The Effect of Bandwidth of Semiactive Dampers on Vehicle Ride

1993 ◽  
Vol 115 (3) ◽  
pp. 571-575 ◽  
Author(s):  
J. Lieh
Keyword(s):  
Fourier Transform ◽  
Significant Influence ◽  
Switching Time ◽  
Control Valve ◽  
Mean Square ◽  
Active Suspensions ◽  
Car Model ◽  
Frequency Responses ◽  
And Control ◽  
Valve Switching

A passenger car model with a full car body and four wheel-axle assemblies is used to investigate the influence of semiactive suspensions on ride performance. Mean square values are evaluated for various damping levels and control valve switching times. Due to severe nonlinearities, frequency responses are not obtained directly. They are reconstructed from Fast Fourier Transform (FFT) using a Hanning window. The results are compared with those from LQR active suspensions and pure on-off dampers. The effect of control valve switching time (bandwidth) is studied and shows a significant influence on the vehicle ride, suspension travels, and tire deflections.

Damping of Self-Excited Pressure Pulsations in Petrodiesel Pipeline

2014 ◽  
Vol 630 ◽  
pp. 375-382 ◽  
Author(s):  
Daniel Himr ◽  
Vladimir Haban
Keyword(s):  
Hydraulic System ◽  
Check Valve ◽  
Control Valve ◽  
Sampling Frequency ◽  
Pressure Pulsations ◽  
One Dimensional ◽  
Fuel Storage ◽  
Excited Oscillation ◽  
Subsequent Measurement ◽  
And Control

A pumping station in a fuel storage suffered from pressure pulsations in a petrodiesel pipeline. Check valves protecting the station against back flow made a big noise when disc hit a seat. Due to employees complaints we were asked to solve the problem, which could lead to serious mechanical problems. Pressure measurement in the pipeline showed great pulsations, which were caused by self-excited oscillation of control valves at the downstream end of pipeline. The operating measurement did not catch it because of too low sampling frequency. One dimensional numerical model of the whole hydraulic system was carried out. The model consisted of check valve, pipeline and control valve, which could oscillate, so it was possible to simulate the unsteady flow. When the model was validated, a vessel with nitrogen was added to attenuate pressure pulsations. According to the results of numerical simulation, the vessel was installed on the location. Subsequent measurement proved noticeably lower pulsations and almost no noise.

scholarly journals Study of Lamb Waves for Non-Destructive Testing Behind Screens

2018 ◽  
Vol 170 ◽  
pp. 03005 ◽  
Author(s):  
P. Kauffmann ◽  
M.-A. Ploix ◽  
J.-F. Chaix ◽  
C. Gueudré ◽  
G. Corneloup ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Lamb Waves ◽  
Nuclear Industry ◽  
Liquid Sodium ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Leaky Lamb Waves ◽  
Short Time ◽  
And Control ◽  
Non Destructive

The inspection and control of sodium-cooled fast reactors (SFR) is a major issue for the nuclear industry. Ultrasonic solutions are under study because of the opacity of liquid sodium. In this paper, the use of leaky Lamb waves is considered for non-destructive testing (NDT) on parallel and immersed structures assimilated as plates. The first phase of our approach involved studying the propagation properties of leaky Lamb waves. Equations that model the propagation of Lamb waves in an immersed plate were solved numerically. The phase velocity can be experimentally measured using a two dimensional Fourier transform. The group velocity can be experimentally measured using a short-time Fourier transform technique. Attenuation of leaky Lamb waves is mostly due to the re-emission of energy into the surrounding fluid, and it can be measured by these two techniques.

scholarly journals Vibration Analysis and Control of a Vibration Screed System for Asphalt Pavers

2020 ◽  
Vol 25 (3) ◽  
pp. 363-372
Author(s):  
Vanliem Nguyen ◽  
Zhenpeng Wu ◽  
Beiping Zhang ◽  
Zhang Jian Run
Keyword(s):  
Working Conditions ◽  
Vibration Analysis ◽  
Excitation Frequency ◽  
Mean Square ◽  
Dynamic Parameters ◽  
Objective Functions ◽  
Nonlinear Dynamic Model ◽  
Compression Efficiency ◽  
Centre Of Gravity ◽  
And Control

To reduce shaking of a vibration screed system (VSS) and improve the paving performance of an asphalt paver (AP), the root-mean-square (RMS) acceleration responses at points on the front and rear screed floors are analyzed via an experimental method. A 3D nonlinear dynamic model of the VSS is also built to evaluate the influence of the dynamic parameters of the VSS on the compression efficiency, paving quality, and working stability of the AP based on the objective functions of the vertical, pitching, and rolling RMS values at the centre of gravity of the screed. The angular deviations, $alpha$ and $gamma$, of the tamper are then controlled to improve the paving performance. The research results show that the excitation frequency, $f_{t}$, and both angular deviations, $alpha$ and $gamma$, of the tamper strongly affect the paving performance. The compression efficiency is quickly enhanced, while both paving quality and working stability are significantly reduced with increasing the excitation frequency $f_{t}$ and reducing the angular deviations. $alpha$ and $gamma$. and vice versa. Additionally, the screed shaking and paving performance of the AP are remarkably improved by control of the angular deviations, $alpha$ and $gamma$, under different working conditions.

