scholarly journals Modeling of Vibration Behaviors of Turning Machining with the Constant Surface Speed Effect

2021 ◽  
Vol 15 (3) ◽  
pp. 134-145
Author(s):  
Muhamad Royandi ◽  
Iman Effendi ◽  
Bustami Ibrahim ◽  
Jui Hung
Keyword(s):  
Speed Effect

Annealing temperature and spin speed effect on TiO2 nanostructured topology and electrical properties

2015 ◽  
Author(s):  
I.H.H. Affendi ◽  
N. E. A. Azhar ◽  
M.S.P. Sarah ◽  
Salman A.H. Alrokayan ◽  
Haseeb A. Khan ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Annealing Temperature ◽  
Spin Speed ◽  
Speed Effect

scholarly journals Musical expertise generalizes to superior temporal scaling in a Morse code tapping task

2019 ◽  
Author(s):  
Matthew A. Slayton ◽  
Juan L. Romero-Sosa ◽  
Katrina Shore ◽  
Dean V. Buonomano ◽  
Indre V. Viskontas
Keyword(s):  
Temporal Patterns ◽  
Motor Patterns ◽  
Temporal Scaling ◽  
Temporal Precision ◽  
Morse Code ◽  
Extensive Training ◽  
Timing Precision ◽  
Significant Difference ◽  
Speed Effect ◽  
High Level

ABSTRACTA key feature of the brain’s ability to tell time and generate complex temporal patterns is its capacity to produce similar temporal patterns at different speeds. For example, humans can tie a shoe, type, or play an instrument at different speeds or tempi—a phenomenon referred to as temporal scaling. While it is well established that training improves timing precision and accuracy, it is not known whether expertise improves temporal scaling. We quantified temporal scaling and timing precision in musicians and non-musicians as they learned to tap a Morse code sequence. We found that controls improved significantly over the course of days of training at the standard speed. In contrast, musicians exhibited a high level of temporal precision on the first day, which did not improve significantly with training. Although there was no significant difference in performance at the end of training at the standard speed, musicians were significantly better at temporal scaling—i.e., at reproducing the learned Morse code pattern at faster and slower speeds. Interestingly, both musicians and non-musicians exhibited a Weber-speed effect, where absolute temporal precision sharpened when producing patterns at the faster speed. These results are the first to establish that the ability to generate the same motor patterns at different speeds improves with extensive training and generalizes to non-musical domains.

A Comparison of Experimental and Theoretical Forces and Moments Acting on a Restrained Surface Ship in Regular Waves

1963 ◽  
Vol 7 (02) ◽  
pp. 47-61
Author(s):  
Alvin Gersten
Keyword(s):  
Regular Waves ◽  
Ship Wave ◽  
Surface Ship ◽  
Wave Interference ◽  
Exciting Forces ◽  
Speed Effect ◽  
Prediction Techniques ◽  
Made In

A mathematically defined, fully restrained, ship form has been towed in regular waves to measure the exciting forces and moments acting on it. The results of these tests are presented and compared with theoretical values computed both on the basis of assumptions made in the Froude-Krylov hypothesis and an extension of this hypothesis which accounts for ship-wave interference. For low values of draft to wavelength ratio, a number of the presently available prediction techniques are in agreement and are shown to be reasonably accurate. The need for a generally applicable correction for speed effect, however, is demonstrated.

Time Simulation of Water Shipping for a Ship Advancing in Large Longitudinal Waves

1993 ◽  
Vol 37 (02) ◽  
pp. 126-137
Author(s):  
Ming-Chung Fang ◽  
Ming-Ling Lee ◽  
Chwang-Kuo Lee
Keyword(s):  
Nonlinear Effects ◽  
Ship Motion ◽  
Irregular Waves ◽  
Wave System ◽  
Time Step ◽  
Large Wave ◽  
Time Simulation ◽  
Head Waves ◽  
Speed Effect

The technique of time-domain numerical simulation for the occurrence of water shipping on board in head waves is presented. The nonlinear effects of the large-amplitude motion are treated. These nonlinear factors include the effect of large wave amplitude, large ship motion, the change of hull configuration below the free surface and the nonlinear resultant wave. Therefore, the variation of the potentials and the hydrodynamic coefficients for a ship at each time step must be carefully treated. While handling the determination of the instantaneous wave surface around the ship hull, the complete incident, diffracted, and radiated wave system is used rather than the incident wave only. The complexity of the ship speed effect on the related terms is also treated at each time step, especially for the radiation problems. An experimental setup is also designed to measure the motion response and the relative motion, and comparisons are made. The results show excellent agreement and the validity of the theory is confirmed. The successful development of the present technique can be extended to analyze the dynamic stability, capsize phenomena, and ship motion in irregular waves

Kinetic effects during ocean evaporation: observed relationship with wind speed 

2021 ◽  
Author(s):  
Daniele Zannoni ◽  
Hans Christian Steen-Larsen ◽  
Andrew Peters ◽  
Árný Erla Sveinbjörnsdóttir
Keyword(s):  
Water Vapor ◽  
Wind Speed ◽  
Water Interface ◽  
Fractionation Factor ◽  
Wind Speeds ◽  
Air Water Interface ◽  
Kinetic Fractionation ◽  
Speed Effect ◽  
Equilibrium Fractionation ◽  
Non Equilibrium

