Vertical Oscillations Research Articles

Numerical investigation of the dynamic erosion behavior in fluidic oscillators with a periodic oscillating jet

Fluidic oscillators (FOs) containing no moving parts have received extensive attention in recent decades. Applications with FOs in some complex conditions are generally characterized by a high-speed jet of particle-laden flow that periodically switches between two parallel channels. This oscillating flow makes FOs prone to erosion. Using the CFD method, this study investigated the dynamic erosion behavior coupled with periodic oscillating jets. Three primary locations of erosion were observed, namely, in the vicinities of the nozzle, splitter, and vents. The effects of flow rate, particle size, and solid content on erosion were evaluated. It was found that the location of maximum erosion did not remain same. The amount of erosion in the splitter and vents fluctuated cyclically due to the periodic oscillation of the supply jet. Additional erosion occurred during the start-up process of the vertical feedback oscillator, whereas the curved feedback oscillator showed better performance in this respect.

Drop impact on superheated surfaces: short-time dynamics and transition to contact

When a volatile drop impacts on a superheated solid, air drainage and vapour generation conspire to create an intermediate gas layer that delays or even prevents contact between the liquid and the solid. In this article, we use high-speed synchronized reflection interference and total internal reflection imaging to measure the short-time dynamics of the intermediate gas film and to probe the transition between levitation and contact. We observe that the substrate temperature strongly affects the vertical position of the liquid–gas interface and that the dynamic Leidenfrost transition is influenced by both air and vapour drainage (i.e. gas drainage), and evaporation, the latter giving rise to hitherto unreported vertical oscillations of the gas film that can trigger liquid–solid contact. We first derive scaling relations for the height of the gas film trapped under the drop's centreline, called the dimple height, and the minimum film thickness at short times. The former is set by a competition between gas drainage and liquid inertia, similarly as for isothermal impacts, while the latter strongly depends on the vapour production. The gas pressure, at the location where the minimum thickness is reached, is determined by liquid inertia and vapour production and ultimately balanced by the increasing interfacial curvature, determining the minimum thickness. We show that, in the low impact velocity limit, the transient stability of the draining gas film remarkably makes dynamic levitation less demanding than static levitation. We characterize the vertical gas film oscillations by measuring their frequency and monitoring their occurrence in the parameter space spanned by surface temperature and impact velocity. Finally, we model the occurrence of these oscillations and account for their frequency through a hydrodynamic mechanism.

Gait difference between children aged 9 to 12 with and without potential depressive mood

BackgroundIt has been reported that depression has an impact on both temporal spatial parameters and walking kinematics in adults. Given the difference in the walking biomechanics between adults and children, this study aimed to compare the gait difference in children aged 9–12 with and without potential depressive mood (PDM). Methods49 children were recruited from local primary schools. We measured participants’ depression level using Depression Anxiety Stress Scale (DASS) and classified them into control (i.e., DASS depression subscale score = 0.6 ± 1.4; n = 23) or PDM group (i.e., DASS depression subscale score = 21.3 ± 5.3; n = 26). Video gait analysis was employed to assess temporal spatial parameters and sagittal plane kinematics during self-paced overground walking. Independent t tests or Mann-Whitney tests were used to compare the gait parameters between the two groups. ResultsParticipants exhibited similar gait speed, vertical oscillation of the centre of mass, stance time, swing time, step length, upper and lower limb kinematics between the two groups (p > 0.05). However, children with PDM displayed a greater head flexion than controls (p = 0.026; Cohen’s d = 0.66; moderate effect). SignificanceChildren with PDM may present a more slumped posture during walking when compared with their counterparts. This kinematics difference can potentially be used as a biomechanical marker for detection of mood problems in this cohort.

Reliability of the kinematic theory parameters during handwriting tasks on a vertical setup

BackgroundThe Kinematic Theory and its Sigma–Lognormal model have been used extensively in motor control analyses. It has recently shown promise in its ability to detect neuromuscular fatigue in the shoulder. The use of an ergonomic setup composed of a vertically oriented tablet offers a good demonstration for use in future clinical applications. However, parameters’ reliability of this theory needs to be evaluated. The aim of this study is to assess the test–retest reliability of these parameters in the specific case of fatigue detection. MethodForty participants performed two sessions of fast strokes handwriting (simple strokes, triangles, horizontal and vertical oscillations) on a tablet placed at shoulder’s height. Reliability was assessed using the intraclass correlation coefficient (ICC), their relative standard error of measurement (SEM) and coefficient of variation. The minimal detectable change was also reported.Findings: In general, a moderate to excellent reliability was denoted in the main parameters of each test (ICC: 0.54–0.91). The parameters related to shoulder fatigue detection had good to excellent reliability (ICC: 0.77–0.90) with low SEM (SEM: 4.75–6.99%). ConclusionMost of the parameters have good test–retest reliability, and the setup seems adequate for shoulder fatigue detection.

