Research
Publications
729 publications
- 2020
Operational Algorithm for Natural Gas Boiler and Heat Pump System Optimization with PV Panel(opens in a new window)
R. Lazdins and A. Mutule
2020 IEEE 61th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON), Riga, Latvia, p. 1-4
- 2020
Life cycle analysis of electrical motor drive system based on electrical machine type
Rassōlkin A., Belahcen A., Kallaste A., Vaimann T., Orlova S.
Proceedings of the Estonian Academy of Sciences
- 2020
Latvia’s Climate and Energy Policy Goals, Solutions, and Analytical Methods
Cilinskis, E., Klāvs, G., & Reķis, J.
Akadēmiskā dzīve, University of Latvia
- 2020
Automatic tree species classification from Sentinel 2 images using deficient inventory data(opens in a new window)
J. Sinica-Sinavskis, R. Dinuls, J. Zarins, I. Mednieks
Proceedings of the Biennial Baltic Electronics Conference, IEEE Computer Society
Abstract
The paper presents a novel tree species classification approach based on an automated analysis of Sentine1-2 images, where deficient inventory data from an analysis area are available for reference. The procedure proposed involves clustering of one or several multispectral images of the area of interest taken in different seasons, with the subsequent assignment of a particular tree species class to each cluster by using sparse and imprecise inventory data. The analysis is performed only within the forest areas separated using the forest mask obtained from LiDAR scanning data. Classification results are tested against the ground truth prepared manually from remote sensing images or taken from the same kind of imprecise inventory data. An analysis of a sample area in Latvia for which the sparse inventory data was available was performed. Several clustering algorithms were compared, and it is shown that recently proposed Dynland clustering algorithm has advantages over the traditional k-means clustering. Identification of the most important 4 species was targeted, and it is shown that considerable classification accuracy, with a kappa coefficient up to 0.9 can be achieved in this case by the approach proposed. The proposed approach can be used within automatic workflows for estimation of forest microstand parameters from remote sensing data. © 2020 IEEE.
Indexed in Scopus / WoS
- 2020
Functional architecture for autonomous driving and its implementation(opens in a new window)
R. Novickis, A. Levinskis, R. Kadikis, V. Fescenko, K. Ozols
Proceedings of the Biennial Baltic Electronics Conference, IEEE Computer Society
Abstract
It is predicted that due to such technology-driven trends as electrification, connectivity, autonomous driving and diverse mobility, the automotive market will reach a size of 6.7 trillion USD in 2030. Nevertheless, the composition and architectures of the future autonomous vehicles are still unsettled due to the continuous advancement of sensors and computing hardware, availability and interpretation of new data and safety requirements. Given the existing architectures of the autonomous systems, there is a lack of start-To-end depiction of the self-driving car design and components. This scientific article aspires to serve as a starting guide and boilerplate for the evolution of future architectures of such autonomous systems. The article summarizes the previous research in the field, describes the overall hardware and software composition of the EDI Drive-by-Wire car and investigates the components of the autonomous system: data acquisition, perception algorithms, chosen hardware, software component management, vehicle interfacing, approach to failsafe and fail-operational functionalities. © 2020 IEEE.
Indexed in Scopus / WoS
- 2020
Bird's-eye view image acquisition from simulated scenes using geometric inverse perspective mapping(opens in a new window)
D. Justs, R. Novickis, K. Ozols, M. Greitans
Proceedings of the Biennial Baltic Electronics Conference, IEEE Computer Society
Abstract
echnology advancement, major investments, and mainstream interest have reignited the prospect of autonomous driving, nevertheless, the achievement of reliable perception is still an active research topic. This article examines a technique for simplifying path planning and control algorithms by reducing spacial dimensions to two, i.e. by acquiring a Bird's-Eye View (BEV) image. This article aspires to facilitate novel perception fusion approaches by specifying a geometric approach for inverse perspective mapping (IPM), construction of composite BEV of the vehicle, giving suggestions for implementation and proposing a coherent, BEV-based approach for perception fusion. The proposed geometric IPM approach for BEV image acquisition is suited for simulated environments with limited knowledge of the camera's intrinsic parameters. © 2020 IEEE.
