening the distance between suppliers and consumers. The steady breakthrough of computers, Smartphones and landline and/or wireless broadband has been greatly reflected in its large scale use by both individuals and businesses. Business–to–consumer (B2C) e–commerce reached a volume of 9,114 million Euros in Spain in 2010, representing a 17.4% increase with respect to the figure in 2009. This growth is due in part to two different facts: an increase in the percentage of web users to 65.1% en 2010, 43.1% of whom have acquired products or services through the Internet– which constitutes 1.6 percentage points higher than 2010. On the other hand, the average spending by individual buyers rose to 831€ en 2010, constituting a 10.9% increase with respect to the previous year. If we select buyers according to whether or not they have previously made some type of purchase, we can divide them into two categories: the novice buyer–who first made online purchases in 2010– and the experienced buyer: who also made purchases in 2010, but had done so previously as well. The socio–demographic profile of the novice buyer is that of a young person between 15–24 years of age, with secondary studies, middle to lower–middle class, and a non–university educated student who resides in smaller towns and continues to use payment methods such as cash on delivery (23.9%). In 2010, their average purchase grew to 449€. The more experienced buyer, or someone who has previously made purchases online, has a different demographic profile: highly educated, upper class, resident and worker in larger cities, who exercises a mature behavior when making online purchases due to their experience– this type of buyer frequently uses exclusive channels on the Internet that don’t have an actual store. His or her average purchase doubles that of the novice buyer (with an average purchase of 930€ annually.) That said, the experienced buyers constitute the majority of buyers with an average purchase that doubles that of novice buyers. It is therefore of interest to study the factors that help to predict whether or not a web user will buy another product or use another service on the Internet. The answer to this question has proven not to be so simple. In Spain, the majority of goods and services are still bought in person, with a low amount of purchases being made through means such as the Home Shopping Network, through catalogues or Internet sales. To answer the questions that have been posed here, an investigation has been conducted which takes into consideration various viewpoints: it will begin with a descriptive study from the perspective of the supply and demand that characterizes the B2C e–commerce situation in Spain, focusing on the differences between experienced buyers and novice buyers. Subsequently, there will be an investigation concerning the technology acceptance and continuity of use of models as well as the factors that have an effect on their continuity of use –with a special focus on B2C electronic commerce–, which allows for a theoretic approach to the problem from the perspective of the structural equations being able to reach practical conclusions. This investigation follows the classic structure for a scientific investigation: the subject of the investigation is introduced (Chapter 1), then the state of the B2C e–commerce in Spain is described citing official sources of information (Chapter 2), the theoretical framework and state of the art of technology acceptance and continuity models are developed further (Chapter 3) and the main factors that affect their acceptance and continuity (Chapter 4). Chapter 5 explains the hypothesis behind the investigation and poses the theoretical models that will be confirmed or rejected partially or completely. In Chapter 6, the technical statistics that will be used are described briefly as well as an analysis of the empirical results of the models put forth in Chapter 5. Chapter 7 explains the main conclusions of the investigation, its limitations and proposes new projects. First part of the project, chapter 1, introduces the investigation, justifying it from a theoretical and practical point of view. It is also a brief introduction to the theory of consumer behavior from a standard perspective. Technology acceptance models are presented and then continuity and repurchase models are introduced, which are studied more in depth in Chapter 3. In this chapter, both the main and the