Wyniki wyszukiwania - BazTech

1

Node Localization based on Anchor Placement using Fuzzy C-Means in a Wireless Sensor Network

Irid Sidi Mohammed Hadj, Hadjila Mourad, Hachemi Mohammed Hicham, Souiki Sihem, Mosteghanemi Reda, Mostefai Chaima

International Journal of Electronics and Telecommunications

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2023

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Vol. 69, No. 1

99--104

EN

Localization is one of the oldest mathematical and technical problems that have been at the forefront of research and development for decades. In a wireless sensor network (WSN), nodes are not able to recognize their position. To solve this problem, studies have been done on algorithms to achieve accurate estimation of nodes in WSNs. In this paper, we present an improvement of a localization algorithm namely Gaussian mixture semi-definite programming (GM-SDP-2). GMSDP is based on the received signal strength (RSS) to achieve a maximum likelihood location estimator. The improvement lies in the placement of anchors through the Fuzzy C-Means clustering method where the cluster centers represent the anchors’ positions. The simulation of the algorithm is done in Matlab and is based on two evaluation metrics, namely normalized root-mean-squared error (RMSE) and cumulative distribution function (CDF). Simulation results show that our improved algorithm achieves better performance compared to those using a predetermined placement of anchors.

2

Hinf-FEEDBACK/FEEDFRWORD linear control applied to the 3DOF DELTA parallel robot

Thabet Mohammed, Yssaad Benyssaad, Litime Mostafa, Benadda Abdelouahid

Przegląd Elektrotechniczny

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2022

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R. 98, nr 7

36--41

EN

In this paper we propose an implementation of a Hinf-FEEDBACK / FEEDFRWORD multivariate linear controller on a 3DOF DELTA parallel robot. First, we linearized the system around an action point by implementing the "LINMODE" function in an MATLAB environment, then we compared the result of the proposed controller with that of the Hinf controller as well as that of the classic PID controller. We have found that the Hinf controller is robust compared to the PID controller and the proposed controller is more robust compared to the Hinf controller and the classic PID controller, and it follows the trajectory very well with good precision. And so we applied these controls to a system checked out from SOLIDWORKS.

PL

W niniejszym artykule zaproponowano implementację wielowariantowego regulatora liniowego Hinf-FEEDBACK / FEEDFRWORD na robocie równoległym DELTA 3DOF. W pierwszej kolejności dokonano linearyzacji układu wokół punktu akcji poprzez implementację funkcji "LINMODE" w środowisku MATLAB, a następnie porównano wynik działania proponowanego regulatora z wynikiem działania regulatora Hinf oraz klasycznego regulatora PID. Stwierdziliśmy, że kontroler Hinf jest odporny w porównaniu do kontrolera PID, a proponowany kontroler jest bardziej odporny w porównaniu do kontrolera Hinf i klasycznego kontrolera PID, i podąża za trajektorią bardzo dobrze z dobrą precyzją. I tak zastosowaliśmy te regulatory do układu sprawdzonego z SOLIDWORKS.

3

Impact of starting outlier removal on accuracy of time series forecast ING

Romanuke Vadim

Maritime Technical Journal

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2022

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nr 1 (224)

1--15

EN

The presence of an outlier at the starting point of a univariate time series negatively influences the forecasting accuracy. The starting outlier is effectively removed only by making it equal to the second time point value. The forecasting accuracy is significantly improved after the removal. The favorable impact of the starting outlier removal on the time series forecasting accuracy is strong. It is the least favorable for time series with exponential rising. In the worst case of a time series, on average only 7 % to 11 % forecasts after the starting outlier removal are worse than they would be without the removal.

PL

Wartość odstająca w punkcie początkowym jednowymiarowego szeregu czasowego negatywnie wpływa na dokładność prognozowania. W ramach przeprowadzonych badań dokonano analizy wpływu usunięcia wartości odstającej poprzez zrównanie jej z wartością drugiego punktu cza-sowego. Uzyskane wyniki wskazują, że przyjęta metoda znacznie poprawia dokładność progno-zowania dla większości szeregów czasowych. Jednak w przypadku szeregów czasowych z wykładniczym wzrostem, metoda okazała się mniej skuteczna. Minimalny wzrost dokładności prognozowania wynosił w tym przypadku od 7 % do 11 %.

