Aeroacustic and aerodynamic investigating of a new airfoil trailing-edge noise-suppressing design

In this work, a new noise suppressing airfoil trailing-edge design, termed "finned serrations", is presented and numerically evaluated. This brand-new approach consists of the superposition of two different noise suppressing morphological features inspired by the wings of the owl. Embedded Large Eddy Simulations are employed in tandem with the Ffowcs WilliamsHawkings model to predict and analyze the design aerodynamics and aeroacoustics and compare the obtained output to that of a flat trailing-edge airfoil. Finned serrations are shown to combine the effects of having finlets and serrations. Because of the bluntness of the serration roots, the airfoil is subject to vortex shedding, while the flow is generally decorrelated in the spanwise direction, thanks to the channeling effect of the finlets. The turbulent kinetic energy distribution close to the airfoil trailing-edge surface is also significantly altered, as the more energetic eddies are convected away from the airfoil surface. Lastly, mixing across the airfoil surface is improved, and the average size of the turbulent coherent structures near the airfoil trailing-edge is reduced. The presented results suggest that the coupling of different noise-suppressing mechanisms is a promising path to explore, with the goal of coming up with new, quieter trailing-edge configurations.

RBS Channeling MATLAB Application for Automated Measurement Control and Evaluation for 6MV Tandetron Accelerator

Rutherford backscattering spectrometry (RBS) in channeling regimes (RBS/C), as an ion beam analysis method performed on a Tandetron 6MV accelerator, generally gives precise information about the structure of crystalline samples by combining RBS signals in the random and aligned configurations. This paper presents details about the design and implementation of tailored RBS/C measurements (coarse and fine) and data evaluation application developed in MATLAB for in situ accelerator control system ARGUS, delivered by High Voltage Engineering Europa BV (HVEE). Additionally, we examined two different ways of stepping during the measurement to reduce the possible inaccuracies related with goniometer’s backslash affecting the evaluation of spectra. Verification experiment was carried out using a 2-MeV 4He+-beam directed on a Si (100) substrate. The channeling effect is seen as channeling dips of a lower signal in an otherwise rather homogeneous plane. Implemented application significantly facilitates the RBS/C measurement and analysis of the experiments, and also extends the ion beam analysis portfolio of Advanced Technologies Research Institute. Finally, software is ready-to-use for any Tandetron based ion beam facility with the ARGUS software for accelerator control.

Two-Dimensional Numerical Analysis of Non-Darcy Flow Using the Lattice Boltzmann Method: Pore-Scale Heterogeneous Effects

This study simulates pore-scale two-dimensional flows through porous media composed of circular grains with varied pore-scale heterogeneity to analyze non-Darcy flow effects on different types of porous media using the lattice Boltzmann method. The magnitude of non-Darcy coefficients and the critical Reynolds number of non-Darcy flow were computed from the simulation results using the Forchheimer equation. Although the simulated porous materials have similar porosity and representative grain diameters, larger non-Darcy coefficients and an earlier onset of non-Darcy flow were observed for more heterogeneous porous media. The simulation results were compared with existing correlations to predict non-Darcy coefficients, and the large sensitivity of non-Darcy coefficients to pore-scale heterogeneity was identified. The pore-scale heterogeneity and resulting flow fields were evaluated using the participation number. From the computed participation numbers and visualized flow fields, a significant channeling effect for heterogeneous media in the Darcy flow regime was confirmed compared with that for homogeneous media. However, when non-Darcy flow occurs, this channeling effect was alleviated. This study characterizes non-Darcy effect with alleviation of the channeling effect quantified with an increase in participation number. Our findings indicate a strong sensitivity of magnitude and onset of non-Darcy effect to pore-scale heterogeneity and imply the possibility of evaluating non-Darcy effect through numerical analysis of the channeling effect.

Manifestation of the channeling effect when manufacturing JFET transistors

TThe proposed work covers the tasks of such areas as reducing input currents and bias voltage of integrated operational amplifiers (ICs OA) manufactured according to BiFET technology, the prospect of using JFET transistors in digital circuit technology, Si CMOS technology at 22 nm node and beyond, manufacturing bipolar transistors on ultra-thin layers of the active base and emitter, increasing resistance of ICs to external influences. The main method of experimental investigation of channeling is the construction of impurity distribution profiles using SIMS. In this work to study the channeling effect of boron and phosphorus in silicon was chosen the method for constructing the response surface of the saturation current of JFET for a silicon wafer. The choice of method was based on the high sensitivity of the cut-off voltage and saturation current of the JFET transistor to the channel thickness and impurity concentration in it, the relative simplicity of performance and practical benefits in improving BiFET technology.

