A broadband, stable, and noniterative free-space method is proposed for dielectric constant ε′r determination of low-loss dielectric slabs from reflection-only measurements through simple calibration standards (reflect and air). It is applicable for dispersive samples and does not require thickness information. Simulations of nondisperive and dispersive samples are performed to validate our method. Dielectric constant measurements of polyethylene and polyoxymethylene samples (9–11 GHz) are carried out to examine the accuracy of our method.
A technique based on artificial neural network (ANN) is proposed to extract the electromagnetic properties of reflection-asymmetric samples from reference-plane-invariant (RPI) scattering parameter measurements. It first determines reference plane transformation distances and then extracts the material properties. The number of neurons in the hidden layer of the ANN model was evaluated subject to accuracy and time constraints. We examined the conformity of the dataset of the ANN model and the required time for the training process by considering different numbers of neurons in the selected hid ...Daha fazlası
The temporal reflection response of an N -layer composite structure involving bianisotropic behavior is examined for the first time in the literature. Toward this goal, the wave matrix (WM) method, which is fundamental, relatively easier to apply, and compact and iterative suitable for analysis of multilayer structures, is first extended to the analysis of an interface separating two different media involving bianisotropy. Next, the reflection response of the whole structure is derived in terms of series form to better analyze its temporal behavior. Then, frequency-domain and time-domain respo ...Daha fazlası
This paper presents a new waveform correlation based method which determines the individual harmonic voltage contributions of Electric Arc Furnace (EAF) plants supplied from a point of common coupling (PCC). The method is based on the waveform correlation computations between the PCC voltage and the feeder current at the individual harmonic frequency. PCCs supplying multiple EAF plants usually suffer from high voltage harmonic components due to their operation principles. A relationship between the correlation coefficient of the PCC voltage and the feeder current waveforms, and the harmonic vo ...Daha fazlası
A time-domain free-space extraction procedure is proposed to uniquely determine the relative complex permittivity ϵr (ω) based on two sets of natural frequencies of the metal-and air-backed dielectric samples. A graphical analysis is applied for evaluating whether unique ϵr (ω) can be extracted using such natural frequencies. The method is numerically validated using two dielectric samples with different ϵ (ω) for the ideal case (no noise) and under the influence of noise with different signal-to-noise ratios (SNRs).
Keyword: graphical method; natural modes; parameter extraction; unique soluti ...Daha fazlası
The research work presented in this paper proposes a field-data based method for modeling the behavior of the Electric Arc Furnace (EAF) currents for a tap-to-tap period. EAF current DFT distributions and fundamental frequency histograms obtained out of previously collected EAF currents are used to develop the proposed model, which offers a model for each phase of the EAF operation: boring, melting and refining. The model is verified by comparing the THD histograms and the flicker measurements of the original and the modeled EAF current waveforms. The aim of the proposed method is to provide a ...Daha fazlası
A microwave method is proposed to determine the forward and backward propagation constants (gamma ⁺ and gamma ⁻) and the wave impedance ( z_w ) of reciprocal and non-reciprocal microwave networks whose positions are not known within their measurement cells (position-insensitive). The proposed method relies purely on analytical expressions and can also evaluate the reference plane transformation distances. Scattering parameter measurements at the X-band (8.2-12.4 GHz) of a reciprocal network (a waveguide straight) and a non-reciprocal network (a microwave phase shifter) arbitrarily positioned i ...Daha fazlası
A new deembedding technique is proposed for relative complex permittivity epsilon(r) determination of dielectric materials using gated free-space measurements. Its three main features are 1) it does not require any formal calibration procedure (calibration-free); 2) it is position-insensitive; and 3) it extracts ripple-free epsilon(r) due to gating process. The objective function derived to determine epsilon(r) by the proposed method is validated by free-space measurements of three dielectric samples (polypropylene, polyethylene, and polyoxymethylene). Besides, the accuracy of our method is co ...Daha fazlası
In this research work, deep machine learning-based methods together with a novel data augmentation are developed for predicting flicker, voltage dip, harmonics, and interharmonics originating from highly time-varying electric arc furnace (EAF) currents and voltage. The aim with the prediction is to counteract both the response and reaction time delays of active power filters (APFs) specifically designed for electric arc furnaces (EAF). Multiple synchronous reference frame (MSRF) analysis is used to decompose the frequency components of the EAF current and voltage waveforms into dqo components. ...Daha fazlası
This study presents to what extent Kyrgyz-Turkish Manas University students are knowledgeable about cybersecurity in the distance education process. The survey was conducted with a sample of 517 students from all faculties of the university at the undergraduate, graduate, and PhD levels. Our research study shows that although huge numbers of cyberattacks are occurring around the world, the students did not have any knowledge about cybersecurity and the effects of cyberattacks overall. An analysis of cybersecurity awareness was undertaken by asking questions focused on malicious software, passw ...Daha fazlası
The use of online tools is a common practice for evaluating the accessibility of a website, identifying problems, and providing useful feedback on how to fix detected issues. For ease of accessibility validation, many tools have been developed and implemented successfully over the years. Yet, the results of these tools show differences in terms of coverage, correctness, and reporting-related issues. In this study, we compared online accessibility evaluation tools to understand to what extent they differ in detecting accessibility problems in websites. A total of 41 government websites of diffe ...Daha fazlası
In this research work, a new harmonic responsibility measure is proposed to extract the amount of harmonic responsibility of each plant supplied from the point of common coupling (PCC). The proposed method uses a function of the correlation coefficients between the voltage and current signals measured synchronously at the PCC. After the verification of the method on synthetic data generated in simulation environment, field data measurements of voltage and current are used to test the practicability of the proposed method. Harmonic contributions of the iron and steel (I&S) plants obtained using ...Daha fazlası