Elektronika ir Elektrotechnika

Published by Kaunas University of Technology (KTU)
Online ISSN: 2029-5731
Print ISSN: 1392-1215
Publications
Classification of digital devices by types of their language descriptions is introduced. Also, a template of HDL-model of digital device, which will fit verification objectives in a case of using path sensitization methods, is considered. The proposed strategy starts from origin HDL-model transformation into a graph model, which is a composition of two graphs. To identify all functional elements in an informational graph it is necessary and enough to activate all paths in a graph which cover it, starting from the 1(st) rank to graph outputs or control points. Usage of a template allows building a graph model of HDL-description and further verification easier. Adjustments of path sensitization verification strategy are done. Dependence of test length from the type of testing for S27, KP1804BCl, and B06 benchmarks is analyzed. Ill. 1, bibl. 7 (in English; summaries in English, Russian and Lithuanian).
 
‘Blanket’ of thickness 2 δ defined by its upper u δ (x,y) and lower 
‘ Fractal Area ’ ( A δ ) versus iteration δ for each type of terrain (training 
‘ Fractal Dimension ’ ( F D ) versus iteration δ for each type of terrain (training data) obtained from ‘ Fractal Area ’ values, Fig. 6, by using eq. (5). 
In this paper the Modified Fractal Signature method is applied to real Synthetic Aperture Radar images provided to our research group by SET 163 Working Group on SAR radar techniques. This method uses the blanket technique to provide useful information for SAR image classification. It is based on the calculation of the volume of a blanket, corresponding to the image to be classified, and then on the calculation of the corresponding Fractal Area curve and Fractal Dimension curve of the image. The main idea concerning this proposed technique is the fact that different terrain types encountered in SAR images yield different values of Fractal Area curves and Fractal Dimension curves, upon which classification of different types of terrain is possible. As a result, a classification technique for five different terrain types, i.e. urban, suburban, rural, mountain and sea, is presented in this paper.
 
In this paper, the approximation of the optimal compressor function using spline function of the first-degree is done. For the companding quantizer designed on the basis of the approximative spline function of the first-degree, the support region is numerically optimized to provide the minimum of the total distortion for the last segment. It is shown that the companding quantizer with the optimized support region threshold provides the signal to quantization noise ratio that is very close to the one of the optimal companding quantizer having an equal number of levels.
 
In this paper sliding mode controllers (SMCs)' techniques are used and investigated for congestion control problem of differentiated Services (Diff-Serv) networks. Robustness against modeling uncertainties and disturbances are major features of sliding mode controller. Chattering phenomenon affects sliding mode congestion control; to overcome this problem, second order sliding mode control (SOSMC) is proposed as a congestion controller. There are three types of traffics in Diff-Serv networks; i.e. three types of queues and based on that, the quality of their services are categorized. Each of these types of traffic has its own congestion control mechanisms. Stability of each controller is proved by Lyapunov stability law. To evaluate the capabilities of our proposed robust control strategy, simulation results are provided for both sliding mode controllers and second order slide mode controllers and their corresponding efficiencies are compared.
 
I. Sand, G. Duchamp. Accreditation of Experiential Learning From Personal Initiative to Supervised Realization an Experiment at Bordeaux 1 University // Electronics and Electrical Engineering. - Kaunas: Technologija, 2010. - No. 6(102). - P. 39-42. AEL (VAE in French) was set up at the University of Bordeaux 1 in accordance with the provisions of the law of social modernization of January 17, 2002. After a brief rundown on the legislative framework and the local context, the article focuses on the role of the actors involved in a series of meetings with the applicant - steps giving the AEL procedure its pedagogical dimension. It highlights the approach at Bordeaux 1, as to those aspects in the procedure which depend on the choice and initiative of the universities themselves. Through current experimentation, this article also presents the effects of such a procedure on the academic contents and teaching methods used in our university. Finally, we shall complete this presentation by assessing the procedure and indicating the stakes for the future. Bibl. 1 (in English; abstracts in English, Russian and Lithuanian).
 
In this paper, overvoltage transients are investigated and mitigated when a three-phase short-circuit occurs in cable lateral connected with medium voltage (MV) overhead line and fuse is operated. The transients are studied using EMTP-ATP simulation environment and the need of metal oxide varistors (MOVs) is investigated. The cable laterals consist of sub-laterals and their effect on reducing transients is also investigated. The surge arresters are installed at the junction of overhead line and cable and at far end of the cable near short-circuit point. The different mitigation methods are tested and optimal protection scheme to reduce overvoltages is proposed on the basis of surge arresters locations and sub-lateral connections.
 
Light emitting diodes have many positive features comparing with incandescent and fluorescent lamps like its small size; high luminous efficiency, long lifetime and reliability. That features increases the popularity of LEDs using in lighting. However there are many cheap, non-certified light emitting diodes bulbs in the market, where the parameters of the light emitting diodes bulbs are undeclared or declared incorrectly. The simple and low cost evaluation methods for evaluation of efficiency of light sources are presented in the paper.
 
