<abstract>
<title style='display:none'>Abstract</title>
This review paper centers on strategies employed for location determination in regions lacking GPS signals. It primarily explores a range of vision-based methods tailored for this purpose, categorizing them accordingly. The article delves into the utilization of optical flow for feature extraction-based Visual Odometry (VO) and delves into advanced optical flow estimation methods that hinge on deep learning techniques. It compares the efficacy and practical applications of frequently utilized visual localization methods while also checking the efficiency of previous researches by reapplying the algorithms to new data and comparing the results.
</abstract>

A Review of Using Visual Odometery Methods in Autonomous UAV Navigation in GPS-Denied Environment

<abstract><title style='display:none'>Abstract</title>To establish an exercise in open muscular chain rehabilitation (OMC), it is necessary to choose the type of kinematic chain of the mechanical / biomechanical system that constitutes the lower limbs in interaction with the robotic device. Indeed, it’s accepted in biomechanics that a rehabilitation exercise in OMC of the lower limb is performed with a fixed hip and a free foot. Based on these findings, a kinematic structure of a new machine, named Reeduc-Knee, is proposed, and a mechanical design is carried out. The contribution of this work is not limited to the mechanical design of the Reeduc-Knee system. Indeed, to define the minimum parameterizing defining the configuration of the device relative to an absolute reference, a geometric and kinematic study is presented.</abstract>

Design of a Human Knee Reeducation Mechanism

<abstract>
<title style='display:none'>Abstract</title>
Inconel738 is a nickel-based super alloy widely used in manufacturing gas turbines, particularly in the manufacture of blades that are in direct contact with hot gases during their operation. As a result, these blades are subjected to high temperatures, significant static and dynamic stresses, erosion and/or hot corrosion which can be very severe. The use of coatings is one of the most effective strategies to protect materials against corrosion and increase the wear resistance of materials. In this study, β-Ni-Al coatings were sprayed onto an Inconel738 substrate using a wire flame spraying process and characterization of coating has been made.
</abstract>

Experimental Investigation on the Coating of Nickel-Base Super Alloy Using Wire Flame Spraying

<abstract><title style='display:none'>Abstract</title>In the industrial sector, maintenance of production facilities plays an important role to carry out production by increasing the reliability and availability of the production process. Predictive maintenance strategy seems adequate to anticipate the failure and degradation of the state of such equipment. A reliability study is needed to quantify indicators to describe the functioning of any system over time. In this paper, we present the results of a stochastic modeling conducted on the analysis of the availability of motor-pump system, installed in a cooling circuit in an industrial complex. The equipment considered in this study is composed of four subsystems. The proposed model is a dynamic Markovian approach, for the purpose of a comparison with the analytical calculation in terms of the indicators’ evaluation of the dependability of the studied system, including instant availability. The different states of the system components and the transition functions between these states have also been characterized. The results of availability obtained by the model are well correlated with those calculated analytically, confirming that the proposed model is very powerful, it will help predict the future states of the system, in order to predict any necessary preventive maintenance actions.</abstract>

Study of Reliability in a Repairable System by Markov Chains

<abstract>
<title style='display:none'>Abstract</title>
In this work, computational fluid dynamics (CFD) was used to investigate the effect of the bottom shape on the flow field and mixing characteristics in an agitated vessel stirred by six-pitched blade turbine (PBT6). The simulation was based on the resolution of the Navier-Stokes equations using standard k-ε turbulence model. Hydrodynamic behavior of the stirred vessel with four types of bottom shapes was investigated, a flat bottom and three different semi-elliptical bottoms. The results show reasonably satisfactory agreement with the experimental data. The CFD simulation also showed that the semi-elliptical bottom shapes had a significant influence on the velocity profiles and on the turbulent kinetic energy distributions of the local flow generated at the bottom region of the vessel.
</abstract>

