Vytautas Markevicius
Kaunas University of Technology
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Featured researches published by Vytautas Markevicius.
Sensors | 2016
Vytautas Markevicius; Dangirutis Navikas; Mindaugas Zilys; Darius Andriukaitis; Algimantas Valinevicius; M. Cepenas
The vehicle detection process plays the key role in determining the success of intelligent transport management system solutions. The measurement of distortions of the Earth’s magnetic field using magnetic field sensors served as the basis for designing a solution aimed at vehicle detection. In accordance with the results obtained from research into process modeling and experimentally testing all the relevant hypotheses an algorithm for vehicle detection using the state criteria was proposed. Aiming to evaluate all of the possibilities, as well as pros and cons of the use of anisotropic magnetoresistance (AMR) sensors in the transport flow control process, we have performed a series of experiments with various vehicles (or different series) from several car manufacturers. A comparison of 12 selected methods, based on either the process of determining the peak signal values and their concurrence in time whilst calculating the delay, or by measuring the cross-correlation of these signals, was carried out. It was established that the relative error can be minimized via the Z component cross-correlation and Kz criterion cross-correlation methods. The average relative error of vehicle speed determination in the best case did not exceed 1.5% when the distance between sensors was set to 2 m.
Medicina-buenos Aires | 2014
Christer H. Svensen; Edgaras Stankevičius; Jacob Broms; Vytautas Markevicius; Audrius Andrijauskas
BACKGROUND AND OBJECTIVE A mini volume loading test (mVLT) was proposed for estimating hydration status and interstitial fluid accumulation during stepwise infusion of crystalloids. The method is based on both the transcapillary reflux model and the hypothesis that when subjects are dehydrated, venous plasma dilution induced by a fluid challenge is higher than in the capillaries, and that difference is diminished when the fluid challenge is given to more hydrated individuals. Our objective was to test that hypothesis by evaluating the veno-capillary dilution difference during mVLT in subjects with different hydration status. MATERIALS AND METHODS In a prospective randomized crossover study, three mini fluid challenges were given to 12 healthy volunteers on two occasions. The subjects were either dehydrated or hydrated before the experiments. RESULTS In dehydrated subjects only, capillary plasma dilution was significantly lower than venous (P=0.015, 0.005 and 0.006) after each mini fluid challenge. CONCLUSIONS Veno-capillary dilution difference during mVLT depends on the hydration status. The mVLT method could possibly discriminate between the different states of hydration.
information technology interfaces | 2007
Vytautas Markevicius; Dangirutis Navikas
Functional and hardware structures of integrated syringe pumps control system (ISPCS) are presented. ISPCS efficiency evaluation in consideration of economic factors is analyzed. Necessity of such system is analyzed and motivated. Operator errors and error reduction possibilities using ISPCS are considered. Main features of integrated syringe pumps system are presented. Advantages of ISPCS integration into clinical information system (CIS) are discussed.
Sensors | 2017
Vytautas Markevicius; Dangirutis Navikas; Adam Idzkowski; Algimantas Valinevicius; Mindaugas Zilys; Darius Andriukaitis
Methods for estimating a car’s length are presented in this paper, as well as the results achieved by using a self-designed system equipped with two anisotropic magneto-resistive (AMR) sensors, which were placed on a road lane. The purpose of the research was to compare the lengths of mid-size cars, i.e., family cars (hatchbacks), saloons (sedans), station wagons and SUVs. Four methods were used in the research: a simple threshold based method, a threshold method based on moving average and standard deviation, a two-extreme-peak detection method and a method based on the amplitude and time normalization using linear extrapolation (or interpolation). The results were achieved by analyzing changes in the magnitude and in the absolute z-component of the magnetic field as well. The tests, which were performed in four different Earth directions, show differences in the values of estimated lengths. The magnitude-based results in the case when cars drove from the South to the North direction were even up to 1.2 m higher than the other results achieved using the threshold methods. Smaller differences in lengths were observed when the distances were measured between two extreme peaks in the car magnetic signatures. The results were summarized in tables and the errors of estimated lengths were presented. The maximal errors, related to real lengths, were up to 22%.
international conference on methods and models in automation and robotics | 2016
Andrius Laucka; Darius Andriukaitis; Vytautas Markevicius; Mindaugas Zilys
Image technologies nowadays are used not only for keeping personal events safe, but also are widely applied in conjunction with automated electronic systems. Computer vision is widely used for inspection of the production quality in industries. Food industry is not an exception. Containers for food industry are made in very large quantities. This article contains of defect analysis of both external and side area of the bottleneck. Defects were divided into groups according to which the filters are created. For the control of PET preparation quality an automated computer vision algorithms were developed. The algorithms and methods were used for the detection of defective products mainly based on the image segmentation, digital production, erosion, smoothing. The most effective filters for the defect detection of the workpieces have been determined. It was carried out that efficiency of algorithms are close to 100 %.
