358 research outputs found
LIPIcs, Volume 251, ITCS 2023, Complete Volume
LIPIcs, Volume 251, ITCS 2023, Complete Volum
Uncertainty Quantification in Machine Learning for Engineering Design and Health Prognostics: A Tutorial
On top of machine learning models, uncertainty quantification (UQ) functions
as an essential layer of safety assurance that could lead to more principled
decision making by enabling sound risk assessment and management. The safety
and reliability improvement of ML models empowered by UQ has the potential to
significantly facilitate the broad adoption of ML solutions in high-stakes
decision settings, such as healthcare, manufacturing, and aviation, to name a
few. In this tutorial, we aim to provide a holistic lens on emerging UQ methods
for ML models with a particular focus on neural networks and the applications
of these UQ methods in tackling engineering design as well as prognostics and
health management problems. Toward this goal, we start with a comprehensive
classification of uncertainty types, sources, and causes pertaining to UQ of ML
models. Next, we provide a tutorial-style description of several
state-of-the-art UQ methods: Gaussian process regression, Bayesian neural
network, neural network ensemble, and deterministic UQ methods focusing on
spectral-normalized neural Gaussian process. Established upon the mathematical
formulations, we subsequently examine the soundness of these UQ methods
quantitatively and qualitatively (by a toy regression example) to examine their
strengths and shortcomings from different dimensions. Then, we review
quantitative metrics commonly used to assess the quality of predictive
uncertainty in classification and regression problems. Afterward, we discuss
the increasingly important role of UQ of ML models in solving challenging
problems in engineering design and health prognostics. Two case studies with
source codes available on GitHub are used to demonstrate these UQ methods and
compare their performance in the life prediction of lithium-ion batteries at
the early stage and the remaining useful life prediction of turbofan engines
Machine Learning Approaches for Semantic Segmentation on Partly-Annotated Medical Images
Semantic segmentation of medical images plays a crucial role in assisting medical practitioners in providing accurate and swift diagnoses; nevertheless, deep neural networks require extensive labelled data to learn and generalise appropriately. This is a major issue in medical imagery because most of the datasets are not fully annotated. Training models with partly-annotated datasets generate plenty of predictions that belong to correct unannotated areas that are categorised as false positives; as a result, standard segmentation metrics and objective functions do not work correctly, affecting the overall performance of the models. In this thesis, the semantic segmentation of partly-annotated medical datasets is extensively and thoroughly studied. The general objective is to improve the segmentation results of medical images via innovative supervised and semi-supervised approaches. The main contributions of this work are the following. Firstly, a new metric, specifically designed for this kind of dataset, can provide a reliable score to partly-annotated datasets with positive expert feedback in their generated predictions by exploiting all the confusion matrix values except the false positives. Secondly, an innovative approach to generating better pseudo-labels when applying co-training with the disagreement selection strategy. This method expands the pixels in disagreement utilising the combined predictions as a guide. Thirdly, original attention mechanisms based on disagreement are designed for two cases: intra-model and inter-model. These attention modules leverage the disagreement between layers (from the same or different model instances) to enhance the overall learning process and generalisation of the models. Lastly, innovative deep supervision methods improve the segmentation results by training neural networks one subnetwork at a time following the order of the supervision branches. The methods are thoroughly evaluated on several histopathological datasets showing significant improvements
Integration of hybrid networks, AI, Ultra Massive-MIMO, THz frequency, and FBMC modulation toward 6g requirements : A Review
