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DLFormer: Enhancing Explainability in Multivariate Time Series Forecasting using Distributed Lag Embedding

arXiv.org Artificial Intelligence

Most of these data are multivariate, with multiple values at each time step (Wilms, Rombouts, & Croux, 2021; Lee, Kim & Sim, 2024). Consequently, utilizing multivariate time series data for knowledge extraction and application to societal issues is becoming increasingly prevalent, making multivariate time series prediction a challenging task widely regarded across most industries (Bidarkota, 1998). The traditional approach to addressing multivariate time series prediction problems involves using statistical methods, such as vector autoregression and autoregressive distributed lag (ARDL) models (Qu, Huang, She, Liad, & Lai, 2024). However, statistical methods may struggle to capture complex sequence patterns in the data because of irregularities and nonlinearities among the features (Salinas, Flunkert, Gasthaus, & Januschowski, 2020). Therefore, layer-based deep-learning models incorporating recurrent layers (Rumelhart, Hinton, & Williams, 1986), long short-term memory layers (Hochreiter & Schmidhuber, 1997), gated recurrent units (Chung, Gulcehre, Cho & Bengio, 2014), and attention mechanisms (Vaswani, Shazeer, Parmar, Uszkoreit, Jones, Gomez, & Polosukhin, 2017) have been widely explored in multivariate time series prediction (Catania, Grassi, & Ravazzolo, 2019). Deep learning-based models effectively learn sequential patterns in time series data and can outperform traditional statistical models, demonstrating superior prediction performance (Ortega, Otero, Solomon, Otero, & Fabregas, 2023). Another approach for improving the accuracy of multivariate time series prediction is to utilize models based on transformers, such as informers (Zhou, Zhang, Peng, Zhang, Li, Xiong, & Zhang, 2021) and autoformers (Wu, Xu, Wang, & Long, 2021). Transformer-based models effectively capture long-and short-term patterns in multivariate time series data and have surpassed traditional approaches in terms of prediction performance (Costa & Machado, 2023).


Coverage Analysis of Multi-Environment Q-Learning Algorithms for Wireless Network Optimization

arXiv.org Artificial Intelligence

Q-learning is widely used to optimize wireless networks with unknown system dynamics. Recent advancements include ensemble multi-environment hybrid Q-learning algorithms, which utilize multiple Q-learning algorithms across structurally related but distinct Markovian environments and outperform existing Q-learning algorithms in terms of accuracy and complexity in large-scale wireless networks. We herein conduct a comprehensive coverage analysis to ensure optimal data coverage conditions for these algorithms. Initially, we establish upper bounds on the expectation and variance of different coverage coefficients. Leveraging these bounds, we present an algorithm for efficient initialization of these algorithms. We test our algorithm on two distinct real-world wireless networks. Numerical simulations show that our algorithm can achieve %50 less policy error and %40 less runtime complexity than state-of-the-art reinforcement learning algorithms. Furthermore, our algorithm exhibits robustness to changes in network settings and parameters. We also numerically validate our theoretical results.


Characterization of point-source transient events with a rolling-shutter compressed sensing system

arXiv.org Machine Learning

Point-source transient events (PSTEs) - optical events that are both extremely fast and extremely small - pose several challenges to an imaging system. Due to their speed, accurately characterizing such events often requires detectors with very high frame rates. Due to their size, accurately detecting such events requires maintaining coverage over an extended field-of-view, often through the use of imaging focal plane arrays (FPA) with a global shutter readout. Traditional imaging systems that meet these requirements are costly in terms of price, size, weight, power consumption, and data bandwidth, and there is a need for cheaper solutions with adequate temporal and spatial coverage. To address these issues, we develop a novel compressed sensing algorithm adapted to the rolling shutter readout of an imaging system. This approach enables reconstruction of a PSTE signature at the sampling rate of the rolling shutter, offering a 1-2 order of magnitude temporal speedup and a proportional reduction in data bandwidth. We present empirical results demonstrating accurate recovery of PSTEs using measurements that are spatially undersampled by a factor of 25, and our simulations show that, relative to other compressed sensing algorithms, our algorithm is both faster and yields higher quality reconstructions. We also present theoretical results characterizing our algorithm and corroborating simulations. The potential impact of our work includes the development of much faster, cheaper sensor solutions for PSTE detection and characterization.


Enhanced forecasting of stock prices based on variational mode decomposition, PatchTST, and adaptive scale-weighted layer

arXiv.org Artificial Intelligence

The significant fluctuations in stock index prices in recent years highlight the critical need for accurate forecasting to guide investment and financial strategies. This study introduces a novel composite forecasting framework that integrates variational mode decomposition (VMD), PatchTST, and adaptive scale-weighted layer (ASWL) to address these challenges. Utilizing datasets of four major stock indices--SP500, DJI, SSEC, and FTSE--from 2000 to 2024, the proposed method first decomposes the raw price series into intrinsic mode functions (IMFs) using VMD. Each IMF is then modeled with PatchTST to capture temporal patterns effectively. The ASWL module is applied to incorporate scale information, enhancing prediction accuracy. The final forecast is derived by aggregating predictions from all IMFs. The VMD-PatchTST-ASWL framework demonstrates significant improvements in forecasting accuracy compared to traditional models, showing robust performance across different indices. This innovative approach provides a powerful tool for stock index price forecasting, with potential applications in various financial analysis and investment decision-making contexts.


