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1

Analysis of the possibilities of the evolutionary algorithm to improve the neural model of the TGE S.A. Day Ahead Market System using selected programming environments

Tchórzewski Jerzy R., Zakrzewski Maciej

Studia Informatica : systems and information technology

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2024

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vol. 2 (31)

87--102

EN

The article contains selected research results regarding the analysis of the possibility of using the Evolutionary Algorithm to improve neural models of intelligent systems using selected programming environments. Choosing an appropriate programming language is one of the basic activities in the process of implementing complex algorithms, which include methods of artificial neural networks and evolutionary algorithms. Due to the fact that the object of the researchwas an intelligent Day Ahead Market system operating on the Polish Power Exchange and the modeling methods were artificial neural networks and evolutionary algorithms, it was decided to use very high-level programming languages such as Python, Matlab and C# for implementation and associated development environments. It turned out, among other things, that each of these languages and programming environments has its advantages and disadvantages, but all of them are very useful due to their useful syntax and rich included libraries. A thorough analysis of the implementation shows, among other things, that the choice of programming language affects the efficiency, speed and quality of the obtained implementations of system models. Against this background, the advantages and disadvantages of individual programming languages are shown, especially in the context of implementing evolutionary algorithms. The research results indicate directions for selecting an appropriate programming language and the associated programming environment for system modeling using artificial neural networks and evolutionary algorithms. In addition, the method of analysis, as well as the method of modeling and implementation was shown on the example of a specific system, which was the Day Ahead Market system of TGE S.A.

2

FPGA-based three edge detection algorithms (Sobel, Prewitt and Roberts) implementation for image processing

Abdullah Hiba-Allah Tariq, Mahmood Riyadh Zaghlool, Alhaj Zber Sanabel Muhson, Mohammed Rasha A., Ahmed Marwa Riyadh, Talab Azhar Waleed

Przegląd Elektrotechniczny

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2024

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R. 100, nr 2

29--33

EN

This technique aims to identify bone boundaries and fractures in noisy images by leveraging information from X-ray images. The computer-aided bone fracture detection method is primarily designed to help doctors generate improved diagnostic reports. Identifying accurate boundaries in noisy images remains challenging. Image processing algorithms have been limited to slow software implementations due to restricted processor speeds, necessitating a dedicated processor for edge detection. The Spartan3E-XC3S1600 FPGA kit will be employed to construct a fast architecture capable of performing edge detection using Sobel, Prewitt and Roberts edge detection systems.

PL

Ta technika ma na celu identyfikację granic kości i złamań na zaszumionych obrazach poprzez wykorzystanie informacji z obrazów rentgenowskich. Wspomagana komputerowo metoda wykrywania złamań kości ma przede wszystkim pomóc lekarzom w generowaniu lepszych raportów diagnostycznych. Identyfikacja dokładnych granic w hałaśliwych obrazach pozostaje wyzwaniem. Algorytmy przetwarzania obrazu zostały ograniczone do powolnych implementacji oprogramowania ze względu na ograniczoną prędkość procesora, co wymagało dedykowanego procesora do wykrywania krawędzi. Zestaw Spartan3E-XC3S1600 FPGA zostanie wykorzystany do zbudowania szybkiej architektury zdolnej do wykrywania krawędzi z wykorzystaniem systemów wykrywania krawędzi Sobel, Prewitt i Roberts.

3

Bi-directional DC-DC converter and fuzzy logic controller based switched reluctance motor for EV applications

Lakshmi G. Sree, Sreeshobha E., Swarupa Malladi Lakshmi, Pandraka Vinodh Kuma

Przegląd Elektrotechniczny

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2024

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R. 100, nr 9

39--43

EN

This work is done on the performance of the switched reluctance motor drives for electric vehicles that are driven by a bi-directional DCDC converter. SRMs are becoming more and more in demand for use in electric vehicle applications due to their superior speed-power characteristics, stable structure, low production costs, absence of permanent magnets, robustness, and fault-tolerance abilities. DC-DC converter with dual direction operation (forward and backward). Thus, this can be used to recharge the battery when backward operation is used. The Switched Reluctance Motor exhibits fault-tolerant behavior and good dynamic response. Performance metrics like speed, torque, fluxes, and state of charge (SOC) were used to assess an electric vehicle powered by an SRM. The analysis was based on a 6/4 SRM simulation that was run in MATLAB/Simulink.

