793 research outputs found
30th European Congress on Obesity (ECO 2023)
This is the abstract book of 30th European Congress on Obesity (ECO 2023
Tradition and Innovation in Construction Project Management
This book is a reprint of the Special Issue 'Tradition and Innovation in Construction Project Management' that was published in the journal Buildings
Data-driven deep-learning methods for the accelerated simulation of Eulerian fluid dynamics
Deep-learning (DL) methods for the fast inference of the temporal evolution of fluid-dynamics systems, based on the previous recognition of features underlying large sets of fluid-dynamics data, have been studied. Specifically, models based on convolution neural networks (CNNs) and graph neural networks (GNNs) were proposed and discussed.
A U-Net, a popular fully-convolutional architecture, was trained to infer wave dynamics on liquid surfaces surrounded by walls, given as input the system state at previous time-points. A term for penalising the error of the spatial derivatives was added to the loss function, which resulted in a suppression of spurious oscillations and a more accurate location and length of the
predicted wavefronts. This model proved to accurately generalise to complex wall geometries not seen during training.
As opposed to the image data-structures processed by CNNs, graphs offer higher freedom on how data is organised and processed. This motivated the use of graphs to represent the state of fluid-dynamic systems discretised by unstructured sets of nodes, and GNNs to process such graphs. Graphs have enabled more accurate representations of curvilinear geometries and higher resolution placement exclusively in areas where physics is more challenging to resolve. Two novel
GNN architectures were designed for fluid-dynamics inference: the MuS-GNN, a multi-scale GNN, and the REMuS-GNN, a rotation-equivariant multi-scale GNN. Both architectures work by repeatedly passing messages from each node to its nearest nodes in the graph. Additionally, lower-resolutions graphs, with a reduced number of nodes, are defined from the original graph,
and messages are also passed from finer to coarser graphs and vice-versa. The low-resolution graphs allowed for efficiently capturing physics encompassing a range of lengthscales.
Advection and fluid flow, modelled by the incompressible Navier-Stokes equations, were the two types of problems used to assess the proposed GNNs. Whereas a single-scale GNN was sufficient to achieve high generalisation accuracy in advection simulations, flow simulation highly benefited from an increasing number of low-resolution graphs. The generalisation and long-term accuracy of these simulations were further improved by the REMuS-GNN architecture, which
processes the system state independently of the orientation of the coordinate system thanks to a rotation-invariant representation and carefully designed components. To the best of the author’s knowledge, the REMuS-GNN architecture was the first rotation-equivariant and multi-scale GNN.
The simulations were accelerated between one (in a CPU) and three (in a GPU) orders of magnitude with respect to a CPU-based numerical solver. Additionally, the parallelisation of multi-scale GNNs resulted in a close-to-linear speedup with the number of CPU cores or GPUs.Open Acces
Dusty star-forming galaxies and their environments
Since their discovery over three decades ago, there has been astounding progress in our understanding of DSFGs. Roughly half all optical and UV emission from star formation is absorbed and re-radiated as infrared light by dust. This dust enshrouded star formation is contained within DSFGs, with some harbouring SFRs of thousands of solar masses per year, yielding infrared luminosities greater than \,L. DSFGs are thought to be the progenitors of elliptical galaxies that are predominantly found within massive, galaxy clusters in the local Universe. This thesis aims to build on this progress by investigating the nature of DSFGs and their environments. We first investigate the molecular gas properties of galaxies in the Antlia cluster, a potentially useful low redshift analogue to developing protoclusters at higher redshifts. We find that the disturbed cluster environment is not strong enough to strip the molecular gas reservoirs of its member galaxies, yielding the observed high SFRs in this population. We also study the properties of candidate members of the massive SpARCS-0330 galaxy cluster at , where we find significant ongoing star formation. Quenching in SpARCS-0330 is likely driven by secular processes that scale with stellar mass rather than environment, suggesting that either the cluster environment cannot truncate star formation or the galaxy members have not yet inhabited the cluster for long enough to be significantly affected. We also investigate the multiplicities and properties of four candidate z > 4 DSFGs. We find that three resolve into multiple components, suggesting that this population is more diverse than predicted by simulations. We additionally investigate SDSS1607, a fascinating quasar-SMG system at z = 3.65, using observations from the VLA, SMA and HST. Finally, we discuss the implications of these results and the exciting avenues for future research produced by this work.Open Acces
Predictive Techniques for Scene Understanding by using Deep Learning in Autonomous Driving