V. Barzdenas, D. Poviliauskas, G. Grazulevicius, K. Kiela. Design of an 8-bit 1GS/s F&I ADC in 0,13 mu m SiGe BiCMOS Technology // Electronics and Electrical Engineering. - Kaunas: Technologija, 2012. - No. 6(122). - P. 55-58. In this paper, design and simulation results of an 8-bit 1 GS/s clock speed folding and interpolating analog-digital converter (F&I ADC) are presented. The converter for four lower bits used folding with interpolation whose coefficients respectively equal to 8 and 6, and four upper bits made using parallel comparators structure. ADC design and simulations carried out with Cadence software packages. Dynamic characteristics of the converter are presented, which shows that signal-to-noise and distortion ratio (SNDR) and spurious-free dynamic range (SFDR) at 1 MHz input signal and 1 GS/s clock frequency is respectively equal to 49,7/54,6 dB. It is also identified effective number of bits (ENOB), which is approximately equal to 8-bit, when the input signal frequency is 1 MHz and at 500 MHz, ENOB drops to around 6-bit. After static characteristics simulation were got that the differential nonlinearity (DNL) did not exceed 0,4 LSB and integral nonlinearity (INL) is less than +/- 0,6 LSB. Ill. 8, bibl. 6, tabl. 1 (in English; abstracts in English and Lithuanian).
 
We have been simulated the submicron CMOS charge sensitive preamplifier (CSP) with the leakage current compensation circuit, which allows reducing equivalent noise charge up to 54 electrons. Simulation has been performed with SPICE simulators using the BSIMV3.3 transistors parameters of the MOSIS 0.13 mu m CMOS. The value of the feedback capacitor C-fb is chosen as the C-GD approximate to 1 fF capacitance of input transistors. The feedback resistance R-fb is implemented by PMOS transistors operating in the linear region. CSP has the following main electrical parameters: the minimum of ENC is in the leakage current region -3 nA...+6 nA and equal 54...70 e, total gain of the chain is K=41.42 mV/ke, while the peaking time is tau(p)approximate to 35 ns. It is a promising solution for X-ray pixel detectors.
 
Sense Amplifier is one of the major circuits in CMOS nonvolatile memories. The aim of this research is to implement Sense Amplifier in 0.18μm CMOS process to achieve both the lower reading power and superior reliability for sensing operation. In RFID transponder, EEPROM are used to store data. Memory access time, power dissipation and the reliability of an EEPROM is vigorously influenced by the features of the SA. Current type SA experience the larger current or power dissipation problems, which is not suitable for low voltage applications of RFID transponder. The proposed voltage-type SA is able to execute under a very low power supply voltage (VDD) between 1V to 2.6V VDD. The SA circuit implemented within the temperature range from-25°C to 125°C. The compact layout design has been carried out to evaluate the efficiency of the circuit. The modified low voltage-type SA is appropriate for low-voltage applications like RFID EEPROM. Ill. 5, bibl. 10, tabl. 1 (in English; abstracts in English and Lithuanian).
 
This paper presents a 3-stage ring voltagecontrolled oscillator (RVCO), designed for active Radio Frequency Identification (RFID) transponders. High frequency local oscillators designed for battery-powered transponders are always crucial concerns for chip designers, as those oscillators consume considerable amount of power. Thus, the primary goal of this research work is to design a low power VCO at 2.45 GHz in the ISM band. In addition, in order to reduce overall oscillator size, ring based architecture has been adopted with easy integration technique. For varying the oscillating frequency from 2.2 GHz to 2.85 GHz, PMOS transistors with fixed value capacitors are utilized. Providing 1.8 V supply, the oscillator dissipates 6.99 mW of power and exhibits phase noise of -112 dBc/Hz at 10 MHz offset. The proposed RVCO is designed in CEDEC 0.18 μm standard CMOS process using Mentor Graphics environment.
 
This paper presents a modified high speed CMOS dynamic phase frequency detector (PFD) for high frequency phase-locked loop (PLL). Design miniaturizations in downscaling CMOS process lead to circuit malfunction due to intrinsic effects and many other reasons. To ensure main characteristics of the PFD are preserved, the proposed dynamic PFD uses 18 transistors operated with 1.2 V power supply. The performance of the design is focused on power supply, power dissipation, wide input frequency range, dead zone size and active layout area. The circuit is designed in 0.18 μm CMOS process using Mentor Graphics environment. In this paper, the dynamic PFD dissipates 59 pW of total power when reference input frequency clock operates at 50 MHz and feedback input frequency clock operates up to 4 GHz. The dead zone has been eliminated. The simulation results show that the circuit offered an alternative for any high speed and low power PLL applications.
 
A power amplifier, implemented in 2 mu m InGaP/GaAs Heterojunction Bipolar Transistor (HBT) is presented. The size of the fabricated chip is 700 mu m x 700 mu m. With an integrated input matching network, the PA observes an input return loss (S-11) of -22 dB. Biased at low quiescent current of 65 mA, it delivers a maximum output power of 1.8 W with 71 % efficiency at 1.85 GHz. The output return loss (S-22) of the PA is -15.2 dB. The output matching network is designed to reduce the mismatch loss between the power amplifier and the antenna without compromising the output power and efficiency. The PA also exhibits a K-factor greater than 1 from DC up to 5 GHz, ensuring unconditional stability. The power gain of the PA is 14.9 dB. The measured results verify that the PA is capable to operate at high efficiency and to deliver high output power with a good output return loss.
 