PL

Praca ta dotyczy wydajności silników reluktancyjnych z przełączaniem dla pojazdów elektrycznych, które są napędzane przez dwukierunkowy przetwornik DC-DC. Silniki SRM stają się coraz bardziej pożądane do zastosowań w pojazdach elektrycznych ze względu na ich lepsze charakterystyki prędkości i mocy, stabilną strukturę, niskie koszty produkcji, brak magnesów trwałych, wytrzymałość i zdolność do tolerancji błędów. Przetwornica DC-DC z pracą w dwóch kierunkach (do przodu i do tyłu). Dzięki temu można jej używać do ładowania akumulatora, gdy używana jest praca wsteczna. Silnik reluktancyjny z przełączaniem wykazuje zachowanie odporne na błędy i dobrą reakcję dynamiczną. Do oceny pojazdu elektrycznego zasilanego przez silnik SRM wykorzystano takie wskaźniki wydajności, jak prędkość, moment obrotowy, strumienie i stan naładowania (SOC). Analiza została oparta na symulacji SRM 6/4, która została uruchomiona w programie MATLAB/Simulink.

4

Dynamic analysis of the wheel suspension arm

Sapieta Milan, Sapietová Alžbeta, Svoboda Martin

Journal of Applied Mathematics and Computational Mechanics

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2024

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Vol. 23, nr 3

74--85

EN

This article is focused on the creation of a model and its dynamic analysis. The model analyzed is a part of the car wheel suspension mechanism. Input load effects are entered as nonlinear waveforms of individual components of forces and moments determined experimentally. Load curves in the pin are defined as a function of time in a three-component force. The load in the bushings is implemented in a six-component force bond (three force components and three moments) as a function of deformation. The output of the simulation process are defor-mations as well as reaction effects in bushings. In order to verify the results, the task was modelled in two simulation programs, namely in Adams and Matlab R2020b Simscape multibody. The monitored parameters of force effects and displacements differed minimally.

5

Precyzyjne wyznaczanie rozkładu kątowego indukcyjności uzwojenia silnika reluktancyjnego przełączalnego z wykorzystaniem dedykowanego, zautomatyzowanego stanowiska laboratoryjnego

Fabiański Bogdan, Zawirski Krzysztof, Pajchrowski Tomasz

Przegląd Elektrotechniczny

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2023

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R. 99, nr 5

177--183

PL

Artykuł opisuje przyjętą metodę uzyskiwania kątowego profilu indukcyjności uzwojenia silnika, w której podstawa jest charakterystyczne przetwarzanie danych pomiarowych uzyskiwanych z dedykowanego stanowiska laboratoryjnego. Podstawą przedstawionej analizy jest badanie przebiegu prądu w towarzystwie wymuszającego go napięcia ujawniając tym samym skończoną dynamikę obwodu RL. Uzasadnieniem użytego określenia precyzyjne jest uwzględnienie nieliniowej funkcji aproksymacji modelującej przebieg prądu w zestawieniu do innych, uproszczonych metod w połączeniu z relatywnie złożonym procesem filtrowania i ekstrakcji wektorów danych. Wybrane parametry procesu poddano analizie statystycznej celem określenia optymalnych nastaw procesu. Uzyskane rezultaty wstępnie sprawdzono pod kątem powtarzalności oraz opisano dalsze kierunki badań.

EN

The article describes the adopted method of obtaining the angular inductance profile of the motor winding. The method basis on the characteristic processing of measurement data obtained from a dedicated laboratory stand. The basis of the presented analysis is the study of the current waveform in the presence of the voltage forcing it, thus revealing the finite dynamics of the RL circuit. The rationale for the precise term used is to take into account the nonlinear approximation function modeling the current waveform in comparison to other, simplified methods. What is equally important, certain parameters of the acquisition process were adopted as a consequence of the performed statistical analysis. Parameterization of the process is possible thanks to the proprietary design of the test stand, which additionally allows for high angular resolution of measurements. The obtained results were initially checked for repeatability and further research directions were described.

