<abstract xmlns="http://www.w3.org/1999/xhtml">

The aim of this work was to investigate the effect of processing parameters of the electrospinning method on the resulting poly (vinylidene fluoride) (PVDF) fiber diameter. A three factorial Box-Behnken experimental design was employed to study the influence of applied voltage, the capillary-to-collector distance and the applied flow rate on the resulting fiber diameter. We successfully prepared bead-free PVDF nanofibers with fiber diameters ranging from 510-1300 nm. The experimental design analysis did not show significant influence of the studied process parameters under the used boundary conditions on the fiber diameter, thus indicating the robustness of the process.
</abstract>

Process Optimization of PVDF Piezoelectric Nanofiber Production via Electrospinning

<abstract xmlns="http://www.w3.org/1999/xhtml">

The presence of the lubricant POE 68 in the refrigeration system changes the thermophysical properties of the refrigerant, which significantly affects the heat transfer and the hydraulic processes. The purpose of this research is to investigate the thermodynamic properties of the R152a, R125, R134a and R123 refrigerant and POE 68 lubricant mixtures at different temperatures from 233,15 to 313,15 K. There have been investigated the values of the densities and kinematic viscosities of the mixtures at different concentrations (100%, 90%, 80%). Finally, it was found that, the density and kinematic viscosity of the R123/POE 68 mixture were most affected by the change of the concentration.
</abstract>

Investigation of the Thermodynamic Characteristics of the Ester Oil and R152a, R125, R134a and R123 Refrigerant Mixtures

<abstract xmlns="http://www.w3.org/1999/xhtml">

The actual energy situation and the significant energy demand of agricultural production require the exploration and analysis of the general laws of the main processes in the field of energy, which is part of the borderline between the technical sciences and the agricultural sciences. Tillage machines change the physical properties of the soil, but at the same time the mechanical properties of the soil react to the implement. One of the basic works of seedbed preparation is harrowing. In this work we study the kinematics and dynamics of the active rotary harrow implements, taking into account the cutting resistance of the soil. The results obtained with the developed modeling methods, give reliable approximations to the experienced tilling processes.
</abstract>

Kinematic and Dynamic Modeling of the Rotary Harrow

<abstract xmlns="http://www.w3.org/1999/xhtml">

This paper presents a study regarding the gear hob’s rake face grinding possibilities and its consequences. A simple theoretical lined surface is considered. The mathematical model of the reciprocate meshing of surfaces was applied. It was proven that the proposed form of the rake face cannot be obtained because an undercut of inacceptable extent occurs. It is also proven and sustained by CAD modeling that using a simplified, flat grinding disk, the undercut is avoided, but the phenomenon of transection appears.
</abstract>

Faculty of Technological Engineering and Industrial Management, Department of Manufacturing Engineering

Sapientia Hungarian University of Transylvania

Faculty of Technical and Human Sciences, Târgu Mureş, Department of Mechanical Engineering

Peculiarities of the Grinding Process of a Gear Hob Helical Rake Face

<abstract xmlns="http://www.w3.org/1999/xhtml">

The paper presents a study regarding the implementation of two representative grid synchronization methods, intended to be used in the control structure of a three phase switch mode voltage rectifier.
The methods considered are the Synchronous Reference Frame Phase Locked Loop (SRF PLL) and the Double Synchronous Frame Phase Locked Loop (DSRF PLL), respectively. These synchronization methods have been compared on a real time development system type dSpace 1104 from the point of view of their performance in case of an unbalanced mains voltage system. Finally, the influence of the chosen grid synchronization method on the performance of a synchronous reference frame controlled three-phase switch mode voltage rectifier is studied by simulation, and better results are demonstrated to be provided by the use of the DSRF PLL.
</abstract>

