Increase In Rotation Frequency Research Articles

Nanomechanical fluctuations of microcantilever under turbulent mixing

Here, we describe the motion of a microcantilever under water, being stirred by a rotating stir bar. Specifically, the thermomechanical fluctuations of the microcantilever are monitored as a function of the rotation frequency of the stir bar and compared with those under stationary water and in air. While the measured probability density functions both in air and stationary water show well-defined Gaussian distributions in displacement, with increasing rotation frequency of the stir bar, we note the growing tail of the probability density function as well as high level of the noise power spectral density, which can be attributed to the turbulent fluctuation within the water, caused by the motion of the stir bar. The work presented demonstrates the cantilever-based mechanical probing of the fluid motion.

Rotary magnetic field combined with pipe fluid technique for efficient extraction of pumpkin polysaccharides

Abstract Pumpkin polysaccharides are considered as functional materials with bioactivities. However, the conventional aqueous extraction method for pumpkin polysaccharides is limited by long time consumption, low efficiency and potential damage to their bioactivities. To improve the efficiency of pumpkin polysaccharides extraction, we designed a new experimental system combining a rotary magnetic field and flowing conductive solution. Polysaccharide extractions by 1) acidic sample solution with agitation, 2) flowing acidic sample solution, 3) static magnetic field combined with flowing acidic sample solution, and 4) rotary magnetic field combined with flowing acidic sample solution were conducted at pH level of 2–4, temperature of 30–50 °C, and treatment time of 0–180 min. The extraction by use of rotary magnetic field combined with flowing acidic sample solution resulted in the highest polysaccharide yield. Then, the effects of rotational frequency, Reynolds number, pH, and temperature on extraction yield were investigated. The yield increased at first and then decreased with an increase in rotational frequency. The high polysaccharide yield was achieved at large Reynolds number, high temperature, and low pH. From the ultraviolet, Fourier transform-infrared spectrum and chromatographic analysis, the extracts proved to be polysaccharides with an average molecular weight of 1.435 × 10 5 Da. The extracted pumpkin polysaccharides exhibited a dose-dependent radical-scavenging capacity within 0.1 to 5 mg/mL in the order of hydroxyl radical > DPPH radical > superoxide radical. Industrial relevance Rare report on the application of the combined magnetic field and pipe-fluid technique in extraction functional components from food materials. In this study, a novel experimental apparatus combining rotary magnetic field and spiral-pipe flow was designed to accelerate the extraction of pumpkin polysaccharides. In comparison with 1) agitation, 2) flowing acidic sample solution, and 3) static magnetic field combined with flowing acidic sample solution, the method combining rotating magnetic field and flowing acidic sample solution 4) significantly increased the polysaccharide yield. The increments were 40.18%, 32.14%, and 23.32%, respectively, after 180-min extraction. The pumpkin polysaccharides extracted by this novel method possessed a molecular weight of 1.435 × 10 5 Da and showed desirable antioxidant activities in vitro. Therefore, the combined magnetic field and pipe-fluid technique it is a potential method for efficient extraction of valuable compounds from food materials.

Enhancement of Salt Uptake with the Application of Rotary Magnetic Field in Brining Cucumber

<p>An experimental system by use of magnetic and hydrodynamic force was established to accelerate mass transport and thus to shorten the salting equilibrium time in salting of fresh-cut cucumbers. The cucumbers were brined with flowing 3% NaCl solution under rotary magnetic field at 22 ºC. During brining period, salt contents of the cucumbers at varying Reynolds number of flowing brine, rotary frequency, and magnetic flux density of magnetic field were separately investigated and the salt uptake kinetics was also analyzed. Results showed that flowing brine disturbed the salt diffusion into cucumber tissues without the application of magnetic field. Consequently, the salt uptake rate decreased compared to the conventional brining. No significant difference in salt content of cucumbers was observed between the conventional brining and static-magnetic-field-assisted brining. The salt uptake rate was improved by the combination of rotary magnetic field and flowing brine. The increment of salt uptake rate during this combined treatment got larger with the increase of magnetic flux density. Salt uptake rate of cucumber increased with the increase of rotational frequency of the magnetic field and Reynolds number of the flowing brine, up to a critical value. A 170% increment in salt uptake rate constant could be achieved at magnetic flux density 0.13 T, rotational frequency 5 Hz and Reynolds number 1127. Thus, an intergrated technique based upon rotary magnetic field and flowing brine is provided for brining of porous agricultural products.</p>

