Experimental Study on the Influence of Design Parameters in Sound-Radiation Analysis of a Gear System

There are style guidelines for authors who highlight important words in static text, e.g., bolded words in student textbooks, yet little research has investigated highlighting in dynamic texts, e.g., captions during educational videos for Deaf or Hard of Hearing (DHH) users. In our experimental study, DHH participants subjectively compared design parameters for caption highlighting, including: decoration (underlining vs. italicizing vs. boldfacing), granularity (sentence level vs. word level), and whether to highlight only the first occurrence of a repeating keyword. In partial contrast to recommendations in prior research, which had not been based on experimental studies with DHH users, we found that DHH participants preferred boldface, word-level highlighting in captions. Our empirical results provide guidance for the design of keyword highlighting during captioned videos for DHH users, especially in educational video genres.

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Experimental study of immersion ratio and shaft inclination angle in the performance of a surface-piercing propeller

Mechanical Sciences ◽

10.5194/ms-10-153-2019 ◽

2019 ◽

Vol 10 (1) ◽

pp. 153-167

Author(s):

Seyyed Mostafa Seyyedi ◽

Rouzbeh Shafaghat ◽

Mohioddin Siavoshian

Keyword(s):

Experimental Study ◽

Free Surface ◽

Surface Water ◽

Inclination Angle ◽

Superior Performance ◽

Design Parameters ◽

Water Tunnel ◽

Hydrodynamic Coefficients ◽

Thrust And Torque ◽

Surface Piercing Propeller

Abstract. Surface-piercing propellers have been widely used in light and high-speed vessels because of their superior performance. Experimental study of these propellers is one of the most reliable and accurate ways which can provide details about the performance and effect of different design parameters on the performance of the surface-piercing propellers. In this research, a five-blade surface-piercing propeller was tested in the free surface water tunnel of Babol Noshirvani University of Technology in order to expand the available experimental data and database for future engineering designs. The effects of immersion ratio and shaft inclination angle on the propeller's efficiency and hydrodynamic coefficients were examined. A free surface water tunnel and a calibrated dynamometer with the measurability of the thrust forces and the torque of a propeller were used for this purpose. Comparing the obtained results with the existing semi-experimental equations shows that the equations presented in various geometric conditions are not accurate enough, and developing the existing database is necessary. The details of the obtained results showed that the hydrodynamic coefficients of the thrust and torque increased by increasing the immersion ratio, but the coefficient of hydrodynamic thrust and efficiency reduced. The results also indicated that the coefficient of torque increased by increasing the shaft inclination angle. The highest efficiency of the propeller was achieved in the range of 40 %–50 % immersion ratios at all angles of shaft inclination. For all immersion ratios, the maximum and minimum efficiencies were obtained at 0 and 15 shaft inclination angles, respectively. The best efficiency of the propeller was at 50 % immersion ratio and zero shaft inclination angle.

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An experimental study of the optimal design parameters of a wind power tower used to improve the performance of vertical axis wind turbines

Advances in Mechanical Engineering ◽

10.1177/1687814018799543 ◽

2018 ◽

Vol 10 (9) ◽

pp. 168781401879954

Author(s):

Soo-Yong Cho ◽

Sang-Kyu Choi ◽

Jin-Gyun Kim ◽

Chong-Hyun Cho

Keyword(s):

Experimental Study ◽

Optimal Design ◽

Wind Turbine ◽

Wind Power ◽

Wind Turbines ◽

Vertical Axis ◽

Power Coefficient ◽

Design Parameters ◽

Vertical Axis Wind Turbine ◽

Vertical Axis Wind Turbines

In order to augment the performance of vertical axis wind turbines, wind power towers have been used because they increase the frontal area. Typically, the wind power tower is installed as a circular column around a vertical axis wind turbine because the vertical axis wind turbine should be operated in an omnidirectional wind. As a result, the performance of the vertical axis wind turbine depends on the design parameters of the wind power tower. An experimental study was conducted in a wind tunnel to investigate the optimal design parameters of the wind power tower. Three different sizes of guide walls were applied to test with various wind power tower design parameters. The tested vertical axis wind turbine consisted of three blades of the NACA0018 profile and its solidity was 0.5. In order to simulate the operation in omnidirectional winds, the wind power tower was fabricated to be rotated. The performance of the vertical axis wind turbine was severely varied depending on the azimuthal location of the wind power tower. Comparison of the performance of the vertical axis wind turbine was performed based on the power coefficient obtained by averaging for the one periodic azimuth angle. The optimal design parameters were estimated using the results obtained under equal experimental conditions. When the non-dimensional inner gap was 0.3, the performance of the vertical axis wind turbine was better than any other gaps.

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