6

Investigation of the possibility of using artificial neural networks in the process of assessing the threat of lightning

Sobieska Emilia, Sobolewski Konrad

Przegląd Elektrotechniczny

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2023

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R. 99, nr 1

211--214

EN

The article presents issues related to the possibility of using an artificial neural network to classify factors describing the lightning hazard. It also analyzed the selection of the most optimal type of neural network for this type of task, as well asthe issue of input data, which both teach the neural network and form the basis for the final classification. Finally, the conclusions and assumptions necessary for the practical implementation of the task were drawn. The practical part of the task is planned as the following consideration stage.

PL

W artykule została przedstawiona problematyka związana z możliwością wykorzystania sztucznej sieci neuronowej do przeprowadzenia klasyfikacji współczynników opisujących zagrożenie piorunowe. Przeanalizowano wybór najbardziej optymalnego rodzaju sieci neuronowej dla tego rodzaju zadania, a także kwestię danych wejściowych, które posłużą zarówno do uczenia sieci neuronowej, jak również stanowią podstawę do końcowej klasyfikacji. Na koniec wyciągnięte zostały wnioski oraz założenia niezbędne do praktycznej realizacji zadania. Praktyczna część zadania będzie stanowić kolejny etap rozważań.

7

Design of a computer code to evaluate the influence of the harmonics in the transient stability studies of electrical networks

Mohammedi Redha Djamel, Souli Aissa, Hellal Abdelhafid

Przegląd Elektrotechniczny

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2023

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R. 99, nr 12

21--25

EN

This paper aims to present the design of a computer code: Transient Stability Code (TRANS_STAB_CODE) for the Transient Stability studies of electrical power systems under the influence of harmonics, using the GUI in MATLAB. The program was run for the loads are linear and nonlinear (Static Var Compensator (SVC), Thyristor controlled Reactor (TCR), and Unified Power Flow Controller ((UPFC)), After describing the program was run for five networks IEEE: 6 Nodes 3 Machines, 09 Nodes 03 Machines, 10 Nodes 02 Machines, 13 Nodes 04 Machines and 14 Nodes 05 Machines. The Transient Stability studies by the methods of: RungeKutta, Euler, and Heun. The results were almost consistent and show the influence of higher harmonics on Transient Stability in electrical networks.

PL

Artykuł ma na celu przedstawienie projektu komputerowego kodu: Transient Stability Code (TRANS_STAB_CODE) do badań stabilności przejściowej systemów elektroenergetycznych pod wpływem harmonicznych, z wykorzystaniem GUI w MATLAB-ie. Program został uruchomiony dla obciążeń liniowych i nieliniowych (Static Var Compensator (SVC), Tyrystorowy Reaktor (TCR) oraz Unified Power Flow Controller ((UPFC)), Po opisaniu program został uruchomiony dla pięciu sieci IEEE: 6 węzłów 3 Machines, 09 Nodes 03 Machines, 10 Nodes 02 Machines, 13 Nodes 04 Machines i 14 Nodes 05 Machines. Badania stabilności przejściowej metodami RungeKutty, Eulera i Heuna. Wyniki były prawie zgodne i pokazują wpływ wyższych harmoniczne dotyczące stabilności przejściowej w sieciach elektrycznych.

8

Identification of the object motion trajectory in a digital image using the Kalman filter

Piątkowski Tomasz

Journal of Automation, Electronics and Electrical Engineering

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2023

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Vol. 5, No. 3

31--45

EN

The paper concerns identification of the object motion trajectories in a digital image. An image analysis procedure was used consisting of two methods: BLOB identification and Kalman filter. BLOB identification is the superior method, and the Kalman filter is an alternative one, used to determine the motion trajectories only in the event of incorrect BLOB identification. Data from the correct BLOB identification are used on an ongoing basis in the process of training the Kalman filter. In this way, the filter becomes a model of a physical object that allows predicting the future state based on the object's current behaviour. The use of two complementary image analysis methods allows to determine the motion trajectories of the object's characteristic points in conditions of uneven scene lighting. The effectiveness of the method was confirmed in experimental rests.

9

Implementation of Type-2 Fuzzy Controller in Matlab Software

Dominik Ireneusz, Flaga Stanisław

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no. 5

374--384

EN

The purpose of this work is to create a Matlab toolbox that makes it easy and accessible to get acquainted with a novel control method called type-2 fuzzy controller. A toolbox for working with type-1 controllers can be found in the Simulink package, while there is only few, simple toolboxes for type-2 fuzzy controllers. The article describes the details of the created software, which allows you to work both with simulation objects, but also enables you to create program code for an PLC industrial controller. This gives you the opportunity to work in a simulation environment with a model of the control object and then, after tuning the controller, to automatically implement the controller to control the real object. In the literature, you can find many methods for reducing type-2 to type-1 fuzzy logic, but most often they are compared to several well-known classical reduction methods, such as the KM algorithm. There is no compilation of the most popular methods and a comparison of their performance. With the new toolbox it was possible to quickly create and add new reduction methods so in the article an analysis of 16 reduction methods is also presented.

