1,044 research outputs found
Advances and Applications of DSmT for Information Fusion. Collected Works, Volume 5
This fifth volume on Advances and Applications of DSmT for Information Fusion collects theoretical and applied contributions of researchers working in different fields of applications and in mathematics, and is available in open-access. The collected contributions of this volume have either been published or presented after disseminating the fourth volume in 2015 in international conferences, seminars, workshops and journals, or they are new. The contributions of each part of this volume are chronologically ordered.
First Part of this book presents some theoretical advances on DSmT, dealing mainly with modified Proportional Conflict Redistribution Rules (PCR) of combination with degree of intersection, coarsening techniques, interval calculus for PCR thanks to set inversion via interval analysis (SIVIA), rough set classifiers, canonical decomposition of dichotomous belief functions, fast PCR fusion, fast inter-criteria analysis with PCR, and improved PCR5 and PCR6 rules preserving the (quasi-)neutrality of (quasi-)vacuous belief assignment in the fusion of sources of evidence with their Matlab codes.
Because more applications of DSmT have emerged in the past years since the apparition of the fourth book of DSmT in 2015, the second part of this volume is about selected applications of DSmT mainly in building change detection, object recognition, quality of data association in tracking, perception in robotics, risk assessment for torrent protection and multi-criteria decision-making, multi-modal image fusion, coarsening techniques, recommender system, levee characterization and assessment, human heading perception, trust assessment, robotics, biometrics, failure detection, GPS systems, inter-criteria analysis, group decision, human activity recognition, storm prediction, data association for autonomous vehicles, identification of maritime vessels, fusion of support vector machines (SVM), Silx-Furtif RUST code library for information fusion including PCR rules, and network for ship classification.
Finally, the third part presents interesting contributions related to belief functions in general published or presented along the years since 2015. These contributions are related with decision-making under uncertainty, belief approximations, probability transformations, new distances between belief functions, non-classical multi-criteria decision-making problems with belief functions, generalization of Bayes theorem, image processing, data association, entropy and cross-entropy measures, fuzzy evidence numbers, negator of belief mass, human activity recognition, information fusion for breast cancer therapy, imbalanced data classification, and hybrid techniques mixing deep learning with belief functions as well
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
Learning-based generative representations for automotive design optimization
In automotive design optimizations, engineers intuitively look for suitable representations of CAE models that can be used across different optimization problems. Determining a suitable compact representation of 3D CAE models facilitates faster search and optimization of 3D designs. Therefore, to support novice designers in the automotive design process, we envision a cooperative design system (CDS) which learns the experience embedded in past optimization data and is able to provide assistance to the designer while performing an engineering design optimization task. The research in this thesis addresses different aspects that can be combined to form a CDS framework.
First, based on the survey of deep learning techniques, a point cloud variational autoencoder (PC-VAE) is adapted from the literature, extended and evaluated as a shape generative model in design optimizations. The performance of the PC-VAE is verified with respect to state-of-the-art architectures. The PC-VAE is capable of generating a continuous low-dimensional search space for 3D designs, which further supports the generation of novel realistic 3D designs through interpolation and sampling in the latent space. In general, while designing a 3D car design, engineers need to consider multiple structural or functional performance criteria of a 3D design. Hence, in the second step, the latent representations of the PC-VAE are evaluated for generating novel designs satisfying multiple criteria and user preferences. A seeding method is proposed to provide a warm start to the optimization process and improve convergence time. Further, to replace expensive simulations for performance estimation in an optimization task, surrogate models are trained to map each latent representation of an input 3D design to their respective geometric and functional performance measures. However, the performance of the PC-VAE is less consistent due to additional regularization of the latent space.
