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Publikācijas
729 publikācijas
- 2024
Precise realtime current consumption measurement in IoT TestBed(atveras jaunā logā)
Rihards Balass, Vladislavs Medvedevs, Andris Ivars Mackus, Juris Ormanis, Armands Ancans, Janis Judvaitis
Open Research Europe, Sēj. 3 (7), Taylor & Francis
Kopsavilkums
Background The Internet of Things, similar to wireless sensor networks, has been integrated into the daily life of almost everyone. These wearable, stationary, or mobile devices are in multiple locations, collecting data or monitoring and executing certain tasks. Some can monitor environmental values and interact with the environment, while others are used for data collection, entertainment, or even lifesaving. To achieve the wireless part of the system, the majority of sensor nodes are designed to be battery-powered. While battery power has become increasingly ubiquitous, it tends to increase the global carbon footprint of electronic devices. This issue can be mitigated by employing some form of energy harvesting so that batteries can be refilled and the gadget lasts longer, but this does not alter the reality that batteries are still used and eventually discarded. Methods In this paper, the authors emphasize the significance of power consumption in battery-powered devices. To be able to monitor devices’ power consumption, one of the measurable parameters is current. When users know the exact current consumption, they can decrease it by polishing the program or tweaking the duty cycle, making radio transmit fewer data or less frequently, thus decreasing overall power draw. Results In order to simplify current consumption monitoring, the authors have developed a testbed facility that provides real-time current consumption measurements, which may be used to enhance the duty cycle and battery life of the aforementioned devices. Conclusions While minimizing total current consumption is a great way to extend the battery life and, thus, the carbon footprint, the primary culprit in the Internet of Things is radio communications. This transmission is the primary source of current consumption. By determining the exact amount of current drawn during transmission and adjusting it, users can significantly extend battery life.
Indeksēts Scopus / WoS · Scopus procentile: 58
- 2024
Evaluation of Two-Electrode System Configurations for Forearm Arteries Bioimpedance Measurement(atveras jaunā logā)
Margus Metshein, Ksenija Pesti, Didzis Lapsa, Paul Annus, Rims Janeliukstis, Atis Elsts, Olev Martens
2024 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), lpp. 1-6
Kopsavilkums
Pulse wave monitoring for hemodynamic parameter acquisition, including blood pressure, constitutes a challenge for wearable device development. Hypertension as a target for such development forms a global health issue. An important aspect is the connection to the object-electrode-skin interface-from which many problems in electrical measurements originate. Finite element model simulations and experimental measurements of forearm arteries' electrical bioimpedance have been presented in this paper to evaluate the two-electrode system compared to the four-electrode system in distal and perpendicular placement relative to the artery. The four-electrode system has been reported to provide higher pulsating blood volume proportions, reaching 0.09% from the total measured impedance in distal placement, while the two-electrode system exhibits lower values (0.05%). A strong positive correlation between the simulation and experimental results appeared in distal two-electrode placement (r=0.718), while the outcome is reversed in the perpendicular approach (r=-0.539). The experimented two-electrode system configurations are applicable in wearable device development but require further analysis for the perpendicular placement.
Indeksēts Scopus / WoS
- 2024
PPG and Bioimpedance-Based Wearable Applications in Heart Rate Monitoring—A Comprehensive Review(atveras jaunā logā)
Didzis Lapsa, Rims Janeliukstis, Margus Metshein, Leo Selavo
Applied Sciences, Sēj. 14 (17), lpp. 7451, MDPI
Kopsavilkums
The monitoring of hemodynamic parameters, such as heart rate and blood pressure, provides valuable indications of overall cardiovascular health. It is preferable that such monitoring is non-invasive and in real time via an affordable, compact and small-scale device for maximum convenience. Numerous literature sources have exploited derivations of these parameters from photoplethysmogram (PPG) and electrical bioimpedance (EBI) signal measurements through the use of calculation algorithms of varying complexity. Compared to electrocardiogram (ECG), these measurement techniques have a merit of well-established practices of designing a wearable device that could conveniently be put on a wrist. The current paper provides a comprehensive review on the use of PPG and EBI measurement techniques in the context of hemodynamic parameter monitoring using a wearable device. A special emphasis is placed on the most basic hemodynamic parameter—heart rate—describing different algorithms of heart rate detection and monitoring. The last section provides an overview of commercially available and in-home wearable device technologies based on PPG and EBI measurements, their design challenges, and future prospects.
