Multiple-frequency synchronization of the four exciters in a far super-resonant vibrating system with an isolation frame

2021 ◽  
pp. 146134842110518
Author(s):  
Xueliang Zhang ◽  
Xu Zhang ◽  
Chen Zhang ◽  
Zhihui Wang ◽  
Bang-Chun Wen
Keyword(s):  
Single Frequency ◽  
Stable Phase ◽  
Frequency Synchronization ◽  
Multiple Frequency ◽  
Double Frequency ◽  
Vibrating System ◽  
Triple Frequency ◽  
Theoretical Condition ◽  
Synchronization Problems ◽  
Phase Differences

Generally, the synchronization studies on two or multiple exciters are preconditioned by being a single frequency, while the multiple-frequency synchronization problems in a vibrating system, including double-frequency and triple-frequency, are less considered, which are also very significant in engineering. This paper attempts to solve this issue by considering a dynamical model with an isolation frame, driven by the four exciters. The synchronization for the four exciters and its stability under the double-frequency and triple-frequency conditions are studied in detail. Firstly, the mathematical modeling of the system is established, and the corresponding motion differential equations are derived. Using the asymptotic method and the average method, yields the theoretical condition of implementing multiple-frequency synchronization, and the theoretical condition for stability of the system complies with the Routh–Hurwitz criterion. The dynamic characteristics of the system, including stable phase differences, stability abilities, responses of the system, and relative motion relationship, are qualitatively discussed by numeric. Finally, simulations are performed by applying a Runge–Kutta program to validate the theoretical and numerical qualitative results. It is shown that, by reasonably matching the key parameters of the system, the stronger, stable, and valuable motion states of vibrating machines, including vibration amplitudes, frequencies, and motion trajectory, can be realized, which are exactly the desires in engineering.

Self-synchronization theory of tri-motor excitation with double-frequency in far resonance system

2020 ◽  
Vol 234 (16) ◽  
pp. 3166-3184 ◽  
Author(s):  
Min Zou ◽  
Pan Fang ◽  
Yongjun Hou ◽  
Guodong Chai ◽  
Jinsong Chen
Keyword(s):  
Drilling Fluid ◽  
Structural Parameters ◽  
Rapid Development ◽  
Low Frequency ◽  
Single Frequency ◽  
Stable Phase ◽  
Resonance System ◽  
Double Frequency ◽  
Differential Motion ◽  
Motor Excitation

With the rapid development of petroleum exploitation industry, vibrating screen actuated with a single frequency is unsuitable to separate cuttings from drilling fluid, since it usually results in screen blocking. Hence, for solving the above-mentioned problem, tri-motor excitation with double-frequency in far resonance system is introduced. This paper aims to explore the self-synchronization mechanism of the proposed system. First, dynamic equation is established according to physical model of the system. Then, displacement response of the system in steady state is obtained with dynamic formulas. Subsequently, synchronous condition among the three exciters is determined by small parameters method, and criterion of synchronous stability among the three exciters is derived by Poincare-Lyapunov method. Finally, in light of the differential motion equation, Runge-Kutta principle is assigned to validate the reliability of self-synchronous theory and the stability of the double-frequency system. The results indicate that electromagnetic torques of low-frequency motors are dynamically antisymmetric in synchronous operation, and synchronous ability of the system is determined by the mass ratio among the rotors. In addition, stable phase difference among the rotors is significantly influenced by the structural parameters of the system. And this study will be helpful for the improvement of separation technology.

Stability Characteristics of a Vibrating System with Double Rigid Frames Driven by Four Co-Rotating Coupling Vibrators

2021 ◽  
pp. 2150137
Author(s):  
Xueliang Zhang ◽  
Hongliang Yue ◽  
Zhenmin Li ◽  
Wenchao Hu ◽  
Jinlin Xu ◽  
...  
Keyword(s):  
Equations Of Motion ◽  
Stable Phase ◽  
Stable Operation ◽  
Response Characteristics ◽  
Vibrating System ◽  
Resonant Region ◽  
Rigid Frames ◽  
Working Region ◽  
The Stability ◽  
Phase Differences

