Power Flow Angle Research Articles

Effect of plasma excitation on aerodynamic characteristics of airfoil under Martian conditions

Due to the low density and pressure of the Martian atmosphere, the aerodynamic performance of the airfoil of the Mars UAV needs to be further improved. Plasma excitation active flow control technology is used to improve the lift of the airfoil and reduce the drag of the airfoil under Martian conditions. The effects of the action position, excitation power and incoming flow angle of attack on the lift and drag of the airfoil are studied under the low Reynolds number conditions on Mars. The results show that plasma excitation increases lift in the trailing edge area of the lower surface, with a maximum lift increase rate 37%; reduces drag in the leading edge area of the lower surface, with a maximum drag reduction rate 8%; the greater the excitation power and the smaller the incoming flow angle of attack, the more obvious the improvement of the airfoil lift-to-drag ratio. Plasma excitation induces pressure waves, forming a pressurization zone and a decompression zone upstream and downstream of the excitation, respectively, resulting in the formation of a pressurization surface and a decompression surface on the airfoil surface. When the excitation position is close to the trailing edge, the pressurization surface expands, and the pressure difference between the upper and lower surfaces of the airfoil increases, thereby achieving lift increase; when the excitation position is close to the leading edge, the decompression surface expands, and the pressure difference drag of the airfoil decreases, thereby achieving drag reduction.

Theoretical investigation of Rayleigh-type surface acoustic waves with high electromechanical coupling coefficient in c-axis-tilted ScAlN film/3C-SiC substrate structure

Surface acoustic wave (SAW) resonators are essential components of mobile communication technology. Advanced performance SAW resonators are needed to support beyond fifth-generation mobile communication technology, which aims to achieve unprecedentedly high data rates and low latency using wide frequency bands in the RF spectrum. This study theoretically investigates the propagation characteristics of a non-leaky Rayleigh-type SAW (RSAW) propagating in a c-axis-tilted ScAlN film/3C-SiC substrate structure. By appropriately selecting the c-axis tilt angle and the film thickness of the ScAlN film, a high electromechanical coupling coefficient (K2) value was obtained in the second-mode RSAW (Sezawa wave). The maximum K2 value for the Sezawa wave was 8.03%, with a phase velocity of 7456 m/s and a power flow angle of 0° under the structural conditions where the K2 value was maximized. These properties offer significant advantages for achieving wide frequency bands, high operating frequencies, and ease of design for SAW resonators. The structural conditions under which good propagation characteristics were obtained in the Sezawa waves were found to coincide with the conditions that maximize the electromechanical coupling coefficient of the quasi-longitudinal wave in the ScAlN film, and a significant increase in the shear vertical component of Sezawa wave particle displacement was observed. Additionally, ScAlN films with a 40% Sc concentration can be fabricated using sputtering and molecular beam epitaxy. Recent advancements have reported the production of high-quality 3C-SiC wafers and large 3C-SiC film/silicon wafers. Therefore, the c-axis-tilted ScAlN film/3C-SiC substrate structure shows great potential as a candidate for next-generation SAW resonators.

SEISMIC, a Python-based code of the quantas package to calculate the phase and group acoustic velocities in crystals

The present work reports the theoretical background and the capabilities of SEISMIC, a Python code specifically developed to calculate the propagation of the sound waves inside crystalline materials. SEISMIC is a tool integrated in the Quantas package and provides a series of useful information for engineers and geophysicists, such as the phase and group velocities, the power flow angle, the enhancement factors, and the polarization vectors, using as input the elastic moduli and the density of the material. Numerical treatments of the derivatives were avoided, using analytical methods to obtain numerically stable results. The code relies only on Python numerical and graphical libraries to ensure a full cross-platform usability.

Non-Zero Power Flow Angles in Surface Acoustic Wave Resonators for Transverse Mode Suppression

Non-Zero Power Flow Angles in Surface Acoustic Wave Resonators for Transverse Mode Suppression

Acoustically driven spin wave resonance in Ni/128° Y-cut LiNbO3 hybrid devices with the beam steering effect

We study the acoustically driven spin wave resonance (ADSWR) in a Ni film sputtered on a 128° Y-cut lithium niobate (LiNbO3) substrate under the condition that the beam steering effect exists due to the surface acoustic waves (SAWs) transmitted along several selected crystal orientations. SAW devices with that effect exhibit significantly different ADSWR spectra from devices without it. By using the magnetoelastic coupling theory and finite element simulation associated with SAW, we find that the beam steering effect of magnetoacoustic waves has an important influence on the acoustic attenuation. The relationship between its group velocity direction and the magnetization vector can be used to define the magnetoacoustic wave mode. The mode affects acoustic attenuation magnitude, which can break the fourfold symmetry. Increasing its power flow angle will significantly increase the maximum acoustic attenuation caused by magnon–phonon coupling.