The fifth-generation (5G) wireless communications have been deployed in many countries with the following features: wireless networks at 20 Gbps as peak data rate, a latency of 1-ms, reliability of 99.999%, maximum mobility of 500 km/h, a bandwidth of 1-GHz, and a capacity of 106 up to Mbps/m2. Nonetheless, the rapid growth of applications, such as extended/virtual reality (XR/VR), online gaming, telemedicine, cloud computing, smart cities, the Internet of Everything (IoE), and others, demand lower latency, higher data rates, ubiquitous coverage, and better reliability. These higher requirements are the main problems that have challenged 5G while concurrently encouraging researchers and practitioners to introduce viable solutions. In this review paper, the sixth-generation (6G) technology could solve the 5G limitations, achieve higher requirements, and support future applications. The integration of multiple access techniques, terahertz (THz), visible light communications (VLC), ultra-massive multiple-input multiple-output ( μm -MIMO), hybrid networks, cell-free massive MIMO, and artificial intelligence (AI)/machine learning (ML) have been proposed for 6G. The main contributions of this paper are a comprehensive review of the 6G vision, KPIs (key performance indicators), and advanced potential technologies proposed with operation principles. Besides, this paper reviewed multiple access and modulation techniques, concentrating on Filter-Bank Multicarrier (FBMC) as a potential technology for 6G. This paper ends by discussing potential applications with challenges and lessons identified from prior studies to pave the path for future research
Automorphisms of a Generalized Quadrangle of Order 6
In this thesis, we study the symmetries of the putative generalized quadrangle of order 6. Although it is unknown whether such a quadrangle Q can exist, we show that if it does, that Q cannot be transitive on either points or lines. We first cover the background necessary for studying this problem. Namely, the theory of groups and group actions, the theory of generalized quadrangles, and automorphisms of GQs. We then prove that a generalized quadrangle Q of order 6 cannot have a point- or line-transitive automorphism group, and we also prove that if a group G acts faithfully on Q such that 259 | |G|, then G is not solvable. Along the way, we develop techniques for studying composite order automorphisms of a generalized quadrangle. Specifically, we deal with automorphisms of order pk and pq, where p and q are prime
End-to-end Autonomous Driving: Challenges and Frontiers
The autonomous driving community has witnessed a rapid growth in approaches
that embrace an end-to-end algorithm framework, utilizing raw sensor input to
generate vehicle motion plans, instead of concentrating on individual tasks
such as detection and motion prediction. End-to-end systems, in comparison to
modular pipelines, benefit from joint feature optimization for perception and
planning. This field has flourished due to the availability of large-scale
datasets, closed-loop evaluation, and the increasing need for autonomous
driving algorithms to perform effectively in challenging scenarios. In this
survey, we provide a comprehensive analysis of more than 250 papers, covering
the motivation, roadmap, methodology, challenges, and future trends in
end-to-end autonomous driving. We delve into several critical challenges,
including multi-modality, interpretability, causal confusion, robustness, and
world models, amongst others. Additionally, we discuss current advancements in
foundation models and visual pre-training, as well as how to incorporate these
techniques within the end-to-end driving framework. To facilitate future
research, we maintain an active repository that contains up-to-date links to
relevant literature and open-source projects at
https://github.com/OpenDriveLab/End-to-end-Autonomous-Driving
Internet and Biometric Web Based Business Management Decision Support
Internet and Biometric Web Based Business Management Decision Support
MICROBE
MOOC material prepared under
IO1/A5 Development of the MICROBE personalized MOOCs content and teaching materials
Prepared by:
A. Kaklauskas, A. Banaitis, I. Ubarte
Vilnius Gediminas Technical University, Lithuania
Project No: 2020-1-LT01-KA203-07810
Autonomous 3D Urban and Complex Terrain Geometry Generation and Micro-Climate Modelling Using CFD and Deep Learning
Sustainable building design requires a clear understanding and realistic modelling of the complex interaction between climate and built environment to create safe and comfortable outdoor and indoor spaces. This necessitates unprecedented urban climate modelling at high temporal and spatial resolution. The interaction between complex urban geometries and the microclimate is characterized by complex transport mechanisms. The challenge to generate geometric and physics boundary conditions in an automated manner is hindering the progress of computational methods in urban design. Thus, the challenge of modelling realistic and pragmatic numerical urban micro-climate for wind engineering, environmental, and building energy simulation applications should address the complexity of the geometry and the variability of surface types involved in urban exposures. The original contribution to knowledge in this research is the proposed an end-to-end workflow that employs a cutting-edge deep learning model for image segmentation to generate building footprint polygons autonomously and combining those polygons with LiDAR data to generate level of detail three (LOD3) 3D building models to tackle