La conducción autónoma es considerada uno de los más grandes retos tecnológicos de la actualidad. Cuando los coches autónomos conquisten nuestras carreteras, los accidentes se reducirán notablemente, hasta casi desaparecer, ya que la tecnología estará testada y no incumplirá las normas de conducción, entre otros beneficios sociales y económicos. Uno de los aspectos más críticos a la hora de desarrollar un vehículo autónomo es percibir y entender la escena que le rodea. Esta tarea debe ser tan precisa y eficiente como sea posible para posteriormente predecir el futuro de esta misma y ayudar a la toma de decisiones. De esta forma, las acciones tomadas por el vehículo garantizarán tanto la seguridad del vehículo en sí mismo y sus ocupantes, como la de los obstáculos circundantes, tales como viandantes, otros vehículos o infraestructura de la carretera. En ese sentido, esta tesis doctoral se centra en el estudio y desarrollo de distintas técnicas predictivas para el entendimiento de la escena en el contexto de la conducción autónoma. Durante la tesis, se observa una incorporación progresiva de técnicas de aprendizaje profundo en los distintos algoritmos propuestos para mejorar el razonamiento sobre qué está ocurriendo en el escenario de tráfico, así como para modelar las complejas interacciones entre la información social (distintos participantes o agentes del escenario, tales como vehículos, ciclistas o peatones) y física (es decir, la información geométrica, semántica y topológica del mapa de alta definición) presente en la escena. La capa de percepción de un vehículo autónomo se divide modularmente en tres etapas: Detección, Seguimiento (Tracking), y Predicción. Para iniciar el estudio de las etapas de seguimiento y predicción, se propone un algoritmo de Multi-Object Tracking basado en técnicas clásicas de estimación de movimiento y asociación validado en el dataset KITTI, el cual obtiene métricas del estado del arte. Por otra parte, se propone el uso de un filtro inteligente basado en información contextual de mapa, cuyo objetivo es monitorizar los agentes más relevantes de la escena en el tiempo, representando estos agentes filtrados la entrada preliminar para realizar predicciones unimodales basadas en un modelo cinemático. Para validar esta propuesta de filtro inteligente se usa CARLA (CAR Learning to Act), uno de los simuladores hiperrealistas para conducción autónoma más prometedores en la actualidad, comprobando cómo al usar información contextual de mapa se puede reducir notablemente el tiempo de inferencia de un algoritmo de tracking y predicción basados en métodos físicos, prestando atención a los agentes realmente relevantes del escenario de tráfico. Tras observar las limitaciones de un modelo de predicción basado en cinemática para la predicción a largo plazo de un agente, los distintos algoritmos de la tesis se centran en el módulo de predicción, usando los datasets Argoverse 1 y Argoverse 2, donde se asume que los agentes proporcionados en cada escenario de tráfico ya están monitorizados durante un cierto número de observaciones. En primer lugar, se introduce un modelo basado en redes neuronales recurrentes (particularmente redes LSTM, Long-Short Term Memory) y mecanismo de atención para codificar las trayectorias pasadas de los agentes, y una representación simplificada del mapa en forma de posiciones finales potenciales en la carretera para calcular las trayectorias futuras unimodales, todo envuelto en un marco GAN (Generative Adversarial Network), obteniendo métricas similares al estado del arte en el caso unimodal. Una vez validado el modelo anterior en Argoverse 1, se proponen distintos modelos base (sólo social, incorporando mapa, y una mejora final basada en Transformer encoder, redes convolucionales 1D y mecanismo de atención cruzada para la fusión de características) precisos y eficientes basados en el modelo de predicción anterior, introduciendo dos nuevos conceptos. Por un lado, el uso de redes neuronales gráficas (particularmente GCN, Graph Convolutional Network) para codificar de una forma potente las interacciones de los agentes. Por otro lado, se propone el preprocesamiento de trayectorias preliminares a partir de un mapa con un método heurístico. Gracias a estas entradas y una arquitectura más potente de codificación, los modelos base serán capaces de predecir distintas trayectorias futuras multimodales, es decir, cubriendo distintos posibles futuros para el agente de interés. Los modelos base propuestos obtienen métricas de regresión del estado del arte tanto en el caso multimodal como unimodal manteniendo un claro compromiso de eficiencia con respecto a otras propuestas. El modelo final de la tesis, inspirado en los modelos anteriores y validado en el más reciente dataset para algoritmos de predicción en conducción autónoma (Argoverse 2), introduce varias mejoras para entender mejor el escenario de tráfico y decodificar la información de una forma precisa y eficiente. Se propone incorporar información topológica y semántica de los carriles futuros preliminares con el método heurístico antes mencionado, codificación de mapa basada en aprendizaje profundo con redes GCN, ciclo de fusión de características físicas y sociales, estimación de posiciones finales en la carretera y agregación de su entorno circundante con aprendizaje profundo y finalmente módulo de refinado para mejorar la calidad de las predicciones multimodales finales de un modo elegante y eficiente. Comparado con el estado del arte, nuestro método logra métricas de predicción a la par con los métodos mejor posicionados en el Leaderboard de Argoverse 2, reduciendo de forma notable el número de parámetros y operaciones de coma flotante por segundo. Por último, el modelo final de la tesis ha sido validado en simulación en distintas