10

New crane bumper design with an energy absorption device system

Haniszewski Tomasz, Margielewicz Jerzy, Gąska Damian, Opasiak Tadeusz

Transport Problems

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2022

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T. 17, z. 3

5--16

EN

This article presents research carried out using physical data from the experimental construction of an overhead crane. This article aims to determine the dynamic behaviour of the cart-pendulum system when the hoisting mechanism hits the new bumper design at the end of the girder support structure with selected speed and bumper material to the length of the wire rope. This research shows the influence of the horizontal speed of the hoisting mechanism on the bumper force during a collision with a standard buffer and its modifications. The presented model can be the basis for modelling more complex cases, and its assumed role (i.e. the ability to determine the angle of deflection of the rope during an impact) has been confirmed and is possible to use in a specific case of an overhead crane on an industrial scale. Preliminary analysis of the construction of the bumper considered reveals its positive features, aiming, among other goals, to reduce the acceleration and force acting on the crane cart in emergency situations.

11

Comparative analysis of multilevel voltage source inverters used to supply a five-phase Permanent Magnet Synchronous Motor

Parfianowicz Kamil

Przegląd Elektrotechniczny

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2022

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R. 98, nr 10

90--94

EN

The paper presents the comparative analysis of the use a two-level, three-level and five-level voltage source inverter (VSI) for supplying a five-phase synchronous motor with permanent magnets (PMSM). The motor was controlled by Indirect Field Oriented Control (IFOC) with Space Vector Modulation (SVM). Simulation tests showing influence of the inverter topology on the drive system were performed in the Matlab/Simulink environment for various values of the switching frequency - from 1 to 30 kHz. The aim of the presented simulation research is analysis of the prototype five-phase PMSM machine and preliminary development of the power supply system based on multilevel inverters. As a result it will allow to correct determination of the rated parameters of the selected devices (mainly the measurement system and semiconductors). The created model can also be used as part of a larger simulation system, e.g. in an electric vehicle.

PL

W pracy przedstawiona została analiza porównawcza zastosowania dwupoziomowego, trójpoziomowego oraz pięciopoziomowego falownika napięcia (VSI) służącego do zasilania pięciofazowego silnika synchronicznego z magnesami trwałymi. Do sterowania układu napędowego zaimplementowano tzw. sterowanie polowo-zorientowane pośrednie (IFOC) z użyciem modulatora wektora przestrzennego SVM (Space Vector Modulation). Przeprowadzone badania symulacyjne w środowisku Matlab/Simulink zostały wykonane dla różnych wartości częstotliwości kluczowania – od 1 do 30 kHz. Celem prezentowanych badań symulacyjnych jest analiza prototypowej pięciofazowej maszyny PMSM oraz wstępne opracowanie układu zasilania opartego na falownikach wielopoziomowych. W rezultacie pozwoli to na poprawne określenie parametrów znamionowych wybranych urządzeń (głównie układu pomiarowego i półprzewodników). Stworzony model może być również wykorzystany w ramach większego systemu symulacyjnego, np. w pojeździe elektrycznym.

12

Application of Matlab software in static calculations of bridge structures

Hawryszków Paweł, Czaplewski Bronisław

Archives of Civil Engineering

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2022

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Vol. 68, nr 1

299--317

EN

Mathematical package Matlab is a very convenient programming language, used for calculations in the field of linear algebra for scientists and engineers. Its main advantage for civil engineers is the simplicity of the language and the wide range of application in the field of linear statics. This mathematical platform was used for programming of static calculations of multi-span, continuous, beam bridge structures. In the formulated theoretical approach, the internal forces were calculated using the method of forces. Knowing the influence matrix and load values in the unit states, the envelope of internal forces can be determined. The first step is entering the vector of loads and the second is calculating an envelope using special function. Obtaining the results from individual loads in a variety of operating conditions, it is possible to calculate the global envelope of internal forces and proceed with modifications of the model. The theoretical approach was computationally tested on the example of an alternative design concept of the MA-46 bridge along the A4 motorway. One of the biggest advantages of the discussed computational approach is the wide access to the results of intermediate calculations. Another benefits of working with mathematical packages are improving insight in the field of static calculations and getting used to working with code like in some programs for structural analysis (e.g. SOFiSTiK). The discussed computational approach is a good way to pre-design due to the little time required to compare several variants of solution, so it can be helpful in optimizing the structure.

