Carpathian Journal of Electrical Engineering

28-44

Authors: Abdelouahab ZAATRI

The well-known AM2 model is commonly used for simulation of biotechnological processes of two-phases anaerobic digestions. Nevertheless, numerical simulation and graphical results usually obtained by solving the non-linear system of differential equations characterizing this model do not always enable an easy analysis of the processes as well their sensitivity to the variations of the different parameters and the initial conditions. In this paper, as an alternative to simulation, an analytical approach is proposed for batch reactors. It consists of adopting some approximations to reduce the mathematical complexity of the coupled differential equations of the AM2 model. The aim is to derive approximate analytical expressions concerning the dynamical evolution of the substrates and bacterias involved in reactions. The obtained expressions, therefore, permit a relatively easy analysis of the evolution of the main processes and their sensitivity to the different parameters and initial conditions. Moreover, it provides an explicit mathematical expression that enables to estimate the cummulative production of methane. The comparison of the obtained results by this proposed analytical approach to the numerical simulation of the AM2 model shows a satisfying qualitative convergence of the proposed approach to the AM2 model.

58-70

Authors: Md Murshadul HOQUE, Mithun CHAKRABORTY, Joy RUDRA, Md Arif Iftekhar MAHMOOD

This paper proposes a smart home appliance scheduling management (HASM) system based on demand response. An IoT based HASM system is developed to provide an efficient electricity consumption scheme to residential consumers for scheduling their appliances in a cost-effective way and smartly throughout a day. This smart load scheduler takes residential electricity users’ preferences to shift the appliances with deferrable characteristics at cost effective periods considering the user is aware of dynamic tariff information. The user interaction to the scheduling of loads provides maximum comfort level as well as saving of total electricity bill, and the effective utilization of demand response strategies to reduce peak hour electricity consumption. The results of this development indicate a reduction of daily energy consumption confirming the consumer comfort.

81-93

Authors: Mihaela GRIB, Ionela VLAD, Ovidiu Dorin LĂUDATU, Alexandru Radu GRIB, Mihai IORDACHE

The main objective of this paper is to correctly define the hybrid equivalent circuits. These circuits allow the separation of the linear portions of electronic circuits from the nonlinear ones and in this way the polarization process of electronic devices becomes much more efficient. When linear and/or nonlinear analyzed circuits have a small number of nonlinear circuit elements, their analysis, synthesis, and simulation are performed more efficiently if the nonlinear part of circuit is separated from the linear one. A new modeling technique, called H ~ modeling, is introduced for multi-port networks. It is shown that H ~ models are more dynamic compared to equivalent Thevenin or Norton circuits and have the ability to describe port behavior more accurately. A special type of model H ~ is also introduced, called model H ~ nullified, or simply model H ~ and many properties of H modeling are investigated, including circuit energy management. It is shown that the H models are not limited to single-port networks, but also cover multiport. A major property of H modeling is the local polarization of transistors. It separates the nonlinear components from the linear portion of circuit for faster and more efficient polarization of circuit. Here a designer can take advantage of H-modeling and bias individual transistors (or in combinations) with no need to perform the normal circuit biasing. The proposed strategy separates linear and nonlinear portions of an analog circuit and takes more control of nonlinear portions. This separation of portions (components) of circuit is achieved by introducing a new port model that cancels the ports of nonlinear devices. In turn, this leads to a new technique for polarizing nonlinear components. This separation of portions (components) within the circuit is accomplished by introducing a new port modeling that nullifies the ports of nonlinear devices.

113-120

Authors: Cristian BARZ, Zoltan ERDEI, Oleh ONYSKO, Paul TAMAS, Andreea POP, Teodora UNGUREANU

To control and reduce energy consumption, it demands to install a network of sensors and using a dashboard to monitoring data acquisition from its. Energy monitoring is necessary to keep track of energy consumption according to the season, weather conditions and the flow of use of electrical appliances in the institution. The paper presents an approach for monitoring energy efficiency base on Arduino modules (smart-MAC) through a dashboard application. Dashboard WEB application has the advantage of leting the user a flexible indicator and chart widgets configuration for create an unlimited number of boards and devices connected to the same account. To realize an efficiency use of energy in public institution the date is analyze and on results can be take measurements for it.

131-139

Authors: Irina SMICAL

Integrated circuit boards are component of most Waste Electrical and Electronic Equipment (WEEE). These are generated worldwide at an alert rhythm and their recycling is done to a small extent (about 20%). The paper presents an experimental simulation of the presence of printed circuit board waste (PCBs), from end-of-life computers, in three aquatic environments with different pH (pH 4.00, pH 5.63 and pH 8.00). After stagnation for 17 weeks, values of the concentrations of heavy metals released by the PCBs in the solutions were obtained. These indicated that the presence of these boards in aquatic media may impair water quality by inducing moderate risks for surface water and lower risks for groundwater bodies. Heavy metals such as copper and lead, especially in acidic and neutral environments, fell into the worst quality class for surface water and exceeding of the maximum allowable value for the reference groundwater body (ROSO12) were recorded for copper in the acid and neutral initial solutions.

