Bar Structure Research Articles

Automatic Melody Composition Using Enhanced GAN

In traditional music composition, the composer has a special knowledge of music and combines emotion and creative experience to create music. As computer technology has evolved, various music-related technologies have been developed. To create new music, a considerable amount of time is required. Therefore, a system is required that can automatically compose music from input music. This study proposes a novel melody composition method that enhanced the original generative adversarial network (GAN) model based on individual bars. Two discriminators were used to form the enhanced GAN model: one was a long short-term memory (LSTM) model that was used to ensure correlation between the bars, and the other was a convolutional neural network (CNN) model that was used to ensure rationality of the bar structure. Experiments were conducted using bar encoding and the enhanced GAN model to compose a new melody and evaluate the quality of the composition melody. In the evaluation method, the TFIDF algorithm was also used to calculate the structural differences between four types of musical instrument digital interface (MIDI) file (i.e., randomly composed melody, melody composed by the original GAN, melody composed by the proposed method, and the real melody). Using the TFIDF algorithm, the structures of the melody composed were compared by the proposed method with the real melody and the structure of the traditional melody was compared with the structure of the real melody. The experimental results showed that the melody composed by the proposed method had more similarity with real melody structure with a difference of only 8% than that of the traditional melody structure.

Nanomachining-enabled strain manipulation of magnetic anisotropy in the free-standing GaMnAs nanostructures

Strain perturbs atomic ordering in solids, with far-reaching consequences from an increased carrier mobility to localization in Si, stabilization of electric dipoles and nanomechanical transistor action in oxides, to the manipulation of spins without applying magnetic fields in n-GaAs. In GaMnAs, a carrier-mediated ferromagnetic semiconductor, relativistic spin-orbit interactions – highly strain-dependent magnetic interactions – play a crucial role in determining the magnetic anisotropy (MA) and anisotropic magnetoresistance (AMR). Strain modifies the MA and AMR in a nanomachined GaMnAs structure as measured by the anomalous Hall effect (AHE) and the planar Hall effect (PHE). Here, we report an MA modification by strain relaxation in an isolated GaMnAs Hall bar structure and by applying a range of local strains via fabricating asymmetrically mechanically buckled GaMnAs micro-Hall bar structures. In the AHE and PHE measurements, we observe a reduction in the in-plane MA and an enhancement in the out-of-plane MA as the compressive strain due to the lattice mismatch relaxes in the suspended structure. The functionality of such mechanical manipulation, as well as the two-level mechanical state and the corresponding AHE responses, is demonstrated by a fully scalable binary mechanical memory element in a GaMnAs single Hall cross structure.

Investigation of starting torque in entirely tubular submersible motor with rotor sector piece connected by weldments

The starting performance of a large tubular submersible induction motor is affected by welding slots. To accurately calculate the starting performance of the double bar entirely tubular submersible induction motor (DBETSIM), an equivalent circuit diagram of DBETSIM is established, and the calculation formula of the starting torque of the motor under is derived. Then, the finite element analysis method and the equivalent circuit parameter method were used to calculate the starting parameters, respectively. Comparing DBETSIM with the normal tubular submersible motor, it is found that the second bar structure can improve the starting performance of the motor. Finally, the structure and material of the second bar are optimized and analyzed. It is concluded that the starting performance is improved most when the welding material is aluminum alloy with narrow and deep welding slots, which provides a reference for the design and optimization of DBETSIM. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

A Study of Mechanical Alloying of an Aluminum Composite Material Reinforced with Silicon Carbide Particles

A composite material based on alloy V95 containing 10% silicon carbide and prepared by powder metallurgy is studied. Composite granules are fabricated by mechanical alloying in a planetary mill in an inert gas atmosphere. It is shown that the structure of the composite granules affects the structure of the billets obtained after deformation treatment by extrusion, i.e., the more homogeneous the structure of the granules, the more homogeneous is the bar structure.