Theoretical study of triaxial shapes of neutron-rich Mo and Ru nuclei

Background: Recently, transition quadrupole moments in rotational bands of even-mass neutron-rich isotopes of molybdenum and ruthenium nuclei have been measured. The new data have provided a challenge for theoretical descriptions invoking stable triaxial deformations. Purpose: To understand experimental data on rotational bands in the neutron-rich Mo-Ru region, we carried out theoretical analysis of moments of inertia, shapes, and transition quadrupole moments of neutron-rich even-even nuclei around $^{110}$Ru using self-consistent mean-field and shell model techniques. Methods: To describe yrast structures in Mo and Ru isotopes, we use nuclear Density Functional Theory (DFT) with the optimized energy density functional UNEDF0. We also apply Triaxial Projected Shell Model (TPSM) to describe yrast and positive-parity, near-yrast band structures. Results: Our self-consistent DFT calculations predict triaxial ground-state deformations in $^{106,108}$Mo and $^{108.110,112}$Ru and reproduce the observed low-frequency behavior of moments of inertia. As the rotational frequency increases, a negative-$\gamma$ structure, associated with the aligned $\nu(h_{11/2})^2$ pair, becomes energetically favored. The computed transition quadrupole moments vary with angular momentum, which reflects deformation changes with rotation; those variations are consistent with experiment. The TPSM calculations explain the observed band structures assuming stable triaxial shapes. Conclusions: The structure of neutron-rich even-even nuclei around $^{110}$Ru is consistent with triaxial shape deformations. Our DFT and TPSM frameworks provide a consistent and complementary description of experimental data.

Preparation of an Mg–Gd–Zn alloy semisolid slurry by low frequency electro-magnetic stirring

Abstract The effects of low frequency electromagnetic stirring (LFEMS) including applied voltage, rotational frequency and cooling rate on the microstructure of semisolid slurry of the Mg–2.5Gd–1Zn (at.%) alloy have been investigated. The applied voltage, rotational frequency and cooling rate all have a remarkable influence on the microstructures of the slurries. The LFEMS treatment leads to the morphology of primary Mg particles evolved from dendritic to non-dendritic. The increase of applied voltage leads to refined primary Mg particles, while the increase in rotational frequency makes the α-Mg particles initially refined and then coarsened. The decrease of cooling rate also leads to refinement of primary Mg particles. The optimal processing parameters for the fabrication of semisolid slurry are found to be: applied voltage 300–350 V, rotational frequency 15–20 Hz and cooling rate below 1.4 K/min. Under the optimized parameters, fine and spherical primary Mg particles were obtained, and the average particle size is refined from ~ 680 to ~ 150 μm.

S1110603 ギヤボックス内における潤滑油の挙動について

Lubrication is important for the sake of operate the gear unit. Friction heat have a close relation with gear damage. The generating heat can be dissipated to lubricating oil by lubrication. The viscosity of the lubricating oil is related to lubricating, but it varies with temperature. This study focuses on lubricating oil temperature in gear box. Authors measured a rise in lubricating oil temperature in bath lubrication. Experimental apparatus is gear unit of power circulation system. It was measured lubricating oil temperature in gear box using thermocouple. It changed lubricating oil, load torque and rotational frequency in the experiment. It was found that lubricating oil temperature rises as load torque, rotational frequency and viscosity increases by the experiment. Also calculated a film thickness from the measured lubricating oil temperature, it was found that film thickness reduce as lubricating oil temperature rises. Lubrication form is changed from fluid friction to dry friction by reduce film thickness. It has shown that it is necessary to pay attention to the temperature of the lubricant. Because not maintain proper lubrication.

