This paper presents a pseudodifferential third-order low-pass filter suitable for electrocardiography (ECG) acquisition. The implementation is based on a three real poles topology, where unity gain buffers were used for decoupling. Since from the application perspective (low-pass bandwidth), very large time constants are needed for an on-chip solution, the time constants are obtained by using the output resistance of unity gain buffer, where the transistors are biased in weak inversion and loaded by a capacitance multiplier. Based on the possibility of electronic tunability of a capacitance multiplier, a variable corner frequency over two decades (up to kHz) is obtained. The filter prototype was implemented using 180-nm AMS technology. It is shown that for the nominal case, a cut-off frequency of 250 Hz was obtained using a power consumption of 89 nA from a power supply of 1.8 V, for a pseudodifferential solution, and a figure of merit of 0.6 x 10-15 J. Over global variation, for a 50 Hz input frequency and 0.2 Vp-p amplitude, the filter achieves a total harmonic distortions (THD) bellow -58dB.
In the paper is presented the design of a brushless servomotor, which has its stator made of soft magnetic composite Somaloy 700-3P 600 MPa. This motor will have an industrial purpose in special applications. The finite element method is suitable for a first analyze in the manufacture process and in this step adequate materials are chosen. The cogging torque has low values, fact that proves that motor is a robust one and it has a low-cost integration.
A new type of frequency synthesizer is proposed in this paper. It employs a variable frequency reference, a digital phase lock loop (PLL) including a dead zone circuit for the coarse frequency control, and an analog PLL for the fine frequency control. This structure allows the replacement of the classical variable ratio fractional frequency divider by a constant integer ratio one, that allows a significant reduction of the phase noise.
The paper deals with the simulation and the calculation of output parameters for coaxial and ordinary thermoelectric generators with cylindrical and rectangular thermoelement geometry. It is shown that the thermoelements geometry does not affect the output power. The differences between output parameters of coaxial and ordinary thermoelectric generators are not significant. The calculation has been done by finite element method using ANSYS.
Whether we are talking about the automotive industry or any other field that is based on electronics, in the process of streamlining devices there is a switching-mode power supply. This can be for AC-DC, DC-DC or even DC to AC, in which case several cascading stages take place. As efficiency becomes more and more important, in order to obtain greater mobility (greater autonomy in telephones, laptops or electric cars) there is a growing interest in achieving the most efficient switching-mode power supply. As home grid systems become more popular, solutions are sought to reduce costs and the performance of voltage converters are improved.
Image processing is the most preferred technique in Computer-Aided Design (CAD) studies, and therefore the enhancement of image processing plays an essential role in the advancement of technology. The primary purpose of this study is to examine the effect of fixed threshold value on images of different sizes when using the binarization method in image processing. The analyzes are made based on the change in the detection accuracy percentage of the K-Nearest Neighbor (k-NN), Support Vector Machine (SVM), and Convolutional Neural Networks (CNN) classification methods on the MATLAB software platform. At the same time, the effect of the binarization threshold value on images with different pixel dimensions (8x8, 16x16, 32x32, 64x64, and 128x128) are investigated. CNN classification obtained the best accuracy percentage in the used malaria disease blood cell data 97.5%, followed by k-NN with 95% and SVM with 91.5%.
This paper was based on data obtained from a 20/0.4 kV substation, from a working day, purchased using a class A power quality analyzer. From the set of data obtained, from the analyzer reports, the study of case was limited to data acquisition, data analysis and statistical processing of data on currents and voltages.
This paper deals with the performance assessment of a Current Source Inverter (CSI)-fed synchronous motor drive system using 2D Finite Element (FE) electromagnetic field calculations. The numerical analysis is carried out using FLUX 2D ® software package and the physical support for the proposed investigations is represented by an inverse construction salient pole wound rotor synchronous motor with a rated power of 3.2 kW. Parts of the numerical results are validated by experimental measurements.
The microcontroller based STFT-vibration analyzer (STFT-VA) performs iteratively the short-time Fourier transform (STFT) on a windowed non-stationary signal, resulting in a more accurately spectrum achievement. Actually, the signal is windowed in relation to the lowest frequency value of a range, and the STFT is applied on the signal segments obtained by iteratively decreasing a number of samples from that window. Resulted spectrum is accomplished by identifying the biggest amplitude of each frequency bin. The period of frequency scanning is inversely related to the lowest frequency value and the spectrum refresh rate as well. High-resolution ADC and high-frequency processing microcontroller's features help to achieve an almost continuous spectrum. The device can be useful in many vibration based implementations, and its most significant advantages are the easy operation, small dimension and low-cost.
In order to establish the state of electromagnetic compatibility (EMC) of naval systems, a special place is to obtain the EMC of radio communications systems on board military ships. This is a special challenge for any specialist in the domain both due to the particularly high density of technical means that are available on board military ships, and the fact that radio communication systems can be both sources of disturbance and victims. In obtaining the EMC of the systems, the inter and intrasystem disturbances must be identified and analysed. In order to fulfil the missions of combat, search and rescue and more recently, maritime surveillance and interception of boats with emigrants or refugees, military ships are constituted in naval groups. Such a group often includes ships under different flags, which are equipped with equipment and equipment from different suppliers and from different generations. In this sense, the entire naval grouping must be considered as a system, and the success of the mission may depend on the EMC's provision of the entire system.In the present paper, the authors present an algorithm for calculating the interference margins, necessary to obtain the EMC of a communications system related to a naval grouping starting from the basic EMC equation. The authors develop the EMC equation for radio communication systems aboard military ships.