secondary objectives are developed through a mind map and a timetable which highlights the milestones of the project. The second part of the project corresponds to Chapters Two, Three and Four. Chapter 2 describes the B2C e–commerce in Spain from the perspective of its demand, citing secondary official sources. A diagnosis concerning the e–commerce sector and the status of its maturity in Spain is taken on, as well as the barriers and alternative methods of e–commerce. Subsequently, the differences between experienced buyers, which are of particular interest to this project, and novice buyers are analyzed, highlighting the differences between their profiles and their main transactions. In order to study both groups, aspects such as the place of purchase, frequency with which online purchases are made, payment methods used and the attitudes of the purchasers concerning making online purchases are taken into consideration. Chapter 3 begins by developing the main concepts concerning consumer behavior theory in order to continue the study of the main existing acceptance models (among others, TPB, TAM, IDT, UTAUT and other models derived from them) – paying special attention to their application in e–commerce–. Subsequently, the models of technology reuse are analyzed (CDT, ECT; Theory of Justice), focusing again specifically on their application in e–commerce. Once the main technology acceptance and reuse models have been studied, Chapter 4 analyzes the main factors that are used in these models: quality, value, factors based on the contradiction of expectations/failure to meet expectations– satisfaction, perceived usefulness– and specific factors pertaining to special situations– for example, after receiving a complaint justice, emotions or confidence. The third part– which appears in Chapter 5– develops the plan for the investigation and the sample selection for the models that have been designed. In the first section of the Chapter, the hypothesis is presented– beginning with general ideas and then becoming more specific, using the detailed factors that were analyzed in Chapter 4– for its later study and validation in Chapter 6– as well as the corresponding statistical factors. Based on the hypothesis and the models and factors that were studied in Chapters 3 and 4, two original theoretical models are defined and organized in order to answer the questions posed in Chapter 1. In the second part of the Chapter, the empirical investigation is designed, defining the following aspects: geographic–temporal scope, type of investigation, nature and setting of the investigation, primary and secondary sources used, data gathering methods, instruments according to the extent of their use and characteristics of the sample used. The results of the project constitute the fourth part of the investigation and are developed in Chapter 6, which begins analyzing the statistical techniques that are based on the Models of Structural Equations. Two alternatives are put forth: confirmatory models which correspond to Methods Based on Covariance (MBC) and predictive models– Methods Based on Components–. In a well–reasoned manner, the predictive techniques are chosen given the explorative nature of the investigation. The second part of Chapter 6 explains the results of the analysis of the measurement models and structural models built by the formative and reflective indicators defined in Chapter 4. In order to do so, the measurement models and the structural models are validated one by one, while keeping in mind the threshold values of the necessary statistic parameters for their validation. The fifth part corresponds to Chapter 7 which explains the conclusions of the study, basing them on the results found in Chapter 6 and analyzing them from the perspective of the theoretical and practical contributions, and consequently obtaining conclusions for business management. The limitations of the investigation are then described and new research lines about various topics that came up during the project are proposed. Lastly, all of the references that were used during the project are listed in a final bibliography. Key Words: constant buyer, repurchase models, continuity of use of technology, e–commerce, B2C, technology acceptance, technology acceptance models, TAM, TPB, IDT, UTAUT, ECT, intention of repurchase, satisfaction, perceived trust/confidence, justice, feelings, the contradiction of expectations, quality, value, PLS.