scholarly journals Design and construction of a prototype for the analysis of vibrations in an induction motor for the detection of faults

2020 ◽  
pp. 27-33
Author(s):  
Javier Garrido ◽  
Beatris Escobedo-Trujillo ◽  
Guillermo Miguel Martínez-Rodríguez ◽  
Oscar Fernando Silva-Aguilar
Keyword(s):  
Fourier Transform ◽  
Induction Motor ◽  
Wavelet Transforms ◽  
Data Acquisition System ◽  
Time Frequency ◽  
Different Types ◽  
Control Devices ◽  
The Fourier Transform ◽  
And Control ◽  
Types Of Faults

The contribution of this work is to present the design of a prototype integrated by an induction motor, a data acquisition system, accelerometers and control devices for stop and start, to generate and identify different types of faults by means of vibration analysis. in the domain: time, frequency or frequency-time, through the use of the Fourier Transform, Fast Fourier Transform or Wavelet Transforms (wavelet transform). In this prototype, failures can be generated in the induction motor such as: unbalance, different types of misalignment, mechanical looseness, and electrical failures such as broken bars or short-circuited rings, an example of a misalignment failure is presented to show the process of analysis and detection.

scholarly journals Form design in interface of display and control system based on visual search

2021 ◽  
Vol 336 ◽  
pp. 05003
Author(s):  
Dayan Wang ◽  
Jue Qu ◽  
Wei Wang ◽  
Shuai Zhu ◽  
Kang Li
Keyword(s):  
Experimental Data ◽  
Control System ◽  
Reaction Time ◽  
Significant Influence ◽  
Design Guidelines ◽  
Color Combination ◽  
Form Design ◽  
Color Form ◽  
Color Grouping ◽  
And Control

To explore the design pattern and guidelines for the forms displayed on the interfaces, we studied the factors of form design from the perspective of ergonomics. These factors include orientation (horizontal, vertical), color grouping and color combination. In combination with the analysis and conclusion of the experimental data, we proposed some design guidelines for human-computer interface that has many forms, such as weapon command and control system. A visual searching program was designed to simulate the display interface. Reaction time and accuracy are recorded by orthogonal experiment. Analyses such as double factor variance analysis, simple main effect are conducted on the experimental data. The following conclusions are obtained: two-color form has a faster reaction time than single color form; reaction time of the horizontal form is shorter than the vertical form. Color combination has significant influence on accuracy, and the blue-green is suiTable for form design; color grouping has significant influence on reaction time and accuracy; the interaction of color grouping and color combination shows significant differences. When designing forms in display interface, we should choose the horizontal layout with sparse coloring density as much as possible, and the effect of color combination on the recognition efficiency should be considered.

NOTE ON THE VLASOV EQUATION FOR PLASMAS

1963 ◽  
Vol 41 (12) ◽  
pp. 1960-1966 ◽  
Author(s):  
Ta-You Wu ◽  
M. K. Sundaresan
Keyword(s):  
Distribution Function ◽  
Fourier Transform ◽  
Vlasov Equation ◽  
Hermite Polynomials ◽  
Infinite Matrix ◽  
Mean Square ◽  
Initial Value ◽  
Positive Ions ◽  
The Mean ◽  
The Fourier Transform

The linearized Vlasov equation is solved as an initial value problem by expanding (the Fourier components of) the distribution function in a series of Hermite polynomials in the momentum, with coefficients which are functions of time. The spectrum of frequencies is given by the eigenvalues of an infinite matrix. All the frequencies ω are real, extending from small values of order ω2 = k2(u22), where (u22) is the mean square velocity of the positive ions (of mass M), to [Formula: see text], where ω1, (u12) are the plasma frequency and mean square velocity of the electrons (of mass m). The classic work of Landau solves the Vlasov equation for (the Fourier transform of) the potential for which he obtains the "damping", whereas Van Kampen and the present writers solve the equation for (the Fourier transform of) the distribution function itself. While the present work gives results equivalent to those of Van Kampen, the method is simpler and in fact elementary.

scholarly journals A Time Domain Passivity Control Scheme for Bilateral Teleoperation

Electronics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 325 ◽  
Author(s):  
Long Sheng ◽  
Usman Ahmad ◽  
Yongqiang Ye ◽  
Ya-Jun Pan
Keyword(s):  
Time Domain ◽  
Parametric Design ◽  
Switching Time ◽  
Experimental Results ◽  
Division Problem ◽  
Bilateral Teleoperation ◽  
Safe Operation ◽  
Guaranteed Stability ◽  
Control Scheme ◽  
And Control

Conventional time domain passivity control inevitably embodies division. Zero division can occur under a tiny force or velocity, which may be inevitable, and will be the cause of control crash. To avoid the zero division problem and control crash, we propose a switching dissipation controller for guaranteed stability. The parametric design of the proposed approach is discussed. The switching time domain passivity control is then applied to teleoperation and safe operation is achieved. Simulation and experimental results are demonstrated to validate the effectiveness of the proposed control scheme.

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