Implementation of Grid Synchronization Methods on a Real Time Development System

<abstract xmlns="http://www.w3.org/1999/xhtml">

Majority of the optimal control techniques can only be applied successfully if the model of the controlled process is known and it is linear. If the system model is nonlinear, then this nonlinear model can be approximated with different simple, linear models. However, these models are valid only in the neighbourhood of the operating points. The success of the control algorithms is highly dependent on the used linearization methods. The aim of the paper is to compare different optimal control algorithms and linearization methods. The presented optimal control algorithms have been also tested in constrained and unconstrained versions.
</abstract>

Theoretical Study of the Unconstrained and Constrained Nonlinear Optimal Discrete Time State Feedback Control

<abstract xmlns="http://www.w3.org/1999/xhtml">

The paper presents the energy loss minimization of a hybrid energy storage system used in an electric vehicle, composed by a battery and a supercapacitor. The optimization is carried out by searching the optimal power sharing between the energy storage devices. The power sharing factor is defined as a discrete time variable, with constant values during each subdivision of the driving cycle. The elements of the optimal solution vector are the power sharing factors and the time instants that define the subdivisions. The particle swarm optimization algorithms have been validated using the Rastrigin test function, and three versions of the boundary behaviour have been compared in case of the constrained optimization. The algorithms have been tested for the energy loss minimization in case of a simple driving cycle, and their performance has been assessed by statistical analysis for different swarm sizes.
</abstract>

Faculty of Electrical Engineering, Department of Electrical Machines and Drives

Sapientia-Hungarian University of Transylvania

Faculty of Technical and Human Sciences, Târgu Mureş, Department of Electrical Engineering

Particle Swarm Optimization of a Hybrid Energy Storage System

<abstract xmlns="http://www.w3.org/1999/xhtml">

In this paper we discuss some image processing methods that can be used for motion recognition of human body parts such as hands or arms in order to interact with robots. This interaction is usually associated to gesture-based control. The considered image processing methods have been experienced for feature recognition in applications involving human robot interaction. They are namely: Sequential Similarity Detection Algorithm (SSDA), an appearance-based approach that uses image databases to model objects, and Kanade-Lucas-Tomasi (KLT) algorithm which is usually used for feature tracking. We illustrate the gesture-based interaction by using KLT algorithm. We discuss the adaptation of each of these methods to the context of gesture-based robot interaction and some of their related issues.
</abstract>

Brothers Mentouri University Constantine1

Image Processing Methods for Gesture-Based Robot Control

<abstract xmlns="http://www.w3.org/1999/xhtml">

5G cellular networks have introduced a completely novel air interface called New Radio (NR). This technology delivers numerous benefits compared to previous generations, including significantly higher peak data rates. However, due to the propagation properties of the frequencies used in NR, the volatility of the available downlink capacity also increases. In this paper, we study two TCP congestion control algorithms which are designed to be able to quickly utilize sudden increases in available capacity. We present an implementation of TCP SIAD in the ns-3 open source network simulator and compare its performance with TCP BBR using the mmWave module of the simulator.
</abstract>

Comparison of TCP SIAD and TCP BBR Congestion Control in Simulated 5G Networks

AHEAD OF PRINT

Volume 15 (2023): Issue 1 (December 2023)

Volume 14 (2022): Issue 1 (December 2022)

Volume 13 (2021): Issue 1 (December 2021)

Volume 12 (2020): Issue 1 (December 2020)

Volume 11 (2019): Issue 1 (December 2019)

Volume 10 (2018): Issue 1 (December 2018)

Volume 9 (2017): Issue 1 (December 2017)

Volume 8 (2016): Issue 1 (December 2016)

Acta Universitatis Sapientiae, Electrical and Mechanical Engineering

 Series Acta Universitatis Sapientiae, Electrical and Mechanical Engineering surveys in various fields of Electrical and Mechanical Engineering. All papers are peer-reviewed. The language of the journal is English.  Why submit Strict review, open access, various fields covered.  Why subscribe and read Series Acta Universitatis Sapientiae, Electrical and Mechanical Engineering publishes only original papers and surveys in various fields of Electrical and Mechanical Engineering. All papers are peer reviewed. Rejection Rate   40%   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. 