Karlis Freivalds

Dr. Karlis Freivalds


Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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28 June 2023 in Applied Sciences
Verified
Journal Article
Open access
PDF file
OVOskars Vismanis
Oskars Vismanis
Janis ArentsJanis Arents
Janis Arents
KFKarlis Freivalds
Karlis Freivalds
VAVaibhav Ahluwalia
Vaibhav Ahluwalia
Kaspars OzolsKaspars Ozols
Kaspars Ozols
Parcel sorting is becoming a significant challenge for delivery distribution centers and is mostly automated by using high-throughput sorting machinery, but manual work is still used to feed these machines by placing the parcels on the conveyor belt. In this paper, an AI-based robotic solution that automates the parcel placement task was developed. The architecture of the proposed system along with methods on how to implement it are described by using the currently available hardware and software components. The described choices lead to a well-functioning system and the gained insights will facilitate building similar systems for parcel delivery automation.

1 January 2022
Verified
Book Chapter
Closed access
PDF file
EGElīza Gaile
Elīza Gaile
ADAndis Draguns
Andis Draguns
EOEmīls Ozoliņš
Emīls Ozoliņš
KFKarlis Freivalds
Karlis Freivalds

14 September 2023
Verified
Book Chapter
Closed access
PDF file
RZRonalds Zakovskis
Ronalds Zakovskis
ADAndis Draguns
Andis Draguns
EGEliza Gaile
Eliza Gaile
EOEmils Ozolins
Emils Ozolins
KFKarlis Freivalds
Karlis Freivalds

22 September 2023
Verified
Book Chapter
Closed access
PDF file
KFKarlis Freivalds
Karlis Freivalds
EOEmīls Ozoliņš
Emīls Ozoliņš
GBGuntis Bārzdiņš
Guntis Bārzdiņš

13 March 2026 in Applied Sciences
Verified
Journal Article
Open access
PDF file
Arturs NikulinsArturs Nikulins
Arturs Nikulins
KFKarlis Freivalds
Karlis Freivalds
INIvars Namatevs
Ivars Namatevs
KSKaspars Sudars
Kaspars Sudars
AAAudris Arzovs
Audris Arzovs
Kaspars OzolsKaspars Ozols
Kaspars Ozols
Accurate remaining useful life (RUL) prediction is essential for the safe and cost-effective operation of safety-critical systems such as electronic components and engines. While data-driven machine learning approaches have demonstrated strong performance for RUL estimation, their effectiveness is limited by the lack of full run-to-failure data and by strict privacy and intellectual property constraints in industrial settings. Federated learning (FL) enables collaborative model training across multiple data owners without direct data sharing, but it does not, by itself, provide formal privacy guarantees and remains vulnerable to information leakage. This paper presents a privacy-preserving DP-enhanced FL setup for RUL prediction that combines federated learning with differential privacy (DP). We describe an end-to-end implementation based on the Opacus DP library, highlight practical challenges arising from the integration of DP into recurrent neural network architectures, and propose solutions to address them. Using two representative RUL datasets (CMAPSS and SiC MOSFET), we analyze the effect of DP noise on prediction performance and on the functional dependence between the predicted RUL and the already lived life feature. The results demonstrate that differential privacy can be integrated into federated RUL prediction with limited degradation in predictive performance, providing practical insights for deploying privacy-aware collaborative models in industrial environments.

22 November 2023 in arXiv
Verified
Preprint
Open access
PDF file
RZRonalds Zakovskis
Ronalds Zakovskis
ADAndis Draguns
Andis Draguns
EGEliza Gaile
Eliza Gaile
EOEmils Ozolins
Emils Ozolins
KFKarlis Freivalds
Karlis Freivalds
Recurrent neural networks have flourished in many areas. Consequently, we can see new RNN cells being developed continuously, usually by creating or using gates in a new, original way. But what if we told you that gates in RNNs are redundant? In this paper, we propose a new recurrent cell called Residual Recurrent Unit (RRU) which beats traditional cells and does not employ a single gate. It is based on the residual shortcut connection, linear transformations, ReLU, and normalization. To evaluate our cell's effectiveness, we compare its performance against the widely-used GRU and LSTM cells and the recently proposed Mogrifier LSTM on several tasks including, polyphonic music modeling, language modeling, and sentiment analysis. Our experiments show that RRU outperforms the traditional gated units on most of these tasks. Also, it has better robustness to parameter selection, allowing immediate application in new tasks without much tuning. We have implemented the RRU in TensorFlow, and the code is made available at https://github.com/LUMII-Syslab/RRU .