Effect of Formation Pattern on Schooling Energetics in Fish-Like Swimming

In the present study, an immerse-boundary-method-based in-house numerical solver is employed to investigate the effects of school pattern on energetics in fish-like swimming. Following Weihsys theory, two-dimensional diamond schools are formed for numerical simulations. The effects of the lateral distance and the longitudinal distance have been investigated to reveal the energetic saving mechanism in a fish school. It is found that the energetic performance in a narrow diamond school (2dy = 0.4) is very different from that in a wide school. In the wide school, the beneficial effect will decay gradually with the increase of longitudinal distance; however, in the narrow school, the variation of the effect is needed to divide into three phases. When the longitudinal spacing is small (2dx = 0.4 ∼ 2), the variation of power efficiency is complex. It increases sharply when 2dx changes from 0.4 to 1.2, then decrease. When the longitudinal distance is larger than two, the variation of energetics in a narrow diamond school has the same trend as that in a wide school. It is because, in the narrow school, the channeling effect is harmful to the energetics of individuals and plays an important role when the longitudinal distance is small. However, the detrimental effect will decay quickly with the increase of the longitudinal distance. Besides, when the longitudinal distance is large (2dx > 3.4), the narrow school shows a better power efficiency than the wide school. It is because, at this time, the fishes at the rear of school are still located at the instructive vortex wake produced by fishes in the front. These findings will give insight on how to form a power-efficient robotic school under water.

SPECTRUMS OF SUPERCONDUCTING STATES AND TRIPLET EFFECTS IN SUPERCONDUCTOR/FERROMAGNET MULTILAYERS

We report the results of studies of triplet superconductivity in structures with alternating superconductor and ferromagnet layers, as a part of the general problem of the properties of the spectra of superconductivity states depending on the magnetic state of the multilayer structure. Ferromagnetic layers are assumed monodomain and possessing inplane magnetic moments. In numerical examples, we used the parameters of the well-studied Nb/PdNi system. The critical temperatures and distributions of singlet and triplet currents depending on the relative orientation of the magnetic moments of the ferromagnetic layers are calculated in the formalism of the Usadel equations for 5- and 3-layer irregular structures. The following results are obtained. (1) The channeling effect of triplet pairs by a narrow central layer of a superconductor with complete suppression of the singlet component in it was confirmed. (2) The “0–1”-transition between the phases of a superconducting condensate of opposite symmetry induced by the transport current is predicted. (3) The effect of a double crossover of states on the dependence of the critical temperature, Tc, versus the angle θ between the magnetic moments of the ferromagnetic layers adjacent to the central layer of the superconductor in a 3-layer structure is predicted. The crossovers are reflected by a sharp turns in the Tc (θ) curve, while the infinitely small asymmetry of the structure eliminates the non-analyticity of this characteristic.

Влияние зарядового состояния ионов ксенона на профиль распределения по глубине при имплантации в кремний

Experimental depth distributions of the concentration of implanted xenon ions depending on their charge state and irradiation energy are presented. Xenon ions in charge states q = 1–20 and energies in the range from 50 to 400 keV are incorporated into single-crystal silicon. Irradiation is performed in the direction not coinciding with the crystallographic axes of the crystal to avoid the channeling effect. The ion fluence varies in the range of 5 × (10^14–10^15) ion/cm^2. The irradiation by singly charged ions and investigation of the samples by Rutherford backscattering spectroscopy is performed using an HVEE acceleration complex at Moscow State University. Multiply charged ions are implanted using a FAMA acceleration complex at the Vinća Institute of Nuclear Sciences. The depth distribution profiles of the incorporated ions are found using Rutherford backscattering spectroscopy. Experimental results are correlated with computer calculations. It is shown that the average projective path of multiply charged ions in most cases is shorter when compared with the average projected path of singly charged ions and the results of computer modeling.