P-20: Display Related Effects of Terrain-Texture Density and Contrast on Perceived Air Speed in Simulated Flight

2003 ◽  
Vol 34 (1) ◽  
pp. 276
Author(s):  
Shama Chaudhry ◽  
George A. Geri
Keyword(s):  
Texture Density ◽  
Air Speed

Experimental study on the effect of surface texture on tribological properties of nanodiamond films under water lubrication

2021 ◽  
pp. 135065012110334
Author(s):  
Ying Yan ◽  
Xuelin Lei ◽  
Yun He
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Tribological Properties ◽  
Surface Texture ◽  
Diamond Film ◽  
Diamond Films ◽  
Nanocrystalline Diamond ◽  
Water Contact ◽  
Texture Density ◽  
Short Run

The effect of nanoscale surface texture on the frictional and wear performances of nanocrystalline diamond films under water-lubricating conditions were comparatively investigated using a reciprocating ball-on-flat tribometer. Although the untreated nanocrystalline diamond film shows a stable frictional state with an average friction coefficient of 0.26, the subsequent textured films show a beneficial effect on rapidly reducing the friction coefficient, which decreased to a stable value of 0.1. Furthermore, compared with the nanocrystalline diamond coating, the textured films showed a large decreasing rate of the corresponding ball wear rate from 4.16 × 10−3 to 1.15 × 10−3 mm3/N/m. This is due to the fact that the hydrodynamic fluid film composed of water and debris can provide a good lubrication environment, so the entire friction process has reached the state of fluid lubrication. Meanwhile, the surface texture can greatly improve the hydrophilicity of the diamond films, and as the texture density increases, the water contact angle decreases from 94.75° of the nanocrystalline diamond film to 78.5° of the textured films. The proper textured diamond film (NCD90) exhibits superior tribological properties among all tested diamond films, such as short run-in period, low coefficient of friction, and wear rate.

scholarly journals An Optimized Flutter-Driven Triboelectric Nanogenerator with a Low Cut-In Wind Speed

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 366
Author(s):  
Yang Xia ◽  
Yun Tian ◽  
Lanbin Zhang ◽  
Zhihao Ma ◽  
Huliang Dai ◽  
...  
Keyword(s):  
Power Generation ◽  
Wind Speed ◽  
Energy Harvesting ◽  
Wind Energy ◽  
Output Power ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Triboelectric Nanogenerator ◽  
Vibration Behavior ◽  
Air Speed

We present an optimized flutter-driven triboelectric nanogenerator (TENG) for wind energy harvesting. The vibration and power generation characteristics of this TENG are investigated in detail, and a low cut-in wind speed of 3.4 m/s is achieved. It is found that the air speed, the thickness and length of the membrane, and the distance between the electrode plates mainly determine the PTFE membrane’s vibration behavior and the performance of TENG. With the optimized value of the thickness and length of the membrane and the distance of the electrode plates, the peak open-circuit voltage and output power of TENG reach 297 V and 0.46 mW at a wind speed of 10 m/s. The energy generated by TENG can directly light up dozens of LEDs and keep a digital watch running continuously by charging a capacitor of 100 μF at a wind speed of 8 m/s.

Determination of the flight trajectory in terms of emission and fuel consumption minimization

2021 ◽  
pp. 095441002110122
Author(s):  
Małgorzata Pawlak ◽  
Michał Kuźniar ◽  
Andrzej R. Majka
Keyword(s):  
Fuel Consumption ◽  
Negative Impact ◽  
Weather Conditions ◽  
Air Transport ◽  
Cycle Phase ◽  
Horizontal Flight ◽  
Pollutants Emission ◽  
Aircraft Trajectory ◽  
Air Speed ◽  
Constant Altitude

