<abstract xmlns="http://www.w3.org/1999/xhtml">Some dynamical linear elements including on-off elements such as electro-mechanical relays and electronic components used in switching mode for some feedback control systems can present special features such as the capability to autonomously generate stable self-oscillations. This paper concerns the comparison of two approaches enabling to determine the frequency of self-oscillations in these systems. We examine Tsypkin’s approach which can provide analytical solutions to determining the frequency of existing self-oscillations. On the other hand, we examine the Describing Function (DF) approach which has been developed as an alternative to approximate these solutions.We will compare these two approaches for nonlinear systems of first and second orders. We will examine particularly the possibilities and limits of each approach for calculating the self-oscillations. Simulation of these systems will be performed to visualizes their behaviors. An experimental feedback control system based on electronic circuits used in switching mode has been built as a setup enabling testing and envisioning some applications.</abstract>

Determination of Self-Oscillations in Relay Control Systems

<abstract xmlns="http://www.w3.org/1999/xhtml">ANSYS Q3D Extractor tool (AQ3DE), using the quasi-static solvers (method of moments, integral equations and FEMs), is very efficient for computing and simulating two- and three-dimensional electromagnetic field. This simulation is used to extract parameters of interest, such as: resistance (R), conductance (G), self-inductance (L), mutual inductance (M) and capacitance (C). These parameters can be further used to optimize and to obtain automatically the design of a wireless power transfer systems (WPTS). The resulting matrices allow the generation of new matrices for any selected parameters. To complete the analysis, the model which is computed will be exported as an equivalent circuit. In this paper, starting from a given WPTS, using AQ3DE tool, the parameters of interest (R, G, L, M, C) were automatically calculated, and the SPICE equivalent circuit was obtained. The analysis was performed for two different distances between the emitter and the receiver. The electrical circuit theory was used for the system analysis of magnetically coupled coil (MCC) system. Starting from the parameters extracted by the AQ3DE tool, the performance of the WPTS has been analysed both in time and frequency domain.</abstract>

On Magnetically Coupled Coils Parameter Calculation

<abstract xmlns="http://www.w3.org/1999/xhtml">Electricity distribution systems are subject to a variety of faults such as permanent and transient short circuits due to the extent and multiplicity of equipment. In principle, short circuit fault causes the existing protective equipment to operate and to no electricity the various parts of the distribution network. Rapid and accurate determination of fault location, repair and recovery, it has not prevented the distribution of energy. This will satisfy consumers and prevent the losses of electricity companies. In this paper, the artificial neural network and fault current profiles are used to determine the distance of the fault, determine the type of fault and detect the short circuit. This method provides the information needed to locate the fault by sampling the current before and after the fault occurs from the SCADA system. The effect of connectivity local resistance changes and the effect of load changes on fault location were evaluated. The results show that this method is more accurate than the voltage droop profile variation method in determining the fault distance and short circuit breakdown. If only the net fault current changes profile is used, the effect of the load changes in determining the short-circuit breakdown is much less.</abstract>

Fault Location in Radial Distribution Network Based on Fault Current Profile and the Artificial Neural Network

<abstract xmlns="http://www.w3.org/1999/xhtml">Statistics show that there is an increase in production of cars every year worldwide. Similarly, there is an increase in car theft attempts and carjacking cases worldwide. This paper is meant to increase the user’s situational awareness. The user is able to check for surrounding of the vehicle and judge for himself/ herself before approaching the vehicle. Raspberry Pi is used as the controller in this paper. A Universal Serial Bus (USB) webcam plugged into the Raspberry Pi enables the user to view the images captured in real time by use of an application installed on the user’s smartphone.</abstract>

Car Security System Based on Raspberry Pi

<abstract xmlns="http://www.w3.org/1999/xhtml">With the advancement in microprocessor technology, mobile phones are becoming more preferable in our day to day lives as compared to personal computers since most phones are capable of functionalities as sophisticated as our PC’s or laptops. Mobile phones nowadays have processor speeds as high as 1GHz and can have a storage capacity of about 32Gb and they also have long hours of battery life. In addition to these feature, there is the aspect of great portability. When all these are combined into one, the mobile phones can be viewed as a very powerful device that rivals PC’s. Advancements of hardware also had made mobile phones much smaller and more efficient whereas including an increasing of peripherals number. The scope of this paper is basically to make a mobile phone application and how to interface the mobile phone to the scanner. The mobile application is to be developed in the Linux-based Android platform. An algorithm based on the operation principles is also to be developed during the work.</abstract>