the geometry modelling issue in climate modelling and solar power potential assessment. Urban and topography geometric modelling is a challenging task when undertaking climate model assessment. This paper describes a deep learning technique that is based on U-Net architecture to automate 3D building model generation by combining satellite imagery with LiDAR data. The deep learning model used registered a mean squared error of 0.02. The extracted building polygons were extruded using height information from corresponding LiDAR data. The building roof structures were also modelled from the same point cloud data. The method used has the potential to automate the task of generating urban scale 3D building models and can be used for city-wide applications. The advantage of applying a deep learning model in an image processing task is that it can be applied to a new set of input image data to extract building footprint polygons for autonomous application once it has been trained. In addition, the model can be improved over time with minimum adjustments when an improved quality dataset is available, and the trained parameters can be improved further building on previously learned features. Application examples for pedestrian level wind and solar energy availability assessment as well as modeling wind flow over complex terrain are presented
Dense Visual Simultaneous Localisation and Mapping in Collaborative and Outdoor Scenarios
Dense visual simultaneous localisation and mapping (SLAM) systems can produce 3D
reconstructions that are digital facsimiles of the physical space they describe. Systems that
can produce dense maps with this level of fidelity in real time provide foundational spatial
reasoning capabilities for many downstream tasks in autonomous robotics. Over the past
15 years, mapping small scale, indoor environments, such as desks and buildings, with a
single slow moving, hand-held sensor has been one of the central focuses of dense visual
SLAM research.
However, most dense visual SLAM systems exhibit a number of limitations which
mean they cannot be directly applied in collaborative or outdoors settings. The contribution
of this thesis is to address these limitations with the development of new systems and
algorithms for collaborative dense mapping, efficient dense alternation and outdoors
operation with fast camera motion and wide field of view (FOV) cameras. We use
ElasticFusion, a state-of-the-art dense SLAM system, as our starting point where each of
these contributions is implemented as a novel extension to the system.
We first present a collaborative dense SLAM system that allows a number of
cameras starting with unknown initial relative positions to maintain local maps with the
original ElasticFusion algorithm. Visual place recognition across local maps results in
constraints that allow maps to be aligned into a common global reference frame, facilitating
collaborative mapping and tracking of multiple cameras within a shared map.
Within dense alternation based SLAM systems, the standard approach is to fuse
every frame into the dense model without considering whether the information contained
within the frame is already captured by the dense map and therefore redundant. As the
number of cameras or the scale of the map increases, this approach becomes inefficient. In
our second contribution, we address this inefficiency by introducing a novel information
theoretic approach to keyframe selection that allows the system to avoid processing
redundant information. We implement the procedure within ElasticFusion, demonstrating
a marked reduction in the number of frames required by the system to estimate an accurate,
denoised surface reconstruction.
Before dense SLAM techniques can be applied in outdoor scenarios we must
first address their reliance on active depth cameras, and their lack of suitability to fast
camera motion. In our third contribution we present an outdoor dense SLAM system. The system overcomes the need for an active sensor by employing neural network-based depth
inference to predict the geometry of the scene as it appears in each image. To address the
issue of camera tracking during fast motion we employ a hybrid architecture, combining
elements of both dense and sparse SLAM systems to perform camera tracking and to
achieve globally consistent dense mapping.
Automotive applications present a particularly important setting for dense visual
SLAM systems. Such applications are characterised by their use of wide FOV cameras and
are therefore not accurately modelled by the standard pinhole camera model. The fourth
contribution of this thesis is to extend the above hybrid sparse-dense monocular SLAM
system to cater for large FOV fisheye imagery. This is achieved by reformulating the
mapping pipeline in terms of the Kannala-Brandt fisheye camera model. To estimate depth,
we introduce a new version of the PackNet depth estimation neural network (Guizilini et
al., 2020) adapted for fisheye inputs.