Spatial effects on rural commerce

Commerce in rural territories should not be considered as a needed service, but as a basic infrastructure, that impact not only existent population, but also tourism, and rural industrialization. So, the rural areas need not only agriculture but industry and services, to have a global and balanced development, including for the countryside and the population. In the work presented in this paper, we are considering the formulation of the direct relation between population and the endowment of commerce sites within a geographical territory, the ?area of commercial interactions?. These are the closer set of towns that can gravitate to each other to cover the required needs for the populations within the area. The products retailed, range from basic products for the daily lives, to all other products for industry, agriculture, and services. The econometric spatial model developed to evaluate the interactions and estimate the parameters, is based on the Spatial Error Model, which allows for other spatial hidden effects to be considered without direct interference to the commercial disposition. The data and territory used to test the model correspond to a rural area in the Spanish Palencia territory (NUTS-3 level). The parameters have dependence from population levels, local rent per head, local and regional government budgets, and particular spatial restrictions. Interesting results are emerging form the model. The more significant is that the spatial effects can replace some number of commerce sites in towns, given the right spatial distribution of the sites and the towns. This is equivalent to consider the area of commercial interactions as the unit of measurement for the basic infrastructure and not only the towns.

Reuse of vacant agro-industrial buildings. The case of the public slaughterhouses in Spain

Nearly 3000 slaughterhouses (74% of them public facilities) were built in Spain during the last decades of the nineteenth century and the first half of the twentieth century. The need to comply with new technical requirements and regulations on the hygiene of the meat passed in the 70s and the gradual replacement of public facilities by larger and more modern private slaughterhouses have subsequently led to the closure and abandonment of many of these buildings. Public slaughterhouses generally consisted of several single-storey and open-plan buildings located around a courtyard. Although originally they were preferably located on the outskirts of the towns, many slaughterhouses are now placed inside the built up areas, due to the urban development. The present work aims to contribute to a better understanding of these agro-industrial buildings and to provide ideas for their conservation and reuse. A review on the historical evolution and the architectural features of the public slaughterhouses in Spain is presented and different examples of old vacant slaughterhouses reused to accommodate libraries, offices, community centres, exhibition halls or sports centres, among others, are shown in the paper.

Characterization of underground cellars in the Duero Basin by GNSS, LIDAR and GPR techniques

The underground cellars of the Duero River basin are part of spread and damaged agricultural landscape which is in danger of disappearing. These architectural complexes are allocated next to small towns. Constructions are mostly dug in the ground with a gallery down or "barrel" strait through which you access the cave or cellar. This wider space is used to make and store wine. Observation and detection of the winery both on the outside and underground is essential to make an inventory of the rural heritage. Geodetection is a non-invasive technique, suitable to determinate with precision buried structures in the ground. The undertaken works include LIDAR survey techniques, GNSS and GPR obtained data. The results are used to identify with centimetric precision construction elements forming the winery. Graphic and cartographic obtained documents allow optimum visualization of the studied field and can be used in the reconstruction of the place.

An evaluation of seismic hazard in La Hispaniola, after the 2010 Haiti earthquake

An evaluation of the seismic hazard in La Hispaniola Island has been carried out, as part of the cooperative project SISMO-HAITI, supported by the Technical University of Madrid (UPM) and developed by several Spanish Universities, the National Observatory of Environment and Vulnerability) ONEV of Haiti, and with contributions from the Puerto Rico Seismic Network (PRSN) and University Seismological Institute of Dominican Republic (ISU). The study was aimed at obtaining results suitable for seismic design purposes. It started with the elaboration of a seismic catalogue for the Hispaniola Island, requiring an exhaustive revision of data reported by more than 20 seismic agencies, apart from these from the PRSN and ISU. The final catalogue contains 96 historical earthquakes and 1690 instrumental events, and it was homogenized to moment magnitude, Mw. Seismotectonic models proposed for the region were revised and a new regional zonation was proposed, taking into account geological andtectonic data, seismicity, focal mechanisms, and GPS observations. In parallel, attenuation models for subduction and crustal zones were revised in previous projects and the most suitable for the Caribbean plate were selected. Then, a seismic hazard analysis was developed in terms of peak ground acceleration, PGA, and spectral accelerations, SA (T), for periods of 0.1, 0.2, 0.5, 1 and 2s, using the Probabilistic Seismic Hazard Assessment (PSHA) methodology. As a result, different hazard maps were obtained for the quoted parameters, together with Uniform Hazard Spectra for Port au Prince and the main cities in the country. Hazard deaggregation was also carried out in these towns, for the target motion given by the PGA and SA (1s) obtained for return periods of 475, 975 and 2475 years. Therefore, the controlling earthquakes for short- and long-period target motions were derived. This study was started a few months after the 2010 earthquake, as a response to an aid request from the Haitian government to the UPM, and the results are available for the definition of the first building code in Haiti.