Indexed in Scopus / WoS
- 2019
Reliability of Loading Rate in Gait Analysis(opens in a new window)
V. Abolins, K. Nesenbergs, E. Bernans
IOP Conference Series: Materials Science and Engineering, Vol. 575 (1), p. 012002, Institute of Physics Publishing
Abstract
Loading rate is an important parameter of running gait as it is commonly associated with increased risk of injury. In this paper we show, that most of the research related to calculating loading rate values from ground reaction force data cannot be directly compared, as the absolute loading rate values and the related first impact peak location and height are highly dependent on the filtering method used, cut-off frequency selected as well as loading rate calculation method selected. The results are based on running trial data from non-forefoot striking long distance runners gathered by the authors.
Indexed in Scopus / WoS · SNIP: 0.484
- 2019
Life cycle cost analysis of BBTM and traditional asphalt concretes in Latvia(opens in a new window)
A. Riekstins, V. Hartinovs, V. Abolins, V. Straupe, J. Tihonovs
Engineering for Rural Development, Vol. 18, p. 1065 - 1072, Latvia University of Life Sciences and Technologies
Abstract
Effective investing of public money in the road infrastructure should be the basis for construction of new roads or reconstruction of the existing ones. Funding for the maintenance of the road infrastructure in Latvia has been insufficient since the restoration of independence. This means the existing budget funds should be used sustainably. One of the solutions that are offered is the use of thin asphalt layers (BBTM). This solution has proven to be a cost-effective and sustainable asphalt wearing course. One of the main problems at the road design stage is to determine which asphalt concrete types would be most beneficial in the long-term due to the maintenance cost, which can significantly increase the overall cost. The current practice in Latvia is that there are some guidelines for choosing the best asphalt concrete types depending on the intensity. However, the initial construction costs do not reflect the costs of the owner to restoring and maintaining this road in the long term; for example, for a period of 40 years. For this purpose, the life cycle cost analyses (LCCA) is widely used worldwide. It is a method based on statistical data and the probable distribution of their forecasts, which makes it possible to compare different options for the road pavement. The aim of this study is to evaluate the possibilities of using thin asphalt concrete layers (BBTM) in Latvia and to compare it with traditionally used asphalt layers using the life-cycle cost analysis (LCCA). High-performance results were obtained from the Wheel Tracking test and Shear test during the research of testing a thin asphalt layer (BBTM) in the laboratory. Also, the life cycle cost analysis (LCCA) of asphalt mixes was performed for the road section. © 2019 Latvia University of Agriculture. All rights reserved.
Indexed in Scopus / WoS
- 2019
I-MECH – Smart System Integration for Mechatronic Applications(opens in a new window)
Martin Čech, Arend-Jan Beltman , Kaspars Ozols
IEEE International Conference on Emerging Technologies and Factory Automation, p. 843 - 850, IEEE
Abstract
Emerging mechatronic applications aim to work at limit performance and reliability while their size and operational space is getting restricted more and more. To reach those targets, often fast integration of customized components is necessary, either electronic systems, SW modules, sensors or actuators. Such diverse set of components needs special tool-chains and methods for fast customization and optimization respecting MBSE (model based system engineering) principles. Large-scale I-MECH project is a natural, fully industry driven initiative trying to follow those demands. The purpose of this paper is to describe its core scientific content, report initial milestones and show a variety of application where I-MECH components, so called building blocks, are being applied.
Indexed in Scopus / WoS
- 2019
Влияние нелинейности быстрого пилообразного напряжения на стробоскопическое преобразование сигналов в приёмниках сенсоров - локаторов
В. Аристов.
Автоматика и вычислительная техника, Vol. 2019 (4), p. 45-53
Abstract
<p>В. Аристов. Влияние нелинейности быстрого пилообразного напряжения на стробоскопическое преобразование сигналов в приёмниках сенсоров - локаторов. Рига, Автоматика и вычислительная техника. 2019 (4), стр. 45-53.</p> <p>Для стробоскопического преобразователя, применяемого в импульсных сверхширокополосных сенсорах-локаторах гигагерцового диапазона, произведено моделирование пилообразного напряжения с возможностью изменения нелинейности последнего. Математически описан механизм автосдвига импульсов выборки сигнала, на основании которого получена формула закона сдвига вышеуказанных импульсов при нелинейном быстром пилообразном напряжении. Показано влияние нелинейности этого напряжения на выходной сигнал стробоскопического преобразователя.</p>
- 2019
The Effect of Inaccuracy of Digital-to-Analog Conversion on Properties of the Up-and-Down Method for Digital Signal Processing(opens in a new window)
V. Plocins
Automatic Control and Computer Sciences, Vol. 52 (4), p. 317 - 321, Pleiades Publishing
Abstract
The effect of nonideality of the digital-to-analog conversion on properties of the up-anddown method is investigated. Two models for implementation of the up-and-down method, with their own reasons for inaccuracy, are considered and the consequences compared. © 2018, Allerton Press, Inc.