2009 Second International Conference on Advances in Circuits, Electronics and Micro-electronics | 2009
Vidas Cepulis; Vytautas Markevicius; Dangirutis Navikas
Abstract – Cone penetration testing (CPT) is a fast and reliable means for exploring soils and soft ground (to 40 m depth) for support of buildings, retaining walls, pavement subgrades, and bridge foundations. A cone can deviate from verticality due to misalignment, a bent push rods, soil layering, or by being pushed off a vertical course during penetration if it encounters an obstacle such as a large rock. Deviation reduces probing accuracy, or large deviation from the initial alignment can cause breakage of the cone rods and loss of the cone down the hole. The inclination and trajectory calculation techniques of cone penetration test (CPT) probe are presented. Two-dimensional inclinometer was used on purpose to calculate probe trajectory and (if needed) to generate an alarm signal to avoid breakage of the cone rods.
information technology interfaces | 2004
Vidas Cepulis; Vytautas Markevicius; Dangirutis Navikas; P. Tarvydas
Using finite element method, model of design of electronic optical system was made. Libraries of electronic optical system components and presumable electron trajectories were made. Analysis of finite element mesh creation was completed and finite element mesh spacing was determined in the zones of presumable electron trajectories. There are presented analysis of different electron trajectories in electric, magnetic and electromagnetic fields calculation methods, on purpose to determine accuracy and calculation terms. Three methods are analyzed: coordinate method, time method and step method. Electron gun electron trajectories calculation and visualization program is created using MATLAB. There is presented electric field analytical model: electrical field potential is approximated using power polynomial and polynomial coefficients are interpolated by spline junctions. Electric field linearity feature is used to reduce calculation term. 5D interpolation is used in order to reduce calculation term
Sensors | 2018
Vytautas Markevicius; Dangirutis Navikas; Adam Idzkowski; Darius Andriukaitis; Algimantas Valinevicius; Mindaugas Zilys
The proper operation of computing resources in a microprocessor-embedded system plays a key role in reducing computing time. Processing the variable amount of collected data in real-time improves the performance of a microprocessor-embedded system. In this regard, a vehicle’s speed measurement system is no exception. The computing time for evaluating any speed value is expected to be reduced as much as possible. Four computational methods, including cross-correlation, are discussed. An exemplary pair of recorded signals presenting the change in magnetic field magnitude is analyzed. The sample delay values are compared. The results of the evaluated speed and the execution time of the program code are presented for each method based on a dataset of 200 randomly driven vehicles. The results of the performed tests confirm that the cross-correlation-based methods are not always reliable in situations when the sample size is small, i.e., it is a segment of the impulse response caused by a driving vehicle.
Bio-medical Materials and Engineering | 2017
Vytautas Pockevicius; M. Cepenas; Donatas Miklusis; Vytautas Markevicius; Lina Zabuliene; Dangirutis Navikas; Algimantas Valinevicius; Darius Andriukaitis
This article explores a non-invasive method to determine interstitial fluid level and pressure in tissue. Interdigital electrodes were chosen by simulated results in software “Comsol multiphysis 4.3a”. Environment model similar to human body was created. Measurements were carried out at different situations which can occur during preoperative and afterwards surgery. Non-invasive method decreases possibility of infection and will improve recovery process in postoperative period.
ubiquitous computing | 2016
Ning Ye; Zhong–qin Wang; Reza Malekian; Ru–chuan Wang; Ting–ting Zhao; Darius Andriukaitis; Algimantas Valinevicius; Dangirutis Navikas; Vytautas Markevicius
The road transport of dangerous goods RTDG arouses more and more attentions in recent years. Vehicle location devices only based on GPS technology have played an important role on the current market. However, there are obvious shortcomings by using a simple GPS method in the aspect of positioning accuracy and coverage. In the blind area of GPS, a vehicles route could not be detached in real time, which will lead to manage and follow the tracks of vehicle difficultly. In this paper, we propose an approach based on hidden Markov model HMM to provide static predictions on driver routes. Our approach is based on building the probabilistic model through observation of the drivers habits from a map database involving RFID information. Before we predict a vehicles route, we firstly compute the shortest path from starting point to destination point. Then through this path we could filter some redundant data. Finally, experiments demonstrate that we acquire high prediction accuracy under different periods of traffic conditions by training the HMM.