aplicaciones de conducción autónoma. En primer lugar, se integra el modelo para proporcionar predicciones a un algoritmo de toma de decisiones basado en aprendizaje por refuerzo en el simulador SMARTS (Scalable Multi-Agent Reinforcement Learning Training School), observando en los estudios como el vehículo es capaz de tomar mejores decisiones si conoce el comportamiento futuro de la escena y no solo el estado actual o pasado de esta misma. En segundo lugar, se ha realizado un estudio de adaptación de dominio exitoso en el simulador hiperrealista CARLA en distintos escenarios desafiantes donde el entendimiento de la escena y predicción del entorno son muy necesarios, como una autopista o rotonda con gran densidad de tráfico o la aparición de un usuario vulnerable de la carretera de forma repentina. En ese sentido, el modelo de predicción ha sido integrado junto con el resto de capas de la arquitectura de navegación autónoma del grupo de investigación donde se desarrolla la tesis como paso previo a su implementación en un vehículo autónomo real
2022 Review of Data-Driven Plasma Science
Data-driven science and technology offer transformative tools and methods to science. This review article highlights the latest development and progress in the interdisciplinary field of data-driven plasma science (DDPS), i.e., plasma science whose progress is driven strongly by data and data analyses. Plasma is considered to be the most ubiquitous form of observable matter in the universe. Data associated with plasmas can, therefore, cover extremely large spatial and temporal scales, and often provide essential information for other scientific disciplines. Thanks to the latest technological developments, plasma experiments, observations, and computation now produce a large amount of data that can no longer be analyzed or interpreted manually. This trend now necessitates a highly sophisticated use of high-performance computers for data analyses, making artificial intelligence and machine learning vital components of DDPS. This article contains seven primary sections, in addition to the introduction and summary. Following an overview of fundamental data-driven science, five other sections cover widely studied topics of plasma science and technologies, i.e., basic plasma physics and laboratory experiments, magnetic confinement fusion, inertial confinement fusion and high-energy-density physics, space and astronomical plasmas, and plasma technologies for industrial and other applications. The final section before the summary discusses plasma-related databases that could significantly contribute to DDPS. Each primary section starts with a brief introduction to the topic, discusses the state-of-the-art developments in the use of data and/or data-scientific approaches, and presents the summary and outlook. Despite the recent impressive signs of progress, the DDPS is still in its infancy. This article attempts to offer a broad perspective on the development of this field and identify where further innovations are required
Self-Supervised Shape and Appearance Modeling via Neural Differentiable Graphics
Inferring 3D shape and appearance from natural images is a fundamental challenge in computer vision. Despite recent progress using deep learning methods, a key limitation is the availability of annotated training data, as acquisition is often very challenging and expensive, especially at a large scale. This thesis proposes to incorporate physical priors into neural networks that allow for self-supervised learning.
As a result, easy-to-access unlabeled data can be used for model training. In particular, novel algorithms in the context of 3D reconstruction and texture/material synthesis are introduced, where only image data is available as supervisory signal.
First, a method that learns to reason about 3D shape and appearance solely from unstructured 2D images, achieved via differentiable rendering in an adversarial fashion, is proposed.
As shown next, learning from videos significantly improves 3D reconstruction quality. To this end, a novel ray-conditioned warp embedding is proposed that aggregates pixel-wise features from multiple source images.
Addressing the challenging task of disentangling shape and appearance, first a method that enables 3D texture synthesis independent of shape or resolution is presented. For this purpose, 3D noise fields of different scales are transformed into stationary textures. The method is able to produce 3D textures, despite only requiring 2D textures for training.
Lastly, the surface characteristics of textures under different illumination conditions are modeled in the form of material parameters. Therefore, a self-supervised approach is proposed that has no access to material parameters but only flash images. Similar to the previous method, random noise fields are reshaped to material parameters, which are conditioned to replicate the visual appearance of the input under matching light
CERNAS: Current Evolution and Research Novelty in Agricultural Sustainability
Climate changes pose overwhelming impacts on primary production and, consequently, on
agricultural and animal farming. Additionally, at present, agriculture still depends strongly on
fossil fuels both for energy and production factors ,such as synthetized inorganic fertilizers and
harmful chemicals such as pesticides. The need to feed the growing world population poses many
challenges. The need to reduce environmental impacts to a minimum, maintain healthy ecosystems,
and improve soil microbiota are central to ensuring a promising future for coming generations.