Measuring Method for Strand Current of Stator Bars Based on Search Coils

It is very important to uniform the strand current in stator bars’ design of a large generator. As the stator bars are made of several parallel strands that are closely adjacent to one another, the strand current cannot be measured by straight-through current transformer. In order to measure the strand current without changing the structure of the stator bar, a measuring method for strand current of stator bars based on the superposition magnetic field measurement surround the strand by using search coils is proposed in this paper. The optimal position assembly is determined by the structure and the magnetic field of the stator bar in end region. The leakage magnetic field surrounding the measuring position is measured by search coils, and the strand current is solved by the algorithm of least square error function. The correctness of this method is verified by comparing with the result of current transformers. This measuring method not only provides an evaluation basis for the transposition design of stator windings in large generators but also provides a technical support for the current measuring of adjacent transmission lines and large capacity parallel cables.

Role of interface quality for the spin Hall magnetoresistance in nickel ferrite thin films with bulk-like magnetic properties

We utilized spin Hall magnetoresistance (SMR) measurements to experimentally investigate pure spin current transport in thin film heterostructures of nickel ferrite (NiFe2O4,NFO) and normal metals (NM) Ta and Pt. We grew (001)-oriented NFO thin films by pulsed laser deposition on lattice-matched magnesium gallate (MgGa2O4) substrates, thereby significantly improving their magnetic and structural properties. We performed SMR measurements at room temperature in patterned Hall bar structures for charge currents applied in the [100]- and [110]-directions of NFO. We found that the extracted SMR magnitude for NFO/Pt heterostructures depends crucially on the Pt resistivity of the investigated Hall bar structure. We further study this resistivity scaling of the SMR effect at different temperatures for NFO/Pt. Our results suggest that the spin mixing conductance of the NFO/Pt interface and the Pt resistivity depend on the interface quality and thus a correlation between these two quantities exists.

Time-slicing spiral galaxies with SDSS-IV MaNGA

ABSTRACT Spectra of galaxies contain a wealth of information about the stellar populations from which they are made. With integral field unit (IFU) surveys, such data can be used to map out stellar population properties across the face of a galaxy, allowing one to go beyond simple radial profiles and study details of non-axisymmetric structure. To-date, however, such studies have been limited by the quality of available data and the power of spectral analysis tools. We now take the next step and study the barred spiral galaxy MCG + 07-28-064 from observations obtained as part of the SDSS-IV MaNGA project. We find that we can decompose this galaxy into ‘time slices,’ which reveal the varying contributions that stars of differing ages make to its bar and spiral structure, offering new insight into the evolution of these features. We find evidence for the ongoing growth of the bar, including the most recent star formation on its leading edge, and for the underlying density wave responsible for spiral structure. This pilot study indicates that there is a wealth of untapped information on the spatial distribution of star formation histories available in the current generation of IFU galaxy surveys.

Study of sense current effect on magnetization switching behavior from anomalous Hall effect in TbFeCo thin films

Abstract The control of magnetic properties by electric current in nanoscale devices is critical for advanced applications of spintronics. Here, we study the anomalous Hall effect in amorphous TbFeCo/Ta/MgO structure for various dc sense currents using the Hall bar pattern. The aspect ratio of the Hall bar structure is changed by simply interchanging the current and voltage terminals. It is found that the increase in the sense current decreases both the anomalous Hall resistivity and the coercivity in the TbFeCo. The decreasing trend of resistivity and coercivity with sense current is unusual which is explained on the basis of Joule heating and spin-orbit torque. In addition, a simple analysis is performed to relate the magnetization switching speed as a function of dc sense current.

Structural and kinematic aspects of some bar mechanisms for deployable structures

Transformable structures in architecture can change their shape or function in response to varying climatic conditions, changing environment and needs for different functional requirements or to emergency situations. Depending on how the transformation is doing, transformable structures can be deployable or demountable, as a kit-parts system. Deployable structures can also be divided in four main groups: spatial bar structures; foldable plate structures; tensegrity structures; and membrane structures. In this paper, some planar bar mechanisms proposed by Ten Fold Engineering company, which can be integrated in deployable structures, will be discussed.