Theory and simulation of ion Coulomb crystal formation in a Penning trap

Ion Coulomb crystals (ICCs) are formed by laser-cooled ions in both radio-frequency and Penning traps. In radio-frequency traps, the crystals are generally stationary. In Penning traps, ICCs always rotate. The frequency of rotation is often set by an applied rotating wall drive that forces the crystal to rotate at the same frequency as the drive. In the absence of any applied rotating or oscillating fields, ICCs in a Penning trap can be in stable equilibrium with a range of rotation frequencies. The density and shape of the crystal adjust with the rotation frequency to ensure that equilibrium is reached. Here, we show that the parameters of the radial laser-cooling beam determine the rotation frequency of a small crystal in a Penning trap when no driving fields are present. We demonstrate, using an approximate theoretical treatment and realistic simulations, that the crystal rotation frequency is independent of the number of ions and the trap parameters, so long as the crystal radius remains smaller than the cooling laser beam waist. As the rotation frequency increases, the crystal eventually becomes a linear string, at which point it is no longer able to adjust its density. Instead, a small amplitude vibration in the zigzag mode of oscillation manifests itself as a rotation of the crystal at a fixed frequency that depends only on the applied trap potential.

Vortex chain in anisotropic spin-orbit-coupled spin-1 Bose-Einstein condensates

We investigate the rotating spin-1 Bose-Einstein condensates with anisotropic spin-orbit coupling by using the damped projected Gross-Pitaevskii equation. The anisotropic spin-orbit coupling can cause some vortices to form the vortex chain, where the vortices link up with each other in a line. The formation of the vortex chain starts from very small rotation frequency and coexists with more remanent vortices with the increasing rotation frequency. By increasing the anisotropy of the spin-orbit coupling, the creation of the vortex chain is enhanced, accompanied by the emergence of several types of vortex chain and other vortex configurations. When the vortices of the ${m}_{F}=\ensuremath{-}1$ and ${m}_{F}=+1$ components are of synchronous phases, such vortex configurations do not cause any topological excitation in the spin texture.

Transition to turbulence in a flow of a shear-thinning viscoelastic solution in a Taylor-Couette cell

The transition to turbulence in a flow of semidilute shear-thinning viscoelastic solution with a moderate elasticity was investigated in the Taylor-Couette system with a fixed outer cylinder. As the cylinder rotation frequency increases, the base flow bifurcates to a pattern of ribbons and then to disordered oscillations (DOs). Within these DOs, we have identified two particular regimes of turbulence: spatiotemporal intermittency (STI) followed by inertioelastic turbulence (IET) with a net transition between them. This transition is evidenced by a sharp peak of a diffusion velocity and a Weissenberg number.

Refining the calculation procedure for estimating the influence of flashing steam in steam turbine heaters on the increase of rotor rotation frequency during rejection of electric load

A refined procedure for estimating the effect the flashing of condensate in a steam turbine’s regenerative and delivery-water heaters on the increase of rotor rotation frequency during rejection of electric load is presented. The results of calculations carried out according to the proposed procedure as applied to the delivery-water and regenerative heaters of a T-110/120-12.8 turbine are given.

Effects of rotation frequency and task order on localised muscle fatigue and performance during repetitive static shoulder exertions

Though widely considered to reduce physical exposures and increase exposure variation, there is limited evidence that rotating between tasks is effective in reducing the risk of work-related musculoskeletal disorders (WMSDs). The purpose of this study was to assess the effects of rotation, specifically focusing on rotation frequency and task order, on muscle fatigue and performance when rotating between tasks that load the same muscle group. Twelve participants completed six experimental sessions during which repetitive static shoulder abduction tasks were performed at two exertion levels for one hour either with or without rotation. Compared to only performing a higher or lower exertion task, rotating between the two tasks decreased and increased fatigue, respectively. Increasing rotation frequency adversely affected task performance, and task order had a minor effect on muscle fatigue. These rotation parameters may be important considerations when implementing rotation in the workplace. Practitioner Summary: Rotation is widely used and assumed to reduce the risk of WMSDs, yet little research supports that it is effective in doing so. Results here show that specific aspects of a rotation scheme may influence muscle fatigue and task performance, though further research is needed under more realistic task conditions.

