A Feedforward Correction Method for Multi-Shaker Excitation System in Sine Testing

1997 ◽  
Author(s):  
I. Bucher
Keyword(s):  
Systematic Approach ◽  
Operation Mode ◽  
Interaction Mechanism ◽  
Experimental System ◽  
Correction Method ◽  
Specific Pattern ◽  
Automatic Tuning ◽  
Excitation System ◽  
Electro Magnetic ◽  
Linearized Model

Abstract In experiments aimed at structural dynamics testing, it is often required to precisely control a multi-shaker system in order to replicate the conditions a machine experiences during typical operation mode. For that purpose one seeks to create a specific pattern of responses or forces motivated by actual measured data. Another use of such tuning is for diagnostic purposes where certain forcing patterns amplify hidden features of the dynamic response. For lightly-damped structures that are normally excited by magnetic or electro-magnetic shakers, this task appears to be difficult, especially when high accuracy is desired. The excitation system, under certain conditions, creates an inherent feedback between the force and the response and often some non-linearity exist in the force path. In this paper, a systematic approach for automatic tuning the amplitude and phase of a multi-shaker in an experimental system is developed. The method is particularly useful in the presence of feedback, mild non-linearity and coupling between the force and response. The usual approach is to use a linear model and to assumed that the non-linearity is small, an approach that is valid for identification of slightly non-linear structures, but which fails when precise tuning of forces is based on this identified model. It is therefore suggested to use a general linearized model, rather than a linear one, so that any irregularities attributed to the non-linearity can be handled. Throughout the paper some simulated and experimental examples of tuning are shown. The interaction mechanism between the shakers and the structure is discussed and modeled and an appropriate strategy allowing us to overcome the demonstrated difficulties, is presented.

Numerical Simulation and Analysis of Hydraulic Excitation System Based on Water Hammer by the Method of Characteristics

2011 ◽  
Vol 295-297 ◽  
pp. 2210-2215 ◽  
Author(s):  
Hui Xian Zhang ◽  
Zi Ming Kou ◽  
Juan Wu ◽  
Chun Yue Lu
Keyword(s):  
Numerical Simulation ◽  
Method Of Characteristics ◽  
Experimental System ◽  
Water Hammer ◽  
Vibration Exciter ◽  
Transient Pressure ◽  
Excitation System ◽  
The Method Of Characteristics ◽  
System Pressure ◽  
Excitation Pressure

To study artificially produced and actively controlled water hammer wave caused by hydraulic vibration exciter, a mathematical model was established and an experimental system was designed to verify it. Through the given partial differential equations, a computer code based on the method of characteristics was developed to calculate transient pressure distributed along the pipe under different rotational frequency of vibration exciter. The numerical simulation indicates that there is a simple harmonic vibration rising at the cross sections along the pipe, corresponding to different excitation pressure at every cross section. In addition, the excitation pressure can also be adjusted by system pressure via overflow valve. So, this work is expected to serve for the optimum design of the hydraulic excitation system and play a theoretical guiding role to experimental research in future.

Control Strategy of Microgrid Based on Distributed Generation

2012 ◽  
Vol 430-432 ◽  
pp. 1277-1280
Author(s):  
Yao Zhao ◽  
Ru Qi Cheng ◽  
Xin Gong ◽  
Geng Shen Zhao
Keyword(s):  
Distributed Generation ◽  
Control Strategy ◽  
Power Flow ◽  
Control Method ◽  
Operation Mode ◽  
Experimental System ◽  
Control Unit ◽  
Energy Utilization ◽  
Control Mode ◽  
Power Point

Upon the traditional wind-solar hybrid distributed generation system,a single-phase microgrid experimental system platform has been built based on the DC bus,Z topology was used to increase the energy utilization ratio. On the basic of realizing the maximum power point tracker of the new energy, different microgrid controlling strategy has been designed to apply to the island and grid connected operation mode: in the cases of island running, master slave control mode will be utilized in the system and the battery will be used as the main control unit to provide the reference voltage; on the other hand, a control method which can merge the generation into the grid as much as possible will be adopted in the case of grid connected. By the use of system model, the simulation of the two operation mode switch state and power flow has been done and the feasibility and effectiveness of the control strategy can be guaranteed,it also has been verified by the microgrid experimental platform.

scholarly journals Visibility Video Detection with Dark Channel Prior on Highway

2016 ◽  
Vol 2016 ◽  
pp. 1-21 ◽  
Author(s):  
Jiandong Zhao ◽  
Mingmin Han ◽  
Changcheng Li ◽  
Xin Xin
Keyword(s):  
Extinction Coefficient ◽  
Optimization Algorithms ◽  
Experimental System ◽  
Region Growing ◽  
Video Camera ◽  
Correction Method ◽  
Dark Channel Prior ◽  
Physical Relationship ◽  
Dark Channel ◽  
Set Up

