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Anomaly Detection


Research Assistant/Associate in Machine Learning (Fixed Term) at University of Cambridge

#artificialintelligence

We are seeking a Research Assistant / Associate to join the Toyota-Cambridge Centre for Next Generation AI, a unique and significant research partnership between the Department of Engineering at the University of Cambridge and Toyota Motor Corporation which is developing new fundamental tools for machine intelligence and machine learning. The position will lead the Cambridge-Toyota-Future Prediction project which will develop methods for predicting future events and environmental changes drawing on a range of approaches such as predictive modelling, novelty detection, change-point detection, self-supervised learning, deep learning, online learning, continual learning and meta-learning. The Research Assistant/Associate will join the Machine Learning Group at the Department of Engineering at the University of Cambridge (http://mlg.eng.cam.ac.uk/), and will be supervised by Prof. The project will receive additional supervision from Dr. Daniel Olmeda Reino and Dr. Rahaf Al Jundi from Toyota Motor Europe. The programme is funded by a research contract with Toyota Motor Corporation.


Data Science Road Map 2021 -- The Ultimate Guide

#artificialintelligence

To stand out, we recommend you master one of these fields. They are very popular in the jobs market now. Remote Sensing is the use of satellite or aircraft-based sensor technologies to detect and classify objects on Earth. Download opensource satellite images using packages like Rasterio and Folium, get meaningful and insightful data from every pixel in a satellite image.


GitHub - salesforce/Merlion: Merlion: A Machine Learning Framework for Time Series Intelligence

#artificialintelligence

Merlion is a Python library for time series intelligence. It provides an end-to-end machine learning framework that includes loading and transforming data, building and training models, post-processing model outputs, and evaluating model performance. It supports various time series learning tasks, including forecasting and anomaly detection for both univariate and multivariate time series. This library aims to provide engineers and researchers a one-stop solution to rapidly develop models for their specific time series needs, and benchmark them across multiple time series datasets. The table below provides a visual overview of how Merlion's key features compare to other libraries for time series anomaly detection and/or forecasting.


Council Post: 14 Smart Ways Businesses Can Leverage AI For Growth And Efficiency

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Artificial intelligence may not be a fringe technology anymore, but that doesn't mean businesses are using it to its full potential. From automating repetitive processes to forecasting to better serving customers and clients, companies can realize significant productivity gains and cost savings from the smart application of AI. Even though AI's potential applications are widespread, businesses would be wise to take focused, careful steps in applying the technology to best meet their unique needs. Below, 14 industry experts from Forbes Technology Council share smart ways leaders can introduce AI into their businesses right now. We use AI to automate manual processes--especially when it comes to data entry.


How To Improve Data Quality When With Unsupervised Machine Learning

#artificialintelligence

There won't be any business insights if the data quality is poor. When preparing data, I often go through many different approaches to reach a level of quality of data that can provide accurate results. In this article, I describe how unsupervised ML can help in data preparation for machine learning projects and how it helps to get more accurate business insights. For accurate predictions, the data must not only be properly labeled, de-deputed, broad, consistent, etc. The point is that the machine learning model should process the "right" data.


An Evaluation of Anomaly Detection and Diagnosis in Multivariate Time Series

arXiv.org Machine Learning

Several techniques for multivariate time series anomaly detection have been proposed recently, but a systematic comparison on a common set of datasets and metrics is lacking. This paper presents a systematic and comprehensive evaluation of unsupervised and semi-supervised deep-learning based methods for anomaly detection and diagnosis on multivariate time series data from cyberphysical systems. Unlike previous works, we vary the model and post-processing of model errors, i.e. the scoring functions independently of each other, through a grid of 10 models and 4 scoring functions, comparing these variants to state of the art methods. In time-series anomaly detection, detecting anomalous events is more important than detecting individual anomalous time-points. Through experiments, we find that the existing evaluation metrics either do not take events into account, or cannot distinguish between a good detector and trivial detectors, such as a random or an all-positive detector. We propose a new metric to overcome these drawbacks, namely, the composite F-score ($Fc_1$), for evaluating time-series anomaly detection. Our study highlights that dynamic scoring functions work much better than static ones for multivariate time series anomaly detection, and the choice of scoring functions often matters more than the choice of the underlying model. We also find that a simple, channel-wise model - the Univariate Fully-Connected Auto-Encoder, with the dynamic Gaussian scoring function emerges as a winning candidate for both anomaly detection and diagnosis, beating state of the art algorithms.


