Rod-like particles matching algorithm based on SOM neural network in dispersed two-phase flow measurements

A matching algorithm based on self-organizing map (SOM) neural network is proposed for tracking rod-like particles in 2D optical measurements of dispersed two-phase flows. It is verified by both synthetic images of elongated particles mimicking 2D suspension flows and direct numerical simulations-based results of prolate particles dispersed in a turbulent channel flow. Furthermore, the potential benefit of this algorithm is evaluated by applying it to the experimental data of rod-like fibers tracking in wall turbulence. The study of the behavior of elongated particles suspended in turbulent flows has a practical importance and covers a wide range of applications in engineering and science. In experimental approach, particle tracking velocimetry of the dispersed phase has a key role together with particle image velocimetry of the carrier phase to obtain the velocities of both phases. The essential parts of particle tracking are to identify and match corresponding particles correctly in consecutive images. The present study is focused on the development of an algorithm for pairing non-spherical particles that have one major symmetry axis. The novel idea in the algorithm is to take the orientation of the particles into account for matching in addition to their positions. The method used is based on the SOM neural network that finds the most likely matching link in images on the basis of feature extraction and clustering. The fundamental concept is finding corresponding particles in the images with the nearest characteristics: position and orientation. The most effective aspect of this two-frame matching algorithm is that it does not require any preliminary knowledge of neither the flow field nor the particle behavior. Furthermore, using one additional characteristic of the non-spherical particles, namely their orientation, in addition to its coordinate vector, the pairing is improved both for more reliable matching at higher concentrations of dispersed particles and for higher robustness against loss of particle pairs between image frames.     

First principle study of magnetic and electronic properties of single X (X = Al,Si) atom added to small carbon clusters (C<Subscript> <Emphasis Type="Italic">n</Emphasis> </Subscript>X, <Emphasis Type="Italic">n</Emphasis> = 2–10)

In this paper, the magnetic and electronic properties of single aluminum and silicon atom added to small carbon clusters (C_nX; X = Al, Si; n = 2–10) are studied in the framework of generalized-gradient approximation using density functional theory. The calculations were performed for linear, two dimensional and three dimensional clusters based on full-potential local-orbital (FPLO) method. The total energies, HOMO–LUMO energy gap and total magnetic moments of the most stable structures are presented in this work. The calculations show that C_nSi clusters have more stability compared to C_nAl clusters. In addition, our magnetic calculations were shown that the C_nAl isomers are magnetic objects whereas C_nSi clusters are nonmagnetic objects.     

Facile synthesis of PtSnZn nanosheet thin film at oil–water interface by use of organometallic complexes: An efficient catalyst for methanol oxidation and p‐nitrophenol reduction reactions

PtSnZn nanosheet thin film with stable and high activity towards methanol electro‐oxidation was synthesized via a simple reduction of organometallic precursors including [PtCl₂(cod)] (cod = cis,cis‐1,5‐cyclooctadiene) and [Sn(CH₃)₄] complexes, in the presence of [Zn(acac)₂] (acac = acetylacetonate) complex at toluene–water interface. Catalytic activities of PtSnZn nanosheets were investigated in the p‐nitrophenol (p‐Nip) reduction and methanol oxidation reactions. The obtained results demonstrate that PtSnZn nanosheets exhibit a good electrocatalytic performance for methanol oxidation reaction, the catalytic activity of the PtSnZn nanosheets being at least 3.5 times higher than that of Pt nanoparticle thin film. Also, the apparent rate constant obtained for p‐Nip reduction with the PtSnZn nanosheets is at least 2.3 times higher than that for Pt nanoparticle thin film due to the appropriate interaction between platinum, tin and zinc metals and geometric properties of PtSnZn nanosheet thin film. Nanosheets are highly favourable for superior catalytic performances due to their geometric properties. A facile and efficient route was used to synthesize trimetallic alloy thin film at oil–water interface.     

An augmented subgradient method for minimizing nonsmooth DC functions

Computational Optimization and Applications - A method, called an augmented subgradient method, is developed to solve unconstrained nonsmooth difference of convex (DC) optimization problems. At...     

