scholarly journals Modelling of second mode positive streamer in cyclohexane by considering optimised electron saturation velocity

2020 ◽  
Author(s):  
Donglin Liu ◽  
Qiang Liu ◽  
Zhongdong Wang
Keyword(s):  
Saturation Velocity ◽  
Second Mode ◽  
Positive Streamer

Recent Patents on Abnormal Hydrodynamic Thrust Slider Bearings: Part II-the Second Mode of the Bearings

2020 ◽  
Vol 13 (1) ◽  
pp. 35-40
Author(s):  
Yongbin Zhang ◽  
Huansheng Cheng ◽  
Junyan Wang
Keyword(s):  
Operating Conditions ◽  
Moving Surface ◽  
Friction Coefficients ◽  
Surface Separation ◽  
Slider Bearings ◽  
Stationary Surface ◽  
Boundary Slippage ◽  
Load Carrying ◽  
Second Mode ◽  
Inlet Zone

Background: As a successive part, the paper introduces the second mode of abnormal hydrodynamic thrust slider bearings with divergent surface separations registered in the patents, where the boundary slippage is artificially designed both on the stationary surface in the inlet zone and on the whole moving surface. Objective : To introduce a second method for artificially designing the boundary slippage for the formation of abnormal hydrodynamic thrust slider bearings. Methods: The analytical results are presented for the introduced bearings. The performances of the bearings are demonstrated. Result: : In appropriate operating conditions, the introduced bearings can have considerable loadcarrying capacities with low friction coefficients on the scales 10-3 or 10-4. With the weakening of the boundary slippage on the moving surface, the load-carrying capacities of the bearings are all increased, while the friction coefficients of the bearings are all reduced. Conclusion: When the boundary slippage is present both on the stationary surface in the bearing inlet zone and on the whole moving surface, abnormal hydrodynamic thrust slider bearings can be designed with the surface separation in the bearing inlet zone lower than that in the bearing outlet zone. The performances of these bearings are quite satisfactory.

scholarly journals Barrier-Free Wheelchair with a Mechanical Transmission

2021 ◽  
Vol 11 (11) ◽  
pp. 5280
Author(s):  
Jongseok Lee ◽  
Wonhyeong Jeong ◽  
Jaeoh Han ◽  
Taesu Kim ◽  
Sehoon Oh
Keyword(s):  
The Elderly ◽  
Transmission System ◽  
Motor Drives ◽  
Mechanical Transmission ◽  
Link Structure ◽  
Second Mode ◽  
Important Means ◽  
The Stability ◽  
Flat Ground ◽  
Climbing Stairs

Wheelchairs are an important means of transportation for the elderly and disabled. However, the movement of wheelchairs on long curbs and stairs is restricted. In this study, a wheelchair for climbing stairs was developed based on a mechanical transmission system that rotates the entire driving part through a link structure and an actuator to change the speed. The first mode drives the caterpillar, and the second mode drives the wheels. When driving on flat ground, it uses landing gears and wheels, and when climbing stairs, it uses the caterpillar; accordingly, a stable driving is possible. The stability of the transmission is confirmed through stress analysis. The method used in our study makes it is possible to manufacture lightweight wheelchairs because a single motor drives both the wheel and caterpillar through the transmission system.

scholarly journals Nonlinear vibrations and time delay control of an extensible slowly rotating beam

2020 ◽  
Author(s):  
Jerzy Warminski ◽  
Lukasz Kloda ◽  
Jaroslaw Latalski ◽  
Andrzej Mitura ◽  
Marcin Kowalczuk
Keyword(s):  
Time Delay ◽  
Control Strategies ◽  
Vibration Reduction ◽  
Least Action ◽  
Active Elements ◽  
Principle Of Least Action ◽  
Second Mode ◽  
Delay Control ◽  
Speed Range ◽  
System With Time Delay

AbstractNonlinear dynamics of a rotating flexible slender beam with embedded active elements is studied in the paper. Mathematical model of the structure considers possible moderate oscillations thus the motion is governed by the extended Euler–Bernoulli model that incorporates a nonlinear curvature and coupled transversal–longitudinal deformations. The Hamilton’s principle of least action is applied to derive a system of nonlinear coupled partial differential equations (PDEs) of motion. The embedded active elements are used to control or reduce beam oscillations for various dynamical conditions and rotational speed range. The control inputs generated by active elements are represented in boundary conditions as non-homogenous terms. Classical linear proportional (P) control and nonlinear cubic (C) control as well as mixed ($$P-C$$ P - C ) control strategies with time delay are analyzed for vibration reduction. Dynamics of the complete system with time delay is determined analytically solving directly the PDEs by the multiple timescale method. Natural and forced vibrations around the first and the second mode resonances demonstrating hardening and softening phenomena are studied. An impact of time delay linear and nonlinear control methods on vibration reduction for different angular speeds is presented.

How nose bluntness suppresses second-mode growth

2019 ◽  
Author(s):  
Jordan Sakakeeny ◽  
Armani Batista ◽  
Joseph Kuehl
Keyword(s):  
Second Mode

Heat transfer enhancement using second mode self-oscillating structures

2019 ◽  
Vol 30 (7) ◽  
pp. 3827-3842
Author(s):  
Samer Ali ◽  
Zein Alabidin Shami ◽  
Ali Badran ◽  
Charbel Habchi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Flow Regime ◽  
Vortex Generator ◽  
Reynolds Numbers ◽  
Content Type ◽  
Laminar Flow Regime ◽  
Second Mode

Purpose In this paper, self-sustained second mode oscillations of flexible vortex generator (FVG) are produced to enhance the heat transfer in two-dimensional laminar flow regime. The purpose of this study is to determine the critical Reynolds number at which FVG becomes more efficient than rigid vortex generators (RVGs). Design/methodology/approach Ten cases were studied with different Reynolds numbers varying from 200 to 2,000. The Nusselt number and friction coefficients of the FVG cases are compared to those of RVG and empty channel at the same Reynolds numbers. Findings For Reynolds numbers higher than 800, the FVG oscillates in the second mode causing a significant increase in the velocity gradients generating unsteady coherent flow structures. The highest performance was obtained at the maximum Reynolds number for which the global Nusselt number is improved by 35.3 and 41.4 per cent with respect to empty channel and rigid configuration, respectively. Moreover, the thermal enhancement factor corresponding to FVG is 72 per cent higher than that of RVG. Practical implications The results obtained here can help in the design of novel multifunctional heat exchangers/reactors by using flexible tabs and inserts instead of rigid ones. Originality/value The originality of this paper is the use of second mode oscillations of FVG to enhance heat transfer in laminar flow regime.

Transient response of electrorheological effect to a step field in an immiscible polymer blend: Second mode in type I blend

1999 ◽  
Vol 43 (1) ◽  
pp. 137-146 ◽  
Author(s):  
Kozo Tajiri ◽  
Hiroshi Orihara ◽  
Yoshihiro Ishibashi ◽  
Masao Doi ◽  
Akio Inoue
Keyword(s):  
Polymer Blend ◽  
Transient Response ◽  
Type I ◽  
Immiscible Polymer Blend ◽  
Electrorheological Effect ◽  
Immiscible Polymer ◽  
Second Mode
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