Goto

Collaborating Authors

 South America



Physics-informed neural networks for solving parametric magnetostatic problems

arXiv.org Artificial Intelligence

The objective of this paper is to investigate the ability of physics-informed neural networks to learn the magnetic field response as a function of design parameters in the context of a two-dimensional (2-D) magnetostatic problem. Our approach is as follows. First, we present a functional whose minimization is equivalent to solving parametric magnetostatic problems. Subsequently, we use a deep neural network (DNN) to represent the magnetic field as a function of space and parameters that describe geometric features and operating points. We train the DNN by minimizing the physics-informed functional using stochastic gradient descent. Lastly, we demonstrate our approach on a \mbox{ten-dimensional} EI-core electromagnet problem with parameterized geometry. We evaluate the accuracy of the DNN by comparing its predictions to those of finite element analysis.


An Ontology for Defect Detection in Metal Additive Manufacturing

arXiv.org Artificial Intelligence

In this context, additive manufacturing (AM), and specifically metal additive manufacturing (MAM), is particularly suited to industrial paradigms based on automation, flexibility, and efficiency. Indeed, MAM can be considered as a native digital technology, providing a seamless workflow from the digital design environment to the final product, which can be potentially completed without any human intervention [30]. However, a broader adoption of MAM technologies in industry is still hindered by such factors as: (i) lack of widely adopted standardisations and specifications of material properties, machines, and processes [40]; (ii) lack of adequate digital infrastructures, and interoperability issues between different production environments [7]; (iii) lack of accessible interfaces providing process information that is easily interpretable by non-experts [47]; (iv) lack of advanced control systems capable of automatically adjusting, at run-time, the production parameters [54]; (v) challenges in quality assurance due part accuracy and variability [48]. Thus, achieving semantically transparent and interoperable data sets and systems, to address Points (i), (ii) and (iii) above, is arguably of paramount importance. In this direction, several approaches based on ontology engineering and knowledge representation techniques have been proposed [29, 10, 66, 67, 60]. Broadly conceived as formal specifications of conceptualisations over a domain of interest, computational ontologies (cf.


Causal Inference via Nonlinear Variable Decorrelation for Healthcare Applications

arXiv.org Artificial Intelligence

Features Explanation Heart Disease age middle Patients between the ages of 40 and 60 #major vessels0 The number of major vessels (0-3) colored by flourosopy is 0 fixed defect Thalium stress test result is fixed defect pressure normal Blood pressure within the normal range ST-T wave abnormality Resting electrocardiography result is ST-T wave abnormality cholesterol edge Serum cholesterol is in range (200, 220] mg/dl lower than 120mg/ml Fasting blood sugar is lower than 120mg/ml non-anginal pain Chest pain type is non-angina cholesterol high Serum cholesterol is higher than 220 mg/dl no exercise induced angina not Exercise induced angina downsloping Slope of peak exercise ST segment is downsloping heart disease It refers to the presence of heart disease in the patient Esophageal Cancer Modified Ryan Score 2.0 (near complete response): single cells or rare small groups of cancer cells Esophagectomy Procedure 4 Complete MIS/Robotic McKeown (Three-Hole) esophagectomy tobacco use Use tobacco Alcohol Use Use Alcohol Neoadjuvant Radiation Patient underwent neoadjuvant radiation Histological Grade 2 How differentiated the tumor is: Moderately Differentiated Final Histology 1 History: Adenocarcinoma Histological Grade 3 How differentiated the tumor is: Poorly Differentiated clinical m Stage 1 Details any spread (metastasis) to other sites of the body: M0 esoph tumor location 4 Lower Thoracic, including GE junction Esophagectomy Procedure 5 Hybrid (Laparoscopy + Thoracotomy) McKeown (Three-Hole) esophagectomy recurrence Details whether the patient experience recurrence of their cancer Cauda Equina Syndrome elixsum


REST: REtrieve & Self-Train for generative action recognition

arXiv.org Artificial Intelligence

This work is on training a generative action/video recognition model whose output is a free-form action-specific caption describing the video (rather than an action class label). A generative approach has practical advantages like producing more fine-grained and human-readable output, and being naturally open-world. To this end, we propose to adapt a pre-trained generative Vision & Language (V&L) Foundation Model for video/action recognition. While recently there have been a few attempts to adapt V&L models trained with contrastive learning (e.g. CLIP) for video/action, to the best of our knowledge, we propose the very first method that sets outs to accomplish this goal for a generative model. We firstly show that direct fine-tuning of a generative model to produce action classes suffers from severe overfitting. To alleviate this, we introduce REST, a training framework consisting of two key components: an unsupervised method for adapting the generative model to action/video by means of pseudo-caption generation and Self-training, i.e. without using any action-specific labels; (b) a Retrieval approach based on CLIP for discovering a diverse set of pseudo-captions for each video to train the model. Importantly, we show that both components are necessary to obtain high accuracy. We evaluate REST on the problem of zero-shot action recognition where we show that our approach is very competitive when compared to contrastive learning-based methods. Code will be made available.


Rethinking and Recomputing the Value of ML Models

arXiv.org Artificial Intelligence

In this paper, we argue that the way we have been training and evaluating ML models has largely forgotten the fact that they are applied in an organization or societal context as they provide value to people. We show that with this perspective we fundamentally change how we evaluate, select and deploy ML models - and to some extent even what it means to learn. Specifically, we stress that the notion of value plays a central role in learning and evaluating, and different models may require different learning practices and provide different values based on the application context they are applied. We also show that this concretely impacts how we select and embed models into human workflows based on experimental datasets. Nothing of what is presented here is hard: to a large extent is a series of fairly trivial observations with massive practical implications.