Gain spectrum provided by the single-pump FOPA with 590 mW 192.929 THz pumping radiation.
Dependence of system maximal BER values on the length of the HNLF for the LRA with 590 mW 209.975 THz pumping radiation.
Gain spectrum provided by the single-pump LRA with 590 mW 209.975 THz counter-propagating pumping radiation.
Raman amplifiers and Fiber optical parametric amplifiers (FOPA) are positioned as the main future leading techniques for all-optical signal amplification. Distributed Raman amplifiers are known as the least noisy, but this type of amplifiers suffers from poor pumping efficiency at low input signal powers, therefore, discrete (lumped) Raman amplifiers (LRA) could be used instead. Both FOPAs and LRAs are the likeliest replacements of conventional EDFAs, but at this point it is not clear which of these two approaches is the most promising taking into account the quality of the amplified signal. Therefore, the goal of this article is to determine which of the two amplification techniques ensures less amplifier produced signal impairments in a 16-channel 10 Gbps dense wavelength division multiplexed (DWDM) transmission system. DOI: 10.5755/j01.eie.25.1.22740
 
The worldwide demand of bandwidth has led to the expansion of fiber optics access technologies. However, TDM-PON (Time Division Multiplexing PON) concept has its limitations due to the concept of time division. Another way of increasing the bit rate is WDM-PON (Wavelength Division Multiplexing PON) solution. To satisfy the growing demand the system must have high bit rate and be cost-effective. Spectral-slicing technique can achieve this aim. ASE-source (Amplified Spontaneous Emission) as the OLT (Optical Line Terminal) and colorless LED (Light Emitting Diode) as ONU (Optical Network Unit) hybrid solution is proposed in this paper. In this paper is demonstrated 16 channel WDM-PON system with optical slicing technique. All the central wavelength conversions are made with the help of spectral slicing in the AWG (Arrayed Waveguide Grating) with FSR (Free Spectral Range). III. 8, bibl. 5, tabl. 2 (in English; abstracts in English and Lithuanian).
 
In this paper design and simulation of a 10 GHz, divide-by-16⋯511 programmable frequency divider based on ETSPC and TSPC logic flip-flops in 65 nm CMOS are presented. Main blocks of the divider are three-stage dual modulus divide by 2/3 divider chain, 6-bit counter, jitter removal and synchronisation flip-flops. Extended True Single Phase Clock (ETSPC) logic is used for 2/3 dividers to achieve high input frequency and low power and TSPC logic is used for 6-bit counter. Simulation of the divider was made using Cadence software. Divider's operation frequency is up to 10 GHz. Resulted phase noise is -143.7 dBc/Hz at 1 kHz offset from output frequency and power dissipation is 29.35 mW when input frequency is 10 GHz, division ratio is set to 23, supply voltage 1.2 V. The main application of such divider is as feedback divider in frequency synthesizer for wireless communication systems.
 
Experimentally measured SMF fiber span: (a) chromatic dispersion coefficient and (b) total chromatic dispersion depending on bandwidth and wavelength used.
Experimentally measured DCF fiber spool: (a) chromatic dispersion coefficient and (b) total chromatic dispersion depending on bandwidth and wavelength used.
Comparison of experimentally measured BER versus received optical power with use of: (1) fiber Bragg grating dispersion compensation module (FBG-DCM), (2) dispersion compensation fiber (DCF) depending of bitrate per channel for investigated 4-channel 100 GHz spaced DWDM optical transmission system.
Optical spectra: (a) after B2B transmission through SSMF fiber; (b) after 40 km transmission through SSMF fiber; (c) after 40 km transmission through SSMF fiber with use of dispersion compensation by DCF for multiplexed 4-channel NRZ modulated DWDM optical transmission system at bitrates of up to 40 Gbit/s per channel.
The exponential growth of data traffic related to the progress of newest technologies (e.g., 4K/8K live stream videos, virtual reality (VR) applications, etc.), new services, and a fast-growing number of end-users require higher bandwidth and increase of user bitrate, as a result pushing hard the telecommunication infrastructure for upgrading. Expected usage of more complex modulation formats in fiber optical link infrastructure for cellular network transmission and data center interconnections (DCI) are still affected with fundamental chromatic dispersion influence on the signal quality, which consequently increases bit error rate (BER). We experimentally demonstrate a real-time comparison of commercially used dispersion compensation techniques for 100 GHz spaced dense wavelength division multiplexed (DWDM) optical transmission system with a total transmission speed capacity of 160 Gbit/s.
 
The Pelliconi based Favrat charge pump topology as illustrated in [20].
System overview of charge pump implementation with assisting circuitry.
Clock generator topology.
Test setup used for measurements of the bonded charge pumps.
This paper presents two variants of a high step-up ratio charge pump for high voltage micro electro-mechanical system and condenser microphones. The implementations are based on an additive charge pump topology where respectively 46 and 57 cascaded stages are used to generate an output voltage of 182 V from a supply voltage of 5 V. The two charge pumps have been fabricated in a 180 nm SOI process with a breakdown voltage of more than 200 V and respectively occupy an area of 0.52 mm2 and 0.39 mm2. The charge pumps can output up to 182.5 V and 181.7 V and are designed to drive a capacitive load with a leakage of 2 nA. When driven with a 100 kHz clock, their power consumption is respectively 40 µW and 20 µW. The rise time of the charge pumps output from 0 V to 182 V is less than 5 ms. The implemented charge pumps exhibit state-of-the-art performance for very high voltage dc-dc capacitive drive applications.
 
Framework of the proposed methodology.
In this study, Turkish and English tweets through Twitter Application Program Interface (API) between 1-31 January 2021 are analyzed with respect to Covid-19. The collected tweets are preprocessed, labeled with the Vader Sentiment library, and then analyzed by topic modeling with Nonnegative Matrix Factorization. The analysis show that the most frequently mentioned word is “vaccine/aşı” after “Covid”. The topics modelled in the study are grouped into themes and the themes are seen to be similar in both languages, which means that the Turkish and world agenda are not very different in terms of themes in pandemics. Moreover, hypothesis tests are conducted to understand whether language and time period are related to sentiment class. The results show that the Turkish people are more neutral about the Covid-19 issue than other people in the world during the given period of time. Moreover, independent of the language, there are more negative and neutral tweets in the first half of January 2021, whereas there are more positive tweets in the second half of the month. To the best of our knowledge, this is the first study to analyze Covid-19 related tweets in two languages to compare the local and global agendas using topic modeling, sentiment analysis, and hypothesis testing methods.
 