4

Characterization of Propagation Models in Wireless Communications for 4G Network

Al-Aamri Nawal, Nadir Zia, Al-Lawati Hassan, Suwailam Mohammed Bait

International Journal of Electronics and Telecommunications

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2022

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Vol. 68, No. 1

137--143

EN

Estimating the pathloss and signal strength of the transmitted signal at specific distances is one of the main objectives of network designers. This paper aims to provide generalized pathloss models appropriate for urban areas in Muscat the capital city of the Sultanate of Oman environment. The research includes studying different models of pathloss for the 4G cellular network at Muttrah Business District (MBD) at Muscat. Different models (Free Space model, Okumura Hata, Extended Sakagami, Cost231 Hata, ECC-33 Hata – Okumura extended, Ericsson, Egli, and SUI) are used with 800MHz. The results of the prediction models are compared with real measured data by calculating RMSE. The generalized models are created by modified original models to get accepted RMSE values. Different cells at MBD are tested by modified models. The RMSE values are then calculated for verification purposes. To validate the modified pathloss models of 4G, they are also applied at different cells in a different city in the capital. It has approximately the same environment as MBD. The modified pathloss models provided accepted predictions in new locations.

5

Characterization of Propagation Models at 5G Network and Effects of SAR on Human Brain

Al-Aamri Nawal, Nadir Zia, Bait-Suwailam Mohammed, Al-Lawati Hassan

International Journal of Electronics and Telecommunications

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2022

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Vol. 68, No. 2

343--349

EN

Nowadays, the world is turning into technology, fast internet and high signal quality. To ensure high signal quality, the network planners have to predict the pathloss and signal strength of the transmitted signal at specific distances in the design stage. The aim of this research is to provide a generalized pathloss model to suit the urban area in Muscat Governorate in the Sultanate of Oman. The research covers 5G network pathloss in the Muttrah Business District (MBD) area. It includes Close In (CI) model and Alpha Beta Gamma (ABG) model with 3.45GHz. The results of 5G models were compared with real experimental data in MBD by calculating Root Mean Square Error RMSE. Other cells at MBD area were used for reverification. To validate the modified pathloss models of 5G, they were applied at different cells in Alkhoud area. Furthermore, this paper also deals the effect of Specific Absorption Rate (SAR) on the human brain for ensuring safety due to close proximity to cell towers. The SAR values were calculated indirectly from the electric field strength of different antennas. Calculated results were compared with the international standards defined limits on the human brain.

6

A comparative study between PID and PD-SMC and PD-ASMC control applied on a delta robot

Thabet Mohammed, Yssaad Benyssaad, Litime Mostafa

Przegląd Elektrotechniczny

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2021

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R. 97, nr 10

1--7

EN

This paper presents the modelling and control of a delta robot. The software SOLIDWORKS is used in this work to get a performing model that is very close to real system. The proportional integrator derivative (PID) control is used in this proposal. The results are compared with PDSliding mode (PD-SMC) and PD a robust SMC (PD-ASMC). This is an important comparative study where the advantages of each controller are presented: the PD-SMC improve the performance of the trajectory tracking, where the control signal performances and the robustness was improved by the PD-ASMC. Results presented are done with matlab-simulink and with Solidworks.

PL

Atykuł przedstawia modelowanie i sterowanie robotem delta. Oprogramowanie SOLIDWORKS jest używane w tej pracy do uzyskania wydajnego modelu, który jest bardzo bliski rzeczywistemu systemowi. tak jak będziemy wyniki porównywane pomiędzy kontrolerami PID i (PD-SMC) i (PD-ASMC). Jest to ważne badanie porównawcze, w którym przedstawione są zalety każdego sterownika: PD-SMC poprawia wydajność śledzenia trajektorii, gdzie wydajność sygnału sterującego i odporność zostały ulepszone przez PD-ASMC. Przedstawione wyniki zostały wykonane za pomocą matlab-simulink oraz Solidworks.

7

The study of local terrain modeling methods for vertical planning of the territory

Trevoho Ihor, Ostrovskiy Apollinariy, Kolb Ihor, Ostrovska Olena, Zhyvchuk Viacheslav