Livestock production under cover crop systems helps to alleviate compaction so that oxygen and
water can sufficiently flow in the soil, add organic matter, and help hold soil in place, reducing
crusting and protecting against erosion. The use of organic plant production practices allied to
the control of substances used in agriculture also decisively contributes to alleviating the pressure
on ecosystems. Some of the goals of this new decade are to use enhanced sustainable production
methodologies to improve the input/output ratios of primary production, reduce environmental
impacts, and rely on new innovative technologies.
This reprint addresses original studies and reviews focused on the current evolution and
research novelty in agricultural sustainability. New developments are discussed on issues related
to quality of soil, natural fertilizers, or the sustainable use of land and water. Also, crop protection
techniques are pivotal for sustainable food production under the challenges of the Sustainable
Development Goals of the United Nations, allied to innovative weed control methodologies as a
way to reduce the utilization of pesticides. The role of precision and smart agriculture is becoming
more pertinent as communication technologies improve at a rapid rate. Waste management, reuse of
agro-industrial residues, extension of shelf life, and use of new technologies are ways to reduce food
waste, all contributing to higher sustainability in food supply chains, leading to a more rational use
of natural resources. The unquestionable role of bees as pollinators and contributors to biodiversity
is adjacent to characterizing beekeeping activities, which in turn contributes, together with the
valorization of endemic varieties of plant foods, to the development of local communities. Finally,
the short circuits and local food markets have a decisive role in the preservation and enhancement of
rural economies.info:eu-repo/semantics/publishedVersio
Perception and Prediction in Multi-Agent Urban Traffic Scenarios for Autonomous Driving
In multi-agent urban scenarios, autonomous vehicles navigate an intricate network of interactions with a variety of agents, necessitating advanced perception modeling and trajectory prediction. Research to improve perception modeling and trajectory prediction in autonomous vehicles is fundamental to enhance safety and efficiency in complex driving scenarios. Better data association for 3D multi-object tracking ensures consistent identification and tracking of multiple objects over time, crucial in crowded urban environments to avoid mis-identifications that can lead to unsafe maneuvers or collisions. Effective context modeling for 3D object detection aids in interpreting complex scenes, effectively dealing with challenges like noisy or missing points in sensor data, and occlusions. It enables the system to infer properties of partially observed or obscured objects, enhancing the robustness of the autonomous system in varying conditions. Furthermore, improved trajectory prediction of surrounding vehicles allows an autonomous vehicle to anticipate future actions of other road agents and adapt accordingly, crucial in scenarios like merging lanes, making unprotected turns, or navigating intersections. In essence, these research directions are key to mitigating risks in autonomous driving, and facilitating seamless interaction with other road users.
In Part I, we address the task of improving perception modeling for AV systems. Concretely our contributions are: (i) FANTrack introduces a novel application of Convolutional Neural Networks (CNNs) for real-time 3D Multi-object Tracking (MOT) in autonomous driving, addressing challenges such as varying number of targets, track fragmentation, and noisy detections, thereby enhancing the accuracy of perception capabilities for safe and efficient navigation. (ii) FANTrack proposes to leverage both visual and 3D bounding box data, utilizing Siamese networks and hard-mining, to enhance the similarity functions used in data associations for 3D Multi-object Tracking (MOT). (iii) SA-Det3D introduces a globally-adaptive Full Self-Attention (FSA) module for enhanced feature extraction in 3D object detection, overcoming the limitations of traditional convolution-based techniques by facilitating adaptive context aggregation from entire point-cloud data, thereby bolstering perception modeling in autonomous driving. (iv) SA-Det3D also introduces the Deformable Self-Attention (DSA) module, a scalable adaptation for global context assimilation in large-scale point-cloud datasets, designed to select and focus on most informative regions, thereby improving the quality of feature descriptors and perception modeling in autonomous driving.
In Part II, we focus on the task of improving trajectory prediction of surrounding agents. Concretely, our contributions are: (i) SSL-Lanes introduces a self-supervised learning approach for motion forecasting in autonomous driving that enhances accuracy and generalizability without compromising inference speed or model simplicity, utilizing pseudo-labels from pretext tasks for learning transferable motion patterns. (ii) The second contribution in SSL-Lanes is the design of comprehensive experiments to demonstrate that SSL-Lanes can yield more generalizable and robust trajectory predictions than traditional supervised learning approaches. (iii) SSL-Interactions presents a new framework that utilizes pretext tasks to enhance interaction modeling for trajectory prediction in autonomous driving. (iv) SSL-Interactions advances the prediction of agent trajectories in interaction-centric scenarios by creating a curated dataset that explicitly labels meaningful interactions, thus enabling the effective training of a predictor utilizing pretext tasks and enhancing the modeling of agent-agent interactions in autonomous driving environments
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