Numerical Study of Bottom Shape Effect on the Mixing for Stirred Tank

<abstract>
<title style='display:none'>Abstract</title>
This study explores the enhancement of wireless communication through the integration of OFDM with MIMO and advanced techniques like COFDM, adaptive MIMO, and beamforming. It evaluates a 2×2 and 4×4 MIMO-DWPT-COFDM system, considering modulation (BPSK and QPSK) and equalization (ZF-SIC and MMSE-SIC) over a Rayleigh fading channel. MATLAB results reveal that more antennas, BPSK modulation, and MMSE-SIC equalization significantly improve BER performance. Specifically, for a BER of 10−4, the 2×2 MIMO system requires <italic>E</italic>b / <italic>N</italic>0 values of 10.4 (MMSE-SIC) and 11.4 (ZF-SIC), while the 4×4 MIMO system needs 5.5 (MMSE-SIC) and 5.9 (ZF-SIC). These findings emphasize the need for thoughtful system design and parameter optimization in achieving reliable and efficient wireless communication.
</abstract>

Performance Analysis of Combining Beamforming and ZF/MMSE-SIC Equalization Techniques for MIMO DWPT-COFDM Systems

<abstract>
<title style='display:none'>Abstract</title>
This case study presents a possible solution for monitoring wind induced waves in shallow water lakes. Currently widely used instruments for measuring water waves are expensive due to extreme environmental requirements and the technology used. The use of IoT solutions is not common. Water wave measurements require low power consumption and medium to long range communication. Due to the network specifications, it is not obvious that LPWAN technologies are suitable for transmitting the amount of data generated. For the devices developed, LoRaWAN was investigated as the cheapest and 5G as the most reliable network solution, with attention to energy consumption.
</abstract>

IoT Sensor Network Solution for Monitoring Wind Induced Waves in Shallow Water

<abstract>
<title style='display:none'>Abstract</title>
This paper focuses on a new investigation of the rheological properties of the nanocomposites of surface charged superparamagnetic iron oxide nanoparticles with polyethylene glycol. Both studied nanocomposites showed the steady-state behavior at 20 °C and 40 °C. Moreover, the increase of viscosity versus shear strain, shear rate or time for the nanocomposites was small at 60 °C. The effect of the coating of nanoparticles with the polymer was comparable for different nanocomposites. The data presented in this paper can provide the required information for the preparation of assemblies of nanocomposites with polymers.
</abstract>

Comparative Rheological Investigation of Nanocomposites of Surface Charged Superparamagnetic Iron Oxide Nanoparticles with Polyethylene Glycol

<abstract>
<title style='display:none'>Abstract</title>
Optimization is one of the best techniques used in industries to assess the quality of the drilling machine at a lower cost. This work is based on the rotary drilling mode with different methods based on the physicomechanical properties of the rock, machine setting parameters, and tool geometry parameters. The aim of the research presented is to develop quality of methods for determining the parameters of the rational operating regime of the rotary drilling machine during its operation in geological and mining conditions.
</abstract>

Development of a Methodology for Assessing the Quality of Drilling Machines

<abstract><title style='display:none'>Abstract</title>This work is about the validation of a Common Rail (CR) injector model. The model describes injector internal behavior in a detailed way, validation is done using dosage measurements and needle lift traces.The model contains fluid dynamic, mechanic and electro-magnetic parts describing all important internal processes. To compare the modelling results against measurement data, three test cases were chosen on a medium duty test engine to represent a wide range of operation points. Dosage measurements were done by averaging the injected mass of 1500 injections, each measurement repeated three times. Needle displacement was measured using an injector equipped with a needle lift sensor in the same operating points. The results of the simulated injector and the measured values showed good conformity both in needle displacement and injected fuel mass, so the model can be a basis for further injector and combustion analyses.</abstract>

