104,889 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

    What is the importance of sperm subpopulations?

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    .The study of sperm subpopulations spans three decades. The origin, meaning, and practical significance, however, are less clear. Current technology for assessing sperm morphology (CASA-Morph) and motility (CASA-Mot) has enabled the accurate evaluation of these features, and there are many options for data classification. Subpopulations could occur as a result of the stage of development of each spermatozoon in the subpopulation. Spermatogenesis might contribute to the production of these subpopulations. Insights from evolutionary biology and recent molecular research are indicative of the diversity among male gametes that could occur from unequal sharing of transcripts and other elements through cytoplasmic bridges between spermatids. Sperm cohorts exiting the gonads would contain different RNA and protein contents, affecting the spermatozoon physiology and associations with the surrounding environmental milieu. Subsequently, these differences could affect how spermatozoa interact with the environmental milieu (maturation, mixing with seminal plasma, and interacting with the environmental milieu, or female genital tract and female gamete). The emergence of sperm subpopulations as an outcome of evolution, related to the reproductive strategies of the species, genital tract structures, and copulatory and fertilization processes. This kind of approach in determining the importance of sperm subpopulations in fertilization capacity should have a practical impact for conducting reproductive technologies, inspiring and enabling new ways for the more efficient use of spermatozoa in the medical, animal breeding, and conservation fields. This manuscript is a contribution to the Special Issue in memory of Dr. Duane GarnerS

    Interactive Sonic Environments: Sonic artwork via gameplay experience

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    The purpose of this study is to investigate the use of video-game technology in the design and implementation of interactive sonic centric artworks, the purpose of which is to create and contribute to the discourse and understanding of its effectiveness in electro-acoustic composition highlighting the creative process. Key research questions include: How can the language of electro-acoustic music be placed in a new framework derived from videogame aesthetics and technology? What new creative processes need to be considered when using this medium? Moreover, what aspects of 'play' should be considered when designing the systems? The findings of this study assert that composers and sonic art practitioners need little or no coding knowledge to create exciting applications and the myriad of options available to the composer when using video-game technology is limited only by imagination. Through a cyclic process of planning, building, testing and playing these applications the project revealed advantages and unique sonic opportunities in comparison to other sonic art installations. A portfolio of selected original compositions, both fixed and open are presented by the author to complement this study. The commentary serves to place the work in context with other practitioners in the field and to provide compositional approaches that have been taken

    Rainfall Prediction: A Comparative Analysis of Modern Machine Learning Algorithms for Time-Series Forecasting

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    Rainfall forecasting has gained utmost research relevance in recent times due to its complexities and persistent applications such as flood forecasting and monitoring of pollutant concentration levels, among others. Existing models use complex statistical models that are often too costly, both computationally and budgetary, or are not applied to downstream applications. Therefore, approaches that use Machine Learning algorithms in conjunction with time-series data are being explored as an alternative to overcome these drawbacks. To this end, this study presents a comparative analysis using simplified rainfall estimation models based on conventional Machine Learning algorithms and Deep Learning architectures that are efficient for these downstream applications. Models based on LSTM, Stacked-LSTM, Bidirectional-LSTM Networks, XGBoost, and an ensemble of Gradient Boosting Regressor, Linear Support Vector Regression, and an Extra-trees Regressor were compared in the task of forecasting hourly rainfall volumes using time-series data. Climate data from 2000 to 2020 from five major cities in the United Kingdom were used. The evaluation metrics of Loss, Root Mean Squared Error, Mean Absolute Error, and Root Mean Squared Logarithmic Error were used to evaluate the models' performance. Results show that a Bidirectional-LSTM Network can be used as a rainfall forecast model with comparable performance to Stacked-LSTM Networks. Among all the models tested, the Stacked-LSTM Network with two hidden layers and the Bidirectional-LSTM Network performed best. This suggests that models based on LSTM-Networks with fewer hidden layers perform better for this approach; denoting its ability to be applied as an approach for budget-wise rainfall forecast applications

