scholarly journals Research on the Plasma Anemometer Based on AC Glow Discharge

2017 ◽  
Vol 2017 ◽  
pp. 1-12
Author(s):  
Bing Yu ◽  
Enyu Shen ◽  
Pei Yuan ◽  
Huaxu Shen
Keyword(s):  
Glow Discharge ◽  
Negative Feedback ◽  
Velocity Measurement ◽  
System Optimization ◽  
Measurement Range ◽  
System Stability ◽  
Airflow Velocity ◽  
Coupling Capacitance ◽  
Coupling Resistance ◽  
Anemometer System

A new plasma anemometer based on AC glow discharge is designed in this article. Firstly, theoretical analysis of plasma anemometer working principle is introduced to prove the feasibility of the experimental measurement method. Then the experiments are carried out to study the effects of different parameters on the static discharge characteristics of the plasma anemometer system, by which the system optimization methods are obtained. Finally, several groups of appropriate parameters are selected to build the plasma anemometer system based on resistance capacitance coupling negative feedback AC glow discharge, and different airflow speeds are applied to obtain the achievable velocity measurement range. The results show that there is a linear relationship between airflow velocity and discharge current in an allowable error range, which can be applied for airflow velocity measurement. Negative feedback coupling module, which is composed of the coupling resistance and the coupling capacitance, has good effects on improving the system stability. The measurement range of the airflow velocity is significantly increased when the electrode gap is 3 mm, coupling resistance is 470 Ω, and coupling capacitance is 220 pF.

Velocity measurement in hypersonic flows using electron-beam-assisted glow discharge

AIAA Journal ◽  
1998 ◽  
Vol 36 ◽  
pp. 1061-1064
Author(s):  
S. Larigaldie ◽  
D. Bize ◽  
A. K. Mohamed ◽  
M. Ory ◽  
J. Soutade ◽  
...  
Keyword(s):  
Electron Beam ◽  
Glow Discharge ◽  
Velocity Measurement ◽  
Hypersonic Flows

Ventilation Characteristics of Modeled Compact Car Part 1 Airflow Velocity Measurement with PIV

2008 ◽  
Vol 1 (1) ◽  
pp. 631-639 ◽  
Author(s):  
Yoshiichi Ozeki ◽  
Jeong-Hoon Yang ◽  
Hideaki Nagano ◽  
Shinsuke Kato ◽  
Eiji Nomura ◽  
...  
Keyword(s):  
Velocity Measurement ◽  
Airflow Velocity

The importance of conduction versus convection in heat pulse sap flow methods

2020 ◽  
Vol 40 (5) ◽  
pp. 683-694
Author(s):  
Michael A Forster
Keyword(s):  
Flux Density ◽  
Sap Flow ◽  
Peclet Number ◽  
Velocity Measurement ◽  
Measurement Range ◽  
Heat Pulse ◽  
Sap Flux ◽  
Sap Flux Density ◽  
Péclet Number ◽  
Fast Methods

Abstract Heat pulse methods are a popular approach for estimating sap flow and transpiration. Yet, many methods are unable to resolve the entire heat velocity measurement range observable in plants. Specifically, the Heat Ratio (HRM) and Tmax heat pulse methods can only resolve slow and fast velocities, respectively. The Dual Method Approach (DMA) combines optimal data from HRM and Tmax to output the entire range of heat velocity. However, the transition between slow and fast methods in the DMA currently does not have a theoretical solution. A re-consideration of the conduction/convection equation demonstrated that the HRM equation is equivalent to the Péclet equation which is the ratio of conduction to convection. This study tested the hypothesis that the transition between slow and fast methods occurs when conduction/convection, or the Péclet number, equals one, and the DMA would be improved via the inclusion of this transition value. Sap flux density was estimated via the HRM, Tmax and DMA methods and compared with gravimetric sap flux density measured via a water pressure system on 113 stems from 15 woody angiosperm species. When the Péclet number ≤ 1, the HRM yielded accurate results and the Tmax was out of range. When the Péclet number > 1, the HRM reached a maximum heat velocity at approximately 15 cm hr −1 and was no longer accurate, whereas the Tmax yielded accurate results. The DMA was able to output accurate data for the entire measurement range observed in this study. The linear regression analysis with gravimetric sap flux showed an r2 of 0.541 for HRM, 0.879 for Tmax and 0.940 for DMA. With the inclusion of the Péclet equation, the DMA resolved the entire heat velocity measurement range observed across 15 taxonomically diverse woody species. Consequently, the HRM and Tmax are redundant sap flow methods and have been superseded by the DMA.

