Wyniki wyszukiwania - BazTech

1

An Efficient Cooperative Spectrum Sensing Method Using Renyi Entropy Weighted Optimal Likelihood Ratio for CRN

Shrote Sandip B., Poshattiwa Sadhana D.

Journal of Telecommunications and Information Technology

|

2023

|

nr 3

41--48

EN

The main concept behind employing cognitive radio is to enable secondary users (SUs) or unlicensed users to utilize the available spectrum. Spectrum sensing methods detect the existence of primary users (PUs) and have become the main topic of research in the CRN industry and in academia. This paper proposes a new framework based on the Adam gradient descent (Adam GD) algorithm to develop a spectrum sensing mechanism used in CRNs and detecting the availability of free channels. The signal's components are extracted from the received signal and the spectrum is searched for availability which is detected through a fusion center using the proposed algorithm. The proposed Adam GD algorithm attains the maximum detection probability rate and the minimum false alarm probability of 0.71 and 0.39, respectively, for a Rayleigh channel.

2

Amplitude-energy parameters of acoustic radiation with composite properties changing and mises destruction

Filonenko Sergii, Stakhova Anzhelika

Journal of Automation Mobile Robotics and Intelligent Systems

|

2022

|

Vol. 16, No. 4

19--24

EN

The main problem with using acoustic emission to control and diagnostics of composite materials and products from composite materials is the interpretation and identification of recorded information during development processes occurring in the material’s structure. This is due to the high sensitivity of the acoustic emission method to various influencing factorsand the practical absence of acoustic radiation models. To solve this problem, it is necessary to determine the influence of various factors on acoustic radiation parameters. In this study, based on the acoustic radiation developed model we simulate the influence of one parameter characterizing composite properties on acoustic emission energy parameters during composite material destruction by shear forces according to the von Mises criterion. Simulation of acoustic radiation under given conditions makes it possible to determine the patterns of acoustic emission signals energy parameters changes and their sensitivity to changes of influencing factor, as well as to obtain mathematical expressions for describing obtained patterns. The results of this case study can be useful for developing methods of control, monitoring and diagnostics of composite materials and products made from composite materials.

3

Denoising and detrending of measured oscillatory signal in power system

Yang D., Rehtanz C., Li Y., Liu Q., Görner K.

Przegląd Elektrotechniczny

|

2012

|

R. 88, nr 3b

135-139

EN

This paper presents a novel method for denoising and detrending of oscillatory signal measured from wide area measurement system (WAMS) using empirical mode decomposition (EMD) and time-frequency analysis. First of all, the measured signal is decomposed into a set of intrinsic mode functions (IMFs) by EMD. Next, the IMFs are divided into three parts based on their time and frequency distributions. Then, the noise and higher frequency components, trend components and meaningful oscillation modes are identified respectively. The proposed method are validated by the actual measured signal from WAProtector and the estimated trend is confirmed by comparing with the sliding linear trend estimated method and other nonlinear trend estimated methods.

PL

W artykule zaprezentowano nową metodę usuwania szumu z sygnału okresowego w systemach WAMS. W pierwszej kolejności przeprowadza się dekompozycję sygnału na funkcje, które następnie dzielone są na trzy części w zależności od rozkładu czasowoczęstotliwościowego.

4

Energy of intrinsic mode function for gas-liquid flow pattern identification

Sun Z., Gong H.

Metrology and Measurement Systems

|

2012

|

Vol. 19, nr 4

759-766

EN

Gas-liquid flows abound in a great variety of industrial processes. Correct recognition of the regimes of a gas-liquid flow is one of the most formidable challenges in multiphase flow measurement. Here we put forward a novel approach to the classification of gas-liquid flow patterns. In this method a flow-pattern map is constructed based on the average energy of intrinsic mode function and the volumetric void fraction of gas-liquid mixture. The intrinsic mode function is extracted from the pressure fluctuation across a bluff body using the empirical mode decomposition technique. Experiments adopting air and water as the working fluids are conducted in the bubble, plug, slug, and annular flow patterns at ambient temperature and atmospheric pressure. Verification tests indicate that the identification rate of the flow-pattern map developed exceeds 90%. This approach is appropriate for the gas-liquid flow pattern identification in practical applications.