Indeksēts Scopus / WoS · Scopus procentile: 75
- 2024
Clock Synchronization and Network Delay Evaluation over a Private 5G Standalone Network
Marcis Kalnins, Artis Rusins, Atis Elsts
2024 International Workshop on Fiber Optics in Access Networks (FOAN)
Kopsavilkums
5G Standalone (SA) networks are the next generation of cellular networks, with broad applications envisioned in domains including IoT. In this article, we evaluate the feasibility of using Precision Time Protocol (PTP) to tightly synchronize User Equipment (UE) devices connected to a private 5G SA network. Our goal is to achieve sub-millisecond time synchronization accuracy in order to make the system applicable for industrial-automation IoT networks with stringent timing requirements. We measure the network delay and clock synchronization accuracy through clock comparison utilizing the pulse-per-second output from a UE network card and conclude that the desired accuracy remains challenging, with typical experiments demonstrating multi-millisecond clock offsets with significant and unpredictable drift.
Indeksēts Scopus / WoS
- 2024
Resilience and Vulnerability of Consumer Wireless Devices to Cyber Attacks(atveras jaunā logā)
Peteris Paikens, Krisjanis Nesenbergs
International Conference on Cyber Conflict, CYCON, NATO CCD COE Publications
Informācija
Indeksēts Scopus / WoS
- 2024
On an Eigenplace Function - Mapping Relational to Absolute Space
Jurģis Šķilters, Līga Zariņa, Guntis Vilnis Strazds
Baltic Journal of Modern Computing, Sēj. 12 (3), University of Latvia, Institute of Mathematics and Informatics
Kopsavilkums
In this study we provide a descriptive framework of an Eigenplace function that maps from the relational space between objects to the numerical coordinate space that is a part of external reality. Our approach assumes that the Eigenplace function maps cognitively valid space (the relational structure linked with temporal intervals) to a mathematical set of coordinates. After a description of a detailed spatial ontology, some generalizations are discussed.
Indeksēts Scopus / WoS · Scopus procentile: 34
- 2024
E-Poster: The effect of osteoporosis on the bone quantity and quality of the edentulous mandible(atveras jaunā logā)
Anda Slaidina, Laura Neimane, Oskars Radzins, Ivars Namatevs, Kaspars Sudars
Clinical Oral Implants Research, Sēj. 35 (28), John Wiley & Sons
Informācija
Indeksēts Scopus / WoS · Scopus procentile: 97
- 2024
Automated classification of pollens relevant to veterinary medicine(atveras jaunā logā)
Blaz Cugmas, Eva Štruc, Inese Bērziņa, Mindaugas Tamošiūnas, Laura Goldberga, Thierry Olivry, Kārlis Zviedris, Roberts Kadiķis, Maksims Ivanovs, Miran Bürmen, Peter Naglič
2024 IEEE 14th International Conference Nanomaterials: Applications & Properties (NAP), IEEE
Kopsavilkums
Pollen monitoring is helpful for medical purposes, weather or crop forecasting, and climate change analysis. Several automatic pollen sampling and identification systems based on digital microscopy, elastic light scattering, fluorescence, and digital holography have been proposed as an aid for real-time monitoring. Pollens are important aeroallergens also in veterinary medicine, leading to flares of atopic dermatitis in dogs, cutaneous or respiratory allergy in horses, and feline atopic syndrome. In this study, we tested a machine learning model, MobileNet V3 Large, for pollen classification in whole slide images. We included four pollen types relevant to veterinary medicine: Bermuda (Cynodon dactylon) and Timothy grass (Phleum pratense), silver birch (Betula pendula), and olive tree (Olea europaea). The average classification accuracy was 88 %. Most misidentifications occurred between the two grass pollens. After grouping Bermuda and Timothy grass together, the average classification accuracy increased to 98%. We showed that the machine learning model can be beneficial for the automated identification of pollens relevant to veterinary medicine.