Learning to Rank Anomalies: Scalar Performance Criteria and Maximization of Two-Sample Rank Statistics

arXiv.org Machine Learning

The ability to collect and store ever more massive databases has been accompanied by the need to process them efficiently. In many cases, most observations have the same behavior, while a probable small proportion of these observations are abnormal. Detecting the latter, defined as outliers, is one of the major challenges for machine learning applications (e.g. in fraud detection or in predictive maintenance). In this paper, we propose a methodology addressing the problem of outlier detection, by learning a data-driven scoring function defined on the feature space which reflects the degree of abnormality of the observations. This scoring function is learnt through a well-designed binary classification problem whose empirical criterion takes the form of a two-sample linear rank statistics on which theoretical results are available. We illustrate our methodology with preliminary encouraging numerical experiments.


Deep Spatio-temporal Sparse Decomposition for Trend Prediction and Anomaly Detection in Cardiac Electrical Conduction

arXiv.org Artificial Intelligence

Electrical conduction among cardiac tissue is commonly modeled with partial differential equations, i.e., reaction-diffusion equation, where the reaction term describes cellular stimulation and diffusion term describes electrical propagation. Detecting and identifying of cardiac cells that produce abnormal electrical impulses in such nonlinear dynamic systems are important for efficient treatment and planning. To model the nonlinear dynamics, simulation has been widely used in both cardiac research and clinical study to investigate cardiac disease mechanisms and develop new treatment designs. However, existing cardiac models have a great level of complexity, and the simulation is often time-consuming. We propose a deep spatio-temporal sparse decomposition (DSTSD) approach to bypass the time-consuming cardiac partial differential equations with the deep spatio-temporal model and detect the time and location of the anomaly (i.e., malfunctioning cardiac cells). This approach is validated from the data set generated from the Courtemanche-Ramirez-Nattel (CRN) model, which is widely used to model the propagation of the transmembrane potential across the cross neuron membrane. The proposed DSTSD achieved the best accuracy in terms of spatio-temporal mean trend prediction and anomaly detection.


A Simple Unified Framework for Anomaly Detection in Deep Reinforcement Learning

arXiv.org Artificial Intelligence

Abnormal states in deep reinforcement learning~(RL) are states that are beyond the scope of an RL policy. Such states may make the RL system unsafe and impede its deployment in real scenarios. In this paper, we propose a simple yet effective anomaly detection framework for deep RL algorithms that simultaneously considers random, adversarial and out-of-distribution~(OOD) state outliers. In particular, we attain the class-conditional distributions for each action class under the Gaussian assumption, and rely on these distributions to discriminate between inliers and outliers based on Mahalanobis Distance~(MD) and Robust Mahalanobis Distance. We conduct extensive experiments on Atari games that verify the effectiveness of our detection strategies. To the best of our knowledge, we present the first in-detail study of statistical and adversarial anomaly detection in deep RL algorithms. This simple unified anomaly detection paves the way towards deploying safe RL systems in real-world applications.


Towards a Rigorous Evaluation of Time-series Anomaly Detection

arXiv.org Artificial Intelligence

In recent years, proposed studies on time-series anomaly detection (TAD) report high F1 scores on benchmark TAD datasets, giving the impression of clear improvements. However, most studies apply a peculiar evaluation protocol called point adjustment (PA) before scoring. In this paper, we theoretically and experimentally reveal that the PA protocol has a great possibility of overestimating the detection performance; that is, even a random anomaly score can easily turn into a state-of-the-art TAD method. Therefore, the comparison of TAD methods with F1 scores after the PA protocol can lead to misguided rankings. Furthermore, we question the potential of existing TAD methods by showing that an untrained model obtains comparable detection performance to the existing methods even without PA. Based on our findings, we propose a new baseline and an evaluation protocol. We expect that our study will help a rigorous evaluation of TAD and lead to further improvement in future researches.