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Evaluating Short-Term Forecasting of Multiple Time Series in IoT Environments

arXiv.org Artificial Intelligence

Modern Internet of Things (IoT) environments are monitored via a large number of IoT enabled sensing devices, with the data acquisition and processing infrastructure setting restrictions in terms of computational power and energy resources. To alleviate this issue, sensors are often configured to operate at relatively low sampling frequencies, yielding a reduced set of observations. Nevertheless, this can hamper dramatically subsequent decision-making, such as forecasting. To address this problem, in this work we evaluate short-term forecasting in highly underdetermined cases, i.e., the number of sensor streams is much higher than the number of observations. Several statistical, machine learning and neural network-based models are thoroughly examined with respect to the resulting forecasting accuracy on five different real-world datasets. The focus is given on a unified experimental protocol especially designed for short-term prediction of multiple time series at the IoT edge. The proposed framework can be considered as an important step towards establishing a solid forecasting strategy in resource constrained IoT applications.


Ubisoft confirms 'Assassin's Creed Mirage,' a stand-alone title in the Middle East

Engadget

After plenty of leaks, Ubisoft has confirmed that Assassin's Creed Mirage is the next entry in its long-running series. More details are expected to drop during the Ubisoft Forward event September 10th, but for now we can gleam some tidbits from the announcement image. It shows Basim Ibn Ishaq, a character from the recent Assassin's Creed Valhalla, leaping with his hidden blade in front of the Palace of the Golden Gate in Baghdad (via Polygon). That lines up with previous leaks around the game's setting, which also indicated that Mirage would be a return to stealth gameplay for the series. The new title was originally intended to be DLC for Valhalla, but Bloomberg reports that it was later transformed into a standalone experience to fill out Ubisoft's release schedule. No matter its conception, it's nice to see the series return to its Middle Eastern roots.


Taiwan's military shoots down first drone over Kinmen island

Al Jazeera

Taipei, Taiwan โ€“ Taiwan's military has said it shot down an unidentified civilian drone over the outlying island of Kinmen amid a continuing increase in Chinese military activity around the island since last month's controversial visit by US House of Representatives Speaker Nancy Pelosi. The drone, which was shot down on Thursday, is the first to be hit following a warning from Taiwan that it would use live ammunition against drones. The threat came after a video of Taiwanese soldiers throwing rocks at a Chinese drone went viral. Drone flights have reportedly escalated near Kinmen, which is located a few kilometres off the coast of China, and around the Matsu Islands in the East China Sea. The decision to fire on Chinese drones is a departure for Taiwan's military, said Yen-Chi Hsu, an assistant researcher at Taiwan's Council on Strategic and Wargaming Studies.


Hybrid Artifact Detection System for Minute Resolution Blood Pressure Signals from ICU

arXiv.org Artificial Intelligence

Physiological monitoring in intensive care units (ICU) generates data that can be used in clinical research. However, the recording conditions in clinical settings limit the automated extraction of relevant information from physiological signals due to noise and artifacts. Therefore, removing artifacts before clinical research is essential. Manual annotation by experienced researchers, which is the gold standard for removing artifacts, is time-consuming and costly due to the volume of the data generated in the ICU. In this study, we propose a hybrid artifact detection system that combines a Variational Autoencoder with a statistical detection component for the labeling of artifactual samples to automate the costly process of cleaning physiological recordings. The system is applied to minute-by-minute mean blood pressure signals from an intensive care unit dataset. Its performance is verified by manual annotations made by an expert. We benchmark the performance of our system with two other systems that combine an ARIMA or an autoencoder-based model with our statistical detection component. Our results indicate that the system consistently achieves sensitivity and specificity levels of over 90%. Thus, it provides an initial foundation to automate data cleaning in recordings from ICU.


ARMA Cell: A Modular and Effective Approach for Neural Autoregressive Modeling

arXiv.org Artificial Intelligence

The autoregressive moving average (ARMA) model is a classical, and arguably one of the most studied approaches to model time series data. It has compelling theoretical properties and is widely used among practitioners. More recent deep learning approaches popularize recurrent neural networks (RNNs) and, in particular, long short-term memory (LSTM) cells that have become one of the best performing and most common building blocks in neural time series modeling. While advantageous for time series data or sequences with long-term effects, complex RNN cells are not always a must and can sometimes even be inferior to simpler recurrent approaches. In this work, we introduce the ARMA cell, a simpler, modular, and effective approach for time series modeling in neural networks. This cell can be used in any neural network architecture where recurrent structures are present and naturally handles multivariate time series using vector autoregression. We also introduce the ConvARMA cell as a natural successor for spatially-correlated time series. Our experiments show that the proposed methodology is competitive with popular alternatives in terms of performance while being more robust and compelling due to its simplicity.


