velocity effect
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2021 ◽  
Author(s):  
Gregory Shay

In well documented studies, walking and music have independently shown substantial medical, health, productivity, and other human benefits. When music is combined with walking, and especially when the walking is done in synchrony to the beat, the music can stimulate faster walking without apparent awareness, the “velocity effect”. Some studies have reported that music that is either familiar, more enjoyable, and/or has higher “groove” tends to be more stimulating, and that some music can actually be sedating resulting in a slower speed relative to that of walking to a metronome at the same cadence. Research illuminating the velocity effect has mostly been conducted over relatively short stepping distances in a laboratory or similar outdoor setting. The current study examines walking on a real-world long distance outdoor track with a single genre of music that was at least somewhat familiar and somewhat enjoyable to the test subject. In this study, the test subject stepped in self-instructed synchrony with confirmed high accuracy to two types of auditory stimuli – either to the beat of a metronome (a presumed neutral source or what might be considered a most rudimentary form of music), or to the beat of a broad-spectrum of country music continuously over a 2-mile course. Nine metronome tempos and twenty-one country music tempos were examined in a walkable range of 90 to 130 beats per minute (BPM), and the effects of the music and metronome on walking performance were examined and quantified. Overall, the mix of country music was significantly more energizing than the metronome providing a relatively consistent 10% increase in step length and a resulting 10% increase in speed over the entire tempo/cadence range. Speed as a function of tempo was essentially linear in the beat range for both auditory stimuli with an apparent increase in speed relative to the trendlines occurring near 120 BPM, a preferred human response frequency reported in some prior investigations.


Author(s):  
Anshan Zhang ◽  
Xianli Liu ◽  
Caixu Yue ◽  
Rongyi Li ◽  
Steven Y. Liang ◽  
...  

Author(s):  
Wan Faezah Wan Azmi ◽  
Ahmad Qushairi Mohamad ◽  
Lim Yeou Jiann ◽  
Sharidan Shafie

Casson fluid is a non-Newtonian fluid with its unique fluid behaviour because it behaves like an elastic solid or liquid at a certain condition. Recently, there are several studies on unsteady Casson fluid flow through a cylindrical tube have been done by some researchers because it is related with the real-life applications such as blood flow in vessel tube, chemical and oil flow in pipelines and others. Therefore, the main purpose of the present study is to obtain analytical solutions for unsteady flow of Casson fluid pass through a cylinder with slip velocity effect at the boundary condition. Dimensional governing equations are converted into dimensionless forms by using the appropriate dimensionless variables. Dimensionless parameters are obtained through dimensionless process such as Casson fluid parameters. Then, the dimensionless equations of velocity with the associated initial and boundary conditions are solved by using Laplace transform with respect to time variable and finite Hankel transform of zero order with respect to the radial coordinate. Analytical solutions of velocity profile are obtained. The obtained analytical result for velocity is plotted graphically by using Maple software. Based on the obtained result, it can be observed that increasing in Casson parameter, time and slip velocity will lead to increment in fluid velocity. Lastly, Newtonian fluid velocity is uniform from the boundary to the center of cylinder while Casson fluid velocity is decreased when approaching to the center of cylinder. The present result is validated when the obtained analytical solution of velocity is compared with published result and found in a good agreement.


2021 ◽  
Author(s):  
Anshan Zhang ◽  
Xianli Liu ◽  
Caixu Yue ◽  
Rongyi Li ◽  
Steven Y. Liang ◽  
...  

Abstract Ball-end cutters are widely used in industries of dies, molds, and aerospace, which have the problem of poor machined surface quality due to the low cutting speed near the tool-tip. With the increase in the complexity of parts, it will become more and more difficult to avoid the tool-tip participating in the cutting. In this paper, the velocity effect sensitivity of ball-end cutter is analyzed, and several key positions, including the intersection points of the CWE boundaries, are selected to describe the cutting speed in three dimensions. The relationships between the cutting speed of the critical points and important variables such as: machining inclination angle and the feed direction were investigated. The optimal range of feed direction is obtained when the tool-tip engages in the contact circle. The core aim of the feed direction selection is to make the tool engagement area in a high position by changing the feed direction, to avoid surface damage caused by ploughing and improve the quality of the machined surface. Finally, an experimental study was carried out, and the results corroborate the effectiveness of the selection method. In the experiment, it was also found that cutting-out from the cutter contact position can improve the surface quality in the directions of non-optimal range, and the milling force and chips shape will vary with the change of the feed direction.