150-158

Authors: Luminița TODEA, Anamaria FĂLĂUȘ, Ramona DEMARCSEK

The employability of graduates has become an issue that countries around the world have imposed on their national higher education systems to varying extents. Acquiring effective employability skills becomes increasingly important for both employers and employees in the field of engineering. Employers generally see a graduate’s achievements related to the subject discipline as necessary but not sufficient for them to be recruited. Achievements outside the boundaries of the discipline, the so-called soft skills, are generally considered to be relevant in the recruitment of graduates. A certain level of awareness among engineering undergraduates should be addressed regarding lacking or mismatching specific soft skills required in their potential workplace context. Therefore, the purpose of the article is to identify and discuss engineering students’ perception on the importance of employability skills such as: communication skills, problem solving and interpersonal skills so that they should overcome problems in getting suitable jobs in the future.

166-172

Authors: Bogdan-Vasile CIORUȚA, Mihaela ȘTEȚ, Mirela COMAN

The construction and commissioning of micro-hydropower plants is a solution for obtaining cheap electricity, but it also has a not negligible impact on the environment. Romania, like any of the member states of the European Union, has committed itself to a share of energy, in the sense of obtaining electricity in the most environmentally friendly way possible. Micro-hydropower plants also fall into this category. From our point of view, their construction started with too much exuberance because we not only have some European rules that we must obey about the green energy quota, but we also have some European rules provided by directives that refer to the protection of ecosystems. And then we must judge a balance between getting the share of green energy we are committed to, but at the same time protecting our ecosystem. We have synthesized, reported, and analyzed the impact of micro hydropower plants according to good practice guidelines aimed at the harmonious development of communities about nature.

188-193

Authors: Marius COSMA, Dinu DARABĂ, Norbert GAȘPAR

The paper presents the optimization of the control process of a family of complex aircraft parts by designing a modular device for the CMM (coordinate measuring machine), how to assemble the elements, how to align the device on the machine table and the presentation of real advantages and disadvantages regarding the designed device.

203-212

Authors: Mirko SAJIĆ, Dušanka BUNDALO, Željko VIDOVIĆ, Zlatko BUNDALO, Dejan LALIĆ, Luka SAJIĆ

The paper considers, proposes and describes the possibilities and ways of transforming teller/counter services using modern and mobile information technologies in order to increase the efficiency of such business. The shortcomings of the traditional teller/counter services are pointed out, and the reasons that will lead to the transition to a modern automated way of providing teller/counter services, without the physical presence of a person, are presented. Then, various variants of partial or complete automation of teller/counter services using modern mobile information technologies are considered. The impact of the pandemic on accelerating the online working and services is mentioned. Then, ways of transforming teller/counter business are proposed and described, through several variants, such as the use of intelligent digital teller/counter terminals and the application of remote online services, through several practical examples. Factors that influence the limitation of the degree of automation and what needs to be done to overcome these limitations are highlighted. Groups of users are profiled who, according to their objective and subjective reasons, will use certain types of automation of teller/counter operations. Appropriate intelligent multifunctional devices are presented, which are already used in some areas as a transitional solution in the automation of the provision of teller/counter services.

227-235

Authors: Adina POP-VĂDEAN

An intelligently developed society is defined by a concept that integrates information technology in all its fields in which man is the direct beneficiary of this environmentally friendly process. Man is both the main actor and the direct beneficiary of the products and services of the intelligent society. This detail must be the determining factor for the development of any society from a classical to a smart one and here comes the concept of Human Informational Field (HIF) accompanies the human being in his interactions. But smart society is about connecting between people, systems, about sharing information and so we get to the Internet of things, or IoT a system of interrelated computing devices, mechanical and digital machines, objects, animals or people. The internet of things helps people live and work smarter, as well as gain complete control over their lives. Because IoT is a sensor network of billions of smart devices the problem of energy supply appears. Energy recovery or harvesting systems is a possible solution that could enable IoT nodes to scavenge self-sustaining energy from environmental sources. In this article we will review these systems and emphasize their importance in the development of smart society or smart city.

252-261

Authors: Marina Daniela SAS

The paper presents a theoretical study and a practical realization of a system for access based on the imprint of a room and keeping track of people who are unauthorized. The assembly is done on a small scale (at the model level). For the practical realization we used the FPM10A fingerprint reader module, the Arduino AT Mega 2560 control unit equipped with the AT mega2560 microprocessor and an ESP32Cam camera equipped with the ESP32 microprocessor. The role of the fingerprint reader will be to check and recognize the fingerprints already stored in his memory, to the people who will want you to enter the rooms. The role of the camera will be to take a picture of the person whose fingerprint is not recognized. To view the allowed or not allowed access status, we mounted the 1.8” TFT LCD display. For the power supply of the assembly I used a 12V source that supplied my electromagnetic lock and from this source with the help of a low voltage converter you could power your Arduino board and ESP32Cam board, these being necessarily supplied at 5V voltage. The advantage of this application is that it secures the entrance to a room and can keep track of remote unauthorized persons who have tried to enter the room.

277-282

Authors: Paul TAMAS, Andreea POP

In this paper we talk about the user’s movement in virtual reality. The programmable part of the application is made in the C ++ programming language, and as the engine for running the graphic image we used Unreal Engine developed by Epic Games. Fragments of code appear in the paper for the calculation and positioning of the user in space, on a two-dimensional plane. The work also contains instructions to be able to make the settings so that the application can be controlled by the glasses levers. The whole project is developed for HTC VIVE PRO virtual reality smart glasses.