Steady state Contingency Analysis of IEEE-39 Bus system Using PSS/E

Nowadays the stable, secure and reliable power system operation is the main objective of anyelectric power utility. The Power system is vulnerable to any contingency i.e. loss of Transmission line,Transformer, Generating unit etc. The power system control engineer should have detail analysis of at leastthe most probable and sever contingencies of the system and accordingly devise the remedial action plan.Thus, Power system contingency analysis and evaluation play vital role in ensuring power system stabilityand reliability. Keeping in view the importance of contingency analysis in power system operation andcontrol, this research focuses on steady state Contingency analysis of IEEE-39 bus system using newtonRaphson method. PSS/E is used for the analysis, different contingencies are evaluated and ranked basedupon the Power flow (Overloading), Voltage and phase angle deviation. Once the ranking is performed, thePV and QV analysis is performed for most severe contingencies. Remedial Actions is proposed for themost severe contingencies and this research could be applied to any real time network.

Gigahertz Acoustic Delay Lines in Lithium Niobate on Silicon Carbide With Propagation-Q of 11174

This work demonstrates gigahertz wideband acoustic delay lines (ADLs) with record-breaking propagation-Q using a thin-film X-cut lithium niobate on silicon carbide (LiNbO3-on-SiC) platform. Benefiting from the high bulk wave velocity and excellent mechanical <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{f}\times \text{Q}$ </tex-math></inline-formula> of SiC, the shear horizontal surface acoustic wave (SH-SAW) excited by unidirectional transducers propagates in the top-surface of LiNbO3-on-SiC with low acoustic loss. The zero power flow angle (PFA) of −3° to +Y axis is obtained through simulation analysis and experiment validation, which leads to acoustic wave transmission perpendicular to the electrodes. Oriented at zero PFA, the fabricated ADLs show scalable center frequencies from 1.19 GHz to 2.11 GHz, 3-dB fractional bandwidth ranging from 2.7% to 11.5%, and a record-high propagation-Q of 11174. The performance has shown the great potential of the LiNbO3-on-SiC acoustic platform for various signal processing applications.

Theoretical investigation of the piezoelectric and surface acoustic wave properties of GeSn alloys

The piezoelectric and dielectric constants of Ge1-xSnx with varying concentrations (x∈(0–1.0) were calculated using the first-principles method based on the density functional theory, and the surface acoustic wave (SAW) properties such as phase velocity, electromechanical coupling coefficient k2, and power flow angle (PFA) were obtained for Ge0.5Sn0.5 from using the Christopher equations in different orientations (0–90°, 0–90°, and 0–180°). The results demonstrate that the piezoelectric and dielectric constants of Ge1-xSnx deviate from Vegard's law when the x is varied, and the piezoelectric constant value reaches a maximum when x = 0.5. Additionally, the SAW velocity of Ge1-xSnx can be tuned by changing the Sn concentration. It can be seen from the contour maps of Ge0.5Sn0.5 at orientations (45°, 0–90°, and 0–180°), many orientations exhibit outstanding SAW performance. Orientations with large k2 and zero PFA are selected as promising candidates for fabricating SAW devices, which has important significance for experimental research.

Two-Dimensional Coupling-of-Modes Model for Surface Acoustic Wave Devices Considering Power Flow Angle

A new form of two-dimensional coupling-of-modes (2D-COM) equations considering power flow angle was proposed and verified experimentally. By adopting a wave vector relationship in elliptic approximation form, the parabolic 2D-COM equations were improved into an elliptic form which is applicable to the simulation of surface acoustic wave resonators considering power flow angle (PFA-SAWR). Combined the method with COMSOL PDE module, a complete simulation model for PFA-SAWR’s frequency response was established. Take the periodic grating structure on the AT-22° quartz substrate (PFA ≈5.4°) as an example, a case analysis was carried out based on this new simulation model. The accuracy of the model was confirmed by comparing the results of 3D FEM analysis. Then, in the experiment part, a PFA-SAWR on the AT-22° quartz substrate was fabricated and measured, the frequency responses obtained by simulation and experiments are in good agreement. Finally, a new resonator structure which can effectively suppress the transverse modes and improve the Q value of resonators was introduced. This new simulation model provides an effective technique for accurately analyzing and designing PFA-SAWRs.