On the ridges, undulations & streams in Gaia DR2: Linking the topography of phase-space to the orbital structure of an N-body bar

Abstract We explore the origin of phase-space substructures revealed by the second Gaia data release in the disc of the Milky Way, such as the ridges in the Vφ-r plane, the undulations in the Vφ-r-Vr space and the streams in the Vφ-Vr plane. We use a collisionless N-body simulation with co-spatial thin and thick discs, along with orbit integration, to study the orbital structure close to the Outer Lindblad Resonance (OLR) of the bar. We find that a prominent, long-lived ridge is formed in the Vφ-r plane due to the OLR which translates to streams in the Vφ-Vr plane and examine which closed periodic and trapped librating orbits are responsible for these features. We find that orbits which carry out small librations around the x1(1) family are preferentially found at negative Vr, giving rise to a ‘horn’-like feature, while orbits with larger libration amplitudes, trapped around the x1(2) and x1(1) families, constitute the positive Vr substructure, i.e. the Hercules-like feature. This changing libration amplitude of orbits will translate to a changing ratio of thin/thick disc stars, which could have implications on the metallicity distribution in this plane. We find that a scenario in which the Sun is placed close to the OLR gives rise to a strong asymmetry in Vr in the Vφ-Vr plane (i.e. Hercules vs. ‘the horn’) and subsequently to undulations in the Vφ-r-Vr space. We also explore a scenario in which the Sun is placed closer to the bar corotation and find that the bar perturbation alone cannot give rise to the these features.

Current-induced picosecond magnetization dynamics in a Ta/CoFeB/MgO hall bar

Time-resolved Kerr microscopy (TRSKM) has been used to explore the small amplitude picosecond magnetization dynamics induced by spin–orbit torques in a Ta(4 nm)/Co40Fe40B20(1 nm)/MgO(1.6 nm)/Ta(1 nm) Hall bar structure. The time dependent polar magneto optical Kerr effect was recorded following injection of a current pulse of 70 ps duration. Macrospin simulations provide a reasonable description of the precession and a transient background response as the field strength and current polarity are varied, while confirming that the in-plane spin–orbit torque is dominant within this system. Increasing the current density within the simulations leads to coherent magnetization reversal. Inclusion of a modest in-plane bias field is found to reduce both the switching current and the time required for switching. The orientation of the in-plane field relative to the direction of the current determines whether the magnetization can be switched backwards and forwards by current pulses of the same or opposite polarity.

Another relic bulge globular cluster: ESO 456-SC38 (Djorgovski 2)

Context. The object ESO 456-SC38 (Djorgovski 2) is one of the globular clusters that is closest to the Galactic center. It is on the blue horizontal branch and has a moderate metallicity of [Fe/H] ∼ −1.0. It is thus similar to the very old inner bulge globular clusters NGC 6522, NGC 6558, and HP 1, and therefore appears to be part of the primeval formation stages of the Milky Way. Aims. The aim of this work is to determine an accurate distance and metallicity for ESO 456-SC38, as well as orbital parameters, in order to check similarities with other clusters in the inner bulge that have previously been well studied in terms of spectroscopy and photometry. This is a considerably fainter cluster that is contaminated by a rich stellar field; it is also quite absorbed by the dusty foreground. Methods. We analyzed ESO 456-SC38 based on HST photometry, with the filters F606W from ACS, F110W and F160W from WFC3, and photometry in V and I from FORS2 at the VLT. We combined this with identified stars that are covered by Gaia Data Release 2. Results. The isochrone fitting was carried out with the statistical Markov chain Monte Carlo method. We derive an accurate distance of d⊙ = 8.75 ± 0.12 kpc and a reddening of E(B−V) = 0.81+0.02−0.02. The best-fitting BaSTI isochrones correspond to an age of 12.70+0.72−0.69 Gyr and a metallicity of [Fe/H] = −1.11+0.03−0.03. Conclusions. ESO 456-SC38 adds to the list of moderately metal-poor globular clusters located in the inner bulge. It has a blue horizontal branch and is very old. The cluster is confined to the bulge and bar region, but it does not support the Galactic bar structure. The old stellar population represented by clusters like this has to be taken into account in models of Galactic bulge formation. Studying them also provides indications on the formation times of the globular clusters themselves.