TERMinator: A system for scientific texts processing

arXiv.org Artificial Intelligence

This paper is devoted to the extraction of entities and semantic relations between them from scientific texts, where we consider scientific terms as entities. In this paper, we present a dataset that includes annotations for two tasks and develop a system called TERMinator for the study of the influence of language models on term recognition and comparison of different approaches for relation extraction. Experiments show that language models pre-trained on the target language are not always show the best performance. Also adding some heuristic approaches may improve the overall quality of the particular task. The developed tool and the annotated corpus are publicly available at https://github.com/iis-research-team/terminator and may be useful for other researchers.


Watch What You Pretrain For: Targeted, Transferable Adversarial Examples on Self-Supervised Speech Recognition models

arXiv.org Artificial Intelligence

A targeted adversarial attack produces audio samples that can force an Automatic Speech Recognition (ASR) system to output attacker-chosen text. To exploit ASR models in real-world, black-box settings, an adversary can leverage the transferability property, i.e. that an adversarial sample produced for a proxy ASR can also fool a different remote ASR. However recent work has shown that transferability against large ASR models is very difficult. In this work, we show that modern ASR architectures, specifically ones based on Self-Supervised Learning, are in fact vulnerable to transferability. We successfully demonstrate this phenomenon by evaluating state-of-the-art self-supervised ASR models like Wav2Vec2, Hu-BERT, Data2Vec and WavLM. We show that with low-level additive noise achieving a 30dB Signal-Noise Ratio, we can achieve target transferability with up to 80% accuracy. Next, we 1) use an ablation study to show that Self-Supervised learning is the main cause of that phenomenon, and 2) we provide an explanation for this phenomenon. Through this we show that modern ASR architectures are uniquely vulnerable to adversarial security threats. Adversarial audio algorithms are designed to force Automatic Speech Recognition (ASR) models to produce incorrect outputs. They do so by introducing small amounts of imperceptible, carefully crafted noise to benign audio samples that can force the ASR model to produce incorrect transcripts. Specifically, targeted adversarial attacks (Carlini & Wagner, 2018; Qin et al., 2019) are designed to force ASR models to output any target sentence of the attacker's choice. However, these attacks have limited effectiveness as they make unreasonable assumptions (e.g., white-box access to the model weights), which are unlikely to be satisfied in real-world settings. An attacker could hypothetically bypass this limitation by using the transferability property of adversarial samples: they generate adversarial samples for a white-box proxy model; then pass these to a different remote black-box model, as we illustrate in Figure 1a.


Patients' Severity States Classification based on Electronic Health Record (EHR) Data using Multiple Machine Learning and Deep Learning Approaches

arXiv.org Artificial Intelligence

This research presents an examination of categorizing the severity states of patients based on their electronic health records during a certain time range using multiple machine learning and deep learning approaches. The suggested method uses an EHR dataset collected from an open-source platform to categorize severity. Some tools were used in this research, such as openRefine was used to pre-process, RapidMiner was used for implementing three algorithms (Fast Large Margin, Generalized Linear Model, Multi-layer Feed-forward Neural Network) and Tableau was used to visualize the data, for implementation of algorithms we used Google Colab. Here we implemented several supervised and unsupervised algorithms along with semi-supervised and deep learning algorithms. The experimental results reveal that hyperparameter-tuned Random Forest outperformed all the other supervised machine learning algorithms with 76% accuracy as well as Generalized Linear algorithm achieved the highest precision score 78%, whereas the hyperparameter-tuned Hierarchical Clustering with 86% precision score and Gaussian Mixture Model with 61% accuracy outperformed other unsupervised approaches. Dimensionality Reduction improved results a lot for most unsupervised techniques. For implementing Deep Learning we employed a feed-forward neural network (multi-layer) and the Fast Large Margin approach for semi-supervised learning. The Fast Large Margin performed really well with a recall score of 84% and an F1 score of 78%. Finally, the Multi-layer Feed-forward Neural Network performed admirably with 75% accuracy, 75% precision, 87% recall, 81% F1 score.


Online Weighted Q-Ensembles for Reduced Hyperparameter Tuning in Reinforcement Learning

arXiv.org Artificial Intelligence

Reinforcement learning is a promising paradigm for learning robot control, allowing complex control policies to be learned without requiring a dynamics model. However, even state of the art algorithms can be difficult to tune for optimum performance. We propose employing an ensemble of multiple reinforcement learning agents, each with a different set of hyperparameters, along with a mechanism for choosing the best performing set(s) on-line. In the literature, the ensemble technique is used to improve performance in general, but the current work specifically addresses decreasing the hyperparameter tuning effort. Furthermore, our approach targets on-line learning on a single robotic system, and does not require running multiple simulators in parallel. Although the idea is generic, the Deep Deterministic Policy Gradient was the model chosen, being a representative deep learning actor-critic method with good performance in continuous action settings but known high variance. We compare our online weighted q-ensemble approach to q-average ensemble strategies addressed in literature using alternate policy training, as well as online training, demonstrating the advantage of the new approach in eliminating hyperparameter tuning. The applicability to real-world systems was validated in common robotic benchmark environments: the bipedal robot half cheetah and the swimmer. Online Weighted Q-Ensemble presented overall lower variance and superior results when compared with q-average ensembles using randomized parameterizations.