In this paper we propose a new economical selective low-pass finite impulse response filter function. First, we describe the two types of already developed filters, and then we obtain three new different types of filters, by combining the previous ones. Also, the general form of the proposed filter is given. In order to verify the effectiveness of the proposed filter function, the cut-off frequencies of the stop-band and pass-band of the filter, for equal constant group delay, are analysed and compared with classical first and second type of filters. It is shown that proposed filter is efficient related to high selectivity and high values of attenuation in the stop-band of the filter.
 
2009 Enrollment in the study programmes at the TEF 
Admission scores for 2009 enrollment at KTU by study area 
Students' aim of study at the TEF 
Students' average grades for the first semester 
R. Krivickas, A. Valinevicius, D. Eidukas, D. Andriukaitis, B. Dekeris. First-Year Undergraduate Student Academic Profile: 2009 Enrollment // Electronics and Electrical Engineering. - Kaunas: Technologija, 2010. - No. 6(102). - P. 95-98. Academic profile and performance, opinions about learning environment of the first year students' is assessed and analyzed in order to increase effectiveness of education at the TEF. Results and discussion are based on survey data, collected aTEFr the first semester of study. Bibl. 3, tabl. 6 (in English; abstracts in English, Russian and Lithuanian).
 
Effect of barrier numbers on efficiency and torque.
Effect of starting diameters of barriers on efficiency, torque, and torque ripple.
Effect of radial ribs on efficiency, torque, and torque ripple.
Substantial increase in energy consumption in all around the world has led to researchers to need to produce electrical machines with high energy efficiency since majority of energy has been consumed at industry, especially by electrical machines. Among electrical machines, the Synchronous Reluctance Machines (SynRMs) have been preferred to investigate in recent years due to lack of Induction Machines (IMs) in terms of efficiency and high price of the Permanent Magnet Synchronous Machines (PMSMs). In this study, the Finite Element Analysis (FEA) showing the effects of phase angle of current, number of flux barriers, starting diameter of flux barriers, and ribs on machine performance of 22 kW Transversally Laminated Anisotropic (TLA)-SynRM with distributed winding have been carried out in ANSYS Electronics. The design is based on creating a novel rotor considering these rotor parameters since the utilized SynRM consists of same stator with same sized 22 kW IM. The performance of the machine has been investigated through torque, torque ripple, efficiency, saliency, and power factor. Moreover, the effect of the phase angle of the current on the machine performance and the comparison of the 22 kW-SynRM with the same sized and powered IM and with a different SynRM have been carried out in this study. This study has concluded that although the novel SynRM has high torque ripple values, it is better than the IM due to lack of copper losses of rotor and the previously utilized SynRM considering their efficiency classes. The efficiency class of novel SynRM is IE4, whereas that for utilized IM and previously created SynRM are IE1 and IE3, respectively.
 
Insulator failure generally occurs due to improper design, and if there exists sharp edges over the insulator surface. There is a need to detect the fragile parameters in the insulator design as they can cause large electrical stress, leading to insulation failure. In this paper, machine learning based approach is used to identify the fragile design parameter and thus determine an optimized design of the insulator, which will eventually decrease the voltage stress over it. A 220 kV insulator is designed and electric field intensity and potential distribution for an assembly of live, ground and insulator is calculated for different geometries. The design parameters of the insulator are considered and varied. The electric field is calculated for the whole assembly of insulator to generate the most optimized design. The optimized design reduces the overall stress by 13.12 %.
 
In this paper a simple and robust method for estimation of distorted video quality, which is perceived by human observer in mobile video streaming applications, is proposed and assessed. Increasing bandwidth of mobile communication systems expand the variety of offered multimedia services such as video streaming. However, the quality of these services is very dependent on rapidly varying mobile communication conditions. Most widely used video quality estimation methods, such as Peak Signal to Noise Ratio (PSNR), Structural Similarity (SSIM), and Video Quality Metric (VQM) are based on the presence of full or reduced reference video. These methods could be used to assess video quality of video transmission system only during test stage and in the limited number of scenarios. In order to assess user experienced video quality in real conditions, methods with no reference must be employed. Such existing methods as video quality metric use bit-error rate that has low correlation with human perceived video quality. More precise methods usually are too complex and require too much processing power that cannot be tolerated in handheld mobile devices. In this paper it is shown that developed no reference low complexity video quality estimation method based on H.264/AVC video stream packet structure delivers estimate of received video quality comparable with results of subjective MOS tests.
 
This work discusses the possibilities of some novel applications for the high frequency (200 kHz-500 kHz), high sensitivity (-20 dB- -35 dB) and wide band (> 50 % @ -20 dB) air-coupled transducers that have been used so far for nondestructive testing and materials characterization at CSIC. These applications refer to non-contact human-machine interfaces, gesture recognition and echolocation. Compared with other technologies, the relatively higher frequency and bandwidth permit to achieve better resolution and the higher sensitivity permit to reach longer distances. In addition, this later feature also permits to reduce the number of transducers. This is achieved by using a conical reflector that provides an omnidirectional (2D) acoustic field. Examples of applications and realizations are shown by using single element 250 kHz transducers; and 8-elements 400 kHz sectorized array transducers. This later type of air-coupled array is introduced here for the first time.
 