In this study, the dielectric measurement of homogeneous materials via short-circuited circular waveguides is examined. The proposed method is numerically tested against homogeneous materials with varying permittivities, as well as in different shapes and positions. Synthetic data is generated via the moment method solution of the related integral equation. In the inversion algorithm, Newton-Raphson method with multi-frequency data is used. The complex part of the material is modeled in a linear fashion.
The paper presents an approach for designing different Boolean functions with a cascade of decoders and additional logic gates based on their schematic view and their testing on the laboratory module built with Spartan-6 FPGA units. The module, developed at the University of Ruse, is planned for using in the courses "Digital Electronics" and "Pulse and Digital Devices", familiarizing the bachelors of the electro-specialties to the basic problems of digital electronics.
The present status regarding the power consumption in electric networks reveals a higher number of events caused by conducted electromagnetic disturbances. The impact of short and repetitive interruptions of electric voltage represents an important issue in the operation of electric and electronic equipments. Tracing the sensitivity characteristics of electromagnetic immunity type CBEMA of electrical equipment to power failure and short duration interruptions is an effective method for estimating the domain of operability and to improve the operational safety of electrical equipments. The assessment of electrical equipment functionality is emphasized in this paper through an experimental research on AC electromagnetic contactors. The study comprises theoretical and experimental research on the low voltage AC contactors as equipment under tests, description of the test stand and the developed procedure for obtaining the CBEMA immunity curves at abrupt and gradual, individual and repetitive voltage dips, with different dip initiation angle values. Some interpretations of the results are given.
It was implemented in this study a steady-state, non- isothermal, two-phase model for Nafion-based PEMFC systems using the Finite Element Method (FEM) based Comsol Multiphysics software. Inside this numerical model were considered different parametrization laws for ionic conductivity, water diffusivity in ionomer, electro-osmotic drag coefficient and equilibrium water uptake, established based on the experimental data reported in the literature by various researchers for the widely available Nafion 117 membrane. The overall impact of this uncertainty in Nafion material parametrization on the fuel cell model performance was evaluated here. It was reported the variation of electrolyte potential and ionomer water content in correlation with electrolyte current density and water ionomer flux, along with temperature and heat flux gradients. Simulated polarization plots were compared with the experimental polarization curve registered with Nafion 117 MEA based BEKKTECH BT-552 system under testing at some specific operation settings.
AntiBubbles are gas particles that contain a liquid droplet core. They have a wide range of applications, but in this study, we are only focused on using them as contrast agents. There are several methods to produce AntiBubbles, but one of the most common involve the use of ultrasounds. Following this trend, we investigated the influence of the excitation signal parameters to obtain a better visualization.
The results of an experimental study of a struc-ture in the form of a coplanar transmission line containing regulated nonlinear elements under impulse action are presented. Time and frequency characteristics are analyzed. The transformation coefficient of the reflected signal spectrum S TR is defined as the ratio of the amplitudes of the spectral components of the response in the presence of nonlinear elements and the amplitudes of the spectral components in the absence of non-linear elements. It is shown that due to nonlinear distortions of the structure's response to pulse action the |S TR | is greater than 1 in narrow frequency bands. It is concluded that the structure is partially non-reciprocal due to the appearance of nonlinear distortions in the reflected signal.
Faults in the design of battery-powered circuits can lead to battery destruction. Battery simulation is an extremely important topic as simulation of the battery and the circuit together emphasizes a detailed functioning before the physical implementation and can also reveal hidden faults. In this paper, a SPICE model for LiFePO4 battery cells was implemented and simulated. The model targets specifically the CALB CA180FA LiFePO4 cell used in automotive industry for Electric Vehicles (EV) or in Energy Storage Systems (ESS). There are no models currently implemented for the LiFePO4 battery cells, which affects the simulation process of the systems. The model proves of utmost importance in simulating battery-powered systems, energy storage systems and Battery Management Systems (BMS), helping in understanding the impact these circuits have on batteries they are powered from or are designed for. The most important characteristics implemented are the OCV (Open-Circuit Voltage) - SOC (State of Charge) curve and the internal resistance. The LiFePO4 cell model can be parameterized by choosing the values for cell capacity and internal resistance.
There are many operating systems on the market, but, being free and having great user interface, connectivity and graphics features, Linux can be used in various scenarios like communication, trading and control systems. The PREEMPT_RT patch brings hard real-time behavior to Linux, but it lacks a real-time networking stack. RTnet is a mature hard real-time open source networking stack. This paper presents the main part port of the RTnet on PREEMPT_RT Linux kernel 5.9, along with stress tests that were run to prove the efficiency of the RTnet stack on PREEMPT_RT Linux.
The paper proposes a new set of Quantum-behaved Particle Swarm Optimization (QPSO) multi-objective algorithms with the final goal to use them for the optimization of a two objective electromagnetic benchmark inspired by a real world application. Starting from some various flavors of single-objective QPSO algorithms, known as: classic, with Gaussian attractor and with random mean, the new multi-objective QPSO implementations integrate principles inspired from notorious algorithms such as NSGA II, OMOPSO and ε-MOEA. The proposed algorithms are tested on benchmark problems proposed by scientific communities working in Evolutionary Computation and Computational Electromagnetics.
This paper presents a Robotics Laboratory conceived for Bioengineering students. The laboratory work is structured in two stages - in the first one, students use simulators and the ready-to-use platforms and in the second stage, which is structured as a project, they are involved in carrying out their own platforms. The solutions chosen for the development of these platforms must be inexpensive and must makes students to experience the basic stages of a hands-on bioengineering project. The project include simulation, hardware development, software design and implementation. For the project stage, the steps for making an affordable prosthetic hand with a high flexibility and functionality will be presented. The paper describes the project phases, the students activities and some relevant results of the survey regarding the students' opinion about this laboratory.
