60,022 research outputs found

    Analysis of reliable deployment of TDOA local positioning architectures

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    .Local Positioning Systems (LPS) are supposing an attractive research topic over the last few years. LPS are ad-hoc deployments of wireless sensor networks for particularly adapt to the environment characteristics in harsh environments. Among LPS, those based on temporal measurements stand out for their trade-off among accuracy, robustness and costs. But, regardless the LPS architecture considered, an optimization of the sensor distribution is required for achieving competitive results. Recent studies have shown that under optimized node distributions, time-based LPS cumulate the bigger error bounds due to synchronization errors. Consequently, asynchronous architectures such as Asynchronous Time Difference of Arrival (A-TDOA) have been recently proposed. However, the A-TDOA architecture supposes the concentration of the time measurement in a single clock of a coordinator sensor making this architecture less versatile. In this paper, we present an optimization methodology for overcoming the drawbacks of the A-TDOA architecture in nominal and failure conditions with regards to the synchronous TDOA. Results show that this optimization strategy allows the reduction of the uncertainties in the target location by 79% and 89.5% and the enhancement of the convergence properties by 86% and 33% of the A-TDOA architecture with regards to the TDOA synchronous architecture in two different application scenarios. In addition, maximum convergence points are more easily found in the A-TDOA in both configurations concluding the benefits of this architecture in LPS high-demanded applicationS

    An√°lisis experimental del √°rea de influencia peatonal a partir del gasto energ√©tico ‚Äď caso: Estaci√≥n ‚ÄúLas Palmeras‚ÄĚ ‚Äď Corredor Rojo

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    En el dise√Īo actual de las ciudades se busca promover todos los tipos de desplazamientos de las personas dentro de los lineamientos de la movilidad sostenible. Para lograrlo, se debe promover la caminata como medio de transporte para distancias cortas y, para viajes de larga distancia, como complemento a otro medio de transporte, como el transporte p√ļblico. Para este caso, hace falta dise√Īar la ubicaci√≥n estrat√©gica y alcance de los paraderos de transporte p√ļblico, y evaluar la accesibilidad de las rutas peatonales alrededor de ellos. Para incluir destinos de alta demanda peatonal en el alcance de los peatones, y cuantificar el impacto positivo o negativo de cambios en la infraestructura peatonal, hace falta estudiar y definir cu√°nto est√°n dispuestos a caminar los peatones para alcanzar su destino. Esto se puede lograr con el ‚Äú√°rea de influencia peatonal‚ÄĚ, que delimita el entorno hasta donde los peatones est√°n dispuestos a caminar alrededor de un punto de origen. Actualmente existen diversos m√©todos, algunos m√°s complejos que otros, para hallar el √°rea de influencia peatonal de un paradero de transporte p√ļblico. La forma m√°s sencilla y difundida lo define como un radio de influencia que no considera las caracter√≠sticas del entorno de las rutas peatonales alrededor de la estaci√≥n o punto de origen. Es decir, no toma en cuenta las caracter√≠sticas de las rutas alrededor de la estaci√≥n ni las caracter√≠sticas de los peatones. Se plantea un m√©todo para definir el √Ārea de Influencia Peatonal (AIP) basado en el c√°lculo de gasto energ√©tico peatonal, a partir de una ecuaci√≥n que permite incluir variables que describen la trama alrededor de la estaci√≥n y caracter√≠sticas del peat√≥n. Este m√©todo se desarrolla, describe, y codifica para que pueda ser aplicado a cualquier estaci√≥n de transporte p√ļblico. Para probar su utilidad se aplica al caso de la estaci√≥n ‚ÄúLas Palmeras‚ÄĚ del ‚ÄúCorredor Rojo‚ÄĚ. De su aplicaci√≥n se obtuvo que el √°rea de influencia peatonal para una trama como la que colinda al del paradero en estudio, sin mayores impedancias en las rutas peatonales, asciende a 2 Km2 aproximadamente. Finalmente, se analizan los efectos de diversos factores en el √°rea de influencia peatonal como: distintos valores de gasto energ√©tico, distintas ubicaciones del paradero o restricciones al tr√°nsito de los peatones en cruces