<p>Water vapor has a fundamental role in weather and climate, being the strongest natural greenhouse gas in the Earth’s atmosphere. The main source of water vapor in the atmosphere is ocean evaporation, which transfers a large amount of energy via latent heat fluxes. In the past, evaporation was intensively studied using stable isotopes because of the large fractionation effects involved during water phase changes, providing insights on processes occurring at the air-water interface. Current theories describe evaporation near the air-water interface as a combination of molecular and turbulent diffusion processes into separated sublayers. The importance of those two sublayers, in terms of total resistance to vapor transport in air, is expected to be dependent on parameters such as moisture deficit, temperature and wind speed. Non-equilibrium fractionation effects in isotopic evaporation models are then expected to be related to these physical parameters. In the last 10 years, several water vapor observations from oceanic expeditions were focused on the impact of temperature and wind speed effect, assuming the influence of those parameters on non-equilibrium fractionation in the marine boundary layer. Wind speed effect is expected to be small on total kinetic fractionation and was discussed at length but was not completely ruled out. With a gradient-diffusion approach (2 heights above the ocean surface) and Cavity Ring-Down Spectroscopy we have estimated non-equilibrium fractionation factors for <sup>18</sup>O/<sup>16</sup>O during evaporation, showing that the wind speed effect can be detected and has no significant impact on kinetic fractionation. Results obtained for wind speeds between 0 and 10 m s<sup>-1</sup> in the North Atlantic Ocean are consistent with the Merlivat and Jouzel (1979) parametrization for smooth surfaces (mean ε<sub>18</sub>=6.1‰). A small monotonic decrease of the fractionation parameter is observed as a function of 10 m wind speed (slope  ≅ 0.15 ‰ m<sup>-1</sup> s), without any evident discontinuity. However, depending on the data filtering approach it is possible to highlight a rapid decrease of the kinetic fractionation factor at low wind speed (≤ 2.5 m s<sup>-1</sup>). An evident decrease of fractionation factor is also observed for wind speeds above 10 m s<sup>-1</sup>, allowing to hypothesize the possible effect of sea spray in net evaporation flux. Considering the average wind speed over the oceans, we conclude that a constant kinetic fractionation factor for evaporation is a more simple and reasonable solution than a wind-speed dependent parametrization. </p><p> </p><p>Merlivat, L., & Jouzel, J. (1979). Global climatic interpretation of the deuterium‐oxygen 18 relationship for precipitation. Journal of Geophysical Research: Oceans, 84(C8), 5029-5033.</p>

scholarly journals Modulation of Individual Alpha Frequency with tACS shifts Time Perception

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Giovanna Mioni ◽  
Adam Shelp ◽  
Candice T Stanfield-Wiswell ◽  
Keri A Gladhill ◽  
Farah Bader ◽  
...  
Keyword(s):  
Time Perception ◽  
Human Subjects ◽  
Peak Frequency ◽  
Alpha Oscillations ◽  
Standard Interval ◽  
Alpha Frequency ◽  
Temporal Intervals ◽  
Transcranial Alternating Current Stimulation ◽  
Speed Effect ◽  
Individual Alpha Frequency

Abstract Previous studies have linked brain oscillation and timing, with evidence suggesting that alpha oscillations (10 Hz) may serve as a “sample rate” for the visual system. However, direct manipulation of alpha oscillations and time perception has not yet been demonstrated. To test this, we had 18 human subjects perform a time generalization task with visual stimuli. Additionally, we had previously recorded resting-state EEG from each subject and calculated their individual alpha frequency (IAF), estimated as the peak frequency from the mean spectrum over posterior electrodes between 8 and 13 Hz. Participants first learned a standard interval (600 ms) and were then required to judge if a new set of temporal intervals were equal or different compared with that standard. After learning the standard, participants performed this task while receiving occipital transcranial Alternating Current Stimulation (tACS). Crucially, for each subject, tACS was administered at their IAF or at off-peak alpha frequencies (IAF ± 2 Hz). Results demonstrated a linear shift in the psychometric function indicating a modification of perceived duration, such that progressively “faster” alpha stimulation led to longer perceived intervals. These results provide the first evidence that direct manipulations of alpha oscillations can shift perceived time in a manner consistent with a clock speed effect.

Aero-thermodynamic and chemical process interactions in an axial high-pressure turbine of aircraft engines

2018 ◽  
Vol 20 (6) ◽  
pp. 653-669 ◽  
Author(s):  
Trung Hieu Nguyen ◽  
Phuong Nguyen-Tri ◽  
Xavier Vancassel ◽  
Francois Garnier
Keyword(s):  
High Pressure ◽  
Three Dimensional ◽  
Chemical Processes ◽  
Rotor Blades ◽  
Rotor Speed ◽  
High Pressure Turbine ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Speed Effect ◽  
Flow Vortex

Precise investigation of aero-thermodynamic and chemical processes relating to environmental precursor pollutants in an aircraft turbine is challenging because of the complexity of transformation processes at high temperature and high pressure. We present here, for the first time, new insights into the study of aero-thermodynamic processes, formation of nitrate and sulfate aerosol precursors, and investigate the influence of chemical processes on aero-thermodynamics. We also shed light on the effect of three-dimensional blade profile, radial spacing, and rotor speed on the performance of a high-pressure turbine. We highlight that flow vortex and the variation of chemical formation which appear in both rear stator blades and rear rotor blades. We found that the chemical processes were affected by the evolution of temperature (maximum of 16.9%) and flow velocity (maximum of 38.8%). Contrary to the conservative one-dimensional and two-dimensional modeling, which provide only the flow trends and flow evolution at cylindrical surface, respectively, our three-dimensional modeling approach offers the possibility of combining information on radial spacing and rotor-speed effect by providing three-dimensional images of spatial-geometry effect on aero-thermodynamic and chemical processes. Quantitatively, the magnitude of change in aero-thermodynamics and nitrogen oxidation may be expected to be up to 17% and 48%, respectively, over a stage of the high-pressure turbine.

Sign in / Sign up

Export Citation Format

Share Document