Anomalous Mode Research Articles

Detection of ferroresonance occurrence in inductive voltage transformers through vibration analysis

Steady state ferroresonances in isolated neutral electrical systems result in sustained abnormal system oscillations, which can damage inductive voltage transformers (IVTs) and other system elements. During this phenomenon, the IVT becomes saturated; consequently, the dimensions of the ferromagnetic material of the IVT change owing to magnetostriction. Because of this inherently nonlinear behaviour, the natural vibration modes of the IVT are excited. The aim of this study is to take advantage of these anomalous vibration modes to reveal the occurrence of ferroresonance in IVTs. The methodology for ferroresonance detection in IVTs through vibration analysis is described and demonstrated experimentally.

Chlorinated styrene butadiene rubber/ zinc sulfide: novel nanocomposites with unique properties- structural, flame retardant, transport and dielectric properties

Chlorinated styrene butadiene rubber (Cl-SBR)/ zinc sulfide (ZnS) nanocomposites were prepared by a simple two-roll mill mixing technique. The interaction between the ZnS nanoparticles and Cl-SBR was assessed using Fourier transform infrared (FTIR) and UV-Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The dielectric constant, oil resistance, flame retardancy and the transport properties of nanocomposites with aromatic hydrocarbons were also analyzed with special attention to the loading of nanoparticles. The spectroscopic studies revealed the existence of a strong interfacial interaction between rubber chain and ZnS nanoparticles. TEM analysis showed the attachment of ZnS nanoparticles in the chlorinated SBR having nanosize region. SEM and XRD showed the uniform arrangement of nanoparticles in the elastomeric network. The presence of ZnS nanoparticles in the rubber matrix was confirmed through EDX spectroscopy. The thermal stability, flame retardancy and oil resistance properties of the nanocomposites were significantly enhanced by the addition of nanoparticles. Composite with 7 phr loading showed the maximum dielectric constant and beyond this loading, the dielectric property decreased due to the agglomeration of nanoparticles. Transport behavior of nanocomposites in benzene, toluene and xylene were analyzed in the temperature range of 27 to 70 °C. Swelling parameters such as rate constant, sorption, diffusion, and permeation coefficient were estimated. The mechanism of transport of the aromatic solvents in the filled Cl-SBR was found to be following anomalous mode. Temperature dependence of diffusion was used to study the activation parameters of the prepared samples.

Thermal effects on the sedimentation behavior of elliptical particles

We investigate thermal effects on the sedimentation behavior of elliptical particles via particle-resolved direct numerical simulation. Two scenarios of fluid-particle heat transfer in an infinitely long channel are considered: one is a cold particle settling in a hot fluid, while the other is a hot particle settling in a cold fluid. Results show that when an elliptical particle sediment in a wide channel (i.e., the block ratio is large), in addition to the two sedimentation modes reported in the literature for the particle sediments in isothermal fluids, there exist another three modes arising from thermal effects: the tumbling mode, the anomalous rolling mode and the inclined mode. Specifically, for a cold particle settling in a hot fluid, we found the tumbling mode and inclined mode, while for a hot particle settling in a cold fluid, we found the anomalous rolling mode and inclined mode. The phase diagrams of the sedimentation modes as functions of Archimedes and Grashof numbers are given. Analyses of the relationship between particle Reynolds number and Grashof number indicates that the mode presented depends on the competition between channel wall confinement, combined forced and natural convection.

Topological phases and the bulk-edge correspondence in 2D photonic microring resonator lattices.

We show that 2D photonic lattices consisting of coupled microring resonators can emulate quantum systems driven by periodic Hamiltonians and can thus be used to realize photonic Floquet topological insulators. By transforming a 2D microring lattice into an equivalent array of coupled waveguides with periodic boundary conditions, we explicitly derive the Floquet-Bloch Hamiltonian of the system and determine the winding numbers characterizing the band topology and bulk-edge correspondence of the lattice. By varying the coupling strengths between adjacent resonators, we show that a 2D microring lattice can support both anomalous Floquet insulator edge modes and Chern insulator edge modes over a wide range of coupling parameters.