Phase separation in melt-casting of ceramic materials by high-gravity combustion synthesis

The phase separation in melt-casting of ceramic materials by high-gravity combustion synthesis has been investigated based on experimental results. It is proposed that the extent of phase separation depends on the high-gravity factor, the viscosity of matrix melt, the size of Ni droplets or bubbles, and the lifetime of matrix melt. A greater high-gravity factor, lower viscosity of matrix melt, larger size of Ni droplets or bubbles, and longer lifetime of matrix melts facilitates phase separation. Pure and dense ceramics can be prepared from optimization of processing parameters, which includes enhancement of the high-gravity field by increasing rotation frequency and radius, elevation of reaction temperature by choosing more exothermic reactants or by preheating, and application of an extra pressure to promote the removal of bubbles as well as shrinkage cavities.

Fault Diagnosis for Civil Aviation Engine Test Based on the Vibration Signal

In this paper, the fault diagnosis for excessive vibration value of LP Rotor in a turbofan engine test is analyzed. The vibration data collected in the test indicates that the amplitude enlarges with the increase in rotation frequency and reaches its maximum value at a certain frequency-doubling point. By various analysis and judgment, the main reason that causes the vibration of engine's high pressure rotor is the blade damage. The conclusion has certain significance for the fault diagnosis for civil aviation engine test.

A VERY LARGE GLITCH IN PSR B2334+61

Seven years of pulse time-of-arrival measurements have been collected from observations of the young pulsar PSR B2334+61 using the Nanshan radio telescope of Urumqi Observatory. A phase-connected solution has been obtained over the whole data span, 2002 August to 2009 August. This includes a very large glitch that occurred between 2005 August 26 and September 8 (MJDs 53608 and 53621). The relative increase in rotational frequency for this glitch, $\Delta\nu_{g}/\nu~\sim~20.5\times10^{-6}$, is the largest ever seen. Although accounting for less than 1\% of the glitch, there were two well-defined exponential decay terms with time constants of 21 and 147 days respectively. There was also a large long-term increase in the spindown rate with $\Delta\dot\nu_p/\dot\nu \sim 0.011$ at the time of the glitch. A highly significant oscillation with a period of close to one year is seen in the post-glitch residuals. It is very unlikely that this can be accounted for by a pulsar position error or proper motion -- it appears to result from effects interior to the neutron star. Implications of these results for pulsar glitch models are discussed.

Dust ion-acoustic wave in a superthermal plasma containing elongated and rotating dust particles

The dispersion relation and the growth rate of a dust ion-acoustic wave propagating in a complex superthermal plasma containing elongated and rotating dust particles are kinetically investigated by employing Vlasov–Maxwell equations. The negatively charged dust particles are assumed to rotate around an axis perpendicular to the direction of elongation. The condition for an unstable dust ion-acoustic wave is obtained in terms of the rotation frequency and the wave number. In the low frequency regime, the growing mode of the wave is found to be enhanced by the increase in dust particle rotation frequency. However, the dust charge state does not affect the growth rate so much, especially in the high δ = ni0/ne0 regime.