Study of the Influence of Conditions of Combined Casting and Rolling-Extruding and Two-Stage Annealing on the Structure and Properties of Semi-Finished Electrical Products from an Al–Zr System Alloy

This article presents the results of the study of the joint effect of the processing conditions of the new composition of the Al-Zr system alloy by combined casting and rolling-extruding and two-stage annealing on the structure and properties of round bars used in the manufacture of heat-resistant wires. The research show patterns of changes in the properties, the specific electrical resistance of the bars, depending on different conditions of deformation and heat treatment of aluminum alloy with a content of 0.3% zirconium and 0.2% iron. The results of micro-X-ray spectral analysis and the granular structure of the samples before and after two-stage annealing confirming the stability of the structure after heating and preserving the strength of semi-finished products. Presented parameters of combined casting and rolling-extruding and two-stage annealing for the manufacture of rods from the studied alloy make it possible obtaining good combination of mechanical properties and electrical conductivity.

Investigation of the resistance characteristics of a multi-AUV system

The multiple autonomous underwater vehicles (AUV) sailing in a specific configuration can reduce resistance if properly using the hydrodynamic interactions. This paper investigated the resistance characteristics of a multi-AUV system with both experimental and numerical approaches. A center-beam-support bar structure was designed to conduct the experiment. Validation of our numerical method was carried out by comparing with the experimental data. Parametric studies were then performed on the distance, the speed and the number of AUVs. The numerical results showed that SST-transition model is more suitable for simulating the multi-AUV system at Reynolds numbers (Re) ranging from 2.46 × 106 to 6.69 × 106. At Re = 6.14 × 106, the largest reduction of resistance can be 35.14% at d/L = 0. In the meantime, there appears some undesirable interference area between d/L = 0.042 and d/L = 0.063 where the total resistance of the fleet increases sharply. Apart from that, higher reduction of resistance can be expected with the increase of the speed and the number of AUVs.

Control of Edge Plate Stray Grain of Single-Crystal Turbine Blade by Using Process Bar Method

Single-crystal (SX) turbine blade is the key component for aero-engines. However, the quality of the SX turbine blade is limited by the stray grain defects. When the structure and material are determined, in order to eliminate this defect, the process bar method is used to control the formation of stray grain. However, the structure of process bar is not researched. Generally, the process bar is designed by experience. In this paper, the simulation method is used to design the process bar structure. In order to describe the stray grain features, the critical stray grain cooling rate is put forward to predict the stray grain defect. With the help of the CAE analysis, the process bar dimension and position are determined by this method for a sample turbine blade. The result shows the process bar could modify the shape of the solidification interface and control the stray grain defect. Meanwhile, it also could control the dimension of the platform. And then, the effectiveness of this process bar design method is confirmed in the sample turbine blade experiment. The experiment result illustrated that the stray grain was eliminated.

Modeling and Mechanical Analysis of Snake Robots on Cylinders

Abstract The narrow and redundant body of the snake robot makes it suitable for the inspection of complex bar structures, such as truss or tree structures. One of the key issues affecting the efficient motion of snake robots in complex bar structures is the development of mechanical models of snake robots on cylinders. In other words, the relationship between the payload and structural and performance parameters of the snake robot is still difficult to clarify. In this paper, the problem is approached with the Newton–Euler equations and the convex optimal method. Firstly, from the kinematic point of view, the optimal attitude of the snake robot wrapped around the cylinder is found. Next, the snake robot is modeled on the cylinder and transformed into a convex optimization problem. Then, the relationship between the payload of the snake robot on the cylinder and the geometric and attitude parameters of the body of snake robots is analyzed. Finally, the discussion for the optimal winding attitude and some advices for the design of the snake robot are proposed. This study is helpful toward the optimal design of snake robots, including geometry parameters and motor determination.