Low-frequency phase diagram of irradiated graphene and a periodically driven spin- 12 XY chain

We study the Floquet phase diagram of two-dimensional Dirac materials such as graphene and the one-dimensional (1D) spin-1/2 $XY$ model in a transverse field in the presence of periodic time-varying terms in their Hamiltonians in the low drive frequency ($\omega$) regime where standard $1/\omega$ perturbative expansions fail. For graphene, such periodic time dependent terms are generated via the application of external radiation of amplitude $A_0$ and time period $T = 2\pi/\omega$, while for the 1D $XY$ model, they result from a two-rate drive protocol with time-dependent magnetic field and nearest-neighbor couplings between the spins. Using the adiabatic-impulse method, we provide several semi-analytic criteria for the occurrence of changes in the topology of the phase bands of such systems. For irradiated graphene, we point out the role of the symmetries of $H(t)$ and $U$ behind such topology changes. Our analysis reveals that at low frequencies, phase band topology changes may also happen at $t= T/3, 2T/3$ (apart from $t=T$). We chart out the phase diagrams at $t=T/3, 2T/3,\, {\rm and }\, T$ as a function of $A_0$ and $T$ using exact numerics, and compare them with the prediction of the adiabatic-impulse method. We show that several characteristics of these phase diagrams can be analytically understood from results obtained using the adiabatic-impulse method and point out the crucial contribution of the high-symmetry points in the graphene Brillouin zone to these diagrams. Finally we study the 1D $XY$ model with a two-rate driving protocol using the adiabatic-impulse method and exact numerics revealing a phase band crossing at $t=T/2$ and $k=\pi/2$. We also study the anomalous end modes generated by such a drive. We suggest experiments to test our theory.

Anomalous Phonon Modes in Black Phosphorus Revealed by Resonant Raman Scattering.

Black phosphorus (BP), a layered material with puckered crystalline structure in each layer, has drawn intense interest due to its unique optical and electronic properties. In particular, the intricate Raman scattering effect in BP is intriguing and provides a platform for researchers to probe the physical properties of BP in depth. Here we report the first observation of anomalous modes with the frequency in the range of 100-900 cm-1 in BP due to the resonant Raman effect. The origin and assignment of the anomalous modes are discussed based on the excitation energy- and angle-dependent Raman measurements. Density functional theory (DFT) calculated electronic band structure is used to support our understanding. The newly observed phonon modes could serve as a unique probe for the fine electronic structures and the exciton-phonon couplings, which promote a better understanding of BP for potential nanoelectronic and nanophotonic applications in the future.

Dark-dark-soliton dynamics in two density-coupled Bose-Einstein condensates

We study the 1D dynamics of dark-dark solitons in the miscible regime of two density-coupled Bose-Einstein condensates having repulsive interparticle interactions within each condensate ($g>0$). By using an adiabatic perturbation theory in the parameter $g_{12}/{g}$, we show that, contrary to the case of two solitons in scalar condensates, the interactions between solitons are attractive when the interparticle interactions between condensates are repulsive $g_{12}>0$. As a result, the relative motion of dark solitons with equal chemical potential $\mu$ is well approximated by harmonic oscillations of angular frequency $w_r=(\mu/\hbar)\sqrt{({8}/{15}){g_{12}}/{g}}$. We also show that in finite systems, the resonance of this anomalous excitation mode with the spin density mode of lowest energy gives rise to alternating dynamical instability and stability fringes as a function of the perturbative parameter. In the presence of harmonic trapping (with angular frequency $\Omega$) the solitons are driven by the superposition of two harmonic motions at a frequency given by $w^2=(\Omega/\sqrt{2})^2+w_r^2$. When $g_{12}<0$, these two oscillators compete to give rise to an overall effective potential that can be either single well or double well through a pitchfork bifurcation. All our theoretical results are compared with numerical solutions of the Gross-Pitaevskii equation for the dynamics and the Bogoliubov equations for the linear stability. A good agreement is found between them.

