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

The paper aims to present the usefulness of Field Programmable Gate Array - based systems, the elasticity of hardware design for reuse, and the use of hardware and software resources. The proposed measurement system is a starting point for the design of a weather station capable of interpreting the variation of the size of atmospheric pressure, temperature, and humidity, which could make local weather predictions.

In this article we want to highlight the forced digitalization we are dealing with due to the COVID-19 pandemic and the fact that this crisis also brings benefits to the education system. The first steps in this direction were to switch to online courses to protect both teachers and students. For them at home it has become a smart home because they need online platforms, internet, PC/laptop, smartphones, webcam, all this to have access to education and to be able to develop without problems.

The study determines the time and frequency behavior of the LM324 operational amplifier. It determines the voltage amplification, the amplification given in dB, the waveforms made with the help of the Octave and Orcad Lite simulator and the observation a fairly good correlation between the analytical calculation and the simulation media used.

The study determines the behavior type of the parallel-series amplifier and determines the amplification of the basic amplifier, the input and output resistance, as well as the amplification of the reaction network and the input and output resistance of the reaction network. With the help of the negative reaction, the designer can change the properties of the amplifier. Thus, a dynamic, automatic stability of the amplification system is obtained.

The paper proposes the development of an IoT measurement system that offers the user the possibility to monitor and record the electricity consumed by a consumer through the Blynk application. In monitoring electricity one of its most important aspects is the calibration of the sensors used. Accurate and reliable detection is the key factor in measuring and managing electrical equipment. Fundamental physical quantities such as voltage and current are useful for determining all other electrical quantities. The ESP32 development board used to develop the system has 18 channels ADC (analog to digital converter) and supports a Wi-Fi connection at the access point and implicitly to the internet. The developed system can measure the voltage (U), current (I), power consumption (W) and consumption / hour (kWh) of a consumer, in my case for the consumer I used a light bulb with a power given by the manufacturer of 10W. The measured values are displayed on the LCD display of the system or through the Blynk application which also allows the registration of these values for a period of 12 months.

This paper presents how in the business market of oil products marketing, an entrepreneur should be constantly aware of the needs, policies and purchasing techniquesxof companies, for the precise purpose of understanding what quantity of oil/complementary oil products and liquefied petroleum gas (LPG) products he can sell. In addition, the entrepreneur must also take into account the sales aimed at individuals, which are done, in particular, through the fuel distribution stations or through the points of sale of LPG loads.

The business market in the field of selling petroleum products includes the totality of the companies that purchase petroleum products, complementary products and LPG loads. The purpose of such companies is to produce otherxgoodsxand servicesxthat can bexsold, rented or provided to others.

In the electric vehicle industry, a battery management system is needed when voltages are in the value of hundreds of volts. The battery management system is not only used to estimate the remaining capacity of the batteries but also to prevent various hazards that may occur in case of improper use. The paper offers a review of the battery management system that is used in the modern electric vehicles. The system is described along with its functions including the practical methods for balancing the battery and the type of batteries used in the automotive industry.

This paper presents a simplified version of analog modeling for humidity of an agricultural soil, both isolated and included in a simple control scheme, being emphasized the application aspects for such a system. This article also includes preliminaries for agricultural soil model included in a simple humidity control scheme with some interpretation variants for evolution of processed signals for possible applications.

The main objectives of this paper are to correctly define the equivalent Thévenin and Norton circuits and to presents the complete and exact proof of Thévenin and Norton theorems. These circuits allow the separation of the linear portions of the electronic circuits from the nonlinear ones and in this way the polarization process of the 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 much more efficiently if the nonlinear part of the circuit is separated from the linear one. By determining the equivalent Thévenin or Norton circuits in relation to the load to connected terminals of a system with two or more magnetic coupled coils, that are part of the wireless power transfer systems, optimal load parameters are determined so that the maximum active power is transmitted to the load.

The fusion between the layers of a 3D printed part greatly influences the overall mechanical properties and can reduce its applications in certain domains. In order to obtain a better bonding between layers a study on the influence of printing temperature on the tensile strength of 3D printed parts is needed. The mechanical experiments were made on printed parts with polylactic acid material (PLA) on an open-source 3D printer with filament fabrication technology (FFF). The study is made on parts with the same layer height, infill ratio, dimensions, printed at the same speed. The obtained results show the influence of material printing temperature and the fast cooling on the mechanical properties of the 3D printed parts.

The paper presents an applicative study on the power quality and energy efficiency operation for a photovoltaic power station with an installed capacity of 8.5 MW. The various operating regimes of the main network elements within the investigated photovoltaic plant are qualitatively and quantitatively. The reactive power flow in the plant that is permanently connected to the grid is especially examined. Thus, the losses within the power transformers and medium voltage cables in the plant are calculated due to the imposed by the load (often deforming and unbalanced regimes). In this manner, opportunities are identified to increase the energy efficiency of the entire system but also methods to improve the quality of energy delivered at the point of its connection to the local energy system.

This paper proposes the creation of a home automation system using an ESP8266 microcontroller and the Blynk application. The system consists of 2 sensors responsible for measuring the temperature/humidity and the level of brightness in the building, a 4-channel relay module responsible for controlling 4 devices/appliances/electrical installations and an LED that demonstrates its control through a PWM signal provided by the ESP8266 microcontroller. Using the Blynk application this system can be controlled and monitored via a Wi-Fi connection directly on the mobile device which makes this system an IoT (Internet of Things) one. The programming of the system was done in the Arduino IDE program using the already existing libraries for the sensors and for the Blynk application. The mobile application used for controlling and monitoring the system is able to display information about temperature /humidity, brightness and on the control side, the application allows the user to individually operate each channel of the relay module and the LED.