    The influence of blockchains and internet of things on global value chain

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    Despite the increasing proliferation of deploying the Internet of Things (IoT) in global value chain (GVC), several challenges might lead to a lack of trust among value chain partners, e.g., technical challenges (i.e., confidentiality, authenticity, and privacy); and security challenges (i.e., counterfeiting, physical tempering, and data theft). In this study, we argue that Blockchain technology, when combined with the IoT ecosystem, will strengthen GVC and enhance value creation and capture among value chain partners. Thus, we examine the impact of Blockchain technology when combined with the IoT ecosystem and how it can be utilized to enhance value creation and capture among value chain partners. We collected data through an online survey, and 265 UK Agri-food retailers completed the survey. Our data were analyzed using structural equation modelling (SEM). Our finding reveals that Blockchain technology enhances GVC by improving IoT scalability, security, and traceability when combined with the IoT ecosystem. Which, in turn, strengthens GVC and creates more value for value chain partners – which serves as a competitive advantage. Finally, our research outlines the theoretical and practical contribution of combining Blockchain technology and the IoT ecosystem

    Investigation of Mobile Games for Cognitive Assessment and Screening with a Focus on Touch-based and Motion Features

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    Early detection of cognitive decline is important for timely intervention and treatment strategies to prevent further deterioration or development of more severe forms of cognitive dysfunction. Therefore, many tests have been developed for screening and monitoring changes in cognitive status. However, these existing assessment and screening tools are not designed for self-administration without a trained examiner. Moreover, the lack of multiple variations of these paper-based measures and repeated exposure to such tests could reduce their sensitivity to detect cognitive changes due to practice effects. These limitations pose clinical challenges to early identification of cognitive deficits and monitoring of longitudinal changes in cognitive function, especially in resource-limited settings. To this end, a number of studies have adopted mobile technology and gamification to facilitate remote and self-administered cognitive assessment and screening in a less effortful and engaging manner. Despite this, existing literature has so far only examined the feasibility of using gameplay performance as a means for cognitive assessment. There has not been any attempt to explore gameplay behaviours as revealed through patterns of touch interactions and device motions as indicative features for cognitive evaluation. Therefore the aim of this thesis is to investigate the use of touch and motions features in game-based cognitive assessment and screening. This is achieved through two studies. The first study was carried out to examine the links between cognitive abilities and underlying patterns of user-game interaction with a focus on touch gestures and device motions. Twenty-two healthy participants took part in the two-session experiment where they were asked to take a series of standard cognitive assessments followed by playing three casual mobile games in which user-game interaction data were passively collected. The results from bivariate analysis indicated that increases in swipe length and swipe speed, in the game context, were significantly correlated with declines in response inhibition ability but increased performance on attention. However, it remained unclear whether the device motion features alone could be used to identify cognitive ability as the results provide only weak evidence for relationships between cognitive performance and the underlying device motion patterns while playing the games. In the second study, we evaluated the potential use of these behavioural features and mobile games as a potential screening tool for clinical conditions with cognitive impairment. Alcohol-related brain damage (ARBD) is often found to be associated with deficits in multiple cognitive functions in patients with alcohol dependence, which is the focus of this thesis. Based on findings from the preliminary study, the second experimental study was carried out to investigate the feasibility of using such user-game interaction patterns on mobile games to develop an automated screening tool for alcohol-dependent patients. The classification performance of various supervised learning algorithms was evaluated on data collected from 40 patients and 40 age-matched healthy adults. The results showed that patients with alcohol dependence could be automatically identified accurately using the ensemble of touch, device motion, and gameplay performance features on 3-minute samples (accuracy=0.95, sensitivity=0.95, and specificity=0.95). The findings provide evidence suggesting the potential use of user-game interaction metrics on existing mobile games as discriminant features for developing an implicit measure to identify alcohol dependence conditions. In addition to supporting healthcare professionals in clinical decision-making, the game-based method could be used as a novel strategy to promote self-screening, especially outside of clinical settings. The findings from this thesis were also applied to guidelines to aid researchers in the game interaction design to capitalise on the use of touch and device motion features with regard to cognitive assessment and screening