Dark channel prior (DCP) has advantages in image enhancement and image haze removal and is explored to detect highway visibility according to the physical relationship between transmittance and extinction coefficient. However, there are three major error sources in calculating transmittance. The first is that sky regions do not satisfy the assumptions of DCP algorithm. So the optimization algorithms combined with region growing and coefficient correction method are proposed. When extracting atmospheric brightness, different values lead to the second error. Therefore, according to different visibility conditions, a multimode classification method is designed. Image blocky effect causes the third error. Then guided image filtering is introduced to obtain accurate transmittance of each pixel of image. Next, according to the definition meteorological optical visual range and the relationship between transmittance and extinction coefficient of Lambert-Beer’s Law, accurate visibility value can be calculated. A comparative experimental system including visibility detector and video camera was set up to verify the accuracy of these optimization algorithms. Finally, a large number of highway section videos were selected to test the validity of DCP method in different models. The results indicate that these detection visibility methods are feasible and reliable for the smooth operation of highways.

Requirements for the Excitation System in the Development of Units and Grid Coordination

2014 ◽  
Vol 668-669 ◽  
pp. 707-714
Author(s):  
Yi Yu Wen ◽  
Miao Huang ◽  
Guo Ping Liu ◽  
Yu Ming Liu ◽  
Ke Zhao
Keyword(s):  
Power System ◽  
Operation Mode ◽  
Excitation Control ◽  
Reliable Operation ◽  
Excitation System ◽  
Planning Stage ◽  
Generator Unit ◽  
Selection Of

The concept of Units and Grid Coordination (UGC) is introduced. Problems about UGC are drawn from some power interruptions. Some attentive issues are present in excitation selection and design in future power system such as reliable operation of PSS, coordination between excitation limiters and protections, operation mode of excitation control in running stage. Special attention should be paid to the selection of excitation type, parameters design of 1000MW class generator unit in planning stage.

scholarly journals Electronic devices for studying mechanical properties of biological tissues

2020 ◽  
pp. 40-47
Author(s):  
A. G. Dubko ◽  
R. S. Osipov ◽  
Yu. V. Bondarenko ◽  
O. F. Bondarenko
Keyword(s):  
Mechanical Properties ◽  
Mathematical Models ◽  
Biological Tissue ◽  
Low Cost ◽  
Operation Mode ◽  
Experimental System ◽  
Biological Tissues ◽  
Optimal Operation ◽  
Biocompatible Materials ◽  
Tissue Samples

The paper shows the relevance of studying the mechanical properties of biological tissues and biocompatible materials for solving the problems of general and reconstructive surgery, transplantology, manual therapy, virtual simulation of surgical operations, robotic surgery, etc. The authors present basic information about biological tissue as an object of research and give a brief overview of the devices used for studying the mechanical characteristics of biological tissues. An experimental system for testing deformations of biological tissues and biocompatible materials during compression is described. The system is developed using modern hardware and software, as well as effective technical solutions. The results of the practical use of the developed device are presented and the obtained dependences of the mechanical stress of biological tissue samples on their deformation under pressure are analyzed. The system has high metrological characteristics and low cost, and allows performing all the necessary functions for measuring, processing and visualizing the data. The measurements obtained with this system can help form the recommendations for doctors on choosing the optimal operation mode of medical devices and instruments in each specific case. In addition, the measured data can be used to create mathematical models of biological tissues and biocompatible materials in order to further carry out virtual experiments. In further studies, the authors plan to create the mathematical models of biological tissues based on the finite element method and using the actual values characterizing the tissue, obtained with the developed system.

scholarly journals Research on coordinated controller design method based on fault early warning model

2020 ◽  
Vol 213 ◽  
pp. 03008
Author(s):  
Jian Xu ◽  
Shaokun Jia ◽  
Jie Bai ◽  
Kunpeng Zhao ◽  
Minglei Wu ◽  
...  
Keyword(s):  
Predictive Control ◽  
Controller Design ◽  
Design Method ◽  
Operation Mode ◽  
State Space Model ◽  
Interaction Mechanism ◽  
Parameter Setting ◽  
Facts Devices ◽  
Pi Controllers ◽  
Warning Model

With increasing degree of power electronics in power system, the interaction between controllers of different FACTS devices poses a greater threat to security and stability of the system. In this paper, a linearized state space model with SVC and STATCOM was established, and the negative interaction mechanism of FACTS device in transient process was analyzed and summarized considering control characteristics, operation mode and setting principle of PI controllers. A model predictive control (MPC) is proposed to replace traditional PI link to establish a coordination controller to overcome the difficulties of PI control parameter setting and global optimization.