PL

Pakiet Matlab jest środowiskiem programistycznym służącym do obliczeń w zakresie algebry liniowej, pomocnym zarówno dla naukowców, jak i dla inżynierów. Znajduje on zastosowanie zarówno przy obliczeniach prostych, jak i bardzo złożonych. Jego główna zaleta z perspektywy inżyniera budowlanego jest prostota języka, niewymagająca dużych umiejętności programistycznych i możliwość szerokiego zastosowania w obliczeniach z zakresu statyki liniowej. Platforma matematyczna została użyta do oprogramowania obliczeń statycznych wieloprzęsłowych, ciągłych, belkowych konstrukcji mostowych. W sformułowanym podejściu teoretycznym wykorzystano metodę sił do wyznaczania wykresów sił wewnętrznych w stanach jednostkowych, które to uporządkowane tworzą macierz wpływu. Mając macierz wpływu, wprowadzano wektor obciążeń, a następnie wyznaczano obwiednie sił przekrojowych przy użyciu specjalnej funkcji. Znając wyniki od poszczególnych obciążeń, możliwe jest wyznaczenie globalnej obwiedni sił wewnętrznych i przystąpienie do ewentualnych modyfikacji modelu. Podejście teoretyczne zostało przetestowane obliczeniowo na przykładzie alternatywnej koncepcji projektowej mostu MA-46 w ciągu autostrady A4. Jedną z większych zalet omówionego podejścia analitycznego jest szeroki dostęp do wyników obliczeń posrednich oraz praca z kodem zbliżonym do niektórych programów obliczeniowych (np. SOFiSTiK). Omówione podejście obliczeniowe jest dobrym sposobem do wstępnego projektowania ze względu na niewielki czas potrzebny do porównania kilku wariantów rozwiązania, a co za tym idzie, może być pomocne w optymalizacji konstrukcji.

13

Model of the motion of a navigation object in a geocentric coordinate system

Džunda M.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2021

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Vol. 15 No. 4

791--794

EN

In this paper we describe the creation of a model of the motion of a flying object in a geocentric coordinate system (ECEF - Earth-Centered, Earth-Fixed). Such a model can be used to investigate the accuracy and resistance of radio navigation systems to interference. The essence of the design of the model lies in the mathematical description of the motion of a flying object in a geocentric coordinate system. The flight trajectory of a flying object consists of one straight section and two turns. When creating a model, we assume a flight at a constant altitude. In this paper, we present one of the possible procedures for modelling the motion of a flying object in a geocentric coordinate system. We chose the initial coordinates of the flying object according to flightradar 24. We used the Matlab software for computer simulation.

14

Influence of mutual position of communication network users on accuracy of positioning by telemetry method

Džunda M., Dzurovčin P.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2021

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Vol. 15 No. 2

299--306

EN

In this paper we solve the problem of the influence of the mutual position of the users of the communication network on the accuracy of the telemetric navigation system. We present the principle of operation of a telemetry navigation system and examine the accuracy of determining the position of users of the communication network depending on their mutual position. The telemetric method of determining the position of users of a communication network can be used in shipping or air transport. The simulation of the telemetry system will be performed in the Matlab software environment.

15

Analysis of dynamic characteristics of selected pneumatic systems with rractional calculus. simulation and laboratory research

Luft M., Krzysztoszek K., Pietruszczak D., Nowocień A.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2021

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Vol. 15 No. 4

835--843

EN

The section of the paper on simulation studies presents the application of fractional calculus to describe the dynamics of pneumatic systems. In the construction of mathematical models of the analysed dynamic systems, the Riemann-Liouville definition of differ-integral of non-integer order was used. For the analysed model, transfer function of integer and non-integer order was determined. Functions describing characteristics in time and frequency domains were determined, whereas the characteristics of the analysed systems were obtained by means of computer simulation. MATLAB were used for the simulation research. The section of the paper on laboratory research presents the results of the laboratory tests of the injection system of the internal combustion engine with special attention to the verification of simulated tests of selected pneumatic systems described with the use of fractional calculus.