Evaluation of spectral, thermal, flame retardant, dielectric, solvent diffusion, and transport behavior of novel nanocomposite derived from chlorinated styrene butadiene rubber and manganous tungstate

Novel nanocomposites based on chlorinated styrene butadiene rubber (Cl‐SBR) and manganous tungstate (MnWO4) nanoparticles have been developed using a simple and efficient open two roll mixing mill at room temperature. The nanocomposite containing varying loading of nanoparticles have been assessed for their spectral behavior, thermal, dielectric, flammability properties as well as the transport of aromatic solvents through their networks. Intermolecular interaction between the chlorinated moieties of SBR and MnWO4 has been revealed by Fourier transform infrared and UV‐Vis spectral studies. The uniform dispersion of nanoparticles and the crystalline peaks of MnWO4 nanoparticles in Cl‐SBR were observed from SEM and XRD, respectively. Thermogravimetric analysis and flame resistance analysis showed that the thermal stability and flame retardancy of Cl‐SBR increased with increasing ratio of MnWO4. The dielectric constant was much improved with the entire range of frequencies and the optimum dielectric constant was obtained for 7 phr loading. Transport parameters like the sorption, diffusion, and permeation coefficients were tabulated in terms of the nature of solvent, and the loading of nanoparticles. The solvent uptake reduced by the addition of nanoparticles up to 7 phr and thereafter the solvent uptake increases. The activation energy for the diffusion, sorption, and permeation process was evaluated and these values were highest in xylene at all filler loading. The mechanism of transport of the aromatic solvents through Cl‐SBR/MnWO4 nanocomposite was found to be anomalous mode. POLYM. COMPOS., 39:E1880–E1889, 2018. © 2018 Society of Plastics Engineers

The inter‐decadal change in anomalous summertime water vapour transport modes over the tropical Indian Ocean–western Pacific in the mid‐1980s

Using the monthly reanalysis data sets of National Center for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) for 1961–2015, the inter‐decadal change in inter‐annual water vapour transport over the tropical Indian Ocean–western Pacific during summer and the related mechanisms were analysed in this article. The results show that two major modes of anomalous water vapour transport over the tropical Indian Ocean–western Pacific (60°–140°E, 10°S–30°N) experienced a significant inter‐decadal change in the mid‐1980s. The first mode (EOF1) shows that the anticyclonic water vapour transport over the northwestern Pacific moves significantly southwards after the mid‐1980s. Before the mid‐1980s, the anomalous water vapour originates from the subtropical western Pacific and moves through the South China Sea to eastern China. However, the anomalous water vapour mainly originates from the tropical western Pacific and moves through the South China Sea to eastern China after the mid‐1980s. The second mode (EOF2) reflects the enhanced effect of the anomalous water vapour transport over the tropical Indian Ocean on East Asia after the mid‐1980s. Before the mid‐1980s, the distribution of the water vapour anomalies is uneven over the tropical Indian Ocean and the magnitude of water vapour is relatively small, so it has a weak effect on rainfall over East Asia. After the mid‐1980s, anomalous anticyclonic water vapour transport originates from the tropical Indian Ocean and moves along the Arabia Sea, Indian Peninsula and Indo‐China Peninsula and then forms an anomalous cyclonic water vapour transport over south China. Furthermore, the possible causes of the inter‐decadal transition in anomalous water vapour transport are investigated for the two major modes. The significant inter‐decadal transition in anomalous water vapour transport is associated with the enhanced effect of the sea surface temperature (SST). Before the mid‐1980s, the relationships between the two major modes and the SST of the tropical oceans are relatively weak. After the mid‐1980s, the EOF1 becomes significantly regulated by the El Niño‐Southern Oscillation (ENSO) in the previous winter, and the positive (negative) phase of the principal component of the first mode (PC1) corresponds to significantly positive (negative) SST anomalies over the tropical northern Indian Ocean and Maritime Continent during the same period. For EOF2, the anomalous water vapour transport over the tropical Indian Ocean is related to the enhanced inter‐annual variability of tropical Indian Ocean dipole (TIOD) after the mid‐1980s.

Flows developing around a finite rotating disk enclosed by a cylindrical casing

Numerical investigation has been performed on the flows around a rotating disk in a cylindrical casing. The sizes of the disk and the casing are finite, and the flow field has a radial clearance and an axial clearance. Taylor-Couette type flow develops in the radial clearance while the rotor-stator cavity flow appears in the axial clearance, and the interaction of the flows in these clearances makes complex flow developments. The flow structures are classified into some types including normal and anomalous modes in the radial clearance and circular and polygonal vortices in the axial clearance. The effect of the acceleration rate of the disk is estimated and it is found that the gradual increase of the disk angular velocity tends to form circular vortices in the normal mode.