Discovery of False Data Injection Schemes on Frequency Controllers with Reinforcement Learning

arXiv.org Artificial Intelligence

While inverter-based distributed energy resources (DERs) play a crucial role in integrating renewable energy into the power system, they concurrently diminish the grid's system inertia, elevating the risk of frequency instabilities. Furthermore, smart inverters, interfaced via communication networks, pose a potential vulnerability to cyber threats if not diligently managed. To proactively fortify the power grid against sophisticated cyber attacks, we propose to employ reinforcement learning (RL) to identify potential threats and system vulnerabilities. This study concentrates on analyzing adversarial strategies for false data injection, specifically targeting smart inverters involved in primary frequency control. Our findings demonstrate that an RL agent can adeptly discern optimal false data injection methods to manipulate inverter settings, potentially causing catastrophic consequences.


A compact neuromorphic system for ultra energy-efficient, on-device robot localization

arXiv.org Artificial Intelligence

Neuromorphic computing offers a transformative pathway to overcome the computational and energy challenges faced in deploying robotic localization and navigation systems at the edge. Visual place recognition, a critical component for navigation, is often hampered by the high resource demands of conventional systems, making them unsuitable for small-scale robotic platforms which still require to perform complex, long-range tasks. Although neuromorphic approaches offer potential for greater efficiency, real-time edge deployment remains constrained by the complexity and limited scalability of bio-realistic networks. Here, we demonstrate a neuromorphic localization system that performs accurate place recognition in up to 8km of traversal using models as small as 180 KB with 44k parameters, while consuming less than 1% of the energy required by conventional methods. Our Locational Encoding with Neuromorphic Systems (LENS) integrates spiking neural networks, an event-based dynamic vision sensor, and a neuromorphic processor within a single SPECK(TM) chip, enabling real-time, energy-efficient localization on a hexapod robot. LENS represents the first fully neuromorphic localization system capable of large-scale, on-device deployment, setting a new benchmark for energy efficient robotic place recognition.


Fire rages at oil depot in Russia's Rostov after Ukraine drone attack

Al Jazeera

A Ukrainian drone attack has set an oil depot in Russia's southern region of Rostov alight, the authorities said. On Wednesday, regional Governor Vasily Golubev confirmed the overnight strike, saying on the Telegram messaging app that firefighters were extinguishing the blaze at the depot in Rostov's Kamensky district, with no casualties reported. Russia's Ministry of Defence earlier said air defence units destroyed four drones over the region overnight, without mentioning the attack on the oil depot. Three tanks were burning at the oil depot after two drones fell in the area, according to the Baza Telegram channel, which is close to Russian security services. Ukraine's strike marked its latest attack on Russian oil and gas facilities in retaliation for attacks on its energy infrastructure.


Comparison of Model Predictive Control and Proximal Policy Optimization for a 1-DOF Helicopter System

arXiv.org Artificial Intelligence

This study conducts a comparative analysis of Model Predictive Control (MPC) and Proximal Policy Optimization (PPO), a Deep Reinforcement Learning (DRL) algorithm, applied to a 1-Degree of Freedom (DOF) Quanser Aero 2 system. Classical control techniques such as MPC and Linear Quadratic Regulator (LQR) are widely used due to their theoretical foundation and practical effectiveness. However, with advancements in computational techniques and machine learning, DRL approaches like PPO have gained traction in solving optimal control problems through environment interaction. This paper systematically evaluates the dynamic response characteristics of PPO and MPC, comparing their performance, computational resource consumption, and implementation complexity. Experimental results show that while LQR achieves the best steady-state accuracy, PPO excels in rise-time and adaptability, making it a promising approach for applications requiring rapid response and adaptability. Additionally, we have established a baseline for future RL-related research on this specific testbed. We also discuss the strengths and limitations of each control strategy, providing recommendations for selecting appropriate controllers for real-world scenarios.


RMMI: Enhanced Obstacle Avoidance for Reactive Mobile Manipulation using an Implicit Neural Map

arXiv.org Artificial Intelligence

We introduce RMMI, a novel reactive control framework for mobile manipulators operating in complex, static environments. Our approach leverages a neural Signed Distance Field (SDF) to model intricate environment details and incorporates this representation as inequality constraints within a Quadratic Program (QP) to coordinate robot joint and base motion. A key contribution is the introduction of an active collision avoidance cost term that maximises the total robot distance to obstacles during the motion. We first evaluate our approach in a simulated reaching task, outperforming previous methods that rely on representing both the robot and the scene as a set of primitive geometries. Compared with the baseline, we improved the task success rate by 25% in total, which includes increases of 10% by using the active collision cost. We also demonstrate our approach on a real-world platform, showing its effectiveness in reaching target poses in cluttered and confined spaces using environment models built directly from sensor data. For additional details and experiment videos, visit https://rmmi.github.io/.


From cart to truck: meaning shift through words in English in the last two centuries

arXiv.org Artificial Intelligence

This onomasiological study uses diachronic word embeddings to explore how different words represented the same concepts over time, using historical word data from 1800 to 2000. We identify shifts in energy, transport, entertainment, and computing domains, revealing connections between language and societal changes. Our approach consisted in using diachronic word embeddings trained using word2vec with skipgram and aligning them using orthogonal Procrustes. We discuss possible difficulties linked to the relationships the method identifies. Moreover, we look at the ethical aspects of interpreting results, highlighting the need for expert insights to understand the method's significance.