The present-day world is characterized by the intense development of air transport. However, along with it, significant problems appear. Among these problems, the most important are those relating to safety and negative impact of air transport on the environment. Air transport efficiency and profitability issues, although not critical, must also be taken into account because they decide about the intensity of development of this branch of transport. There are currently two large programs in Europe oriented at improving safety, environmental, and efficiency indicators. These are SESAR 2020 and Clean Sky 2, being a continuation of previous ones. One of the ways to reduce negative impact of air transport on the environment and improve its efficiency is to reduce fuel consumption and pollutants emissions resulting from fuel combustion. To find solutions with the abovementioned features, it is necessary to have sufficiently accurate models to estimate the amount of fuel consumed and the amount of pollutants emitted. Developing a sufficiently accurate model to determine fuel consumption and pollutants emission was performed. Due to the specificity of the missions carried out by passenger aircraft, the focus was on the cruise stage when aircraft flies at a constant altitude with a constant air speed. The result of the analysis was the development of methodology for fuel consumption and emission of main pollutants in cruise conditions. Specific fuel consumption is calculated for the thrust required for horizontal flight at cruising altitude. Emission indexes for CO, NOx, HC, and CO2 for the cruise have been determined based on known indexes for the landing and take-off cycle phase, after applying appropriate corrections. An illustration of the application of the developed methodology was the optimization of a medium-sized transport aircraft trajectory on a selected connection to determine a trajectory characterized by a minimum emission value taking into account weather conditions.

The Measurement of Air Speed

1914 ◽  
Vol 18 (71) ◽  
pp. 245-271
Author(s):  
A. P. Thurston
Keyword(s):  
Dynamical Properties ◽  
Air Speed

It is a matter of extreme importance to be able to measure accurately the speed of the air in any situation and under any condition, because all our knowledge of the dynamical properties of the air is dependent upon a correct measurement of its velocity, and because the safety of a pilot depends upon knowing accurately the speed at which he is flying. He is then able to guard himself against the risk of stalling his machine or of attaining too great a speed. An air speed indicator is really as indispensable to a pilot as a foot rule is to a carpenter or a “hooter” to a motorist. The velocity of the air may be determined by three main methods. In the first method the velocity is measured directly by the time taken by a particle, body or substance floating in or dragged along by the air to travel from one point to another.

Air speed indicators for dirigible

1919 ◽  
Vol 188 (4) ◽  
pp. 535-544
Author(s):  
The Aeronautics Staff, U. S. N.
Keyword(s):  
Air Speed

scholarly journals Measuring Device for Air Speed in Macroporous Media and Its Application Inside Apple Storage Bins

Sensors ◽  
2018 ◽  
Vol 18 (2) ◽  
pp. 576 ◽  
Author(s):  
Martin Geyer ◽  
Ulrike Praeger ◽  
Ingo Truppel ◽  
Holger Scaar ◽  
Daniel Neuwald ◽  
...  
Keyword(s):  
Measuring Device ◽  
Air Speed ◽  
Storage Bins

scholarly journals Drops bouncing off macro-textured superhydrophobic surfaces

2017 ◽  
Vol 824 ◽  
pp. 866-885 ◽  
Author(s):  
Ali Mazloomi Moqaddam ◽  
Shyam S. Chikatamarla ◽  
Iliya V. Karlin
Keyword(s):  
Contact Time ◽  
Numerical Study ◽  
Three Dimensional ◽  
Superhydrophobic Surfaces ◽  
Nonlinear Behaviour ◽  
Textured Surfaces ◽  
Texture Density ◽  
Wide Range ◽  
Quantitative Manner ◽  
The Impact

Recent experiments with droplets impacting macro-textured superhydrophobic surfaces revealed new regimes of bouncing with a remarkable reduction of the contact time. Here we present a comprehensive numerical study that reveals the physics behind these new bouncing regimes and quantifies the roles played by various external and internal forces. For the first time, accurate three-dimensional simulations involving realistic macro-textured surfaces are performed. After demonstrating that simulations reproduce experiments in a quantitative manner, the study is focused on analysing the flow situations beyond current experiments. We show that the experimentally observed reduction of contact time extends to higher Weber numbers, and analyse the role played by the texture density. Moreover, we report a nonlinear behaviour of the contact time with the increase of the Weber number for imperfectly coated textures, and study the impact on tilted surfaces in a wide range of Weber numbers. Finally, we present novel energy analysis techniques that elaborate and quantify the interplay between the kinetic and surface energy, and the role played by the dissipation for various Weber numbers.

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