16

Transient Energy Models of Housing Facilities Operation

Deshko Valerii, Bilous Inna, Biriukov Dmytro, Yatsenko Olena

Rocznik Ochrona Środowiska

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2021

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Tom 23

539--551

EN

Buildings are the main consumer of energy resources in the total energy balance of the countries in Central and Eastern Europe, the main energy consumption is allocated for heating. Efficient use of energy resources for heating needs to a large extent depends on the efficiency of regulation of heating systems. In the article, dynamic mathematical models of a two-room typical apartment in Ukraine, built in 2016, were developed in Matlab and EnergyPlus software environment. The simulations were carried out using IWEC hourly climate data for the city of Kyiv. The results of simulations of thermal energy consumption in Matlab are characterized by a larger range of fluctuations of the heating system load, which is typical for the real operating conditions of the system with the controller of ON/OFF type. In EnergyPlus it is assumed that the gas boiler operates continuously in the ON mode. In the research, the change of load on the apartment heating system was studied at different numbers and locations of air temperature control sensors installation, according to which the controller of the autonomous gas boiler operates.

17

Steering structure for a single wheeled vehicle

Beno Patrik, Gutten Miroslav, Simko Milan, Kubis Matej

Przegląd Elektrotechniczny

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2021

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R. 97, nr 1

105--108

EN

Nowadays, there is a need to reduce emissions in the world and use electricity to drive vehicles. There is an increasing interest in small passenger vehicles suitable for crowded cities. In this paper it was designed a universal control structure for a single-wheeled vehicle with a tilt sensor. In this structure is possible to apply a vehicle with parallel wheel arrangement. The paper describes a current and position loop with PI and PD controllers suitable for a single wheeled vehicle. It was designed a simple complementary filter for data processing. A complementary filter evaluate the data from accelerometer and gyroscope, which includes all signal processing requirements for control. Additionally, a program block diagram was also designed to be used in any microprocessor. The results and recommendations of the adjustment for further work with the proposed structure are evaluated in the end of the paper.

PL

W artykule zaprezentowano system sterowania jednokołowym pojazdem elektrycznym stosowanym do poruszania się w zatłoczonym mieście. Do kontroli prądu i pozycji pojazdu zastosowano sterowniki PI i PD. Do kontroli ruchu zastosowano czujniki przyśpieszenia oraz pochyelnia ora żyroskop.

18

Efficient terrestrial digital video broadcasting receivers based OFDM techniques

Alhyani Nazar Jabbar, Hamid Oday Kamil, Ali Sarah yahia, Ibrahim Ayman Mohammed

Przegląd Elektrotechniczny

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2021

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R. 97, nr 11

74--77

EN

This paper presents the design of efficient digital video propagation global receivers based on an orthogonal frequency distribution multiplexing scheme. The technology of DVB-T standards is developed by DVB assignment specifies the framing, modulation, channel, and noise elimination techniques for digital receiver television broadcasting. The OFDM scheme is a particular multicarrier transmission where a single information flow is transmitting in excess of a numeral of lesser speed sub-carrier with enough strength to radio channel effect. This paper provides a top-level simulation of the basic processing include in the transmitted and received OFDM waveforms under physical channel noise. The possibility to carry defined data containers in addition to audio and video transport streams has increased deployed for many services. The suggested structure of the classical digital broadcasting system was designed with permanent modulation methods which used to promise dependable communication even with very aggressive channel effects.

PL

W artykule przedstawiono projekt efektywnych globalnych odbiorników cyfrowej propagacji wideo w oparciu o schemat multipleksowania z ortogonalnym rozkładem częstotliwości. Technologia standardów DVB-T jest opracowywana przez przypisanie DVB, określające techniki ramkowania, modulacji, kanałów i eliminacji szumów dla nadawania telewizji cyfrowej. Schemat OFDM jest konkretną transmisją z wieloma nośnymi, w której pojedynczy przepływ informacji przesyła ponad liczbę mniejszej prędkości podnośnej z wystarczającą siłą dla efektu kanału radiowego. W tym artykule przedstawiono symulację na najwyższym poziomie podstawowego przetwarzania w przesyłanych i odbieranych kształtach fal OFDM w warunkach szumu kanału fizycznego. W wielu usługach wzrosła możliwość przenoszenia zdefiniowanych kontenerów danych oprócz strumieni transportowych audio i wideo. Proponowana struktura klasycznego cyfrowego systemu nadawczego została zaprojektowana z wykorzystaniem trwałych metod modulacji, które zapewniały niezawodną komunikację nawet przy bardzo agresywnych efektach kanałowych.