Measurement of isomeric yield ratios of the 104m,g,106m,gAg in the 45- and 55-MeV bremsstrahlung induced reactions of natural silver

The isomeric yield ratios for the ^natAg(γ,xn)^{104m,g,106m,g}Ag reactions with the end-point bremsstrahlung energies of 45- and 55-MeV have been determined by the off-line γ-ray spectrometric technique using 100 MeV electron linac at Pohang accelerator laboratory, Korea. The present data were compared with literature data in comparable compound nucleus from the ^natAg(γ,xn), ^natPd(p,xn), and ¹⁰³Rh(α,xn) reactions to examine the effects of an excitation energy and an input angular momentum. It is observed that the isomeric yield ratios of ^104,106Ag in ^natAg(γ,xn), ^natPd(p,xn) and ¹⁰³Rh(α,xn) reactions increase with the end-point bremsstrahlung energy, proton and alpha energy, which indicate the role of excitation energy. It is also found that for the similar compound nucleus at same excitation energy, the isomeric yield ratio of ^104m,gAg is higher in the ^natPd(p,xn) and ¹⁰³Rh(α,xn) reactions than those in ^natAg(γ,xn) reaction, which indicate the effect of an input angular momentum.     

Study of thermomechanical properties of hybrid tire cord

Thermomechanical properties of tire cords, which have a considerable influence on tire functions, were investigated in the current research. The nylon and polyester cords are the most commonly used polymers in the tire. Many efforts have been made to produce a new tire cord having the capability of integrating the desired properties of these two polymers into one cord. In this study, a new cord structure was developed using nylon 6,6 and polyester tire yarns. The effect of thermal treatment was studied at the temperatures of 180°C, 200°C, and 220°C under two different loads of 600 and 1800gf on thermomechanical properties of the nylon 6,6/polyester hybrid tire cord. Shrinkage and shrinkage force as thermal properties, as well as static and dynamic mechanical properties, were investigated. The relationship between the aforementioned properties and variation in the crystal structure and fiber orientation obtained from Differential scanning calorimetry (DSC) and Wide‐Angle X‐Ray Scattering (WAXS) analysis were examined too. The results showed that the higher tension leads to the higher initial modulus and storage modulus due to the crystallization of polymers during heat treatment. The shrinkage and shrinkage force also increased, as the tension increased. In addition, a decrease in residual shrinkage and shrinkage force were acquired because of an enhancement in the temperature.     

Detailed study of the flat bands appeared in two-dimensional magnetic photonic crystals with square symmetry

By virtue of the efficiency of the Dirichlet-to-Neumann map method, the details of the band structure of a two-dimensional magnetic photonic crystal having a square array of parallel circular ferrite rods in air background influenced by an external static magnetic field applied in the rod direction has been investigated. We show that there are two sets of flat bands at the band structure of the system for TM-polarization. These flat bands are created around the magnetic surface plasmon frequency and frequency in which the magnetic permeability has singular value. For the frequency around the magnetic surface plasmon, the modes are highly localized at the interface of the cylindrical ferrite rods and air background and also by approaching the modes to the magnetic surface plasmon frequency the localization length decreases and the number of field's nodes increases considerably. Moreover, we realized that the modes with frequencies lying immediately below the singular value act similar to as resonance cavity modes created in a single metallic cylindrical waveguide.     

SO3H-Functionalized Ionic Liquids: Green, Efficient and Reusable Catalysts for the Facile Dehydration of Aldoximes into Nitriles

Easily synthesized aldoximes have been converted to the corresponding nitriles under very mild conditions by a simple reaction using two halogen‐free SO₃H‐functionalized ionic liquids, 3‐methyl‐1‐(4‐sulfonic acid)butylimi‐ dazolium hydrogen sulfate [MIM(CH₂)₄SO₃H][HSO₄] and 1‐(4‐sulfonic acid)butylpyridinium hydrogen sulfate [PY(CH₂)₄SO₃H][HSO₄], as catalyst and reaction medium without any additional organic solvent. The method was equally effective for aromatic aldoximes bearing electron‐donating and electron‐withdrawing substituents. Taking into account environmental and economical consideration, the protocol presented here has the merits of environmentally friendly, simple operation, easy work‐up and very good yields. The catalysts could be recycled and reused for several times without noticeably decreasing in their catalytic activities.     

Modeling and active vibration suppression of a single-walled carbon nanotube subjected to a moving harmonic load based on a nonlocal elasticity theory

This paper investigates active vibration suppression of a single-walled carbon nanotube (SWCNT) under the action of a moving harmonic load using Eringen’s nonlocal elasticity theory. The SWCNT is modeled according to the nonlocal Euler–Bernoulli beam theory. A Dirac-delta function is used to describe the position of the moving load along the SWCNT. Next, a linear classical optimal control algorithm with displacement-velocity feedback is used to suppress vibration in the SWCNT with control forces acting as actuators. The effects of a small-scale parameter, slenderness ratio, moving load velocity, and the excitation frequency of a moving load on the dynamic deflection of the SWCNT are examined. Finally, the ability of the control algorithm to suppress the response of the SWCNT under the effects of a moving load with a number of controlled modes and control forces is surveyed.