Indexed in Scopus / WoS · SNIP: 0.676
- 2019
Automatic data labeling by neural networks for the counting of objects in videos(opens in a new window)
I. Namatevs, K. Sudars, I. Polaka.
Procedia Computer Science, Vol. 149, p. 151 - 158, Elsevier B.V.
Abstract
The paper proposes an efficient method for training a neural network to count moving objects in a video, while another neural network concurrently prepares a labeled dataset for the first one. The detection, tracking, and counting of objects is crucial for effective Intelligence Transportation Systems (ITS), which should reduce congestion and recognize traffic offenders on highways and in urban areas. Creation of labeled data for training a neural network is one of the essential prerequisites for successful application of supervised machine learning. In this paper, the experimental results of the automatic labeling and counting of vehicles under real world conditions are shown. The method shows that by using the Convolutional Neural Network (CNN), the computing power and speed-up time for training a Recurrent Neural Network (RNN) with a Long Short-Term Memory (LSTM) cell for counting moving objects can be decreased. © 2019 The Author(s).
Indexed in Scopus / WoS · Q1/Q2 journal · SNIP: 1.035
- 2019
Low-power wireless sensor network system for early diagnostic of subacute rumen acidosis in cows(opens in a new window)
A. Zabasta, N. Kunicina, K. Vitols, I. Duritis, U. Grunde, J. Judvaitis, M. Greitans, I. Sematovica, A. Malniece I. Galkins
Advances in Information, Electronic and Electrical Engineering, Institute of Electrical and Electronics Engineers Inc.
Abstract
High-yielding cow rations under intensive production conditions contribute to the development of subacute rumen acidosis (SARA), leading to pathologies such as rumenitis, laminitis, reproductive disorders, loss of productivity and reduced longevity. The aim of this work is to develop a reticulo-ruminal long-acting cyber-physical system for monitoring rumen parameters. Three scientific institutions in cooperation with two farmers conduct the research in order to create a prototype of a low-power wireless sensor network system for early diagnostic of subacute rumen acidosis of dairy cows. The new system architecture includes, reticulo-ruminal bolus with pH and temperature sensors, a microcontroller, a radio transmitter and a power supply module. The system includes a base station for data collection from boluses, an MQTT broker, a web server and a database. Data communication solution has been developed and tested in the laboratory, and micro-controllers have been selected and adapted for data processing. In addition, research is under way to create an autonomous long-term power supply system. Work shall be conducted in two directions: (a) stand-alone battery-powered electricity supply system; (b) an autonomous power supply system based on the generation of an electrostatic generator. The results of the initial stage of the research are discussed in this paper.
Indexed in Scopus / WoS
- 2019
Challenges of DevOps ready IoT Testbed
Judvaitis, J., Nesenbergs, K., Balass, R. and Greitans, M
MDE4IoT/ModComp@ MoDELS, Vol. 2442, p. 3-6, CEUR-WS
Abstract
Developing, deploying, testing and validating complex software systems is complicated and as a result security, privacy and quality in general often suffer due to limited resources and rapid development cycles. In the case of IoT system development there are additional levels of complexity and risks. In this paper we present our ongoing effort towards providing and validating a solution for these problems as a toolset/TestBed implementing previously established ENACT IoT DevOps concepts and Framework, aimed at ensuring continued Quality of Service and application of best practices during development cycle of IoT systems. Copyright © 2019 for this paper by its authors.