Indeksēts Scopus / WoS
- 2024
MONOSTATIC PULSED ULTRA-WIDEBAND RADAR ANTENNA FOR STUDYING BIOLOGICAL RHYTHMS OF THE HUMAN BODY AND INTERNAL INHOMOGENEITIES OF DIELECTRIC OBJECTS(atveras jaunā logā)
V. Aristov
Automatic Control and Computer Sciences, Sēj. 58 (1), lpp. 101-108, © Allerton Press
Kopsavilkums
The paper presents a study of the prerequisites and the original way of transition from quasi-monostatic antenna system to monostatic as applied to ultra-wideband pulsed contact radar subsurface sounding at shallow depths. For this purpose, the joint application of ultra-wideband electric "Bow-Tie" and magnetic "Bi-Quad" antennas is investigated. The mutual arrangement proposed in this work allows reducing to zero the distance between the centers of the antennas in the plane orthogonal to the direction of signal emission-reception. Results of full-scale tests with corresponding processing of obtained ensembles by the example of probing human body for detection and determination of parameters of biological rhythms and a tree trunk 58 cm in diameter showed satisfactory results for the radar with a central frequency of 1.5 GHz. At the same time, the suppression of the useful received signal due to application of the described design was only 2.3 dB at an acceptable level of the direct signal, which does not lead to overloading of the radar stroboscopic receiver input.
Indeksēts Scopus / WoS
- 2024
A Set of Tools and Data Management Framework for the IoT–Edge–Cloud Continuum(atveras jaunā logā)
Judvaitis J, Blumbergs E, Arzovs A, Mackus AI, Balass R, Selavo L.
Applied System Innovation (ISSN 2571-5577), 2024, Sēj. 7 (6), MDPI
Kopsavilkums
Developing and managing complex IoT–Edge–Cloud Continuum (IECC) systems are challenging due to the system complexity and diversity. Internet of Things (IoT), Edge, and Cloud components combined with artificial intelligence (AI) in data processing systems must ensure strong security and privacy for data sources. The approach of the IECC Data Management Framework (DMF) introduces a novel combination of multiple easy-to-configure plugin environments using data visualization features. These contributions collectively address the critical challenges inherent in heterogeneous environments such as scalability, data privacy, and configuration management by standardizing data flow configurations and increasing stakeholder trust in sensitive applications, particularly in critical infrastructure monitoring.
Indeksēts Scopus / WoS
- 2024
Permanent Magnets in Sustainable Energy: Comparative Life Cycle Analysis
Orlova, S.; Rassõlkin, A.
Energies 2024
- 2024
Experimental study of a solar trigeneration system prototype
Snegirjovs, A., Klavs, G.
Latvian Journal of Physics and Technical Sciences, Sēj. 61 (4), lpp. 67–74
- 2024
Potential of Renewable Energy Communities in Latvia’s Energy Sector Transformation
Kudrenickis I., Klāvs G., Rekis J.
Proceedings of the 23rd Int. conf. “Engineering for Rural Development”, lpp. 550-557
- 2024
Energy Efficient Renovation of the Multi-Apartment Buildings: Management, Economic and Engineering Aspects
Kudrenickis I., Ernsteins R., Biezina L., Ikstena R.
Ibid, lpp. 978-990
- 2024
Learning to Move Objects With Fluid Streams in a Differentiable Simulation(atveras jaunā logā)
Kārlis Freivalds, Laura Leja, Oskars Teikmanis
2024 7th Iberian Robotics Conference, ROBOT 2024, IEEE
Kopsavilkums
We introduce a method for contactless manipulation of objects in three-dimensional space using controlled fluid streams. To achieve this, we train a neural network controller in a differentiable simulation and evaluate it in a simulated environment consisting of an 8 × 8 grid of vertical emitters. By carrying out various horizontal displacement tasks such as moving objects to specific positions while reacting to external perturbations, we demonstrate that a controller, trained with a limited number of iterations, can generalise to longer episodes and learn the complex dynamics of fluid-solid interactions. Importantly, our approach requires only the observation of the manipulated object's state, paving the way for the development of physical systems that enable contactless manipulation of objects using air streams.