Modeling, reconstruction and visualization of 3D images is crucial in such fields as industrial engineering and manufacture, medicine, game development, etc. A physical object can be transferred to 3D virtual space by using a 3D laser scanner. Quality of the 3D model of the object scanned strongly depends on that of the laser beam's center-line detected in the 2D image. A technique for detection of the laser beam's center-line in a set of 2D images is presented. It uses two shifted kernels of the first-order Gaussian derivatives combined in a nonlinear way. Filtering is performed in a number of directions to select the one with the maximal response. The laser beam's center-line is identified by the local maxima in the filtered image through evaluation of its first- and second-order derivatives. The technique was tested on images with a laser trace left on the object scanned.
 
An application of mathematical method of Aisenberg for restoration of low frequency medical diagnostic signals after influence of noise is described in the paper. The restoration of frequency spectrum of medical diagnostic signals has been done after preliminary analyses of frequency spectrum of signals with noise and disposition of frequency band of noise in the frequency band of information signals. Some experimental results obtained on the base of application of Aisenberg's method for restoration of medical diagnostic signals are described in the paper.
 
Target and scanning line with hole in middle which means that their function value not converged.
Objects with complex geometry need to be inspected quickly and reliably, therefore it is not practical to use fixed focus transducer, because of wave propagation effects. To mitigate the problem with the irregular shape, it is possible to use a phased array with applied delay laws. For calculating required delays, it is required to have an object model with known surface points and have an algorithm which calculates. This paper presents computing friendly analytic method which could be used in the case when the object model is given by lines or it is possible to calculate surface tangents. In this paper is assumed that geometry is approximated with B-splines. Results of the algorithm are verified with finite element method. DOI: 10.5755/j01.eie.25.2.23200
 
The structural schematic of the visual information representation The blind operator moves the miniature electromagnet EM with his finger, and electromagnet glissades on the plane MP. The measurement unit of the position PM fixes the coordinates x M , y M of electromagnet EM and transmits its position into processor P. Processor forms the control signal u p =u p (x M , y M ) of the miniature electromagnet excitation current magnitude, which relates to the intensity
The dependence of the magnetic flux density B y on the gap height l t : I-μ rm =μ rp =1000, II-μ rm =1000, μ rp =100
When blind operator is moving the electromagnet by his finger on ferromagnetic surface, he can "read" the visual information's (height, colour, shadow) variation in some point of the surface by the force, which acts on the electromagnet in this point. The force can be varied by varying the electromagnet excitation current, depending on the point coordinates. The dependence of the force on the excitation current, magnetic circuit parameters and magnetic properties is obtained. For the accurate formation of the relief height, the bottom of the electromagnet must be separated at ferromagnetic surface by a small nonmagnetic gap. The modeling results are presented.
 
Angle estimation errors versus number of characteristic points of face 
Name of expression and code
Intervals of head orientation angles estimation errors with expression compensation
Mean head angle error with expression compensation for CMU PIE images
Percentage of correct experimental estimation which belong to simulation intervals
The method of minimization face expression influence for evaluation of head orientation in space is proposed and investigated. In our previous works 18 characteristic face points were selected for the head orientation evaluation. It is difficult to track all 18 points in real time. It was found by way of mathematical simulation that number of points 7 is optimal number for head orientation tracking. The points were selected at the face places which obtain minimal changes because of face expression. Mathematical simulation helped to establish that errors for head rotations could reach value 13 degrees (for surprised expression), and mean error is about 6-8 degrees. After correction of face specific points coordinates by mean value of change caused by face expression the errors were reduced until range 0.1-0.3 degrees. Intervals of possible errors for every expression and some head orientation angles were calculated. The method was tested using CMU PIE database of face images. The obtained interval for head orientation angles errors is 1.5-2.8. The correspondence of 78-90% was obtained between results of experimental errors and results of mathematical simulation. Ill. 6, bibl. 7 (in English; summaries in English, Russian and Lithuanian).
 
Automatic visual quality assessment of the 3D printed surfaces is currently one of the most demanding challenges in additive manufacturing. Regardless of the applications of the computer vision for the 3D printing process monitoring purposes, a reliable surface quality evaluation during manufacturing may introduce brand new possibilities. The detection of some distortions and their automatic evaluation can be helpful when deciding to stop the process to save time, energy, and filament. In some cases, some further corrections can also be made for relatively small distortions. Since many general-purpose image quality assessment methods have been proposed in recent years, their applications for the quality evaluation in the additive manufacturing are investigated. As most of the metrics are full-reference and require the availability of the original perfect quality image, their direct application is not possible. Therefore, their adaptation is described in the paper together with experimental verification of classification results obtained using various metrics.
 
This paper presents an innovative system for industrial robot manipulation through 3D hand gestures. The interaction between the human operator and the robotic system is done via a dynamically created 3D virtual environment which is a precise copy of the robot's real working environment. The virtual environment enhances the manipulation of different objects and the selection of the desired action, in a natural way, only though hand gestures. Unlike most of the HRI based systems, ours is not meant for moving the robot or its mobile arm from one place to another, but to perform a specific task comprising of a list of specific operations. This kind of interaction has an important advantage: it eliminates the dead-times which are specific to the direct-interaction based systems. The gesture recognition algorithm processes depth maps grabbed from a stereoscopic camera system and uses Dynamic Time Wrapping to compute the similarity between the hand trajectories acquired in real time and those from the gestures dictionary.
 