To demonstrate the effectiveness of our contributions, we present experimental
results, computed by processing the synthetic ICL-NUIM dataset of Handa et al. (2014) as
well as the real-world TUM-RGBD dataset of Sturm et al. (2012). For outdoor SLAM we
show the results of our system processing the autonomous driving KITTI and KITTI-360
datasets of Geiger et al. (2012a) and Liao et al. (2021) respectively
Decentralized Ultra-Reliable Low-Latency Communications through Concurrent Cooperative Transmission
Emerging cyber-physical systems demand for communication technologies that enable seamless interactions between humans and physical objects in a shared environment. This thesis proposes decentralized URLLC (dURLLC) as a new communication paradigm that allows the nodes in a wireless multi-hop network (WMN) to disseminate data quickly, reliably and without using a centralized infrastructure. To enable the dURLLC paradigm, this thesis explores the practical feasibility of concurrent cooperative transmission (CCT) with orthogonal frequency-division multiplexing (OFDM). CCT allows for an efficient utilization of the medium by leveraging interference instead of trying to avoid collisions. CCT-based network flooding disseminates data in a WMN through a reception-triggered low-level medium access control (MAC). OFDM provides high data rates by using a large bandwidth, resulting in a short transmission duration for a given amount of data.
This thesis explores CCT-based network flooding with the OFDM-based IEEE 802.11 Non-HT and HT physical layers (PHYs) to enable interactions with commercial devices. An analysis of CCT with the IEEE 802.11 Non-HT PHY investigates the combined effects of the phase offset (PO), the carrier frequency offset (CFO) and the time offset (TO) between concurrent transmitters, as well as the elapsed time. The analytical results of the decodability of a CCT are validated in simulations and in testbed experiments with Wireless Open Access Research Platform (WARP) v3 software-defined radios (SDRs). CCT with coherent interference (CI) is the primary approach of this thesis.
Two prototypes for CCT with CI are presented that feature mechanisms for precise synchronization in time and frequency. One prototype is based on the WARP v3 and its IEEE 802.11 reference design, whereas the other prototype is created through firmware modifications of the Asus RT-AC86U wireless router. Both prototypes are employed in testbed experiments in which two groups of nodes generate successive CCTs in a ping-pong fashion to emulate flooding processes with a very large number of hops. The nodes stay synchronized in experiments with 10 000 successive CCTs for various modulation and coding scheme (MCS) indices and MAC service data unit (MSDU) sizes. The URLLC requirement of delivering a 32-byte MSDU with a reliability of 99.999 % and with a latency of 1 ms is assessed in experiments with 1 000 000 CCTs, while the reliability is approximated by means of the frame reception rate (FRR). An FRR of at least 99.999 % is achieved at PHY data rates of up to 48 Mbit/s under line-of-sight (LOS) conditions and at PHY data rates of up to 12 Mbit/s under non-line-of-sight (NLOS) conditions on a 20 MHz wide channel, while the latency per hop is 48.2 µs and 80.2 µs, respectively. With four multiple input multiple output (MIMO) spatial streams on a 40 MHz wide channel, a LOS receiver achieves an FRR of 99.5 % at a PHY data rate of 324 Mbit/s. For CCT with incoherent interference, this thesis proposes equalization with time-variant zero-forcing (TVZF) and presents a TVZF receiver for the IEEE 802.11 Non-HT PHY, achieving an FRR of up to 92 % for CCTs from three unsyntonized commercial devices. As CCT-based network flooding allows for an implicit time synchronization of all nodes, a reception-triggered low-level MAC and a reservation-based high-level MAC may in combination support various applications and scenarios under the dURLLC paradigm
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