Indeksēts Scopus / WoS
- 2023
Edge AI LoRa Mesh Technologies(atveras jaunā logā)
Ovidiu Vermesan, Kai vorm Walde, Roy Bahr, Cordula Conrady, Jānis Judvaitis, Gatis Gaigals, Tore Karlsen, Marcello Coppola, Hans-Erik Sand
Advancing Edge Artificial Intelligence System Contexts, River Publishers
Kopsavilkums
Intelligent connectivity at the edge combines wireless communication, edge artificial intelligence (AI), edge computing and internet of things (IoT) technologies to perform machine learning (ML) and deep learning (DL) tasks on connected edge devices. Low latency, ultra-low energy intelligent IoT devices with on-board computing, using a distributed architecture and analytics are essential as the intelligent connectivity advances. Intelligent wireless mesh technologies refer to network architectures that employ multiple interconnected devices or nodes to create a mesh-like distributed network topology integrated with edge AI analytics using ML and DL algorithms and embedded into various IoT systems. In an intelligent wireless mesh network (WMN), each node has embedded intelligence and can communicate directly with its neighbouring nodes and transfer data efficiently to other nodes. The intelligent wireless mesh approach offers several advantages, including increased coverage, embedded intelligence, redundancy, and scalability compared to traditional point-to-point wireless networks. The convergence of technologies (e.g., connectivity, edge AI, IoT, distributed architectures, federated learning) results in intelligent edge mesh communication systems performing efficiently connectivity tasks by optimising data rates, coverage, energy, and interference. This paper overviews the latest advancements in edge AI LoRa mesh technologies and applications, highlights the state-of-the-art mesh communication requirements and implementations, and sketches future research challenges and directions.
- 2023
Method and apparatus for dynamic testing of structural joints(atveras jaunā logā)
Mironovs V, Zemcenkovs V, Serdjuks D, Lapkovskis V, Tatarinovs A, Kurtenoks V
Journal of Physics: Conference Series, Sēj. 2423 (12023), lpp. 012017
Kopsavilkums
The dynamic testing technique is used during the design phase of structures and series production. This test evaluates the structural capacity, especially of the assemblies, to withstand different forces and rates of impact encountered under realistic operational conditions. This study proposes a magnetic pulse exciter for high-speed impact loading in dynamic tests because of its capability to provide single and repeatable pulse loading over a wide range of force up to 20 kN and pulse durations from 10 up to 1000 ms. The method transforms accumulated electrical energy in a capacitor bank into mechanical energy. For experimental investigations, flat and cylindrical coil devices were used for a capacitor-type pulse current generator. The proposed method has been experimentally validated on timber beams in a specified volume of force loading. The technique demonstrated a potential for controlling force and energy parameters. The effects of operating voltage on coil and 'metal plate - coil' distance on the amplitude of dynamic loading have been investigated. Aluminium and steel plates fastened to the object at the point of impact were used to improve excitation efficiency. The developed technique can be used in experimental studies on model joints and real objects.
Indeksēts Scopus / WoS
- 2023
Wide-field Raman spectral band imaging of tumor lesions in veterinary medicine(atveras jaunā logā)
Mindaugas Tamošiūnas, Roberts Kadiķis, Mikus Melderis, Romāns Maļiks, Diāna Duplevska, Daira Viškere, Ilze Matīse-van Houtana, Blaž Cugmas
Translational Biophotonics: Diagnostics and Therapeutics III, Sēj. 12627, lpp. 295-302, SPIE
Kopsavilkums
Skin and subcutaneous tumors are common in companion animals, that can be difficult to diagnose and treat. Raman spectroscopy shows high diagnostic accuracy in identifying malignant tumors and benign lipomas in dogs and cats. However, the traditional single-point raster scanning approach is not ideal for a large-field-of-view Raman imaging due to its time-consuming nature when scanning areas larger than a square centimeter. Additionally, focusing the excitation spot can lead to high levels of light fluency (J/cm2), potentially causing damage to tissue biomolecules. Furthermore, the resulting raster-scan image often lacks sufficient spatial resolution to effectively compare it with tissue morphology findings. In this study, we focused on implementing EMCCD camera-based Raman imaging to accurately capture Raman spectral band signatures and overcome autofluorescence interference in veterinary cancer samples ex vivo. By utilizing the tunable band-pass filters set-up, our system enables large-field-of-view imaging of specific Raman bands, such as the 1437 cm-1 band or 1652 cm-1 band in biological tissue, proposing a more efficient, accurate and safe approach for Raman imaging in the veterinary field.