Изучение сверхструктуры в сильно легированном пористом фосфиде индия рентгеновскими методами

AbstractAn indium-phosphide InP sample subjected to the pore-generation procedure and then doped with S atoms is studied by the methods of X-ray diffraction analysis (XRD) and small-angle X-ray scattering (SAXS) (with Cu K _α1-radiation). The XRD data demonstrate that the sample consists of (coherent) aligned homogeneous components. A point detector is used to obtain, in the anomalous transmission mode by Borrmann, a set of SAXS curves at sample positions varied by azimuthal rotations. The SAXS data are used to simulate a 2D SAXS pattern for the sample under study, which makes it possible to determine the long-distance translation symmetry and, consequently, the presence of a superstructure. The interplanar distances in the superstructure in the directions (110) and (1 0) of the InP lattice are found to be ~260 and 450 nm, respectively. The symmetry group of the superstructure is determined as C _2 v in the (001) plane of the sample lattice.

X-Ray Study of the Superstructure in Heavily Doped Porous Indium Phosphide

An indium-phosphide InP sample subjected to the pore-generation procedure and then doped with S atoms is studied by the methods of X-ray diffraction analysis (XRD) and small-angle X-ray scattering (SAXS) (with CuKα1-radiation). The XRD data demonstrate that the sample consists of (coherent) aligned homogeneous components. A point detector is used to obtain, in the anomalous transmission mode by Borrmann, a set of SAXS curves at sample positions varied by azimuthal rotations. The SAXS data are used to simulate a 2D SAXS pattern for the sample under study, which makes it possible to determine the long-distance translation symmetry and, consequently, the presence of a superstructure. The interplanar distances in the superstructure in the directions (110) and (1 0) of the InP lattice are found to be ~260 and 450 nm, respectively. The symmetry group of the superstructure is determined as C2v in the (001) plane of the sample lattice.

Development and Evaluation of Mucoadhesive Bio-Flexy Films Using a Novel Biopolymer from Solanum melongena Loaded with Nanosized Topiramate

Purpose: To purpose of this research work was to develop nanosized Topiramate loaded bio-flexy films containing biopolymer isolated from natural edible source of Solanum melongena pulp. Soft palate drug delivery bypasses first-pass metabolism in gastrointestinal tract. The biopolymer was isolated from pulp of Solanum melongena as bio-excipient cum retardant for preparing bio-flexy films due to its biodegradable, biocompatible, non-toxic nature, inertness to soft palatal mucosal surface. Topiramate, anticonvulsant drug which is used for treatment of Epilepsy by reducing glutamatergic neurotransmission have adverse effects like stomach pain, inflammation of pharynx, suicidal ideation and sudden unexpected death in epilepsy (SUDEP). Thus, the adverse reactions are minimized by reducing dose, dose frequency which can be achieved by nanosizing of drug and its smart delivery by Soft Palatal route. Method: Topiramate was nanosized using Solvent Evaporation and Sonication methods respectively. Nanosized Topiramate loaded bio-flexy films containing isolated Solanum melongena biopolymer were prepared by Film Solvent Casting Technique. Formulations containing different ratios of Topiramate: Solanum melongena biopolymer (1:1; 1:3, 1:5, 1:6, 1:10) (FMO1-FMO5) were taken in mortar. Optimized quantity of Dextrose, Fructose and Glycerin were added and triturated properly. Added Distilled Water up to 20 mL uniformly triturated for 2 mins. Mixtures were subjected to Magnetic Stirring for 45 mins, followed by sonication for 5 cycles (each cycle 180 seconds). 10 mL of the solutions were poured into petridishes. Kept for natural drying for 24 hours. Removed by rinsing with 0.1 mL of 1% borax solution. Checked filmability of prepared films. Evaluation parameters were performed for Mucoretentivity, Swelling Index, Thickness, Tensile Strength, Folding Endurance, Surface pH, Weight Uniformity, Drug Content Uniformity, Percentage Moisture Uptake (PTU), in vitro release, and stability studies. Results: The isolated Solanum melongena biopolymer showed percentage yield of 0.58% ± 0.02. Significant mucoretention of prepared bio-flexy films was observed on Capra aegagrus intestinal mucosa in comparison with standard Sodium Carboxyl Methyl Cellulose films. Swelling Percentage of nanosized Topiramate loaded bioflexy films containing Solanum melongena biopolymer (FMO1-FMO5) was ranging from: 70% ± 0.5 to 73% ± 0.3, Thickness 0.027 ± 0.006 mm to 0.037 ± 0.002 mm, Tensile Strength: 89.38 g ± 2.8 to 100.05 g ± 2.4, Folding Endurance: 102-167, Surface pH: 7.01 ± 0.05 to 7.01 ± 0.03, Weight Uniformity: 0.020 ± 0.05 to 0.031 ± 0.04, Drug Content Uniformity: 90.4% ± 0.65 to 98.6% ± 0.60, Percentage Moisture Uptake (PTU): 2.2% ± 0.13 to 2.6% ± 0.12. Conclusion: The bio-flexy film FMO1 prepared using Topiramate: Solanum melongena biopolymer in ratio of 1:1 was taken as Best film. It showed Regression square value of 0.9618, Higuchi Matrix equation as best fit model, followed Anomalous Transport release mode of action, Time required for 50%, drug release was 24 hours and for 80% drug release was 32 hours as per BITS Software. Stability study showed stable bio-flexy films. Prepared formulations of Topiramate loaded bio-flexy films containing Solanum melongena biopolymer were appropriate for Soft Palatal Delivery as it showed significant mucoretention due to its bio-polymeric nature.