scholarly journals Time series homogenization with the ACMANT software

2021 ◽  
Author(s):  
Peter Domonkos
Keyword(s):  
Time Series ◽  
Operation Mode ◽  
Method Comparison ◽  
Correction Method ◽  
Step Function ◽  
Pairwise Comparisons ◽  
Reference Series ◽  
Function Fitting ◽  
Wide Range ◽  
Data Gaps

<p>The development of ACMANT homogenization software started during the European COST HOME project, around 2010. Due to its excellent results in method comparison tests, the development of ACMANT has been being continuous since then. While its first version was applicable only to the homogenization of monthly temperature series, the later versions are applicable to a wide range of climatic variables and either for monthly or daily time series.</p><p>The operation of ACMANT is fast and automatic, and it is easy to use that even for large size datasets. The method can homogenize together time series of varied lengths, well tolerate data gaps, includes outlier filtering and infilling of data gaps (optional). ACMANT includes modern and effective statistical tools for the detection and removal of inhomogenities, such as step function fitting, bivariate detection for breaks of annual means and seasonal amplitudes (where applicable), ANOVA correction method and ensemble homogenization with varied pre-homogenization of neighbour series. For these properties, ACMANTv4 was the most accurate homogenization method in most method comparison tests of the Spanish MULTITEST project (https://doi.org/10.1175/JCLI-D-20-0611.1). In these tests, one important exception occurred, namely network mean trend errors were removed with significantly higher certainty by the Pairwise Homogenization Algorithm when approximately a half of the time series were affected with quasi synchronous breaks imitating concerted technical changes in the performance of climate observations. The most recent developments aiming the release of ACMANTv5 include the elimination of this drawback of ACMANT.</p><p>For ACMANTv5, a new break detection method has been developed, in which the combination of two time series comparison methods is applied. The new method contains both the use of composite reference series and pairwise comparisons, and in the detection with composite reference series the step function fitting is forced to include the breaks detected by pairwise comparisons. Another novelty of ACMANTv5 is that it gives options to use metadata in the homogenization procedure. The default operation mode of ACMANTv5 is still fully automatic, with or without the automatic use of a prepared metadata table. ACMANTv5 uses every date of the metadata list as a break indicator, and they are evaluated together with other indicators obtained by pairwise comparisons. Optionally, ACMANTv5 gives access to users to edit the list of detected breaks based on the pairwise detections of the first homogenization round. In the later steps of ACMANTv5 user intervention is not possible, but metadata may be considered by the automatic procedure also in the final estimation of break positions.     </p>

Experimental Study on the Detection of Surface-Breaking Defects on Metal with the Scanning Laser Line Source Technique

2007 ◽  
Vol 364-366 ◽  
pp. 1117-1122
Author(s):  
Gang Yan ◽  
Chen Yin Ni ◽  
Yi Fei Shi ◽  
Zhong Hua Shen ◽  
Jian Lu ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Line Source ◽  
Surface Acoustic Waves ◽  
Interaction Mechanism ◽  
Experimental System ◽  
Laser Line ◽  
Scanning Laser ◽  
Electric Signal ◽  
Inspection Method ◽  
Small Surface

The scanning laser line source (SLLS) technique is a novel laser-based inspection method for the ultrasonic detection of small surface-breaking defects. The SLLS approach is based on monitoring the change in laser generated ultrasound as a laser line source is scanning over a defect. It has provided enhanced signal-to-noise performance compared to the traditional pitch-catch or pulse-echo ultrasonic methods. In this paper, an experimental method is presented to detect surface acoustic waves (SAW) with polyvinylindene fluoride(PVDF) transducer. The ultrasonic signal is converted into electric signal by piezoelectricity of the PVDF, which is attached to a micro-knife edge clamped on a metal device. The SAW are excited by employing a pulsed Nd:YAG laser on aluminum plate with artificial surface-breaking defects. The laser line source is accurately shifted by the motorized translation stage, while the PVDF is located at a fixed position on the specimen. When the laser line source is scanning over the defect, the ultrasonic signals are monitored, meanwhile the characteristic changes in the amplitude and frequency content are observed. Consequently, the position of the defect can be determined by analyzing the obtained signals. The experimental system with high sensitivity provides a detection method of small surface-breaking defects on metal and gives convincing experimental evidence for the interaction mechanism between the SAW and the surface-breaking defects.

scholarly journals Pole ratio and operation mode influence on the excitation system of three-stage synchronous starter/generator

2018 ◽  
Vol 2018 (13) ◽  
pp. 570-575 ◽  
Author(s):  
Chenghao Sun ◽  
Weiguo Liu ◽  
Zan Zhang ◽  
Ningfei Jiao ◽  
Ji Pang ◽  
...  
Keyword(s):  
Operation Mode ◽  
Excitation System ◽  
Starter Generator
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