Fire ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 35
Author(s):  
Domingos Xavier Viegas ◽  
Ricardo Oliveira ◽  
Miguel Almeida ◽  
Donghyun Kim

A conceptual model based on the balance of energy in a system composed of a burning cigarette, ambient flow and a porous fuel bed is proposed to study the burning of a single cigarette and the process of fuel bed dehydration, pyrolysis and its eventual ignition or combustion extinction. Model predictions of time to ignition and of the probability of ignition as a function of fuel bed moisture content and ambient flow velocity are compared with results obtained in laboratory ignition tests of straw fuel beds for various ambient conditions. According to this study, the main parameters influencing the models developed are the fuel bed and tobacco moisture content, as well as the flow velocity.


2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Huabing Cai

AbstractThis paper investigates the stimulated transition process of a uniformly moving atom in interaction with a thermal bath of the quantum electromagnetic field. Using the perturbation theory, the atomic stimulated emission and absorption rates are calculated. The results indicate that the atomic transition rates depend crucially on the atomic velocity, the temperature of the thermal bath, and the atomic polarizability. As these factors change, the atomic stimulated transition processes can be enhanced or weakened at different degrees. In particular, slowly moving atoms in the thermal bath with high temperature ($$T\gg \omega _{0}$$ T ≫ ω 0 ) perceive a smaller effective temperature $$T \big ( 1-\frac{1}{10} v^{2} \big )$$ T ( 1 - 1 10 v 2 ) for the polarizability perpendicular to the atomic velocity or $$T \big ( 1-\frac{3}{10} v^{2} \big )$$ T ( 1 - 3 10 v 2 ) for the polarizability parallel to the atomic velocity. However, ultra-relativistic atoms perceive no influence of the background thermal bath. In turn, in terms of the atomic transition rates, this paper explores and examines the relativity of temperature of the quantum electromagnetic field.


2021 ◽  
Author(s):  
Md. A. Hasem

Generally two types of erosion testers are used in solid particle erosion testing: air blast erosion testers and mechanically powered erosion testers. In the first portion of this thesis, the feasibility of implementing a mechanically powered erosion tester for abrasive jet micro-machining applications using very small particles was studied. It was found that, due to the ultrahigh vacuum requirement, such a device would not be practical. Therefore, in the second part of the thesis, the designed rotary mechanism was utilized as a rotary disc target holder apparatus and blasted with a typical air blast system. The apparatus could add or deduct a tangential velocity component into the system, allowing for detailed studies of the effect that the tangential velocity component has on the erosion of borosilicate glass using 25-150 μm aluminum oxide particles. Although the tangential velocity effect has been ignored for brittle materials by most researchers, the present results show that it can have an important role in erosion rate.Generally two types of erosion testers are used in solid particle erosion testing: air blast erosion testers and mechanically powered erosion testers. In the first portion of this thesis, the feasibility of implementing a mechanically powered erosion tester for abrasive jet micro-machining applications using very small particles was studied. It was found that, due to the ultrahigh vacuum requirement, such a device would not be practical. Therefore, in the second part of the thesis, the designed rotary mechanism was utilized as a rotary disc target holder apparatus and blasted with a typical air blast system. The apparatus could add or deduct a tangential velocity component into the system, allowing for detailed studies of the effect that the tangential velocity component has on the erosion of borosilicate glass using 25-150 μm aluminum oxide particles. Although the tangential velocity effect has been ignored for brittle materials by most researchers, the present results show that it can have an important role in erosion rate.


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