Probabilistic meta-analysis of risk from the exposure to Hg in artisanal gold mining communities in Colombia

Colombia is one of the largest per capita mercury polluters in the world as a consequence of its artisanal gold mining activities. The severity of this problem in terms of potential health effects was evaluated by means of a probabilistic risk assessment carried out in the twelve departments (or provinces) in Colombia with the largest gold production. The two exposure pathways included in the risk assessment were inhalation of elemental Hg vapors and ingestion of fish contaminated with methyl mercury. Exposure parameters for the adult population (especially rates of fish consumption) were obtained from nation-wide surveys and concentrations of Hg in air and of methyl-mercury in fish were gathered from previous scientific studies. Fish consumption varied between departments and ranged from 0 to 0.3 kg d?1. Average concentrations of total mercury in fish (70 data) ranged from 0.026 to 3.3 lg g?1. A total of 550 individual measurements of Hg in workshop air (ranging from menor queDL to 1 mg m?3) and 261 measurements of Hg in outdoor air (ranging from menor queDL to 0.652 mg m?3) were used to generate the probability distributions used as concentration terms in the calculation of risk. All but two of the distributions of Hazard Quotients (HQ) associated with ingestion of Hg-contaminated fish for the twelve regions evaluated presented median values higher than the threshold value of 1 and the 95th percentiles ranged from 4 to 90. In the case of exposure to Hg vapors, minimum values of HQ for the general population exceeded 1 in all the towns included in this study, and the HQs for miner-smelters burning the amalgam is two orders of magnitude higher, reaching values of 200 for the 95th percentile. Even acknowledging the conservative assumptions included in the risk assessment and the uncertainties associated with it, its results clearly reveal the exorbitant levels of risk endured not only by miner-smelters but also by the general population of artisanal gold mining communities in Colombia.

Effects of traffic loads on reinforced concrete railroad culverts

In the context of the present conference paper culverts are defined as an opening or conduit passing through an embankment usually for the purpose of conveying water or providing safe pedestrian and animal crossings under rail infrastructure. The clear opening of culverts may reach values of up to 12m however, values around 3m are encountered much more frequently. Depending on the topography, the number of culverts is about 10 times that of bridges. In spite of this, their dynamic behavior has received far less attention than that of bridges. The fundamental frequency of culverts is considerably higher than that of bridges even in the case of short span bridges. As the operational speed of modern high-speed passenger rail systems rises, higher frequencies are excited and thus more energy is encountered in frequency bands where the fundamental frequency of box culverts is located. Many research efforts have been spent on the subject of ballast instability due to bridge resonance, since it was first observed when high-speed trains were introduced to the Paris/Lyon rail line. To prevent this phenomenon from occurring, design codes establish a limit value for the vertical deck acceleration. Obviously one needs some sort of numerical model in order to estimate this acceleration level and at that point things get quite complicated. Not only acceleration but also displacement values are of interest e.g. to estimate the impact factor. According to design manuals the structural design should consider the depth of cover, trench width and condition, bedding type, backfill material, and compaction. The same applies to the numerical model however, the question is: What type of model is appropriate for this job? A 3D model including the embankment and an important part of the soil underneath the culvert is computationally very expensive and hard to justify taking into account the associated costs. Consequently, there is a clear need for simplified models and design rules in order to achieve reasonable costs. This paper will describe the results obtained from a 2D finite element model which has been calibrated by means of a 3D model and experimental data obtained at culverts that belong to the high-speed railway line that links the two towns of Segovia and Valladolid in Spain