Modeling and controlling a quarter-vehicle active suspension model

This paper presents an application of the LQR active suspension control algorithm for a vertical planar oscillation model developed for ¼ of a vehicle. The wheel smoothness and dynamics with the road surface are two parameters to provide control signals. A simulation model is developed here based on MATLAB software to compare and evaluate the LQR active suspension model with the passive suspension. The results obtained here shows an improvement for a number of parameters when utilizing the active suspension model including fluctuating amplitude; oscillation damping time; the displacement acceleration of the active suspension body.

Diffusive instabilities of baroclinic lenticular vortices

We consider a model of a circular lenticular vortex immersed into a deep and vertically stratified viscous fluid in the presence of gravity and rotation. The vortex is assumed to be baroclinic with a Gaussian profile of angular velocity both in the radial and axial directions. Assuming the base state to be in cyclogeostrophic balance, we derive linearized equations of motion and seek for their solution in a geometric optics approximation to find amplitude transport equations that yield a comprehensive dispersion relation. Applying the algebraic Bilharz criterion to the latter, we establish that the stability conditions are reduced to three inequalities that define the stability domain in the space of parameters. The main destabilization mechanism is either monotonic or oscillatory axisymmetric instability depending on the Schmidt number (Sc), vortex Rossby number, and the difference between radial and axial density gradients as well as the difference between epicyclic and vertical oscillation frequencies. We discover that the boundaries of the regions of monotonic and oscillatory axisymmetric instabilities meet at a codimension-2 point, forming a singularity of the neutral stability curve. We give an exhaustive classification of the geometry of the stability boundary, depending on the values of the Schmidt number. Although we demonstrate that the centrifugally stable (unstable) Gaussian lens can be destabilized (stabilized) by the differential diffusion of mass and momentum and that destabilization can happen even in the limit of vanishing diffusion, we also describe explicitly a set of parameters in which the Gaussian lens is stable for all Sc > 0.

Vertical Oscillations of Water Droplets in the Supporting Vapour–Air Flow

Vertical Oscillations of Water Droplets in the Supporting Vapour–Air Flow

Formation of Optical Images with Synchrotron Radiation Flux of Relativistic Electrons in the X-Ray Generator "Nestor"

When setting up physical experiments involving the use of the polarization properties of synchrotron radiation (SR) or a monoenergetic photon beam, detailed calculation of the spectral angular distribution of SR and its polarization components is of interest. Consideration of the electron beam size shows that in real conditions the radiation propagating in the plane of the equilibrium orbit will not be completely polarized, and the shape and dimensions of the angular distribution of radiation will be distorted. The motion of electrons in the uniform magnetic field and SR of the beam of relativistic particles in the storage ring of "NESTOR" are considered. The effect of the size of the electron beam with the energy of E=225 MeV in the 6-dimensional space on the formation of images of the flux of quanta of SR is analyzed. It is shown that the main contribution to the formation of images is made by the two-dimensional distribution of particles along the vertical direction axis and vertical oscillations. A software simulation code has been developed, the use of which made it possible to simulate the process of optical image formations by the flux of SR quanta (Этого предложения нет в русской аннотации). The formation of images of the radiation of electrons with an energy of E=225 MeV with change in the longitudinal distance L to the registration plane is considered. It is determined that at small longitudinal distances the main contribution to the image is made by the vertical distribution of particles in the beam. With an increase in the basic distance L, the contribution of the distribution of particles over vertical oscillations increases, which becomes decisive for large L value. Numerical simulation of image formation has been carried out. For the base distance of 300 cm and beam parameters with the vertical root mean square size of 0.2 mm and a vertical root mean square size of 0.15 mrad, the family of angular distributions is presented in the form of two-dimensional histograms for wavelengths , , , where , is the critical wavelength of SR. The dimensions of the optical window are obtained, the size of which makes it possible to reliably register the entire flux of SR quanta for the indicated registration characteristics.