Geodesy and Cartography

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2021

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Vol. 70, no. 2

art. no. e09

EN

This work aims to study the vertical planning method for the terrain area as part of the process of construction geodetic support. Such planning will be carried out based on the aerial survey data from UAVs, which allow the creation of a high-quality digital elevation model (DEM) with sufficient node density for reliable surface terrain modelling. During the study, we test the hypothesis of the possibility of using archival aerial photographs from UAVs to model the terrain of the local area. Both the actual achievable accuracy of terrain modeling in the course of photogrammetric processing of archived aerial photographs, and methods for creating a polygonal terrain model using input spatial data in the form of clouds of 3D points of a given density require analysis. To do this, we will perform comparisons of the accuracy of calculating earth masses, carried out based on the digital triangulation elevation models (TIN). These models were based on different algorithms for creating Delaunay triangulation with different degrees of 3D point sparsity.We proposed to use sparsity of dense clouds of points representing the surface of the terrain and which were obtained by the photogrammetric method. Computer terrain modelling and calculation of vertical planning parameters were performed by us for the area with flat terrain at angles up to 3.5 degrees. We evaluated the potential of archived UAV aerial photographs and algorithms for creating Delaunay triangulation at different densities of its nodes for calculating the volumes of earth masses.

8

Techniki budowania świadomości widmowej w radiu kognitywnym

Suchański Marek, Romanik Janusz, Kustra Mateusz

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2019

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nr 6

173--176, CD

PL

W referacie scharakteryzowano metody budowania świadomości widmowej w radiostacjach kognitywnych oparte na mapach środowiska radiowego oraz na sensingu. Omówiono techniki tworzenia map oraz podano miary oceny ich jakości. Porównano przykładowe mapy oraz oceniono ich jakość w odniesieniu do metod interpolacji. Omówiono problematykę optymalizacji sensingu oraz wykorzystania detektora hybrydowego zwiększającego wydajność sensingu.

EN

The paper presents different spectrum awareness techniques suitable for cognitive radios, namely sensing based methods and the concept of the radio environment map (REM). Map construction techniques and quality measures of REMs are discussed. Exemplary maps are compared and the impact of interpolation techniques on map quality is analyzed. The issue of sensing optimization is discussed and the concept of the hybrid detector is presented. Simulation results confirmed that the hybrid detector improves the efficiency of sensing.

9

Positional accuracy evaluation of Google Earth in Addis Ababa, Ethiopia

Mulu Yalemzewd Abere, Derib Sisay Demeku

Artificial Satellites : Journal of Planetary Geodesy

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2019

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Vol. 54, No. 2

43--56

EN

From the time when it was first launched in 2005, satellite data generated from Google Earth are freely available online. Hence, without being conducting concrete studies about the accuracy of satellite data from Google Earth, Google Earth are chiefly used for different field of studies in different sectors for different purposes in Ethiopia. In this regard, it was planned to conduct this study by establishing the main objective to evaluate the positional accuracy of Google Earth. Hence, in order to address the aforementioned objective, a brief methodology for collecting and analyzing data was performed. The positional accuracy of Google Earth for both horizontal and vertical cases was evaluated. The acquired horizontal RMSE of Google Earth was found fit to produce a class-1 map of having 1:20,000 scale as recommended by ASPRS-1990. Unlike for horizontal case, the computed RMSE for vertical positional accuracy of Google Earth was not found fit for preparing class-1 map. However, making correlations between field survey and GE can provide 95% fitness, and also, subtracting the acquired RMSE for the vertical case from the original Google Earth elevation data can provide a 90% fitness for preparing class-1 map as well.

10

Accurate Frequency Estimation Based On Three-Parameter Sine-Fitting With Three FFT Samples

Liu X., Ren Y., Chu C., Fang W.

Metrology and Measurement Systems

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2015

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Vol. 22, nr 3

403--416

EN

This paper presents a simple DFT-based golden section searching algorithm (DGSSA) for the single tone frequency estimation. Because of truncation and discreteness in signal samples, Fast Fourier Transform (FFT) and Discrete Fourier Transform (DFT) are inevitable to cause the spectrum leakage and fence effect which lead to a low estimation accuracy. This method can improve the estimation accuracy under conditions of a low signal-to-noise ratio (SNR) and a low resolution. This method firstly uses three FFT samples to determine the frequency searching scope, then – besides the frequency – the estimated values of amplitude, phase and dc component are obtained by minimizing the least square (LS) fitting error of three-parameter sine fitting. By setting reasonable stop conditions or the number of iterations, the accurate frequency estimation can be realized. The accuracy of this method, when applied to observed single-tone sinusoid samples corrupted by white Gaussian noise, is investigated by different methods with respect to the unbiased Cramer-Rao Low Bound (CRLB). The simulation results show that the root mean square error (RMSE) of the frequency estimation curve is consistent with the tendency of CRLB as SNR increases, even in the case of a small number of samples. The average RMSE of the frequency estimation is less than 1.5 times the CRLB with SNR = 20 dB and N = 512.