Instrumentation system design.
This paper presents a method to generate a Georeferenced 3D point cloud of GPS denied built structures using custom made backpack laser scanning system. An orthogonal combination of 2D Hokuyo laser scanners has been used on the backpack system to generate a 3D point cloud of the surveyed environments. The data logging of scanners and simultaneous localization and mapping (SLAM) of the scanning system have been carried out using Robot Operating System (ROS). The developed local SLAM based 3D point cloud solution has been transformed into global Georeferenced 3D point cloud using observed geographic coordinates of nearby GPS visible vicinities. Multiple indoor environments have been scanned and 3D point clouds have been developed which have been found accurate when compared to the ground truth. In comparison to available surveying solutions present in the local market, the developed system has been found more accurate, faster, and user friendly to generate structural results of the surveyed vicinities in detail. The efficacy of the system has been witnessed by local surveying companies by delivering the unique global coordinated solutions on affordable rates.
 
Calibration of the fuel tanks must be made once in a 5 years. For calibration of the fuel tank 3D laser scanning and data processing method can be used. This article describes the influence of 3D laser scanning data scattering to volume measurement of horizontal fuel tank by means of relative error. It describes how to eliminate data scattering effects using filtering.
 
Plant height measurements using stereo vision 
The focus of this paper is a weed-crop discrimination using 3D information from a binocular stereo vision system. Two methods of optical distance measurement are presented. Extrinsic camera calibration uses four circular calibration objects. The ground plane equation is defined by three points that corresponds to the circle centers of three circular objects placed on the ground plane. Finally, weed-crop discrimination is done by using colour and height thresholds. The function modules used in Matlab program are also presented. Ill. 6, bibl. 9 (in English; abstracts in English and Lithunian).
 
3D program production workflow  
Use Case Diagram of 3D Preproduction Use Case Plan Logistics and Stuff. Short Description: Managers plan logistics and staff needed for production of program item. Actors: Producer, Technical manager. Pre-Conditions: Program idea is investigated, commission results, initial script are made and 3D needs and gains are analysed. Post-Conditions: Production order is issued. Main Flow: (1) Producer (Editor, Director) plans the staff needed for production of 3D item. (2) Technical manager plans the logistics (objects, vehicles, production equipment...) needed for production. (3) Producer and technical manager plan the staffing. (4) Production order is issuing for all members of production team. Use Case terminates. Use Case Make Storyboard and Stereopsis. Short Description: Producer writes storyboard and stereopsis. Actors: Producer. Pre-Conditions: Program idea is investigated, commission results, initial script are made and 3D needs and gains are analysed. Production order is issued. Post-Conditions: Storyboard and stereopsis are made. Main Flow: (1) Producer (Editor, Director) defines the final storyboard based on initial script. Producer makes stereopsis. Use Case terminates. Use Case Add Preproduction Metadata. Short Description: Producer and technical manager add preproduction metadata. Actors: Producer, Technical Manager. Pre-Conditions: Production order is issued. Post-Conditions: Preproduction metadata added. Main Flow: (1) Producer adds metadata related to preproduction (working title, producer's identity, possibly contributor's names, genre and possibly scripts and stereopsis. (2) Technical Manager adds metadata related to equipment used in project. Use Case terminates. Production. Main actors in problem space of the 3D program production are producer, archiving system, 3D essence gathering crew (cameraman, sound recorder) and ingest operator. Use cases important for modelling in problem space of program production are as follows: Capture 3D Essence, Ingest 3D Essence, Add Production Metadata, Manage and Use Archives. Use Case diagram of 3D program production phase is shown in Fig. 3. Use Case Capture 3D Essence. Short Description: 3D video shoots, audio clips and other program items are creating, pre-selecting, and ingesting into production  
Use Case Diagram of 3D Production Use Case Add Postproduction Metadata. Short Description: Processing crew add descriptive metadata. Actors: Video Editor, Sound Editor, Animator. Pre- Conditions: 3D Essence is edited and finalised. Post- Conditions: Postproduction metadata added. Main Flow: (1) Descriptive metadata are manually added. Use Case terminates. Use Case Control. Short Description: Editorial and technical acceptances approve the use of the post produced 3D program item. Actors: Producer, Technical Manager. Pre-Conditions: 3D essence, as well as related metadata, is finalized. Post-Conditions: 3D essence, as well as related metadata, is approved. 3D content is stored in archive. Main Flow: (1) Editor-in-chef checks and approves or disapproves the editorial quality of the produced material. (2) Technical Manager checks and approves or disapproves the technical quality of the  
Domain Model (Class Diagram) of First Generation Stereoscopic 3D Programme Production  
A. Spasic, D. Jankovic. Domain Model of Low-Budget First Generation Stereoscopic 3D TV Production // Electronics and Electrical Engineering. - Kaunas: Technologija, 2012. - No. 3(119). - P. 75-80. Primary aim of this paper is to propose one model-driven approach of software-intensive 3D TV production system applicable and suitable for low-budget broadcasters. The target of the project is to Fig. out one of possible future scenarios for implementing stereoscopic 3D technologies in low-budget TV production and to propose one domain model suitable for further expansion. Modelling in problem space is used as a research method in this paper and first step in modelling of software-intensive 3D television production is presented here. Behavioural description of program production is modelled by the use case diagrams. Domain model is defined and class diagram is used to describe structural static representation the low-budget 3D content production. Ill. 5, bibl. 12 (in English; abstracts in English and Lithuanian).
 