Enhancing the resiliency of transmission lines using extreme gradient boosting against faults

The study presented in the paper aims to reduce the relaying time associated with detection and classification of fault along with accurate fault location estimation with the help of Teager Kaiser energy operator (TKEO) and extreme gradient boost (XGBoost) algorithm. The complete analysis has been conducted on IEEE 14 Bus transmission network. Four XGBoost modules corresponding to each phase have been developed for fault detection, classification, and similarly four regression modules are developed for fault location estimation depending on the type of fault. The proposed methodology is able to precisely determine the fault, locate it and also recognize the faulty phase(s). Special attention has been paid in determining the high impedance fault (HIF) apart from usual low impedance faults (LIF) while varying the fault parameters such as evolving nature of faults, fault inception angle, power flow angle and change in transmission line parameters etc. Voltage and current measurements recorded at the relay location are utilized. Moreover, the proposed XGBoost algorithm-based approach is able to detect and classify faults in around 1–2 ms time. The absolute error in fault location is around 0–2 km in most of the scenarios. A comparative study clearly states the merits of the proposed scheme.

Analysis of surface acoustic wave properties in CaYAl3O7 single crystal

The success on the growth of new piezoelectric materials allows sufficiently increase the operating temperature of the surface acoustic wave (SAW) devices from 300°C to 1000°C. A new calcium yttrium aluminate (CaYAl3O7) single crystal of the tetragonal symmetry has piezoelectric properties up to the temperature of 1000°C. The paper presents a numerical study of the surface acoustic wave properties in the crystal. The SAW velocity, electromechanical coupling coefficient and power flow angle are studied for different crystal cuts of CaYAl3O7. It is shown that the maximum value of SAW coupling coefficient (0.24%) is on the Z+60°-cut and wave propagation direction along the X-axis of the crystal. For the Z-cut and wave propagation direction along the X+45°-axis of crystal, the SAW coupling coefficient is equal to 0.2%. These two cuts of the crystal are potentially useful for SAW device applications.

Visualization of acoustic power flow in suspended thin-film lithium niobate phononic devices

We report direct visualization of gigahertz-frequency acoustic waves in lithium niobate phononic circuits. Primary propagation parameters, such as the power flow angle and propagation loss, are measured by transmission-mode microwave impedance microscopy. Using a fast Fourier transform, we can separately analyze forward and backward propagating waves and quantitatively evaluate the propagation loss. Our work provides insightful information on the propagation, diffraction, and attenuation in piezoelectric thin films, which is highly desirable for designing and optimizing phononic devices for microwave signal processing.

ElATools: A tool for analyzing anisotropic elastic properties of the 2D and 3D materials

We introduce a computational method and a user-friendly code with a terminal-based graphical user interface (GUI), named ElATools, developed to analyze mechanical and anisotropic elastic properties. ElATools enables facile analysis of the second-order elastic stiffness tensor of two-dimensional (2D) and three-dimensional (3D) crystal systems. It computes and displays the main mechanical properties including the bulk modulus, Young's modulus, shear modulus, hardness, p-wave modulus, universal anisotropy index, Chung-Buessem anisotropy index, log-Euclidean anisotropy parameter, Cauchy pressures, Poisson's ratio, and Pugh's ratio, using three averaging schemes of Voigt, Reuss, and Hill. It includes an online and offline database from the Materials Project with more than 13,000 elastic stiffness constants for 3D materials. The program supports output files of the well-known computational codes IRelast, IRelast2D, ElaStic, and AELAS. Four types of plotting and visualization tools are integrated to conveniently interface with GNUPLOT, XMGRACE, view3dscene and plotly libraries, offering immediate post-processing of the results. ElATools provides reliable means to investigate the mechanical stability based on the calculation of six (three) eigenvalues of the elastic tensor in 3D (2D) materials. It can efficiently identify anomalous mechanical properties, such as negative linear compressibility, negative Poisson's ratio, and highly-anisotropic elastic modulus in 2D and 3D materials, which are central properties to design and develop high-performance nanoscale electromechanical devices. Moreover, ElATools can predict the behavior of the sound velocities and their anisotropic properties, such as acoustic phase/group velocities and power flow angles in materials, by solving the Christoffel equation. Six case studies on selected material systems, namely, ZnAu2(CN)4, CrB2, δ-phosphorene, Pd2O6Se2 monolayer, and GaAs, and a hypothetical set of systems with cubic symmetry are presented to demonstrate the descriptive and predictive capabilities of ElATools. Program summaryProgram Title:ElAToolsCPC Library link to program files:https://doi.org/10.17632/njh92x66c6.1Developer's repository link:https://github.com/shahramyalameha/ElAToolsLicensing provisions: GNU General Public Licence 3.0Programming language: Fortran 90External routines/libraries:LaPack, Blas, and Plotly Javascript libraries, GNUPLOT, XMGRACE, view3dscene.Nature of problem: Identifying anisotropic elastic properties of 2D and 3D materials, and calculating acoustic phase and group velocities in homogeneous solids.Solution method: Second-order elastic stiffness tensor analysis using transformation law and calculations of the elastic surfaces properties. Solving the Christoffel equation eigenvalue problem using diagonalization and calculations of the sound velocities.Additional comments: Documentation available at https://yalameha.gitlab.io/elastictools/index.html