scholarly journals A Controller Combining Positive Velocity Feedback with Negative Angle Feedback for a Two-Wheeled Robot

2015 ◽  
Vol 15 (2) ◽  
pp. 159-170 ◽  
Author(s):  
Lingyan Hu ◽  
Henry Leung Ieee ◽  
Shaoping Xu ◽  
Hua Zhang
Keyword(s):  
Nonlinear System ◽  
Negative Feedback ◽  
Tilt Angle ◽  
Positive Feedback ◽  
Pid Controller ◽  
System Stability ◽  
Velocity Control ◽  
Velocity Feedback ◽  
Wheeled Robot ◽  
The Stability

Abstract The two-wheeled robot is a nonlinear system of multi-variables, higherorder and strong coupling. This paper presented a PID Controller with Double Loops (PCDL) to control the tilt angle and velocity of a two-wheeled robot. The angle controller is the regular negative feedback, while the velocity control is the positive feedback. The Double Loops work cooperatively to endow the system with strong anti-interference ability. The stability of the whole system is analyzed and the criterion of the system stability is developed. The simulation and experiments showed that the two-wheeled robot can self-balance and move at an expected velocity and the system has strong anti-interference ability.

Study on Doppler Velocity Measurement System

2012 ◽  
Vol 562-564 ◽  
pp. 1240-1243
Author(s):  
Jian Chao Li ◽  
Jun Hong Su ◽  
Ming Gao
Keyword(s):  
Measurement System ◽  
Velocity Measurement ◽  
High Speed ◽  
Processing System ◽  
Measurement Range ◽  
High Accuracy ◽  
Laser Doppler ◽  
Doppler Velocity ◽  
Dual Frequency ◽  
Frequency Laser

In order to satisfy the high accuracy velocity measurement requirement, using the improved dual-frequency laser Doppler velocity measurement principle, designed a set of laser Doppler velocity measurement system. System consists of two parts: optical system and signal acquisition and processing system. Through the establishment of dual-frequency laser Doppler velocity measurement experimental platform for testing, the result shows that the method can be carried on the high accuracy velocity measurement which in high speed move object. Measurement range from 0.1 m/s to 50 m/s, the error is less than 2 percent and it could increase the speed measurement range.

Velocity Measurement in Hypersonic Flows Using Electron-Beam-Assisted Glow Discharge

AIAA Journal ◽  
10.2514/2.480 ◽  
1998 ◽  
Vol 36 (6) ◽  
pp. 1061-1064 ◽  
Author(s):  
S. Larigaldie ◽  
D. Bize ◽  
A. K. Mohamed ◽  
M. Ory ◽  
J. Soutadé ◽  
...  
Keyword(s):  
Electron Beam ◽  
Glow Discharge ◽  
Velocity Measurement ◽  
Hypersonic Flows

Optimal Design in Flexible Rotor-Sliding Bearing System With Squeeze Film Damper

2003 ◽  
Author(s):  
Yong-Zhong Lu ◽  
Dao-Xun Liao
Keyword(s):  
Optimal Design ◽  
Optimization Design ◽  
System Optimization ◽  
System Stability ◽  
Squeeze Film ◽  
Inertia Force ◽  
Flexible Rotor ◽  
Sliding Bearing ◽  
Squeeze Film Damper ◽  
Bearing System

A dynamic model of a flexible rotor-sliding bearing system with squeeze film damper (SFD) is established. In the model are oil film inertia force, damping force, clearance excitation force, interference force of different frequencies and static load considered, as opposed to the previous research. On the basis of this model, then optimal design of the system is deeply studied. Simulation shows that the system optimization design can effectively improve the system stability.

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