SNIP: 0.345
- 2019
Mobile Robot Performance at Restricted Energy and Autonomy
A. Baums
Automatic Control and Computer Sciences
Abstract
<p>A. Baums Mobile Robot Performance at Restricted Energy and Autonomy</p>
- 2019
Mobile Robot Performance at Restricted Energy and Autonomy(opens in a new window)
A. Baums
Automatic Control and Computer Sciences, Vol. 53 (1), p. 90 - 95, Pleiades Publishing
Abstract
Two methods are proposed to estimate the performance of ground mobile robots. As the performance criterion, the distance the robot is able to cover to reach the event place by using its inner energy source is selected. In the first method, it is assumed that all the distance to the GPS can be overcame by the robot under operator control. In the second method, the distance is divided into operator-controlled and robot autonomous motion ones, and the energy needed in this case is analyzed. © 2019, Allerton Press, Inc.
Indexed in Scopus / WoS · SNIP: 0.676
- 2019
The Effect of Inaccuracy of Digital-to-Analog Conversion on Properties of the Up-and-Down Method for Digital Signal Processing
V. Plocins
Automatic Control and Computer Sciences
Abstract
<p>V. Plocins The Effect of Inaccuracy of Digital-to-Analog Conversion on Properties of the Up-and-Down Method for Digital Signal Processing</p>
- 2019
Equilateral Monogonal Tessellation of Arbitrary Polygons-a Recursive Algorithm(opens in a new window)
K. Nesenbergs
Malaysian Journal of Mathematical Sciences, Vol. 13, p. 51 - 64, Universiti Putra Malaysia
Abstract
Tessellation or tiling can be useful in multiple domains, such as computer graphics, physics, architecture etc. In this article the tessellation problem is explored and a recursive algorithm is proposed, implemented and validated for generating equilateral monogonal tessellations (including all semi-regular tessellations) in two dimensions inside any arbitrary simple polygon
Indexed in Scopus / WoS · SNIP: 0.476
- 2019
Estimating the Precision of a Leading-Edge Discriminator with Amplitude Correction(opens in a new window)
V. Bespaļko, I. Burak, K. Salmiņš
Instruments and Experimental Techniques, Vol. 62 (6), p. 788-793, Pleiades Publishing
Abstract
The formation of time stamps that are independent of the sensor output pulse amplitude in the domain of event timing is well-known problem. It is shown that the time-stamp accuracy (time walk) can be estimated using high-speed arbitrary-signal generators and general-purpose time meters with an uncertainty of the estimate of no worse than 0.2 ps. The efficiency of the technique is demonstrated for a leading-edge discriminator (LED). The proposed LED version combined with an amplitude meter and amplitude correction has a 17-ps time walk.
SNIP: 0.763
- 2019
Differences in vertical ground reaction forces during first attempt of barefoot running in habitual shod runners(opens in a new window)
V. Abolins, E. Bernans, J. Lanka
Journal of Physical Education and Sport, Vol. 18 (4), p. 2308 - 2313, Editura Universitatii din Pitesti
Abstract
Many suggest that switching from shod running to barefoot running decreases injury risk and makes running more natural. Scientists have reported biomechanical differences in shod and barefoot running, with a number of differences related to increased injury risk. Our research is focused on investigating the acute differences when switching to barefoot running for the first time. Twenty long distance runners were subjected to an experiment as part of this research. The subjects ran 5 trials across two force plates both in shod and barefoot conditions. The ground reaction force (GRF) was recorded for each subject. The stance time, the initial impact loading rate (LR), the impact maximum (IM), the time when the IM was reached, the thrust maximum, the average vertical GRF, and the decay rate (DR) were calculated from the obtained GRF. The results show that the mean LR and DR were greater by 42.191 BW/s (p=0.006) and 5.922 BW/s (p<0.001) respectively in barefoot running compared to shod running. The mean stance time and the time to IM was greater by 10.15 ms (p=0.013) and 5.00 ms (p=0.017) respectively in shod running compared to barefoot running. IM and LR had a significant correlation in shod running condition only (r=0.842, p<0.001). Both conditions, however, had significant correlation between LR and time to IM (shod: r=-0.646, p=0.002; Bare: r=-0.741, p<0.001). According to our data, the responses of the subjects to barefoot running were not unambiguous and in some cases not less traumatic. © JPES.
Indexed in Scopus / WoS · Q1/Q2 journal · SNIP: 1