    Diseño de un sistema de control y planeamiento de trayectoria coordinado en el tiempo para múltiples robots móviles no holonómicos en presencia de obstáculos

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    La presente tesis tiene como objetivo diseñar un sistema de control y planeamiento de trayectoria coordinado para múltiples robots móviles no holonómicos en mapas con presencia de obstáculos variados. En esta se simula el control y planeamiento en modelos matemáticos de tipo bicicleta. El sistema implementado consiste de tres partes, las cuales son el planeamiento de caminos, el generador de trayectorias y el control de seguimiento de trayectorias. El planeamiento de caminos se dividió en tres partes. En la primera parte se desarrolló el planeador local para un robot no holonómico, modificando el algoritmo Hybrid A*, de manera que utilice las ecuaciones movimiento circular del móvil en vez de las cinemáticas. Este algoritmo permite al robot encontrar los caminos que lo llevan de una configuración de posición y orientación inicial a una final en mapas con obstáculos variados. En la segunda parte se agregó al planeador local el planeamiento en el tiempo, combinando a este con el algoritmo de planeamiento de caminos en intervalos seguros (SIPP), el cual permite al robot evadir obstáculos en el tiempo. Finalmente, en la tercera parte se desarrolló el planeador global usando el algoritmo de búsqueda basada en conflictos (CBS), el cual resuelve los conflictos que se presentan entre los caminos de los móviles, imponiendo restricciones en el tiempo en el movimiento de cada uno de ellos. Por otro lado, el generador de trayectorias es desarrollado en una única parte, en la cual, se plantea la función de costo a optimizar, se calcula todos los gradientes y se plantea utilizar el algoritmo de descenso de gradiente de forma desacoplada para la optimización de trayectoria de cada móvil. Mientras que el desarrollo del sistema de control de seguimiento de trayectoria se dividió en dos partes. En la primera se linealiza el modelo matemático por extensión dinámica para sistemas flatness diferencial y en la segunda parte se desarrolla el controlador LQR de cada móvil que permite seguir las trayectorias de referencia deseadas. Al término de la tesis se logra el planeamiento, generación de trayectoria y el control de seguimiento de trayectoria de hasta 10 móviles no holonómicos en mapas con obstáculos variados, evitando la colisión con los obstáculos del entorno y la colisión con otros móviles durante el planeamiento y la optimización de trayectoria. Así mismo, se verifica que el planeador es capaz de resolver conflictos en entornos propensos al atasco como mapas tipo T o H

    Integration von Worst-Case Optimal Join Algorithmen in Spalten-Orientierte Datenbanken

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    Arbeit an der Bibliothek noch nicht eingelangt - Daten nicht geprüftAbweichender Titel nach Übersetzung der Verfasserin/des VerfassersBusiness intelligence and analytical systems have to handle an increasing amount of data and require to efficiently answer queries. Therefore, the join evaluation has become a major challenge to be tackled by any database system to efficiently evaluate queries. To that end, plenty of research has been conducted to introduce concepts to compute join queries in a resource and runtime efficient way. The research area of column-oriented database systems has introduced a new database architecture from scratch. Such column-stores vertically partition a database and store columns independently of each other. Another research area that aims for optimizing query performance deals with worst-case optimal joins (WCOJ). Theoretical concepts and algorithms that define tight bounds on join algorithms’ runtime have been introduced in this field. Both areas successfully came up with join optimization concepts independently of each other. Since a combination of concepts from both fields yield great potential for further performance optimization, this thesis aims for integrating WCOJs into column-stores and is the first work to perform and evaluate such combination. This thesis introduces a way of integrating WCOJ algorithms into column-stores. The integration process discusses the query compiler of a specific column-store and the manual translation of a class of WCOJ algorithms into its internal language. Finally, the translation result is integrated into the column-store’s query compiler and the resulting system is evaluated against the original one. The evaluation showed that our system outperforms the original one on a given set of natural join queries in settings with skewed data and underlines the practical potential of WCOJ algorithms for fighting skew in input data. This thesis further showed that the column-store with WCOJ algorithm integrated can evaluate natural join queries with big input relation sizes which cause memory allocation errors for the original systems.10
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