Sustained Release of Green Tea Polyphenols from Liposomal Nanoparticles; Release Kinetics and Mathematical Modelling.

Background: Green tea polyphenols (GTP) are known to have several health benefits. In spite of these benefits, its application as a therapeutic agent is limited due to some of its limitations such as stability, bioavailability, and biotransformation. To overcome these limitations, liposomal nanoparticles have been used as a carrier of the GTP. Objective: Encapsulation of GTP to the liposomal nanoparticles in order to achieve a sustained release of the GTP and to determine the drug release kinetics and the mechanism of the release. Materials and Methods: GTP encapsulated liposomal nanoparticles were prepared using phosphatidyl choline and cholesterol. The synthesized particles were characterized for their particle size and morphology. In vitro release studies were carried out, followed by drug release kinetics, and determining the mechanism of release. In vitro, antioxidant assay was determined following 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Results: Atomic force microscope (AFM) and high resolution scanning electron microscope (HR SEM) images showed spherical particles of the size of 64.5 and 252 nm. An encapsulation efficiency as high as 77.7% was observed with GTP concentration of 5 mg.mL-1. In vitro release studies showed that the loading concentrations of GTP were independent to the cumulative percentage of the drug release. GTP release by varying the pH and temperature showed a direct correlation between the release parameter and the percentage of drug release. The higher the pH and temperature, the higher was the percentage of the drug release. The release data showed a good correlation with Zero order kinetics and the mechanism of the release being anomalous mode. Radical scavenging activity of the released GTP showed a potent scavenging activity. Conclusion: GTP encapsulated liposomal nanoparticles could be used as a delivery vehicle for achieving a sustained release.

Mott dissociation of pions and kaons in hot, dense quark matter

We describe the Mott dissociation of pions and kaons within a Beth-Uhlenbeck approach based on the PNJL model, which allows for a unified description of bound, resonant and scattering states. Within this model we evaluate the temperature and chemical potential dependent modification of the phase shifts both in the pseudoscalar and scalar isovector meson channels for $N_f=2+1$ quark flavors. We show that the character change of the pseudoscalar bound states to resonances in the continuum at the Mott transition temperature is signaled by a jump of the phase shift at the threshold from $\pi$ to zero, in accordance with the Levinson theorem. In particular, we demonstrate the importance of accounting for the scattering continuum states, which ensures that the total phase shift in each of the meson channels vanishes at high energies, thus eliminating mesonic correlations from the thermodynamics at high temperatures. In this way, we prove that the present approach provides a unified description of the transition from a meson gas to a quark-gluon plasma. We discuss the occurrence of an anomalous mode for mesons composed of quarks with unequal masses which is particularly pronounced for $K^+$ and $\kappa^+$ states at finite densities a a possible mechanism to explain the "horn" effect for the $K^+/\pi^+$ ratio in heavy-ion collisions.