Indeksēts Scopus / WoS · Scopus procentile: 8 · SNIP: 0.235
- 2023
Technology Modules Providing Solutions for Agile Manufacturing(atveras jaunā logā)
Miha Deniša, Aleš Ude, Mihael Simoniˇc, Tero Kaarlela, Tomi Pitkäaho, Sakari Pieskä, Janis Arents, Janis Judvaitis, Kaspars Ozols, Levente Raj, András Czmerk, Morteza Dianatfar, Jyrki Latokartano, Patrick Alexander Schmidt, Anton Mauersberger, Adrian Singer, Halldor Arnarson, Beibei Shu, Dimosthenis Dimosthenopoulos, Panagiotis Karagiannis, Teemu-Pekka Ahonen, Veikko Valjus and Minna Lanz
Machines, Sēj. 11 (9), lpp. 877, MDPI
Kopsavilkums
In this paper, we address the most pressing challenges faced by the manufacturing sector, particularly the manufacturing of small and medium-sized enterprises (SMEs), where the transition towards high-mix low-volume production and the availability of cost-effective solutions are crucial. To overcome these challenges, this paper presents 14 innovative solutions that can be utilized to support the introduction of agile manufacturing processes in SMEs. These solutions encompass a wide range of key technologies, including reconfigurable fixtures, low-cost automation for printed circuit board (PCB) assembly, computer-vision-based control, wireless sensor networks (WSNs) simulations, predictive maintenance based on Internet of Things (IoT), virtualization for operator training, intuitive robot programming using virtual reality (VR), autonomous trajectory generation, programming by demonstration for force-based tasks, on-line task allocation in human–robot collaboration (HRC), projector-based graphical user interface (GUI) for HRC, human safety in collaborative work cells, and integration of automated ground vehicles for intralogistics. All of these solutions were designed with the purpose of increasing agility in the manufacturing sector. They are designed to enable flexible and modular manufacturing systems that are easy to integrate and use while remaining cost-effective for SMEs. As such, they have a high potential to be implemented in the manufacturing industry. They can be used as standalone modules or combined to solve a more complicated task, and contribute to enhancing the agility, efficiency, and competitiveness of manufacturing companies. With their application tested in industrially relevant environments, the proposed solutions strive to ensure practical implementation and real-world impact. While this paper presents these solutions and gives an overview of their methodologies and evaluations, it does not go into their details. It provides summaries of comprehensive and multifaceted solutions to tackle the evolving needs and demands of the manufacturing sector, empowering SMEs to thrive in a dynamic and competitive market landscape.
Indeksēts Scopus / WoS · Scopus procentile: 47 · SNIP: 1.102
- 2023
(POSTER) Drone Detection and Localization using Low-Cost Microphone Arrays and Convolutional Neural Networks
Peteris Racinskis, Janis Arents, Modris Greitans
2023 19th International Conference on Distributed Computing in Smart Systems and the Internet of Things (DCOSS-IoT), Sēj. 19 (19), lpp. 80-82, IEEE
Kopsavilkums
This paper examines the possibility of using low-cost commercial off-the-shelf audio recording equipment in combination with machine learning techniques to discover the presence of hostile UAVs. A convolutional neural network (CNN) was trained to detect and localize two types of quadrotor drones using ground truth position data collected with motion capture equipment. System performance was evaluated on pre-recorded validation data sets and in real-time operation. In both cases, drones can be successfully detected and localized within the constrained working volumes studied, achieving angular accuracies in the 8-13 deg range. However, further work remains to be done before system feasibility in outdoor conditions can be established.
Indeksēts Scopus / WoS