    Estudio comparativo de metodologías de análisis de licuación de suelos

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    Debido a que la licuaci√≥n de suelos es un fen√≥meno que ocurre en varias partes del Per√ļ, surge la necesidad de emplear m√©todos de an√°lisis de licuaci√≥n de suelos. Sin embargo, son muy numerosos, por lo que una comparaci√≥n entre estos es √ļtil para determinar si uno u otro resulta m√°s conveniente dado un cierto escenario particular. Por tanto, el objetivo de este trabajo de investigaci√≥n es el de realizar un an√°lisis comparativo entre cuatro m√©todos de licuaci√≥n de suelos. Espec√≠ficamente, se busca presentar los cuatro m√©todos seleccionados, evaluar el potencial de licuaci√≥n para un suelo dado y comparar los resultados obtenidos y par√°metros empleados. Los m√©todos seleccionados fueron los de: R.W. Boulanger e I. M. Idriss (2014), Kayen R. et al. (2013), Euroc√≥digo 8 ‚Äď AENOR (2011) y Cetin et al. (2016). El caso de estudio ser√° para un suelo ubicado en territorio peruano, en espec√≠fico, en la ciudad de Juliaca en Puno, y para dos sismos: uno esperable en la zona y otro cuya ocurrencia es muy improbable. Se analiza de esta manera para observar c√≥mo var√≠an los m√©todos con la magnitud y aceleraci√≥n de un sismo. En este an√°lsis comparativo se encuentra que el m√©todo de Cetin et al. (2016) es el m√°s confiable de utilizar, por ser el que considera m√°s variables; mientras que el del Euroc√≥digo 8 ‚Äď AENOR (2011) es el m√°s pr√°ctico de usar al ser parte de una norma. Adem√°s, para sismos fuertes (factores de seguridad de licuaci√≥n bajos) los m√©todos tienden a asemejarse para estratos licuables y las curvas basadas en el n√ļmero de golpes N del ensayo SPT tienen la misma forma, a diferencia del m√©todo que emplea la velocidad de ondas de corte. La variabilidad de las propiedades del suelo utilizado, complican el an√°lisis de resultados final en cuanto a la b√ļsqueda de relaciones. Sin embargo, es posible obtener diferencias num√©ricas cuantificables y cualitativas entre cada uno de los m√©todos

    M&S highlight: Constantinides et al. (2003), On the use of nanoindentation for cementitious materials

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    In search of 'The people of La Manche': A comparative study of funerary practices in the Transmanche region during the late Neolithic and Early Bronze Age (250BC-1500BC)

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    This research project sets out to discover whether archaeological evidence dating between 2500 BC - 1500 BC from supposed funerary contexts in Kent, flanders and north-eastern Transmanche France is sufficient to make valid comparisons between social and cultural structures on either side of the short-sea Channel region. Evidence from the beginning of the period primarily comes in the form of the widespread Beaker phenomenon. Chapter 5 shows that this class of data is abundant in Kent but quite sparse in the Continental zones - most probably because it has not survived well. This problem also affects the human depositional evidence catalogued in Chapter 6, particularly in Fanders but also in north-eastern Transmanche France. This constricts comparative analysis, however, the abundant data from Kent means that general trends are still discernible. The quality and volume of data relating to the distribution, location, morphology and use of circular monuments in all three zones is far better - as demonstrated in Chapter 7 -mostly due to extensive aerial surveying over several decades. When the datasets are taken as a whole, it becomes possible to successfully apply various forms of comparative analyses. Most remarkably, this has revealed that some monuments apparently have encoded within them a sophisticated and potentially symbolically charged geometric shape. This, along with other less contentious evidence, demonstrates a level of conformity that strongly suggests a stratum of cultural homogeneity existed throughout the Transmanche region during the period 2500 BC - 1500 BC. The fact that such changes as are apparent seem to have developed simultaneously in each of the zones adds additional weight to the theory that contact throughout the Transmanche region was endemic. Even so, it may not have been continuous; there may actually have been times of relative isolation - the data is simply too course to eliminate such a possibility