Restauración virtual del patrimonio sonoro. Aplicación al antiguo rito hispánico

Una de las aplicaciones más interesantes de las tecnologías de Realidad Acústica Virtual es la posibilidad de recuperar el patrimonio cultural del sonido de los recintos históricos que se han perdido o cuyas características se han modificado a lo largo de los siglos. En este trabajo, las tecnologías de realidad acústica virtual se utilizan para tratar de reconstruir virtualmente el sonido producido en las actividades litúrgicas del antiguo rito hispánico. Bajo este nombre se conoce a la liturgia que celebraban los cristianos de la península ibérica hasta su prohibición, en favor del culto romano, a mediados del siglo XI. El rito hispánico -también conocido como rito visigótico-mozárabe- es una de las manifestaciones culturales más interesantes de la Alta Edad Media en occidente. Se trata de un patrimonio cultural desaparecido, tanto desde el punto de vista de las señales sonoras que lo integraban -ya que la mayoría de las melodías que conformaban el rito se han perdido- como desde el punto de vista de los espacios en los que se desarrollaba, debido a que las iglesias conservadas de la época han experimentado modificaciones a lo largo de los siglos que alteran sus condiciones acústicas con respecto a las que tenían en el periodo de vigencia de esta liturgia. Para llevar a cabo este proyecto, se han realizado modelos acústicos digitales de un grupo representativo de iglesias prerrománicas de la Península Ibérica en su estado primitivo. Se ha procurado que las iglesias seleccionadas representen la variedad de comportamientos acústicos esperables en este tipo de edificios. Con este objetivo, se han elegido cinco iglesias prerrománicas que presentan diferencias sustanciales en los parámetros que, a priori, van a influir en mayor manera a su comportamiento acústico: el volumen del recinto, la forma de la planta y el tipo de cubierta. El proceso de creación de los modelos acústicos digitales de las iglesias se ha dividido en dos fases: en la primera se han creado modelos de los edificios en su estado actual, que se han validado a partir de los datos obtenidos en mediciones acústicas realizadas in situ; a partir de los modelos validados de las iglesias en su estado actual, en la segunda fase se han generado los modelos acústicos digitales correspondientes al estado primitivo de las mismas, modificando los modelos anteriores de acuerdo con las hipótesis de reconstrucción propuestas en las investigaciones arqueológicas más recientes. Se han realizado grabaciones en cámara anecoica de una serie de piezas del repertorio original del canto mozárabe. Las grabaciones se han llevado a cabo con un array esférico compuesto por 32 micrófonos, con objeto de obtener información sobre la directividad de la emisión sonora de los cantantes, que se aplicará en las auralizaciones. Finalmente, se han realizado diversas auralizaciones, teniendo en cuenta diferentes configuraciones litúrgicas que eran usuales en este rito. ABSTRACT One of the most interesting applications of the Acoustic Virtual Reality technologies is the possibility to recover the cultural heritage of the sound of the historical sites that have been lost or whose characteristics have been modified through time. In this work, Acoustic Virtual Reality technologies are used to try to reconstruct virtually the sound produced in the liturgical activities of the Hispanic Rite. This is the name given to the liturgy celebrated by Christians of the Iberian Peninsula prior to the introduction of the Roman cult in the mid-eleventh century. The Hispanic Rite (also known as Visigothic or Mozarabic rite) is one of the most interesting cultural manifestations of the Middle Ages. It is a lost cultural heritage, both from the point of view of the sound signals that were used since the majority of the melodies that conformed the rite have been lost, and from the point of view of the spaces in which this liturgy was celebrated, because the churches preserved from that era have changed over the centuries altering its acoustic conditions respect to which they were in the period in which this liturgy was in effect. To carry out this project, acoustic models of a representative group of the pre-Romanesque churches in the Iberian Peninsula have been made in his primitive state. To select the sample of buildings to study, efforts have been made to ensure that the selected churches were representative of the range of expected acoustic behaviors in this type of buildings. Five churches have been selected, showing differences in the parameters that have the greatest influence on their acoustic behavior: the enclosure volume, the shape of the floor plan and the type of roof. The process of creating digital acoustic models of the churches has been divided into two phases. In the first phase acoustic models of the churches in its current state have been created. These models have been validated with the data obtained from in situ acoustic measurements. From the validated models of churches in its current state, in the second phase, changes in the acoustic models have been performed in order to represent the primitive state of the churches, according to the historical reconstruction hypothesis that have been proposed in the most recent archaeological investigations. Anechoic recordings of a series of pieces of the original Mozarabic Chant repertoire have been recorded. The recordings were made with a spherical array composed of 32 microphones, in order to obtain information on the directivity of the sound emission of the singers. These directivity data will be used to simulate the directional radiation of the sound sources in the auralizations. Finally, auralizations were produced corresponding to different liturgical configurations which were common in this rite.