'I'm afraid': critics of anti-cheating technology for students hit by lawsuits

The Guardian

In 2020, a Canadian university employee named Ian Linkletter became increasingly alarmed by a new kind of technology that was exploding in use with the pandemic. It was meant to detect cheating by college and high-school students taking tests at home, and claimed to work by watching students' movements and analyzing sounds around them through their webcams and microphones to automatically flag suspicious behavior. So Linkletter accessed a section of the website of one of the anti-cheating companies, named Proctorio, intended only for instructors and administrators. He shared what he found on social media. Now Linkletter, who became a prominent critic of the technology, has been sued by the company. But he is not the only one.


Physically Constrained Generative Adversarial Networks for Improving Precipitation Fields from Earth System Models

arXiv.org Artificial Intelligence

Precipitation results from complex processes across many scales, making its accurate simulation in Earth system models (ESMs) challenging. Existing post-processing methods can improve ESM simulations locally, but cannot correct errors in modelled spatial patterns. Here we propose a framework based on physically constrained generative adversarial networks (GANs) to improve local distributions and spatial structure simultaneously. We apply our approach to the computationally efficient ESM CM2Mc-LPJmL. Our method outperforms existing ones in correcting local distributions, and leads to strongly improved spatial patterns especially regarding the intermittency of daily precipitation. Notably, a double-peaked Intertropical Convergence Zone, a common problem in ESMs, is removed. Enforcing a physical constraint to preserve global precipitation sums, the GAN can generalize to future climate scenarios unseen during training. Feature attribution shows that the GAN identifies regions where the ESM exhibits strong biases. Our method constitutes a general framework for correcting ESM variables and enables realistic simulations at a fraction of the computational costs.


A differentiable short-time Fourier transform with respect to the window length

arXiv.org Artificial Intelligence

In this paper, we revisit the use of spectrograms in neural networks, by making the window length a continuous parameter optimizable by gradient descent instead of an empirically tuned integer-valued hyperparameter. The contribution is mostly theoretical at this point, but plugging the modified STFT into any existing neural network is straightforward. We first define a differentiable version of the STFT in the case where local bins centers are fixed and independent of the window length parameter. We then discuss the more difficult case where the window length affects the position and number of bins. We illustrate the benefits of this new tool on an estimation and a classification problems, showing it can be of interest not only to neural networks but to any STFT-based signal processing algorithm.


AtmoDist: Self-supervised Representation Learning for Atmospheric Dynamics

arXiv.org Artificial Intelligence

Representation learning has proven to be a powerful methodology in a wide variety of machine learning applications. For atmospheric dynamics, however, it has so far not been considered, arguably due to the lack of large-scale, labeled datasets that could be used for training. In this work, we show that the difficulty is benign and introduce a self-supervised learning task that defines a categorical loss for a wide variety of unlabeled atmospheric datasets. Specifically, we train a neural network on the simple yet intricate task of predicting the temporal distance between atmospheric fields from distinct but nearby times. We demonstrate that training with this task on ERA5 reanalysis leads to internal representations capturing intrinsic aspects of atmospheric dynamics. We do so by introducing a data-driven distance metric for atmospheric states. When employed as a loss function in other machine learning applications, this Atmodist distance leads to improved results compared to the classical $\ell_2$-loss. For example, for downscaling one obtains higher resolution fields that match the true statistics more closely than previous approaches and for the interpolation of missing or occluded data the AtmoDist distance leads to results that contain more realistic fine scale features. Since it is derived from observational data, AtmoDist also provides a novel perspective on atmospheric predictability.


The Development of a Labelled te reo M\=aori-English Bilingual Database for Language Technology

arXiv.org Artificial Intelligence

Te reo M\=aori (referred to as M\=aori), New Zealand's indigenous language, is under-resourced in language technology. M\=aori speakers are bilingual, where M\=aori is code-switched with English. Unfortunately, there are minimal resources available for M\=aori language technology, language detection and code-switch detection between M\=aori-English pair. Both English and M\=aori use Roman-derived orthography making rule-based systems for detecting language and code-switching restrictive. Most M\=aori language detection is done manually by language experts. This research builds a M\=aori-English bilingual database of 66,016,807 words with word-level language annotation. The New Zealand Parliament Hansard debates reports were used to build the database. The language labels are assigned using language-specific rules and expert manual annotations. Words with the same spelling, but different meanings, exist for M\=aori and English. These words could not be categorised as M\=aori or English based on word-level language rules. Hence, manual annotations were necessary. An analysis reporting the various aspects of the database such as metadata, year-wise analysis, frequently occurring words, sentence length and N-grams is also reported. The database developed here is a valuable tool for future language and speech technology development for Aotearoa New Zealand. The methodology followed to label the database can also be followed by other low-resourced language pairs.