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Berken Utku Demirel

9 accepted papers

2025

Learning Without Augmenting: Unsupervised Time Series Representation Learning via Frame Projections

NeurIPS 2025poster

Self-supervised learning (SSL) has emerged as a powerful paradigm for learning representations without labeled data. Most SSL approaches rely on strong, well-established, handcrafted data augmentations to generate diverse views for representation learning. However, designing such augmentations requi…

Cited by 0SourcecodeScholar
2025

Shifting the Paradigm: A Diffeomorphism Between Time Series Data Manifolds for Achieving Shift-Invariancy in Deep Learning

ICLR 2025poster

Deep learning models lack shift invariance, making them sensitive to input shifts that cause changes in output. While recent techniques seek to address this for images, our findings show that these approaches fail to provide shift-invariance in time series, where the data generation mechanism is mor…

2024

An Unsupervised Approach for Periodic Source Detection in Time Series

ICML 2024poster

Detection of periodic patterns of interest within noisy time series data plays a critical role in various tasks, spanning from health monitoring to behavior analysis. Existing learning techniques often rely on labels or clean versions of signals for detecting the periodicity, and those employing sel…

2024

MiBOT: A head-worn robot that modulates cardiovascular responses through human-like soft massage

ICRA 2024poster

Massage therapy is helpful for the rehabilitation of various diseases, such as headaches caused by migraines and stress. Existing robotic systems have focused on massage therapy on the torso and limbs, but performing massage motions through suitable actuation on a person’s head has been a challenge.…

Cited by 0SourceScholar
2024

WildPPG: A Real-World PPG Dataset of Long Continuous Recordings

NeurIPS 2024poster

Reflective photoplethysmography (PPG) has become the default sensing technique in wearable devices to monitor cardiac activity via a person’s heart rate (HR). However, PPG-based HR estimates can be substantially impacted by factors such as the wearer’s activities, sensor placement and resulting moti…

Cited by 0SourcePDFScholar
2023

BeliefPPG: Uncertainty-aware heart rate estimation from PPG signals via belief propagation

UAI 2023poster

We present a novel learning-based method that achieves state-of-the-art performance on several heart rate estimation benchmarks extracted from photoplethysmography signals (PPG). We consider the evolution of the heart rate in the context of a discrete-time stochastic process that we represent as a h…

2023

Cancelling Intermodulation Distortions for Otoacoustic Emission Measurements with Earbuds

ICASSP 2023accepted

This paper presents a novel cancellation method of Intermodulation Distortions (IMDs) for earbud speakers used to measure Distortion Product Otoacoustic Emissions (DPOAE). Speakers’ non-linear behaviour is a significant problem for earbuds with small loudspeakers due to limitations in cone movement.…

Cited by 0SourceScholar
2023

Finding Order in Chaos: A Novel Data Augmentation Method for Time Series in Contrastive Learning

NeurIPS 2023poster

The success of contrastive learning is well known to be dependent on data augmentation. Although the degree of data augmentations has been well controlled by utilizing pre-defined techniques in some domains like vision, time-series data augmentation is less explored and remains a challenging problem…