EXPERIMENTAL RESEARCH INTENSITY OF OSCILLATIONS AGRICULTURAL MACHINE-TRACTOR UNITS

Smoothness of movement of agricultural units is one of the important operational indicators of their work which is estimated on influence of fluctuations (translational vertical, cross, angular longitudinal, etc.) The article presents the method and results of experimental assessment of the smoothness of the movement of the bridge agricultural unit, which moves in the footsteps of a constant technological track. Studies of the smoothness of the bridge unit showed that the graphs of normalized correlation functions of vertical oscillations of the bridge agricultural tool developed by us in its motion in the wake of a constant technological track is characterized by a function containing along with random components harmonic, which are expressed by attenuating periodic oscillations. The frequency spectrum of oscillations of the agricultural tool core is concentrated in the range from 0 to 20 s–1, which agrees with the frequency range 0…0.3 cm−1 in which the variances of oscillations of the irregularities of the profile of the traces of the technological track are concentrated. The length of the correlation connection is approximately 0.25 s, which is equal to 0.25 m at the speed of the agricultural tool within 1.0 m / s.The obtained result is explained by the fact that the main spectrum of oscillations of the profile irregularities has a periodicity that corresponds to the step of ground engagement of the tires of the wheels of the agricultural tool. The research confirmed the effectiveness of the method of estimating the intensity of vertical oscillations of an agricultural unit by a measuring and registration complex based on a tablet computer with Android operating system with built-in accelerometer sensors and Accelerometer Meter application.

Non-linear resonant torus oscillations as a model of Keplerian disc warp dynamics

ABSTRACT Observations of distorted discs have highlighted the ubiquity of warps in a variety of astrophysical contexts. This has been complemented by theoretical efforts to understand the dynamics of warp evolution. Despite significant efforts to understand the dynamics of warped discs, previous work fails to address arguably the most prevalent regime – non-linear warps in Keplerian discs for which there is a resonance between the orbital, epicyclic and vertical oscillation frequencies. In this work, we implement a novel non-linear ring model, developed recently by Fairbairn and Ogilvie, as a framework for understanding such resonant warp dynamics. Here, we uncover two distinct non-linear regimes as the warp amplitude is increased. Initially, we find a smooth modulation theory that describes warp evolution in terms of the averaged Lagrangian of the oscillatory vertical motions of the disc. This hints towards the possibility of connecting previous warp theory under a generalized secular framework. Upon the warp amplitude exceeding a critical value, which scales as the square root of the aspect-ratio of our ring, the disc enters into a bouncing regime with extreme vertical compressions twice per orbit. We develop an impulsive theory that predicts special retrograde and prograde precessing warped solutions, which are identified numerically using our full equation set. Such solutions emphasize the essential activation of non-linear vertical oscillations within the disc and may have important implications for energy and warp dissipation. Future work should search for this behaviour in detailed numerical studies of the internal flow structure of warped discs.

Psychological Effects of Heart Rate and Physical Vibration on the Operation of Construction Machines: Experimental Study.

BackgroundA construction method has emerged in which a camera is installed around a construction machine, and the operator remotely controls the machine while synchronizing the vibration of the machine with the images seen from the operator's seat using virtual reality (VR) technology. Indices related to changes in heart rate (HR) and physical vibration, such as heart rate variability (HRV) and multiscale entropy (MSE), can then be measured among the operators. As these indices are quantitative measures of autonomic regulation in the cardiovascular system, they can provide a useful means of assessing operational stress.ObjectiveIn this study, we aimed to evaluate changes in HR and body vibration of machine operators and investigate appropriate methods of machine operation while considering the psychological load.MethodsWe enrolled 9 remote operators (18-50 years old) in the experiment, which involved 42 measurements. A construction machine was driven on a test course simulating a construction site, and three patterns of operation—riding operation, remote operation using monitor images, and VR operation combining monitor images and machine vibration—were compared. The heartbeat, body vibration, and driving time of the participants were measured using sensing wear made of a woven film-like conductive material and a three-axis acceleration measurement device (WHS-2). We used HRV analysis in the time and frequency domains, MSE analysis as a measure of the complexity of heart rate changes, and the ISO (International Standards Organization) 2631 vibration index. Multiple regression analysis was conducted to model the relationship among the low frequency (LF)/high frequency (HF) HRV, MSE, vibration index, and driving time of construction equipment. Efficiency in driving time was investigated with a focus on stress reduction.ResultsMultiple comparisons conducted via the Bonferroni test and Kruskal-Wallis test showed statistically significant differences (P=.05) in HRV-LF/HF, the vibration index, weighted acceleration, motion sickness dose value (MSDVz), and the driving time among the three operation patterns. The riding operation was found to reduce the driving time of the machine, but the operation stress was the highest in this case; operation based on the monitor image was found to have the lowest operation stress but the longest operation time. Multiple regression analysis showed that the explanatory variables (LH/HF), RR interval, and vibration index (MSDVz by vertical oscillation at 0.5-5 Hz) had a negative effect on the driving time (adjusted coefficient of determination R2=0.449).ConclusionsA new method was developed to calculate the appropriate operating time by considering operational stress and suppressing the physical vibration within an acceptable range. By focusing on the relationship between psychological load and physical vibration, which has not been explored in previous studies, the relationship of these variables with the driving time of construction machines was clarified.