Plasma rotation driven by static nonresonant magnetic fields

Recent experiments in high temperature DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 64 (2002)] plasmas reported the first observation of plasma acceleration driven by the application of static nonresonant magnetic fields (NRMFs), with resulting improvement in the global energy confinement time. Although the braking effect of static magnetic field asymmetries is well known, recent theory [A. J. Cole et al., Phys. Rev. Lett. 99, 065001 (2007)] predicts that in some circumstances they lead instead to an increase in rotation frequency toward a “neoclassical offset” rate in a direction opposed to the plasma current. We report the first experimental confirmation of this surprising result. The measured NRMF torque shows a strong dependence on both plasma density and temperature, above expectations from neoclassical theory. The consistency between theory and experiment improves with modifications to the expression of the NRMF torque accounting for a significant role of the plasma response to the external field and for the beta dependence of the plasma response, although some discrepancy remains. The magnitude and direction of the observed offset rotation associated with the NRMF torque are consistent with neoclassical theory predictions. The offset rotation rate is about 1% of the Alfven frequency or more than double the rotation needed for stable operation at high βN above the n=1 no-wall kink limit in DIII-D.

Reducing fouling and boundary-layer by application of helical flow in ultrafiltration module employed for radioactive wastes processing

Application of helical Couette–Taylor flow (CTF) for reduction of membrane fouling in the process of radioactive wastes treatment was considered. The experiments were carried out with model solutions of cobalt ions (Co2 +). Ultrafiltration process combined with complexation with polyacrylic acid or adsorption on activated carbon seeds was applied. The influence of hydrodynamic conditions in the module on the permeate flux and separation efficiency was tested. It was noticed that the helical flow influenced filtration efficiency: with increase of rotation frequency of the inner cylinder in the module, up to 3-fold enhancement of permeate flux was observed. The estimated thickness of residual polymer layer developed on the membrane surface depended on rotation frequency, too. Slight increase of retention factors was observed when dynamic conditions were applied

Effect of melt convection on the secondary dendritic arm spacing in peritectic Nd–Fe–B alloy

Dendrites are one of the major microstructural constituents of peritectic alloys. In the present work, the effect of melt convection on the secondary dendritic arm spacing (SDAS) and volume fraction of properitectic α-Fe was investigated during solidification of stoichiometric Nd–Fe–B alloys using the forced crucible rotation technique. The resulting microstructure of the alloy in consideration of melt convection has been investigated using scanning electron microscopy and optical microscopy. The average SDAS was determined for each sample from the whole cross-section of the cylindrical test samples using image analyzing software LEICA QWIN. A detailed statistical analysis of the spacing distribution was performed on the basis of the variation of SDAS values, averaged from about 80 to 120 dendrites in different zones. The α-Fe volume fraction, measured by vibrating sample magnetometer (VSM), reduces with increasing crucible rotation frequency. Similarly, the SDAS values decrease with increasing rotation frequency. These results are explained from the viewpoint of a reduced melt convection state under steady forced crucible rotation leading to a reduced effective mass transfer coefficient.

Alignments in the nobelium isotopes

Total-Routhian-Surface calculations have been performed to investigate the deformation and alignment properties of the No isotopes. It is found that normal deformed and superdeformed states in these nuclei can coexist at low excitation energies. In neutron-deficient No isotopes, the superdeformed shapes can even become the ground states. Moreover, we plotted the kinematic moments of inertia of the No isotopes, which follow very nicely available experimental data. It is noted that, as the rotational frequency increases, alignments develop at ħω = 0.2–0.3 MeV. Our calculations show that the occupation of the vj15/2 orbital plays an important role in the alignments of the No isotopes.

浸漬円柱を用いた機械式攪拌時における浴内流動

Vortex flow measurements have been carried out with PIV (particle image velocimetry) to understand the flow in a bath with an immersion cylinder under mechanical agitation condition. An impeller is placed on the centerline of the bath and the cylinder is immersed slightly into the bath at an offset radical position. A horizontal rotational motion of water prevails in the absence of the immersion cylinder and the axis of the rotational motion overlaps the centerline of the bath. On the other hand, the axis of the rotational motion inclines in the presence of the immersion cylinder and a strong downward motion of liquid is induced in the bath. This downward motion enhances the entrainment of low-density particles initially placed on the bath surface. The inclination angle decreases with an increase in the rotation frequency of the impeller. Accordingly, the effect of the immersion cylinder becomes weak as the rotation frequency increases under the present experimental conditions.