Anomalous Acoustic Plasmon Mode from Topologically Protected States.

Plasmons, the collective excitations of electrons in the bulk or at the surface, play an important role in the properties of materials, and have generated the field of "plasmonics." We report the observation of a highly unusual acoustic plasmon mode on the surface of a three-dimensional topological insulator (TI) Bi_{2}Se_{3}, using momentum resolved inelastic electron scattering. In sharp contrast to ordinary plasmon modes, this mode exhibits almost linear dispersion into the second Brillouin zone and remains prominent with remarkably weak damping not seen in any other systems. This behavior must be associated with the inherent robustness of the electrons in the TI surface state, so that not only the surface Dirac states but also their collective excitations are topologically protected. On the other hand, this mode has much smaller energy dispersion than expected from a continuous media excitation picture, which can be attributed to the strong coupling with surface phonons.

Anomalous vibrational modes in few layer WTe2 revealed by polarized Raman scattering and first-principles calculations

When layered transition-metal dichalcogenides (TMDs) are scaled down from a three- to a 2D geometry, electronic and structural transitions occur, leading to the emergence of properties not usually found in the bulk. Here, we report a systematic Raman study of exfoliated semi-metallic WTe2 flakes with thickness ranging from few layers down to a single layer. A dramatic change in the Raman spectra occurs between the monolayer and few-layer WTe2 as a vibrational mode centered at ~86.9 cm−1 in the monolayer splits into two active modes at 82.9 and 89.6 cm−1 in the bilayer. Davydov splitting of these two modes is found in the bilayer, as further evidenced by polarized Raman measurements. Strong angular dependence of Raman modes on the WTe2 film thickness reflects that the existence of directional interlayer interaction, rather than isotropic van der Waals (vdw) coupling, is playing an essential role affecting the phonon modes, especially in anisotropic 2D WTe2 material. Therefore, the strong evolution of Raman modes with thickness and polarization direction, can not only be a reliable fingerprint for the determination of the thickness and the crystallographic orientation, but can also be an ideal probe for such strong and directional interlayer interaction.

Possible acceleration of cosmic rays in a system of rotating gases: Uehling–Uhlenbeck model

Possible acceleration of cosmic rays passing through a kind of amplification channel (via anomalous diffusion modes of propagating plane-wave fronts) induced by a system of rotating gases (or disk-like gases) is presented. Our novel numerical results after detailed analysis were based on the quantum discrete kinetic model (considering Uehling–Uhlenbeck collision term) which has been used to study the propagation of plane (e.g., acoustic) waves propagating in composite-particle gases under uniform gravitational fields.

Generating end modes in a superconducting wire by periodic driving of the hopping

We show that harmonic driving of either the magnitude or the phase of the nearest-neighbor hopping amplitude in a p-wave superconducting wire can generate modes localized near the ends of the wire. The Floquet eigenvalues of these modes can either be equal to $\pm 1$ (which is known to occur in other models) or can lie near other values in complex conjugate pairs which is unusual; we call the latter anomalous end modes. All the end modes have equal probabilities of particles and holes. If the amplitude of driving is small, we observe an interesting bulk-boundary correspondence: the Floquet eigenvalues and the peaks of the Fourier transform of the end modes lie close to the Floquet eigenvalues and momenta at which the Floquet eigenvalues of the bulk system have extrema.

Topological defects in Floquet systems: Anomalous chiral modes and topological invariant

Backscattering-immune chiral modes arise along certain line defects in three-dimensional materials. In this paper, we study Floquet chiral modes along Floquet topological defects, namely, the defects come entirely from spatial modulations of periodic driving. We define a precise topological invariant that counts the number of Floquet chiral modes, which is expressed as an integral on a five-dimensional torus parameterized by $(k_x,k_y,k_z,\theta,t)$. This work demonstrates the possibility of creating chiral modes in three-dimensional bulk materials by modulated driving. We hope that it will stimulate further studies of Floquet topological defects.