Detailed Model of a Common Rail Injector

<abstract><title style='display:none'>Abstract</title>UAS (Unmanned Aerial Systems) are commonly used in 3D (dull, dirty and dangerous) missions, because these are not endangering the operators life, while reduce maintenance costs and increase maneuvering capabilities. Despite of these advantages we should consider the possible vulnerabilities of this technology as well. Unmanned vehicles can be controlled via direct communication link, or they can work in a preprogrammed mode. Usually the preprogrammed mode is based on radio navigation systems, so we can draw a conclusion that both depend on the RF environment. In this paper I analyze a possibility to effectively evaluate the communication link of an UAS. Developers have to consider several key factors (type of operation, endurance, payload type and size, propulsion, communication link, etc.) during the development process. They are also responsible that the final product meets the predefined requirements. On the other side commercial UAS owners should have a possibility to compare and evaluate the UAS before the acquisition. Finally, operators and frequency management entities need tools to diagnose the possible sources of interference regarding the unmanned vehicles. To understand the consequences of interference in the RF spectrum we have to be able to measure the quality of the communication link in different usage scenarios. In my research I evaluate the usage of SDRs (Software Defined Radios) in RF Test and Evaluation processes. After analyzing the possibilities for a flexible testbed, I demonstrate the usability with some measurements in the GNU Radio signal processing framework.</abstract>

GNU Radio Based Testbed (GRaTe-BED) for Evaluating the Communication Link of Unmanned Aerial Systems

<abstract><title style='display:none'>Abstract</title>The presence of a second reactive gas in the magnetron sputtering chamber makes the process much more complicated, and the process control much more difficult than in the case of a single reactive gas. Macroscopic models have been developed in order to explain the complex phenomena and to provide support for the process control. These models are able to explain the nonlinearities of the process and the strong coupling between the control channels.This paper introduces a model created with the intention to of gaining a good grasp of the process, especially regarding the conditions necessary to obtain the required stoichiometry of the film deposited on the substrate. For this purpose, we modelled the formation of the desired ternary compound both directly from the available particle fluxes and from intermediary compounds. The surface of the substrate is divided into eight dynamically variable regions, covered by different compounds, each exposed to the streams of five types of particles.We present the analytical model and provide simulation results in order to demonstrate its capability toof describeing the nonlinear phenomena, which that characterisze the two-gas sputtering process.</abstract>

Macroscopic Thin Film Deposition Model for the Two-Reactive-Gas Sputtering Process

<abstract><title style='display:none'>Abstract</title>This paper focuses on the hardware development of an indoor ultrasound based robot localization system. The problems related to the ultrasound based distance measurements are presented and solutions are proposed related to Time of Flight measurements and measurement synchronization. An optimization based compensation method is introduced to attenuate the effect of the ambient temperature on the distance measurement precision. Experimental measurements were performed to analyze the applicability of the developed system and measurement methods.</abstract>

Ultrasound-Based Indoor Robot Localization Using Ambient Temperature Compensation

<abstract><title style='display:none'>Abstract</title>The objective of this paper is solving of the Modified Filter Algebraic Riccati Equation (MFARE) for calculating of the filter gain. The results are used for model-based fault detection filtering of faults in the air path of diesel engines. The Hinfinity optimization approach requires the solution of a linear-quadratic optimization problem that leads to the solution of MFARE. In our paper two basic concepts for solving MFARE are examined, namely the analytically implemented gamma-iteration and casting the problem as a convex optimization problem based on Linear Matrix Inequalities (LMIs).The algorithms are implemented in MATLAB. Each algorithm has to ensure the condition for a global convergence and also has to deliver an optimal solution. Not at least, the computational cost has to be as small as possible.</abstract>

Solving of the Modified Filter Algebraic Riccati Equation for H-infinity fault detection filtering

<abstract><title style='display:none'>Abstract</title>Dynamic logic circuits are widely popular due to a smaller number of transistors and consume less area. But the time to switch between logics is higher due to higher contention value. A new model of the logic using nMOS based keeper circuit is proposed and the performance is evaluated using Cadence tools. Comparative results demonstrate the suitability and competency of the proposed circuit.</abstract>

A New Model of Dynamic Logic Circuit with NMOS based Keeper

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Acta Universitatis Sapientiae, Electrical and Mechanical Engineering

The Journal of Sapientia Hungarian University of Transylvania

 Series Acta Universitatis Sapientiae, Electrical and Mechanical Engineering surveys in various fields of Electrical and Mechanical Engineering. All papers are peer-reviewed. The...

 Series Acta Universitatis Sapientiae, Electrical and Mechanical Engineering surveys in various fields of Electrical and Mechanical...