Integrated busbar protection scheme utilizing a numerical technique based on coherence method

A Busbar (BB) is one of the most important elements of a power system, which links a variety of elements such as generators, power transformers, transmission lines and loads. The BB fault current magnitude is very large, which has to be immediately cleared in order to minimize the failure in the power system, and to avoid the CT saturation effects. This paper presents a novel BB protection scheme based on closed-tripping characteristics of coherence coefficients computed for BB current signals. Three-phase current signals of each circuit connected to the protected busbar are measured for calculating nine cross-coherence coefficients. These coefficients are compared with each other and with a pre-determined threshold value to identify the fault location, classification and direction discrimination, as well as to differentiate the internal and external faults with CT saturation extent. The scheme is tested under different types of external and internal faults with variations of faulty phase(s), fault locations, fault resistances, fault inception angles, and power flow angles. ATP platform is used for power system simulation, and MATLAB software is applied to validate the proposed protection algorithm. The simulation results prove that the scheme is fast, where its operating time is within a sub-cycle time range, and it has the ability to discriminate between internal and external faults with/without CT saturation condition. Moreover, the numerical technique is immune to CT saturation effect, and it is simple, effective, secure, reliable, stable and feasible.

The effect of Sn doping on the electronic and mechanical properties of Ti3 Al1−x Snx C2 MAX phases

The phase pure synthesis of Ti${}_{3}$AlC${}_{2}$ MAX phase is quite difficult and some additives are required to get a phase pure Ti${}_{3}$AlC${}_{2}$ such as Sn. In this study, Sn doped Ti${}_{3}$AlC${}_{2}$ MAX phase has been investigated taking into account the experimental synthesis conditions where some Sn atoms could replace Al atoms in the structure. For this purpose, Ti${}_{3}$Al${}_{1-x}$Sn${}_{x}$C${}_{2}$ with x ranging from 0 to 1 with 0.1 interval has been studied using the first principles method and the results show that all compositions are thermodynamically stable. The electronic properties of these compositions have been studied using band filling theory in detail. Also, the mechanical properties of these compounds such as shear modulus, Poisson's ratio, Young's modulus, sound wave velocities, polarization of the sound waves, enhancement factor, the power flow angle and etc. have been obtained with the varying directions and the three-dimensional mechanical properties have been visualized.

Teknik Pengujian Kinerja Algoritme Relay Jarak Menggunakan DIgSILENT

Makalah ini menyajikan teknik orisinal pengujian untuk mengevaluasi kinerja algoritme relay proteksi saluran transmisi (relay jarak model SEL-421) menggunakan DIgSILENT. Tujuan yang diharapkan dari publikasi ini adalah untuk memberikan pemahaman tentang penggunakan software DIgSILENT untuk pengujian relay proteksi. Akurasi dari algoritme pengukuran impedans kegagalan yang diakibatkan oleh pengaruh faktor ketidakpastian sistem dapat diamati secara bersamaan dan dilakukan pengujian secara otomatis. Misalnya, pengaruh dari resistans kegagalan dan sudut aliran daya adalah dianggap sebagai faktor ketidakpastian. Pada metode pengujian yang ditawarkan, simulasi gangguan pada saluran transmisi dilakukan pada sejumlah lokasi gangguan yang berbeda dengan perubahan nilai dari parameter ketidakpastian berdasarkan nilai sampel parameter dan diubah secara serentak untuk melihat pengaruh terhadap kinerja relay. Sampel parameter ketidakpastian yang digunakan dibangkitkan secara acak pada rentang nilai tertentu. Pengujian otomatis telah diaplikasikan melalui algoritme yang dikembangkan dengan DIgSILENT Programming Language (DPL) pada DIgSILENT. Contoh yang disajikan pada publikasi ini menjelaskan tentang metode pengujian yang ditawarkan dapat juga digunakan untuk mendemontrasikan kegunaannya secara praktis. Pada makalah ini, metode untuk pengujian relay jarak telah berhasil diimplementasikan melalui kombinasi software DIgSILENT dan MATLAB.