Resolving the distance controversy for Sharpless 269

Context. Sharpless 269 (S 269) is one of a few HII regions in the outer spiral arm of the Milky Way with strong water maser emission. Based on data from the Very Long Baseline Interferometry (VLBI) Exploration of Radio Astrometry (VERA) array, two parallax measurements have been published, which differ by nearly 2σ. Each distance estimate supports a different structure for the outer arm. Moreover, given its large Galactocentric radii, S 269 has special relevance as its proper motion and parallax have been used to constrain the Galactic rotation curve at large radii.Aims. Using recent Very Long Baseline Array (VLBA) observations, we accurately measure the parallax and proper motion of the water masers in S 269. We interpret the position and motion of S 269 in the context of Galactic structure, and possible optical counterparts.Methods. S 269’s 22 GHz water masers and two close by quasars were observed at 16 epochs between 2015 and 2016 using the VLBA. We calibrated the data by inverse phase referencing using the strongest maser spot. The parallax and proper motion were fitted using the standard protocols of the Bar and Spiral Structure Legacy survey.Results. We measure an annual parallax for S 269 of 0.241 ± 0.012 mas corresponding to a distance from the Sun of 4.15+0.22−0.20kpc by fitting four maser spots. The mean proper motion for S 269 was estimated as 0.16 ± 0.26 mas yr−1and −0.51 ± 0.26 mas yr−1forμαcosδandμδrespectively, which corresponds to the motion expected for a flat Galactic rotation curve at large radius. This distance estimate, Galactic kinematic simulations and observations of other massive young stars in the outer region support the existence of a kink in the outer arm atl ≈ 140°. Additionally, we find more than 2000 optical sources in the Gaia DR2 catalog within 125 pc radius around the 3D position of the water maser emission; from those only three sources are likely members of the same stellar association that contains the young massive star responsible for the maser emission (S 269 IRS 2w).

Parallaxes for Star-forming Regions in the Inner Perseus Spiral Arm

Abstract We report trigonometric parallax and proper motion measurements of 6.7 GHz CH3OH and 22 GHz H2O masers in eight high-mass star-forming regions (HMSFRs) based on Very Long Baseline Array (VLBA) observations as part of the Bar and Spiral Structure Legacy (BeSSeL) Survey. The distances of these HMSFRs combined with their Galactic coordinates, radial velocities, and proper motions, allow us to assign them to a segment of the Perseus arm with ℓ ≲ 70°. These HMSFRs are clustered in Galactic longitude from ≈30° to ≈50° neighboring a dearth of such sources between longitudes ≈50° to ≈90°.

Two-dimensional MEMS Fe-based metallic glass micromirror driven by an electromagnetic actuator

A 2D MEMS Fe-based metallic glass micromirror driven by an electromagnetic actuator is studied and proposed. Fe-based metallic glass is an amorphous metal that has excellent mechanical and magnetic properties. In this paper, Fe-based metallic glass is used as magnetic actuation material and torsion bar structure material. The Fe-based metallic glass thin film deposited on a micromirror surface is used as magnetic material that can be magnetically polarized by permanent magnets. Besides, the micromirror consists of two pairs of metallic glass torsion bars to achieve 2D scanning. The excellent mechanical properties of metallic glass were used for increasing the strength and reliability of the micromirror. The fabricated 2D micromirror can be actuated by an electromagnetic solenoid in dual resonant modes. The result shows that the scanning angle of the outer slow axis is 11° at 800 Hz and that of the inner fast axis is 90° at 5249 Hz.

Structure of Our Galactic Bulge from CN Measurements

Abstract The double red clumps (DRCs) are now dominantly believed to be the strong observational line of evidence of the so-called X-shaped Galactic bar structures. Recently, Lee et al. reported a subtle mean δCN(3839) difference between the DRCs and suggested a dichotomic picture that can be seen in globular clusters: the faint red clump is the first generation, while the bright red clump corresponds to the second generation (SG). They argued that the magnitude difference between the DRCs is due to different stellar populations, and is not due to the geometric difference between the DRCs. Our reanalysis shows that their data do not appear to support the idea of multiple population-induced DRCs in our Galactic bulge. We perform fully empirical Monte Carlo simulations and find that the shape of the δCN(3839) distributions is the most stringent evidence to pursue. Our results strongly suggest that the CN distributions toward the Galactic bulge are qualitatively consistent with the X-shaped Galactic bulge with a minor fraction of the SG of about 2%–3%.