Thirdly, to better understand which distinct region of the input 3D design is learned by a particular latent variable of the PC-VAE, a new deep generative model is proposed (Split-AE), which is an extension of the existing autoencoder architecture. The Split-AE learns input 3D point cloud representations and generates two sets of latent variables for each 3D design. The first set of latent variables, referred to as content, which helps to represent an overall underlying structure of the 3D shape to discriminate across other semantic shape categories. The second set of latent variables refers to the style, which represents the unique shape part of the input 3D shape and this allows grouping of shapes into shape classes. The reconstruction and latent variables disentanglement properties of the Split-AE are compared with other state-of-the-art architectures. In a series of experiments, it is shown that for given input shapes, the Split-AE is capable of generating the content and style variables which gives the flexibility to transfer and combine style features between different shapes. Thus, the Split-AE is able to disentangle features with minimum supervision and helps in generating novel shapes that are modified versions of the existing designs.
Lastly, to demonstrate the application of our initial envisioned CDS, two interactive systems were developed to assist designers in exploring design ideas. In the first CDS framework, the latent variables of the PC-VAE are integrated with a graphical user interface. This framework enables the designer to explore designs taking into account the data-driven knowledge and different performance measures of 3D designs. The second interactive system aims to guide the designers to achieve their design targets, for which past human experiences of performing 3D design modifications are captured and learned using a machine learning model. The trained model is then used to guide the (novice) engineers and designers by predicting the next step of design modification based on the current applied changes
Towards Object-Centric Scene Understanding
Visual perception for autonomous agents continues to attract community attention due to the disruptive technologies and the wide applicability of such solutions. Autonomous Driving (AD), a major application in this domain, promises to revolutionize our approach to mobility while bringing critical advantages in limiting accident fatalities.
Fueled by recent advances in Deep Learning (DL), more computer vision tasks are being addressed using a learning paradigm. Deep Neural Networks (DNNs) succeeded consistently in pushing performances to unprecedented levels and demonstrating the ability of such approaches to generalize to an increasing number of difficult problems, such as 3D vision tasks.
In this thesis, we address two main challenges arising from the current approaches. Namely, the computational complexity of multi-task pipelines, and the increasing need for manual annotations. On the one hand, AD systems need to perceive the surrounding environment on different levels of detail and, subsequently, take timely actions. This multitasking further limits the time available for each perception task. On the other hand, the need for universal generalization of such systems to massively diverse situations requires the use of large-scale datasets covering long-tailed cases. Such requirement renders the use of traditional supervised approaches, despite the data readily available in the AD domain, unsustainable in terms of annotation costs, especially for 3D tasks.
Driven by the AD environment nature and the complexity dominated (unlike indoor scenes) by the presence of other scene elements (mainly cars and pedestrians) we focus on the above-mentioned challenges in object-centric tasks. We, then, situate our contributions appropriately in fast-paced literature, while supporting our claims with extensive experimental analysis leveraging up-to-date state-of-the-art results and community-adopted benchmarks
A computational framework for crack propagation along contact interfaces and surfaces under load
We present the first implicit computational framework for simulating crack propagation along contact interfaces and surfaces under load in three-dimensional bodies, which is distinct from modelling the contact interaction associated with crack closure. We restrict ourselves to brittle fracture and frictionless contact and focus on numerical challenges associated with the coupling of unilateral constraints emerging from the Griffith’s criterion and the contact conditions. The formulation is based on the configurational mechanics framework and is solved using the finite element method. The approach utilises a monolithic Arbitrary Lagrangian–Eulerian formulation permitting simultaneous resolution of crack propagation and unilateral contact constraints. Contact is embedded in the model using the well-known mortar contact formulation. Evolving cracks are explicitly modelled as