The investigation of magnetic field distribution via x-y-z directions of multilayer coils has been carried out. Finite elements method was used for numerical simulation of magnetic field components. The model was verified experimentally using experimental PC controlled equipment. The control algorithm for automatic measurements was developed using LabView. programming package. It allows to map a magnetic field at any point over any surface moving a 3-axis magnetic probe through a three dimensional volume while measuring the three orthogonal components of magnetic field strength at designated points and magnetic field distribution profiles can be plotted. The experimental and simulation results were compared and acceptable compliance has been achieved. The results provide a possibility to forecast parameters of multilayer coils avoiding expensive and long lasting experiments.
 
This article addresses the problem of reconstructing 3D surfaces from unorganized point sets (also known as point clouds). This issue is common to many different areas of science and engineering, including computer graphics and computer vision. Unorganized point sets can be acquired in different ways, e.g., using laser scanners, computer tomography, magnetic resonance imaging, multicamera vision systems, etc. This paper presents a method for point cloud merging that allows calculating the initial rotation and translation between point clouds of different viewing angles. By tracking the marker's position, scanning and point cloud registration can be done in real time and with high accuracy.
 
In this study, the mathematical analysis and design of a new 3D printer with 5 degrees of freedom were carried out. Thanks to the developed system, a new concept has been brought to the multi-axis 3D printer mechanisms, and thus, it is aimed to improve the part quality in additive manufacturing (AM) processes. As a result of adding the 4th and 5th axes to the moving platform of the system, the production time of the part was accelerated. It is also possible to print more complex and curved shapes with less support. To design a system with these features, first of all, the kinematic analysis of the system was obtained using vector algebra, and the workspace of the current printer was determined by considering the system constraints in this article. By giving detailed information about the mechanical and electrical components of the designed system, the working principle of the whole system is presented. According to the findings obtained in the studies, the kinematic analyses performed for the proposed system proved to be correct and a new system was proposed especially for additive manufacturing technologies.
 
Proposed algorithm for 3D objects point clouds classification. 
3D point cloud of cow with points that were found using HKS method. 
This paper describes a 3D object classification method by 3D-3D comparison using the numerical surface point signatures on interest points of 3D objects point cloud. Interest or salient points of 3D point cloud were found by Heat Kernel Signature method. The numerical point signatures used for classification were composed only on these points. To investigate the objects classification resistance to the data measurement noise, additionally to original 3D data was added 1.5 % of continuity distributed noise. Object classification was carried out using forty three 3D objects point cloud database. Study of 3D object interest points recognition has shown that the standard Surface Point Signatures methodology is sensitive to the normal vector used for signature composition as well as the object's surface normal is very sensitive to objects mesh error. In order to reduce the sensitivity to the object surface measurement error we have proposed to use one constant vector as average from all object mesh normal's. Such approach on average improved interest point's recognition rate by similar to 16% and allowed to reach 95.9% of classification accuracy on used 43 objects database.
 
Relationships of S ultimate , S outsphere and S insphere . 
Points P and Q in the same 3D cell grid. 
Different types of query points and their K nearest neighbours. 
In this paper, we propose one novel and efficient K nearest neighbours search algorithm based on 3D uniform cell grids. First, a simple min-max box is used to store all the points and a twice division strategy is adopted to determine the edge length of basic grids. Then we limit the search space for each grid with certain query points to control the amount of distance calculations under a suitable level. And the computational cost of sorting operations is reduced effectively through avoiding the unnecessary calculations, with the help of properly determined subspaces and sphere spaces for points. Compared with existing related algorithms, our method can search for the K nearest neighbours accurately and quickly, and it has many possible applications in the fields using 3D scattered point clouds.
 
This work presents the results of a preliminary study conducted to assess the viability of using 3D printing techniques for the manufacturing of microwave passive circuits based on microstrip techniques, both for prototyping new low-cost devices and for fast and costless testing of new circuits designs. The study was aimed to test two crucial factors in the viability of these procedures: the performance of the circuit in terms of its functionality and the structural integrity of the resulting structure. A low-cost 3D printer is proposed for the dielectric substrate design of microstrip circuits. Standard PolyLactic Acid (PLA) material has been characterized in the microwaves frequencies for different substrate sizes and densities. To verify the proposed method, a low-pass stepped impedance filter was designed, simulated, and measured. Finally, a structural analysis using Non-Destructive Testing (NDT) ultrasonic techniques has been carried out based on deconvolution and resonant spectroscopy. Both, electronic and structural results, have shown the feasibility of using low-cost additive techniques in the design of microwave circuits. DOI: 10.5755/j01.eie.25.2.23202
 
This paper presents the procedures enabling the calibration and evaluation of intrinsic parameters in a Velodyne multi-beam laser scanner. As the device will be utilized in field robotics applications, both the evaluated parameters and the calibration are generally aimed to improve the performance of the scanner with advanced mapping algorithms such as robot evidence grids or octree. The measured parameters are compared with the data provided by the manufacturer. A novel calibration method based on conditional adjustment for correlated measurements is proposed and compared with factory calibration.
 
In today modern manufacturing the use of virtual models in prototype development has been increased. Hybrid Layered Manufacturing (HLM) - is a new way to create prototypes of virtual objects. 3d modelling programs are not optimized enough for creating objects by layers. One of the problem is a flat surface printing, because during that process beads are printed which have a parabolic shape. That shape is unsuitable for creating a flat surface. The paper proposes a method that will allow to print layers with flat surface. For this purpose an analysis and calculations were made with the help of a written algorithm, which was used in virtual environment testing it on 3d models.
 