In this paper, a dynamic model is adopted to investigate the stability and response characteristics of a vibrating system driven by four vibrators placed on two different rigid frames (RFs). Using the equations of motion of the system derived, the conditions for synchronization and stable operation of the system are studied by the average method and Hamilton’s rules, respectively. Based on the theoretical results obtained, some factors are further studied concerning the stable phase differences (SPDs), the coefficients for ensuring stability, and the vibration amplitudes of the two RFs in different resonant regions. These serve to reveal the stability and response characteristics of the system that determine the ultimate function of the vibrating machine. Finally, numerical simulations are carried out to examine the validity of the theoretical methods and numerical qualitative results. Based on the results from the theory and simulation analyses, it is suggested that the working region of the system should be selected in the sub-resonant region corresponding to the natural frequency (NF) of the main vibrating system in the [Formula: see text]- and [Formula: see text]-directions. In this case, the ideal relative circular motion for two RFs with a well isolation effect can be achieved, and the energy is saved.

Relationships between ocean bottom noise and the environment

1994 ◽  
Vol 84 (6) ◽  
pp. 1991-2007 ◽  
Author(s):  
Jeffrey M. Babcock ◽  
Barry A. Kirkendall ◽  
John A. Orcutt
Keyword(s):  
Gravity Waves ◽  
Spectral Characteristics ◽  
Low Frequency ◽  
Environmental Data ◽  
Single Frequency ◽  
Frequency Noise ◽  
Ocean Bottom ◽  
Double Frequency ◽  
Frequency Peak ◽  
Northern Atlantic

Abstract Observations of ocean bottom low-frequency noise and surface environmental data over a period of 27 days in the northern Atlantic during the SAMSON and SWADE experiments reveal how closely related the noise is to meteorological conditions. Double-frequency microseisms produced by nonlinear interactions of storm-induced surface gravity waves are especially evident in the frequency band 0.16 to 0.3 Hz and show a high variability in both amplitude and peak frequencies. Bifurcated at times, the peak that characterizes the microseism band contains local and distant or “teleseismic” components, which are generated at different locations. Weather and storm fetch appear to be the major contributions to the size and shape of microseism spectra. Storm development on the sea surface is associated with progressively lower microseism frequencies along with a concurrent increase in amplitude. The single-frequency microseism peak is a continuous feature and is observed to portray the same time-dependent spectral characteristics as the portion of the double-frequency peak associated with distant storms. Coherence studies confirm that both peaks (single and teleseismic double) originate at a distant source. These peaks are generated at roughly the same location with some storm component over the coastline.

Estimation of Total Body and Extracellular Water Using Single-and Multiple-Frequency Bioimpedance

1994 ◽  
Vol 28 (5) ◽  
pp. 565-569 ◽  
Author(s):  
Rakesh V. Patel ◽  
James R. Matthie ◽  
Paul O. Withers ◽  
Edward L. Peterson ◽  
Barbara J. Zarowitz
Keyword(s):  
Deuterium Oxide ◽  
Acute Care Hospital ◽  
Single Frequency ◽  
Care Hospital ◽  
Extracellular Water ◽  
Multiple Frequency ◽  
Open Label ◽  
For Profit ◽  
The Mean ◽  
Total Body

OBJECTIVE: To determine the precision and bias of single- and multiple-frequency bioimpedance estimates of total body water (TBW) and extracellular water (ECW) volumes in comparison with the true values for these volumes established by gold standard dilution techniques. DESIGN: Controlled, prospective, open-label investigation. SETTING: Private, not-for-profit university-affiliated, acute care hospital. PARTICIPANTS: Normal, healthy men (n=8) and women (n=6) volunteers, 25–46 years of age. INTERVENTIONS: A single oral dose of a mixture of deuterium oxide 10 g and bromine 30 mmol; bioimpedance analysis pre- and three hours postrnixture administration. MAIN OUTCOME PARAMETERS: TBW and ECW volumes established by deuterium oxide and bromine dilutional spaces (gold standards), respectively, and single- and multiple-frequency bioimpedance estimates of those same volumes. RESULTS: The mean multiple-frequency bioimpedance (MFB) and single frequency bioimpedance (SFB) estimates of TBW, 41.2 and 42.1 L, respectively, were not statistically different (NS) from the 41.2 L deuterium oxide value. Although the two methods had similar precision (NS), MFB was less biased. For ECW, the mean MFB and SFB values of 19.5 and 24.8 L, respectively, were significantly different from the bromine value of 18.8 L (p=0.013 and p=0.001, respectively). MFB was the more precise and less biased predictor of ECW. CONCLUSIONS: Compared with SFB, the MFB approach is a more precise and less biased predictor of TBW and ECW volumes in young, healthy adults, and may offer more accurate assessment in subjects with aberrant physiology.