Mobile Phone and Barcode Scanner

<abstract xmlns="http://www.w3.org/1999/xhtml">The study aims for the development of a system for cellular extraction, developed at the level of an experimental model, with the help of which the user can generate a series of sessions of cellular extraction from the cultures of specific cells. To move to the prototype level, the system that will materialize in an specialized equipment for cell extraction and inter / intra-cell injection needs a developed user interface, so that the equipment as a whole is easy to use by the human operator. The present project provides a viable technical interfacing solution for the above mentioned equipment, using the Raspberry Pi hardware resources and the Python C. software resources. Demonstrating the capability of the Raspberry Pi - Python technical tandem for the biomedical equipment to be built is the essence of this project, and the further development of a specialized user interface is a natural step.</abstract>

Cell Extractor

<abstract xmlns="http://www.w3.org/1999/xhtml">The Internet of Things is considered an emerging technology with the potential to penetrate all aspects of our lives. However, with great power comes great responsibility and the privacy and security needed for critical infrastructure or sensitive commercial operations is very different than the needs of a Smart Home. Additionally, the available security resources from the private sector are totally different than the ones available to a homeowner. In this context, we developed an open source architecture for IoT which is based on the advantages of a SCADA system and can be easily applied to a Smart Home. This architecture assures a high-security level, even for low technical skills homeowners, with minimal costs.</abstract>

Open Source Architecture for Iot Based SCADA System for Smart Home

<abstract xmlns="http://www.w3.org/1999/xhtml">The study aims for the development of a robotic humanoid arm for prosthesis, developed at the level of a prototype, with the help of which the user can replace a lost or missing limb. The movement of the fingers is done through servomotors and the control for the prototype is obtained by using a mobile application, this control method is used strictly for testing. The present project has a custom control board that is made from a Arduino Nano development board, Bluetooth HC-05 module, power/servo pins and provides a viable technical interfacing solution for testing the above mentioned equipment, using the Arduino Nano resources and the IDE/Java software resources.</abstract>

Robotic Humanoid Arm

<abstract xmlns="http://www.w3.org/1999/xhtml">In this paper, the authors present the modelling methods and numerical calculation of the dispersion magnetic field of electrical machines, as well as the results of their validation through practical measurements. An adequate analytic formula for magnetic induction calculation is proposed by the authors. The experimental results validate the proposed analytic model. Moreover, the proposed model is valid for both near and far field regions.</abstract>

Modeling of Dispersion Magnetic Fields Developed by the Main Electromagnetic Systems Used on Military Ships

<abstract xmlns="http://www.w3.org/1999/xhtml">The common droop method is one of the most effective methods for controlling power-sharing in islanded microgrid. Due to the dependence of the active and reactive power on the voltage and frequency in resistor microgrid, the use of this method in controlling the power-sharing in these types of a microgrid to the undesirable performance of active and reactive power-sharing. In this paper, by applying virtual impedance in the local controller of distributed generation resources, this paper has modified the common droop method and improved power-sharing. The proposed virtual impedance has an adjustable resistor section and a fixed reactance section. Simulation of a typical islanded microgrid in PSCAD / EMTDC software shows that the proposed method is capable of improving the active and reactive power sharing in resistive microgrid controlled by the droop method.</abstract>

Power Control in an Islanded Microgrid Using Virtual Impedance

<abstract xmlns="http://www.w3.org/1999/xhtml">Different methods of dispersion magnetic fields solutions for single phase transformers are presented in this paper. The transformers are with cylinder windings placed onto a single column. The transformer construction transformer is in the mantle. The analytic equation expression of finding dispersion magnetic fields have been delivered and the obtained solution has been verified by the experimental field measurements.</abstract>

Modeling of the Dispersion Magnetic Fields for the Single-Phase Transformers

<abstract xmlns="http://www.w3.org/1999/xhtml">A new approach to a frequency synthesizer is proposed: instead of a fixed frequency reference oscillator and a variable ratio frequency divider we use a variable frequency reference oscillator and a fixed ratio frequency divider. The implementation and characterization of a low phase-noise compensated oscillator used as frequency reference for a wireless transceiver is described. This circuit employs a high Q piezoelectric resonator together with a CMOS cross coupled pair amplifier. A calibration circuit for compensation of frequency errors with respect to process variation is proposed.</abstract>

A Frequency Reference for Carrier Synthesis in Wireless Standard 802.11g

AHEAD OF PRINT

Volume 23 (2023): Issue 2 (December 2023)

Volume 23 (2023): Issue 1 (September 2023)

Volume 22 (2022): Issue 2 (December 2022)

Volume 22 (2022): Issue 1 (July 2022)

Volume 21 (2021): Issue 2 (December 2021)

Volume 21 (2021): Issue 1 (April 2021)