Measuring fingerpad deformation during active object manipulation.

During active object manipulation, the finger-object interactions give rise to complex fingertip skin deformations. These deformations are in turn encoded by the local tactile afferents and provide rich and behaviorally relevant information to the central nervous system. Most of the work studying the mechanical response of the finger to dynamic loading has been performed under a passive setup, thereby precisely controlling the kinematics or the dynamics of the loading. However, to identify aspects of the deformations that are relevant to online control during object manipulation, it is desirable to measure the skin response in an active setup. To that end, we developed a device that allows us to monitor finger forces, skin deformations, and kinematics during fine manipulation. We describe the device in detail and test it to precisely describe how the fingertip skin in contact with the object deforms during a simple vertical oscillation task. We show that the level of grip force directly influences the fingerpad skin strains and that the strain rates are substantial during active manipulation (norm up to 100%/s). The developed setup will enable us to causally relate sensory information, i.e. skin deformation, to online control, i.e. grip force adjustment, in future studies.NEW & NOTEWORTHY We present a novel device, a manipulandum, that enables to image the contact between the finger and the contact surface during active manipulation of the device. The device is tested in a simple vertical oscillation task involving 18 participants. We demonstrate that substantial surface skin strains take place at the finger-object interface and argue that those deformations provide essential information for grasp stability during object manipulation.

Effects of aerodynamic coupling and non-linear behaviour on galloping of ice-accreted conductors

Wind action on ice-covered transmission lines causes galloping, which is a problem because it can introduce interphase short circuits and cause fatigue of the cross-arms of the power line’s towers and insulators. The galloping phenomenon is characterised by a combination of large-amplitude, low-frequency vertical, horizontal, and torsional oscillations. To better understand the dynamic responses of vertical, horizontal and torsional 3-degree-of-freedom (DoF) galloping on four-bundled conductors, time–history analyses were conducted for 2D systems of varying DoFs and frequency ratios. The fundamental characteristics of the conductor’s non-linear 1-DoF vertical response were analysed via time–history analysis, indicating that large oscillations were caused by inclusion of an angular range of relative angle of attack with a high negative lift-coefficient slope. By considering the energy balance of the vertical motion over one oscillation period, we estimated the stable and unstable limit-cycle amplitudes. Then, by comparing the results of the 1-, 2-, and 3-DoF systems, we clarified the effect of aerodynamic coupling on 3-DoF galloping. The oscillation types in the 3-DoF systems were categorised as vertical–horizontal 2-DoF coupling oscillations, vertical–torsional 2-DoF coupling oscillations, and vertical 1-DoF oscillations according to the stationary torsional angle. Finally, we indicated the coupling effects on vertical oscillation by considering the energy balance of the vertical motion with the defined amplitudes and phase differences of the horizontal and torsional motions. The vertical amplitude of the vertical–horizontal 2-DoF coupling oscillation can become very large if the horizontal amplitude increases and the phase difference between horizontal and vertical displacements approaches 180°. Meanwhile, the range of the stationary torsional angle in which the vertical–torsional 2-DoF coupling oscillation occurs becomes wide as the phase difference between the torsional and vertical displacements approaches 90°. However, without horizontal motion, the vertical amplitude has a limited value, even if the torsional amplitude becomes large.