Energy dependency at the urban scale and its social consequences

Spatial planning & energy. Young planners workshop. Final reports - conclusions

Eliminación de nutrientes mediante el empleo de cultivos hidropónicos

La presente investigación se presenta como una alternativa para la reducción de la contaminación por nutrientes que produce el vertido de aguas residuales provenientes de núcleos urbanos que acaban en lagos, lagunas o embalses acelerando los procesos de eutrofización de los mismos. El objetivo de esta tesis es analizar la reducción de nutrientes, fundamentalmente nitrógeno, fósforo y potasio, del agua residual doméstica sometida a tratamiento a través de cultivos hidropónicos en un determinado periodo de tiempo, observando a su vez la evolución del cultivo seleccionado. El sistema se diseñó para funcionar en circuito cerrado con el agua residual circulando por entre las raíces de los vegetales estudiados. El cultivo seleccionado fue el “kenaf”, aunque después de mucho tiempo dedicado a la obtención de semillas de “kenaf “por diferentes proveedores, se decidió comenzar un primer ensayo utilizando plantas de aloe vera durante un periodo de un mes de verano. Se procedió a la colocación de plantas en un tubo conteniendo agua residual de una fosa séptica domiciliaria. La reducción de la DBO5 y la DQO fue notable aunque los resultados de la variación de nitratos y fosfatos no fueron concluyentes. Las altas temperaturas alcanzada en esas fechas por el agua circulante, finalmente imposibilitó la continuación del ensayo. Si bien esta primera puesta en marcha no resultó como se esperaba, aportó numerosa información para modificar el planteo del estudio, la forma de llevarlo a cabo y la puesta a punto de la propia instalación. El segundo ensayo se llevó a cabo en otoño con plantas de kenaf obtenidas del ensayo previo en suelo en una parcela piloto en los llanos de Villamartín, en la provincia de Cádiz. Antes de incorporar el agua al sistema hidropónico se analizaron todos los parámetros requeridos por la normativa española del agua para determinar su clasificación como agua residual doméstica. Luego se le dio seguimiento a la variación de los nutrientes, nitrógeno, fósforo y potasio a lo largo de varias semanas para evaluar la efectividad del tratamiento. Las plantas de kenaf continuaron su desarrollo utilizando las sustancias disueltas en el agua residual como única fuente de nutrientes disponible. This research is presented as an alternative to reduce the pollution that wastewater discharges from towns generate when they end in lakes, ponds and reservoirs, by accelerating the eutrophication processes. The objective of this thesis is to analyze the reduction of nutrients, mainly nitrogen, phosphorus and potassium, of domestic wastewater treated through hydroponics crops in a given period of time, noting at the same time the evolution of the selected crop. The system was designed to operate in closed circuit with the wastewater circulating through the roots of the studied plants. The selected crop was "kenaf", although after much time spent in obtaining seeds of "kenaf"by different vendors and the impossibility of achieving its germination; it was decided to start a first test using Aloe Vera plants for a period of one month in the summer. The plants were introduced in the holes of a tube containing septic wastewater. The BOD5 and COD reduction was remarkable though the results of the variation in nitrates and phosphates were inconclusive. High temperatures achieved in those dates by circulating water, eventually precluded the continuation of the test. Although this first implementation was not running as expected, it provided information to modify the proposal of the study, the way to carry it out and the development of the installation itself. The second test was conducted in autumn with kenaf plants obtained from the previous test in a pilot plant in the flatness of Villamartín, province of Cádiz. Before adding the water to the hydroponic system all the parameters required by the Spanish water regulations were analyzed to determine their classification as domestic waste water. Then, the variation of nutrients, nitrogen, phosphorus and potassium was tracking over several weeks to evaluate the effectiveness of the treatment. Kenaf plants continued its development using the substances dissolved in wastewater as sole source of nutrients available.