Volume 20 (2020): Issue 1 (April 2020)

Volume 19 (2019): Issue 2 (October 2019)

Volume 19 (2019): Issue 1 (April 2019)

Volume 18 (2018): Issue 2 (October 2018)

Volume 18 (2018): Issue 1 (April 2018)

Volume 17 (2017): Issue 2 (October 2017)

The Scientific Bulletin of Electrical Engineering Faculty

 Although the beginning of higher education in Targoviste has its roots in the Middle Ages, it became official and institutionalized after 1990, when, on the 1st of June 1992 University Valahia of Targoviste was set up.  Since 1994, regularly, the scientific life of University was gradually enriched with the first volumes of Annals of Valahia University. Starting from the year 2000, the Faculty of Electrical Engineering periodically organizes the “International Symposium on Electrical Engineering” – ISEE, a national and international scientific event, its works being published with the support of Bibliotheca Publishing House in a special Proceedings volume.  A qualitative step was made with the first issue of the journal „The Scientific Bulletin of Electrical Engineering Faculty - SBEEF” in 2001, which provided to the electrical engineering community an important instrument to express the scientific engineering creation. At the same time, through the strategy for the selection and publication of best scientific contributions, „The Scientific Bulletin of Electrical Engineering Faculty - SBEEF” has constantly followed to manifest the leadership position in education and research in the electrical engineering field.  Currently, the journal encourages and strengthens the scientific cooperation at international level, by conducting exchanges with the journals of several well-known national and international institutions. The editorial committee and reviewers of SBEEF are composed by prestigious personalities of the academic and research life, both at national level – Romanian Academy, University Politehnica of Bucharest, University of Oradea, University of Pitesti, Technical University “Gh. Asachi” Iasi, University Dunarea de Jos of Galati, Univerrsity of Medicine and Pharmacy “Carol Davilla” of Bucharest, CEZ Trade Romania, ICPE Bucharest, University Valahia of Targoviste, and at international level – Politecnico di Torino, University of Poitiers, Technical University of Copenhagen, University of Patras, Polytechnic University of Warsaw, University of Tampere, Technical University of Melbourne, University of Valladolid, Canadian Institute Energy, Technical University of Fes, Institute for Research ABB-Schwartz of Geneva, University of Louvain, Belgium, Univ. Paris8, IUT de Montreuil, University of Zaragoza, Grenoble Institute of Technology, Energy System Institute SB RAS, Irkutsk, Universidade Federal de Santa Catarina Florianopolis, University of Ulster, Nevsehir Haci Bektas University.  The editorial committee receives and analyzes the contributions of authors, the review activities being made in the frame of two main sections, which of them contains eleven subsections, Section A: Electric Circuit Theory and Analysis, Renewable Energy Sources, Electromagnetic Compatibility/Power Quality, Energy Efficiency, Electrical Machines and Drives, Power Systems, Computational Electromagnetic, Materials for Electrotechnics, Measurements Techniques/Virtual Instrumentation/Sensors and Transducers, CAD in Electrical Engineering, and Biomedical Engineering, and Section B: Control Systems, Artificial Intelligence Techniques, Modeling and Simulation, Distributed Systems, Real-time Systems, Telecommunications Technologies and Software, Signals and Image Processing, E-learning, Applied Informatics, Robotics, Educational use of ICT. On these lines, in the Editorial Board academia professors and researchers with scientific competences were co-opted – all of them fully recognized by the scientific international community. The peer-review process of the manuscript proposed for publication in „The Scientific Bulletin of Electrical Engineering Faculty” is conducted in accordance with the common international procedures, including anti-plagiarism verification.  For all the authors, whose number has increased continuously, the doors for affirmation are permanently opened in all the scientific fields of electrical and electronic engineering, power systems, and computer science and also in biomedical engineering and their chirurgical applications. In addition, even if the journal had initially an annual occurrence, in 2008 and 2009 two numbers saw the light of printing and since 2010 there were three occurrences every year and since 2013, 4 volumes every year. Since 2008 SBEEF is indexed in international database Index Copernicus Master List Journals  journals.indexcopernicus.com/karta.php?action=masterlist&amp;id=3797 with IC value 3,61 for 2009, 4,41 for 2010, 4,91 for 2011, 5,19 for 2012, 5,27 for 2013, and 6.5 for 2014.  On behalf of the editors we invite scientific researchers, specialists and teachers involved in electrical engineering and in close areas to work for the preparation and publication of their scientific contributions in the „The Scientific Bulletin of Electrical Engineering Faculty”.   Rejection Rate   8%   Archiving  Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.  Plagiarism Policy  The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process. 