Physico-Chemical Properties and Quantum Chemical Calculation of 2-methoxy-4-(prop-2-en-1-yl) phenol (EUGENOL)

Physico-chemical properties plays an important role in determining toxicity of a material hence were calculated using acdlab/chemsketch and the data predicted is generated using ACD/Labs Percepta Platform - PhysChem Module. Gaussian 09, RevisionA.01, software package was used for the theoretical quantum chemical calculations of 2-methoxy-4-(prop-2-en-1-yl) phenol commonly called Eugenol. DFT/B3LYP/6-311G (d, p) basis was used to perform geometric optimization and vibrational frequency determination of the molecule. The statistical thermochemical calculations of the molecule were done at DFT/B3LYP/6-311G (d, p) basis set to calculate the standard thermodynamic functions: heat capacity (CV), entropy (S) and Enthalpy (E). DFT/B3LYP/6-311G (d, p) basis set was used to calculate the various NLO properties like dipole moment (µ), mean linear polarizability (α), anisotropic polarizability (Δα), first order hyperpolarizability (β), second order hyperpolarizability (γ) in terms of x, y, z components for Eugenol (2-methoxy-4-(prop-2-en-1-yl) phenol. Same basis set was used to carry out Mulliken population analysis. UV-Visible absorption spectra, ECD spectra, electronic transitions, vertical excitation energies and oscillator strengths of Eugenol (2-methoxy-4-(prop-2-en-1-yl) phenol) were computed by Time Dependent DFT (TD-DFT) method using the same basis set. FMO analysis, Molecular electrostatic potential study was also done using the same basis set.

Comparing the physical principles of action of suspension damping devices based on their influence on the mobility of wheeled vehicles

This paper reports the comparison of two physical principles of action of suspension damping devices based on their influence on the mobility indicators for an 8×8 wheeled machine. A radical difference between these principles of action is the dependence of resistance forces on the speed of the relative movement of working bodies (internal friction: hydraulic shock absorbers) or on the relative movement of working bodies (external friction: friction shock absorbers). Widespread hydraulic shock absorbers have certain disadvantages that do not make it possible to further increase the mobility of wheeled or tracked vehicles without the use of control and recuperation systems. In turn, in friction shock absorbers, the use of new materials has eliminated many of their shortcomings and thus can provide significant advantages. It was established that the application of friction shock absorbers for a given wheeled vehicle did not significantly affect the speed compared to hydraulic ones. The main factor that prevented the implementation of the advantages of friction shock absorbers was the insufficient suspension travel. However, friction shock absorbers absorbed 1.76...2.3 times less power, which reduced the load on nodes and increased efficiency (autonomy). In addition, a more uniform load on suspensions was ensured, which improved their resource, and, due to the prevailing vertical oscillations of the suspended body over the longitudinal-angular ones, the geometric passability improved as well. The comparison of two physical principles of action of damper suspension devices in a wheeled vehicle has shown that the use of friction shock absorbers could provide significant advantages in resolving the task relates to improving the mobility and would fundamentally affect the choice of the suspension energy recuperation system if it is applied.

Melt flow and grain refining in laser oscillating welding of β-21S titanium alloy

Properties and serviceability of laser welded joints depend on the defect, weld geometry, and microstructures, which in turns are affected by molten pool behaviors. In this work, beam oscillation was used to improve microstructures and mechanical properties of welded joints by changing molten pool behaviors. The 2 mm-thick β-21S titanium alloy plates were welded using three beam oscillating modes (non-oscillation, transverse oscillation, and vertical oscillation). The molten pool behaviors for three oscillation modes were observed using high-speed cameras, and the weld morphology, microstructures and mechanical properties of the corresponding joints were examined. The results showed that defect-free joint with sound weld appearances could be achieved using beam oscillation that affected molten pool behaviors. The higher probability of equiaxed grain formation and significant grain refinement were found in the joints made using beam oscillation. The average grain sizes of welded joints for non-oscillating, transverse and vertical oscillating modes are 236, 184 and 168 μm, respectively. The welded joint made using beam oscillation also showed a higher tensile strength of 900 MPa at ambient temperature and 534 MPa at 450 °C. Furthermore, the Portevin-Le Chatelier (PLC) effect was observed in the stress-strain curves of welded joint at 450 °C, which was attributed to the precipitation of brittle ω phase.

Coseismic vertical ground deformations vs. intensity measures: Examples from the Apennines

DInSAR data provide a powerful tool to recognize the Earth's surface where permanent deformations are concentrated and undergo the strongest ground motion during an earthquake, i.e., defining the epicentral area. We analyzed three recent seismic events in the Apennines belt in Italy related to extensional and contractional earthquakes and documented that the largest macroseismic intensity is recorded where the ground underwent the largest vertical component of motion and the stronger vertical component of the peak ground acceleration. Besides site amplification effects that may occur everywhere even outside the epicentral area, we infer that the vertical oscillations in the so-called near-field allow the horizontal shaking to be more effective, hence producing larger damage above the active crustal volume. The active volume is the one moving vertically and is contemporaneously crossed by seismic waves nucleated by the shear on the fault. The surrounding passive volume in the far field is only crossed by seismic waves. The near field areas are elliptical and cover areas of 300–600 km2 for a range of Mw 6–6.9, and they should be the areas where the highest seismic hazard must be expected. Therefore, their area is too large to be neglected for seismic hazard assessment.