19

Static response of curved steel thin-walled box-girder bridge subjected to Indian railway loading

Verma V., Nallasivam K.

Journal of Achievements in Materials and Manufacturing Engineering

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2021

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Vol. 108, nr 2

63--74

EN

Purpose: The primary objective of the current study is to numerically model the steel thin-walled curved box-girder bridge and to examine its various response parameters subjected to Indian Railway loading. Design/methodology/approach: The analysis is conducted by adopting a one dimensional curved thin-walled box-beam finite beam element based on finite element methodology. The scope of the work includes a computationally efficient, three-noded, one-dimensional representation of a thin-walled box-girder bridge, which is especially desirable for its preliminary analysis and design phase, as well as a study of the static characteristics of a steel curved bridge, which is critical for interpreting its dynamic response. Findings: The analytical results computed using finite element based MATLAB coding are presented in the form of various stress resultants under the effect of various combinations of Indian Railway loads. Additionally, the variation in different response parameters due to changes in radius and span length has also been investigated. Research limitations/implications: The research is restricted to the initial design and analysis phase of box-girder bridge, where the wall thickness is small as compared to the cross-section dimensions. The current approach can be extended to future research using a different method, such as Extended finite element technique on curved bridges by varying boundary conditions and number of elements. Originality/value: The validation of the adopted finite element approach is done by solving a numerical problem, which is in excellent agreement with the previous research findings. Also, previous studies had aimed at thin-walled box girders that had been exposed to point loading, uniformly distributed loading, or highway truck loading, but no research had been done on railway loading. Moreover, no previous research had performed the static analysis on thin-walled box-girders with six different response parameters, as the current study has. Engineers will benefit greatly from the research as it will help them predict the static behaviour of the curved thin-walled girder bridge, as well as assess their free vibration and dynamic response analysis.

20

Free vibration behaviour of thin-walled concrete box-girder bridge using Perspex sheet experimental model

Verma V., Nallasivam K.

Journal of Achievements in Materials and Manufacturing Engineering

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2021

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Vol. 106, nr 2

56--76

EN

Purpose: Curved box-girder bridges offers an excellent solution to the problems associated with traffic congestion. However, owing to their complex geometry, they are subjected to shear lag, torsional warping and cross-sectional distortion, which must be assessed in their study and design. Furthermore, the dynamic behaviour of curved bridges adds to the complexity of the issue, emphasizing the importance of studying free vibration. The purpose of this study is to numerically model the concrete curved box-girder bridge considering torsional warping, distortion and distortional warping effects and to identify key parameters that influence the free vibration response of the box-girder bridge by validating it with experimental and analytical studies. Design/methodology/approach: The concrete bridge is numerically modelled by means of computationally effective thin-walled box-beam finite elements that consider torsional warping, distortion and distortional warping, which are prominent features of thinwalled box-girders. The free vibration analysis of the concrete curved box-girder bridge is performed by developing a finite element based MATLAB program. Findings: The identification of critical parameters that influence the free vibration behaviour of curved thin-walled concrete box-girder bridges is one of the main findings of the study. Each parameter and its effect has been extensively discussed. Research limitations/implications: The study limits for the preliminary design phase of thin-walled box-girder bridge decks, where a complete three-dimensional finite element analysis is unnecessary. The current approach can be extended to future research using a different method, such as finite element grilling technique on multi-span curved bridges having unequal span. Originality/value: The current research implements a finite element formulation in combination with thin-walled beam theory, where an extensive parametric study is conducted on the free vibration behaviour of a concrete thin-walled box-girder bridge, while also accounting for their complex structural actions. The validity of the given numerical formulation is demonstrated by a comparison of the natural frequencies found experimentally. The study carried out will be of great importance for engineers to help them anticipate the modal characteristics of a curved concrete thin-walled girder bridge, which will further be useful for evaluating their dynamic response analysis.