Anisotropic mechanical properties of Tl4Ag18Te11 compound with low thermal conductivity

The anisotropic mechanical properties of Tl4Ag18Te11 compound was investigated elaborately for the first time by using Density Functional Theory calculations with the Vienna Ab-initio Simulation Package in this work. Tl4Ag18Te11 compound was optimized in the I4mm space group and the formation energy was determined as a negative value that is the indication of the experimental synthesizability of this compound. The optimized crystal structure was employed for the calculations of the elastic constants and the obtained values revealed the mechanical stability of Tl4Ag18Te11 compound. The polycrystalline properties were determined such as shear modulus, Poisson’s ratio, etc. In addition, the anisotropic elastic properties were presented. The direction dependent sound waves velocities, polarization of the sound waves, enhancement factor and the power flow angle were determined. The thermal conductivity studies were performed and the minimum thermal conductivity (0.259 ​W ​m−1K−1) and the diffusion thermal conductivity (0.202 ​W ​m−1K−1) were calculated. This study illustrates the capability of this compound for the thermoelectric materials.

Numerical analysis of SAW propagation characteristics in Ca2Al2SiO7 crystal

The importance of surface acoustic wave (SAW) technology is to integrate signal processing with sensor functions. Recently, SAW sensors can operate at room temperature or around 100°C-200°C. The task associated with materials becomes relevant if it is necessary to increase the operating temperature of the device to 1000°C. A new piezoelectric calcium aluminate silicate (Ca2Al2SiO7) crystal of the tetragonal symmetry has stable piezoelectric properties up to the melting point temperature of 1500°C. The properties of surface acoustic waves a new Ca2Al2SiO7 single crystal are numerically modeled in the paper. The SAW velocity, the electromechanical coupling coefficient, and the power flow angle are modeled for various cuts of the Ca2Al2SiO7 crystal. The SAW has the maximal electromechanical coupling coefficient value (∼0.1%) on Z,X+45°-cut of the crystal. In the Z+63°, X-cut, the SAW electromechanical coupling coefficient is equal to 0.08%. Both of these crystal cuts show the absence of bulk acoustic wave generation by an interdigital transducer, and the Ca2Al2SiO7 crystal is a promising piezoelectric material for use in the SAW device applications.

Adaptive quadrilateral distance relaying scheme for fault impedance compensation

Abstract Impedance reach of numerical distance relay is severely affected by Fault Resistance (RF), Fault Inception Angle (FIA), Fault Type (FT), Fault Location (FL), Power Flow Angle (PFA) and series compensation in transmission line. This paper presents a novel standalone adaptive distance protection algorithm for detection, classification and location of fault in presence of variable fault resistance. It is based on adaptive slope tracking method to detect and classify the fault in combination with modified Fourier filter algorithm for locating the fault. To realize the effectiveness of the proposed technique, simulations are performed in PSCAD using multiple run facility &amp; validation is carried out in MATLAB® considering wide variation in power system disturbances. Due to adaptive setting of quadrilateral characteristics in accordance with variation in fault impedance, the proposed technique is 100 % accurate for detection &amp; classification of faults with error in fault location estimation to be within 1 %. Moreover, the proposed technique provides significant improvement in response time and estimation of fault location as compared to existing distance relaying algorithms, which are the key attributes of multi-functional numerical relay

Comparison of single and modular ANN based fault detector and classifier for double circuit transmission lines

Comparison of single and modular artificial neural network based techniques for shunt faults detection and classification in double end fed double circuit transmission line is presented in this paper. The proposed method uses the voltages and currents signals available at the local end of line. The model of the power system is developed using MATLAB® software. Effects of variations in pre-fault power flow angle, fault inception angle, source strength, fault resistance, fault type, fault distance and CT saturation have been investigated extensively on the performance of the ANN based protection scheme. Additionally, the effects of network changes: double circuit and single circuit operation with other line switched out and grounded (/ungrounded), intercircuit and cross-country faults have also been investigated. Thus, the present work encompasses practically the entire range of possible operating conditions, which has not been reported earlier. The simulation results are presented to validate the effectiveness of the proposed approach. The main advantage of the proposed technique is that the variation in power system parameters under a variety of operating conditions and single/double circuit operations does not affect its performance. And this technique correctly detects and classifies the intercircuit and cross-country faults which have not been reported so-far.Keywords: Artificial neural network, cross country fault; transmission line protection; intercircuit faults and single circuit operation.