Evaluating the energetics of entrainment in a human\u2013machine coupled oscillator system

During locomotion, humans sometimes entrain (i.e. synchronize) their steps to external oscillations: e.g. swaying bridges, tandem walking, bouncy harnesses, vibrating treadmills, exoskeletons. Previous studies have discussed the role of nonlinear oscillators (e.g. central pattern generators) in facilitating entrainment. However, the energetics of such interactions are unknown. Given substantial evidence that humans prioritize economy during locomotion, we tested whether reduced metabolic expenditure is associated with human entrainment to vertical force oscillations, where frequency and amplitude were prescribed via a custom mechatronics system during walking. Although metabolic cost was not significantly reduced during entrainment, individuals expended less energy when the oscillation forces did net positive work on the body and roughly selected phase relationships that maximize positive work. It is possible that individuals use mechanical cues to infer energy cost and inform effective gait strategies. If so, an accurate prediction may rely on the relative stability of interactions with the environment. Our results suggest that entrainment occurs over a wide range of oscillation parameters, though not as a direct priority for minimizing metabolic cost. Instead, entrainment may act to stabilize interactions with the environment, thus increasing predictability for the effective implementation of internal models that guide energy minimization.

Case Study: The Effect Of Stride Frequency On The Over Ground Running Characteristics.

There is a gap in the literature regarding the relationships between stride length (SL), stride frequency (SF), running velocity, and running performance. The majority of research on these relationships is based upon treadmill running. Although the overall running pattern is similar when running on a treadmill vs. overground (OG), there are unique differences. Besides, there are not many studies to focus on measuring the time to completion and running dynamics depend on SF variations during OG running. PURPOSE: To investigate the effect of change in SF on time to complete a specific distance and running dynamics during OG running. METHODS: One male subject (176 cm, 79 kg) completed a total of three OG running sessions at somewhat hard intensity. The given running distance was 2.4 km (1.5 miles) and the participant was instructed to run the same route in three running conditions; running with preferred SF (PSF), faster SF (PSF+5%), and slower SF (PSF-5%). The first session was running with PSF, then 2nd and 3rd sessions were running with a target SF while listening to metronome sound using earbuds. Running dynamics (i.e., SL, SF, ground contact time: GCT, and vertical oscillation: VertO) were measured using a running pod (Running Dynamics Pod, Garmin), heart rate (HR) and running time were measured using a heart rate strap (HRM-Tri™, Garmin) and a sports watch (Forerunner 735XT, Garmin). RESULTS: Running velocity was qualitatively faster during PSF+5% than other conditions (PSF: 11 secs, PSF-5%: 1 min 33 secs), respectively. Both SL and GCT did not change noticeably across SF conditions. The VertO was highest at PSF condition and decreased in both conditions. HR was within a consistent range between the SF conditions.Table 1: Running dynamics and running metricsCONCLUSIONS: A slightly higher SF allows the recreational runner to run faster in OG running (2.4 km). The runner tends to maintain SL and GCT regardless of SF variations. This case study may give an insight into how SF affects running pace and running characteristics.

Role of Longitudinal Waves in Alfvén-wave-driven Solar/Stellar Wind

AbstractWe study the role the the p-mode-like vertical oscillation on the photosphere in driving solar winds in the framework of Alfvén-wave-driven winds. By performing one-dimensional magnetohydrodynamical numerical simulations from the photosphere to the interplanetary space, we discover that the mass-loss rate is raised up to ≈ 4 times as the amplitude of longitudinal perturbations at the photosphere increases. When the longitudinal fluctuation is added, transverse waves are generated by the mode conversion from longitudinal waves in the chromosphere, which increases Alfvénic Poynting flux in the corona. As a result, the coronal heating is enhanced to yield higher coronal density by the chromospheric evaporation, leading to the increase of the mass-loss rate. Our findings clearly show the importance of the p-mode oscillation in the photosphere and the mode conversion in the chromosphere in determining the basic properties of the wind from the sun and solar-type stars.