The hand tracking system in 3D space dedicated for design of new generation user interface is presented. The system is based on 3D computer vision and implemented using open source computer vision library (OpenCV). The further experimental evaluation of the system was performed closer as possible to meet the real environment conditions. The system is able to detect and track user's head and hand and return 3D coordinates in real time. The detection of head and hand is based on adapted Viola-Jones detector. The detection rate is equal to (91 ± 2)%. The tracking is based on Lucas-Kanade optical flow calculation technique which was customized and improved for hand tracking. High tracking robustness ((93 ± 2)%) was achieved. Small variations of the robustness rate, while changing ambient lighting type, intensity and background conditions, are acceptable for alternative computer vision-based user interface.
 
In this paper, we present an approach to sound localization for moving sound sources. We use four conventional microphones and a multi-channel sound recording device for capturing sound signals. A database with different types of moving sound source scenarios is created and one of the scenarios is analysed in this paper. This scenario involves walking of a person and creating sounds simultaneously at certain positions in a room, and our aim is to determine the location of the person as three dimensions. We use time difference of arrival for 3D sound source localization. The time delays between sounds channels are obtained by excitation source information based time-delay estimation algorithm. In addition, signal processing methods are used for increasing the success of moving sound source localization. Savitzky-Golay and threshold filters are utilized to pre-filter the recorded sounds and removing the background noise signals, respectively. The non-linear equation of the sound localization is solved by using the modified Levenberg–Marquardt Algorithm (LMA) on the Time Difference of Arrival (TDOA) process. The results for the 3D localization of the moving sound source are obtained by measuring the differences between the real and estimated positions of the person.
 
Understanding of line-of-sight and non-line-of-sight (LOS/NLOS) visibility conditions is important for radio wave propagation modeling when selecting empirical path loss model. For Monte Carlo statistical simulations a random generator of visibility states can be designed according to a given spatial probability density. In the current paper, a statistical LOS state model is derived based on ITU-R and 3GPP 3D LOS probability models suitable for 5G channel simulations. The generic exponential LOS probability model is improved by dividing the area into LOS and NLOS zones depending on the building density. The accuracy of LOS probability model has been tested against visibility predictions obtained from the digital building data over Manhattan city area. DOI: http://dx.doi.org/10.5755/j01.eie.24.5.21847
 
This paper describes a 4.48 GHz-5.89 GHz LC voltage-controlled oscillator (LC-VCO) as a key component in RF transceivers. The circuit is fully designed in TSMC's 65 nm radio-frequency complimentary metal-oxide-semiconductor technology process. The LC-VCO uses the structure of only one couple of NMOS differential negative resistances, tank circuit which consists of an optimal on-chip spiral inductor with switched capacitor and varactor arrays. The proposed design accomplishes wide tuning range frequency by using 6-bit switch capacitor array in addition to linearly varying MOS varactors. A switched current source block is used to improve the performance of the LC-VCO. The oscillator has a wide tuning range, between 4.48 GHz and 5.89 GHz. The LC-VCO dissipates 15.96 mW from a voltage supply of 1.8 V, whereas its phase noise is -124.1 dBc/Hz at 1 MHz offset of a at 5.89 GHz carrier.
 
Measured ACLR and PAE for LTE Band 1.
A new method to improve the battery life span of a 4G handset power amplifier (PA) is proposed. This technique is realized by employing a novel passive linearization topology on a class-E PA. Implemented in a 2 μm InGaP/GaAs Hetero- Junction Bipolar Transistor (HBT) technology, the PA delivers 49 % of power added efficiency (PAE) at output power of 28 dBm while complying with the Long Term Evolution (LTE) regulation at Band 1(1920 MHz-1980 MHz) with corresponding supply voltage headroom of 4 V. The performance enhancement is achieved at LTE channel bandwidth of 20 MHz. To the best of the author's knowledge, this is the first class-E PA which meets adjacent channel leakage ratio (ACLR) specifications at 20 MHz LTE bandwidth.
 
Simulation scenario.
The amount of data served (both the FUEs and the MUEs) depending on FAPs load while MBS load is at 50 %.
The amount of data served (both the FUEs and the MUEs) depending on MBS load while FAPs load is fixed to 10 Mbit/s.
The amount of backhaul overhead depending on FAPs load while MBS load is at 50 %.  
The amount of backhaul overhead depending on MBS load while FAPs load is fixed to 10 Mbit/s.  
The femto access points (FAPs) with cognitive capabilities, also known as cognitive FAPs, are able to efficiently mitigate interference in two-tier heterogeneous networks. Hence, the concept of cognitive FAPs can be seen as one of the key enablers for future 5G networks, where high density of FAPs is foreseen. However, conventional overlay and underlay spectrum sharing strategies enabling the cognitive FAPs to access spectrum of macrocells have several drawbacks. The main disadvantage of the former one is that its efficiency fully depends on the activity of macrocell users and insufficient resources can remain for the users of the FAP. The main weakness of the latter one is that it can result in low transmission efficiency because transmission power level of the FAPs is restricted. In this paper, we propose a novel hybrid spectrum sharing that allows the FAPs to use both overlay and underlay strategies simultaneously and, thus, increase performance of FAPs' users. The proposed scheme is fully distributed since the FAPs allocate resources autonomously. The results show that the proposed algorithm is able to significantly outperform competitive schemes in terms of served traffic for femtocell users and, simultaneously, served traffic for macrocell users is intact.
 
Top-cited authors
Algimantas Zakarevičius
  • Vilnius Gediminas Technical University
Jurgita Antucheviciene
  • Vilnius Gediminas Technical University
Zenonas Turskis
  • Vilnius Gediminas Technical University
Edmundas Kazimieras Zavadskas
  • Vilnius Gediminas Technical University
Dmitri Vinnikov
  • Tallinn University of Technology