    The Influence of Quality on eWOM: A Digital Transformation in Hotel Management

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    612324There is no doubt that the use of Internet for purchasing products and services has constituted a crucial change in how people go about buying them. In the era of digital transformation, the possibility of accessing information provided by other users about their personal experiences has taken on more weight in the selection and buying processes. On these lines, traditional word-of-mouth (WOM) has given way to electronic word-of-mouth (eWOM), which constitutes a major social change. This behavior is particularly relevant in the services area, where potential users cannot in advance assess what is on offer. There is an abundant literature analyzing the effects of eWOM on different variables of interest in this sector. However, little is known about the factors that determine eWOM. Thus, the main objective of the present paper is to analyze the impact of two variables (objective quality and perceived quality) on eWOM. Both of them are crucial for potential customers in the process of finding hotel accommodations and they can motivate people to make such comments. The results demonstrate that these variables truly have a significant impact on whether or not users make comments on line. Moreover, it proved possible to observe certain differences according to the profile of the tourist involved and the destination where the hotel is located. In the current changing environment, this information is of great use for hotel managers in order to design strategies according to the type of guest they wish to attract.S

    Speciation of organoarsenicals in aqueous solutions by Raman spectrometry and quantum chemical calculations

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    .Knowledge about the existence and stability of different species of organoarsenicals in solution is of the most significant interest for fields so different as chemical, environmental, biological, toxicological and forensic. This work provides a comparative evaluation of the Raman spectra of four organoarsenicals (o-arsanilic acid, p-arsanilic acid, roxarsone and cacodylic acid) in aqueous solutions under acidic, neutral and alkaline conditions. Speciation of some of these organoarsenicals is possible by Raman spectrometry at different selected pHs. Further, we examine the proficiency of computational chemistry to obtain the theoretical Raman spectra of the four organoarsenicals compounds. To this end, we employ a computational protocol that includes explicit water molecules and conformational sampling, finding that the calculated organoarsenicals spectra agree reasonably well with those experimentally obtained in an aqueous solution in the whole pH range covered. Finally, we highlight the effectiveness of quantum chemical calculations to identify organoarsenicals in an aqueous solution.S

    Facial expression recognition and intensity estimation.

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    Doctoral Degree. University of KwaZulu-Natal, Durban.Facial Expression is one of the profound non-verbal channels through which human emotion state is inferred from the deformation or movement of face components when facial muscles are activated. Facial Expression Recognition (FER) is one of the relevant research fields in Computer Vision (CV) and Human-Computer Interraction (HCI). Its application is not limited to: robotics, game, medical, education, security and marketing. FER consists of a wealth of information. Categorising the information into primary emotion states only limit its performance. This thesis considers investigating an approach that simultaneously predicts the emotional state of facial expression images and the corresponding degree of intensity. The task also extends to resolving FER ambiguous nature and annotation inconsistencies with a label distribution learning method that considers correlation among data. We first proposed a multi-label approach for FER and its intensity estimation using advanced machine learning techniques. According to our findings, this approach has not been considered for emotion and intensity estimation in the field before. The approach used problem transformation to present FER as a multilabel task, such that every facial expression image has unique emotion information alongside the corresponding degree of intensity at which the emotion is displayed. A Convolutional Neural Network (CNN) with a sigmoid function at the final layer is the classifier for the model. The model termed ML-CNN (Multilabel Convolutional Neural Network) successfully achieve concurrent prediction of emotion and intensity estimation. ML-CNN prediction is challenged with overfitting and intraclass and interclass variations. We employ Visual Geometric Graphics-16 (VGG-16) pretrained network to resolve the overfitting challenge and the aggregation of island loss and binary cross-entropy loss to minimise the effect of intraclass and interclass variations. The enhanced ML-CNN model shows promising results and outstanding performance than other standard multilabel algorithms. Finally, we approach data annotation inconsistency and ambiguity in FER data using isomap manifold learning with Graph Convolutional Networks (GCN). The GCN uses the distance along the isomap manifold as the edge weight, which appropriately models the similarity between adjacent nodes for emotion predictions. The proposed method produces a promising result in comparison with the state-of-the-art methods.Author's List of Publication is on page xi of this thesis
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