Research on hydraulic servo control system for field test of ground motion parameters
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The hydraulic servo control system of the ground motion parameter field test system is introduced in this paper. The hydraulic servo control system mainly includes the seismic wave generating equipment system and the servo control system. And the equipment system consists of the P-wave and the S-wave generator. The main advantage of the hydraulic servo control system is that P-wave and S-wave generator can generate both p-wave and S-wave. The seismic waves produced are characterized by strong stability and high energy, which can overcome the shortcomings of instability, less energy and poor repeatability of the on-site wave generating device. It is necessary to generate the waveform of different types of seismic waves, such as sine wave, cosine wave, square wave and random wave. The vibration frequency of the seismic wave can be controlled to meet the actual demand of the seismic wave in engineering. The hydraulic servo control system can be run stably for a long time, without interference and unreliable operation in various environments and states, which can be of great significance for the seismic safety evaluation of the engineering site.Keywords:
Sine wave
Servomechanism
Servomechanism
Double integrator
Robustness
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Reproduced waveform with thin film magnetic heads, distortions (wiggles) of reproduced waveform are sometimes observed. In this study, a method for extracting wiggles from reproduced waveform was devised, and wiggle behavior was studied. Extracted wiggles were in pulse width from 40 to 80 ns, in amplitude from 10 to 30μV, and their locations during reproduced waveform were shifted by and external magnetic field, but wiggle width and amplitude were not affected. After write operation, wiggle pulse width and amplitude changed; however, the area under the extracted pulse was verified constant. Peakshifts of reproduced waveform increased when wiggles came close to the peak of the reproduced waveform, and wiggle amplitude increased.
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This paper studies a strong disturbance rejection control strategy for electromechanical servo systems. Design a disturbance observer integrated into a discrete sliding mode closed-loop controller to improve disturbance resistance performance. Simulation results show that the disturbance observer compensation-based discrete-time SMC can improve the dynamic performance of the servo system, reduce steady-state error, and achieve accurate tracking of the position command value.
Servomechanism
Observer (physics)
Tracking (education)
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Sine wave
Arbitrary waveform generator
Square wave
Function generator
Micro computer
Rectangle
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Experimental and Numerical Analyses of the Rational Loading Waveform in SHPB Test for Rock Materials
Aiming at the determination of the rational loading waveform for rock materials, the comparative impact tests under the loadings of rectangular and half-sine stress waves were performed on red sandstone using an Ø50 mm SHPB apparatus. Experimental results with the rectangular stress wave affirm that the waveform dispersion and stress-strain curve oscillation frequently exist during the test of rock materials, which signifies that the accuracy of test results derived from the rectangular stress wave loading cannot be guaranteed. Under the loading of the half-sine stress wave, the phenomenon of wave dispersion during the tests has been eliminated radically, and there is no oscillation in the stress-strain curves. To further demonstrate the rationality of the half-sine wave loading in the SHPB test, by utilizing the three-dimensional numerical simulation approach, the propagations of rectangular, triangular, and half-sine stress waves travelling in the axial and radial directions of the SHPB with four elastic bar diameter sizes are analyzed and compared. The results show that the waveform dispersion of the rectangular and triangular stress waves always exists and will be more and more serious with increasing diameter size and propagation distance. For the half-sine stress wave, the waveform dispersion effect is very weak and not affected by the bar diameter size and propagation distance. The half-sine stress wave is the rational loading waveform for rock SHPB tests with different bar diameters.
Sine wave
Bar (unit)
Oscillation (cell signaling)
Stress wave
Sine
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The biphasic waveform has greater defibrillation efficacy than the monophasic waveform. Yet, the optimal type of biphasic defibrillation waveform is still unknown. Our objective was to compare the defibrillation efficacy of three morphologically different biphasic waveforms (named as truncated exponential waveform, modified Zoll waveform, and Gurvich waveform) in an isolated Langendorff perfused rabbit heart. Optical potential mapping techniques were used. The result showed that the Gurvich waveform has the lowest defibrillation threshold (DFT). A multiple comparison test showed that there is a significant difference of DFTs between the modified Zoll waveform and Gurvich waveform (mean/spl plusmn/SE: 0.31/spl plusmn/0.03 J and 0.25/spl plusmn/0.02 J, p<0.02). We also examined the change of membrane potential caused by shocks. The result showed an homogeneous response for different waveforms.
Defibrillation threshold
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The connecting part of electro-hydraulic servomechanism with load is of high rigidty, so
that the output is easily affected by the changes of load and inertia. Besides speed feedback
compensating method, it is also an effective method for state feedback of observer reconstruction to
decrease and restrain the affect of disturbance of load and inertia. A rotary electro-hydraulic
servomechanism is treated by an observer which estimates and measures the disturbance of load and
inertia, and the state feedback of observer is reconstructed to form this equivalent closed loop system.
By experiments, by analyzing and measuring frequency and step response of this system, it is proved
that the changes of speed caused by the disturbance of load and inertia is decreased markedly by this
observer, and theoretically the state feedback is correct.
Servomechanism
Observer (physics)
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Sine wave
Root mean square
Non-sinusoidal waveform
Square root
Ammeter
Sine
Square wave
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First, the relation between MFM output and head output waveforms from perpendicular magnetic printed media was clarified. Next, the MFM output waveforms from magnetically printed and head-recorded media were compared by using metal-evaporated (ME) tape as a slave medium. The MFM output waveform corresponds very closely with the head output waveform, and it appears that the MFM output is similar to the perpendicular component of the stray field. In the case of a long bit length, the bit-printing (BP) waveform is similar to the head-recording (HR) waveform, while the edge-printing (EP) waveform is significantly different from the HR waveform. On the other hand, in the case of a short bit length, the BP, EP, and HR waveforms are all sinusoidal, but the phase of the EP waveform is 90° shifted from the HR waveform, while the BP waveform is almost identical to the HR waveform.
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This article describes an arbitrary waveform generator based on DDS (Direct Digital frequency Synthesis) technology. The arbitrary waveform generator can easily generate DC, square wave, sine wave or any other arbitrary waveform in mill volt or even microvolt level. The generator uses ARM and 51MCU dual-processor system framework. In the system design, we use multiple reference frequency source and dynamically generated waveform data method to generate waveform, which can effectively improve the stability and reduce the distortion of the output waveform.
Arbitrary waveform generator
Function generator
Sine wave
Direct digital synthesizer
Distortion (music)
Square wave
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