displacement discontinuities within the mesh. Heterogeneous approximation of arbitrary order is used to discretise spatial displacements, enabling -adaptive refinement around the crack front and the contact interfaces traversed by the crack. The result is a holistic approach which handles issues associated with thermodynamic consistency, numerical accuracy and robustness of the computational scheme. Several numerical examples are presented to verify the model formulation and implementation; they also highlight how contact pressure and load applied on surfaces traversed by cracks influence their propagation. The robustness of the approach is validated by comparison of our simulations with existing numerical results and an industrial experiment involving cracks of complex morphologies propagating along contact interfaces between multiple deformable bodies
Estrategias de visión por computador para la estimación de pose en el contexto de aplicaciones robóticas industriales: avances en el uso de modelos tanto clásicos como de Deep Learning en imágenes 2D
184 p.La visión por computador es una tecnología habilitadora que permite a los robots y sistemas autónomos percibir su entorno. Dentro del contexto de la industria 4.0 y 5.0, la visión por ordenador es esencial para la automatización de procesos industriales. Entre las técnicas de visión por computador, la detección de objetos y la estimación de la pose 6D son dos de las más importantes para la automatización de procesos industriales. Para dar respuesta a estos retos, existen dos enfoques principales: los métodos clásicos y los métodos de aprendizaje profundo. Los métodos clásicos son robustos y precisos, pero requieren de una gran cantidad de conocimiento experto para su desarrollo. Por otro lado, los métodos de aprendizaje profundo son fáciles de desarrollar, pero requieren de una gran cantidad de datos para su entrenamiento.En la presente memoria de tesis se presenta una revisión de la literatura sobre técnicas de visión por computador para la detección de objetos y la estimación de la pose 6D. Además se ha dado respuesta a los siguientes retos: (1) estimación de pose mediante técnicas de visión clásicas, (2) transferencia de aprendizaje de modelos 2D a 3D, (3) la utilización de datos sintéticos para entrenar modelos de aprendizaje profundo y (4) la combinación de técnicas clásicas y de aprendizaje profundo. Para ello, se han realizado contribuciones en revistas de alto impacto que dan respuesta a los anteriores retos
CFD Modelling and Simulation of Water Turbines
The design and development of water turbines requires accurate methods for performance prediction. Numerical methods and modelling are becoming increasingly important tools to achieve better designs and more efficient turbines, reducing the time required in physical model testing. This book is focused on applying numerical simulations and models for water turbines to predict tool their performance. In this Special Issue, the different contributions of this book are classified into three state-of-the-art Topics: discussing the modelling of pump-turbines, the simulation of horizontal and vertical axis turbines for hydrokinetic applications and the modelling of hydropower plants. All the contributions to this book demonstrate the importance of the modelling and simulation of water turbines for hydropower energy. This new generation of models and simulations will play a major role in the global energy transition and energy crisis, and, of course, in the mitigation of climate change
1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface
A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance
Mixed approach for coupled flow and mechanics in a fractured medium
Denne avhandlingen presenterer en blandet endelig element metode for Biot ligningene for poroelastisitet i et reservoar, sammenkoblet med en blandet formulering av strømning innenfor en sprekk. Sprekken er representert som et flatt objekt av en dimensjon mindre enn domenet til reservoaret. Den romlige diskretiseringen kombinerer en flerpunkts spenning blandet endelig element (MSMFE) metode for elastisitet og en flerpunkts fluks blandet endelig element (MFMFE) metode for Darcy-strømningen innenfor reservoarmatrisen, sammenkoblet med en MFMFE-metode for strømningen innenfor sprekken. I reservoarmatrisen tar vi i betraktning laveste grad Brezzi-Douglas-Marini blandede endelig elementrom for poroelastisk spenning og Darcy-strømning, og stykkevis konstant forskyvning, trykk og rotasjon. Innenfor sprekken betrakter vi de endelige rommene av sprekk-trykket og fluksen til å være to kompatible par, sammen med konstant mørtelforskyvning. En stabilitetsanalyse utføres både for det kontinuerlige og semi-diskrete problemet. Videre vises eksistens og entydighet for de semi-diskrete og fullt-diskrete løsningene. Ulike numeriske simulasjoner er presentert på slutten.Masteroppgave i anvendt og beregningsorientert matematikkMAB399MAMN-MA
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