Nonparametric Methodology to Estimate Precipitating Ice from Multiple-Frequency Radar Reflectivity Observations

2018 ◽  
Vol 57 (11) ◽  
pp. 2605-2622 ◽  
Author(s):  
Mircea Grecu ◽  
Lin Tian ◽  
Gerald M. Heymsfield ◽  
Ali Tokay ◽  
William S. Olson ◽  
...  
Keyword(s):  
Estimation Method ◽  
Optimal Estimation ◽  
Radar Reflectivity ◽  
Nonparametric Method ◽  
Multiple Frequency ◽  
Radar Observations ◽  
Triple Frequency ◽  
Olympic Mountains ◽  
Field Campaigns

AbstractIn this study, a nonparametric method to estimate precipitating ice from multiple-frequency radar observations is investigated. The method does not require any assumptions regarding the distribution of ice particle sizes and relies on an efficient search procedure to incorporate information from observed particle size distributions (PSDs) in the estimation process. Similar to other approaches rooted in optimal-estimation theory, the nonparametric method is robust in the presence of noise in observations and uncertainties in the forward models. Over 200 000 PSDs derived from in situ observations collected during the Olympic Mountains Experiment (OLYMPEX) and Integrated Precipitation and Hydrology Experiment (IPHEX) field campaigns are used in the development and evaluation of the nonparametric estimation method. These PSDs are used to create a database of ice-related variables and associated computed radar reflectivity factors at the Ku, Ka, and W bands. The computed reflectivity factors are used to derive precipitating ice estimates and investigate the associated errors and uncertainties. The method is applied to triple-frequency radar observations collected during OLYMPEX and IPHEX. Direct comparisons of estimated ice variables with estimates from in situ instruments show results consistent with the error analysis. Global application of the method requires an extension of the supporting PSD database, which can be achieved through the processing of information from additional past and future field campaigns.

scholarly journals A Multispectral Bayesian Classification Method for Increased Acoustic Discrimination of Seabed Sediments Using Multi-Frequency Multibeam Backscatter Data

Geosciences ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 455 ◽  
Author(s):  
Timo Gaida ◽  
Tengku Tengku Ali ◽  
Mirjam Snellen ◽  
Alireza Amiri-Simkooei ◽  
Thaiënne van Dijk ◽  
...  
Keyword(s):  
Ground Truth ◽  
Single Frequency ◽  
Qualitative Comparison ◽  
Ground Truth Data ◽  
Geological Interpretation ◽  
Additional Information ◽  
Triple Frequency ◽  
Acoustic Discrimination ◽  
Multiple Frequencies ◽  
Seabed Sediments

Multi-frequency backscatter data collected from multibeam echosounders (MBESs) is increasingly becoming available. The ability to collect data at multiple frequencies at the same time is expected to allow for better discrimination between seabed sediments. We propose an extension of the Bayesian method for seabed classification to multi-frequency backscatter. By combining the information retrieved at single frequencies we produce a multispectral acoustic classification map, which allows us to distinguish more seabed environments. In this study we use three triple-frequency (100, 200, and 400 kHz) backscatter datasets acquired with an R2Sonic 2026 in the Bedford Basin, Canada in 2016 and 2017 and in the Patricia Bay, Canada in 2016. The results are threefold: (1) combining 100 and 400 kHz, in general, reveals the most additional information about the seabed; (2) the use of multiple frequencies allows for a better acoustic discrimination of seabed sediments than single-frequency data; and (3) the optimal frequency selection for acoustic sediment classification depends on the local seabed. However, a quantification of the benefit using multiple frequencies cannot clearly be determined based on the existing ground-truth data. Still, a qualitative comparison and a geological interpretation indicate an improved discrimination between different seabed environments using multi-frequency backscatter.

Timing Characterization of Multiple Timing Domains

2002 ◽  
Author(s):  
Al an J. Weger ◽  
Moyra McManus ◽  
Peilin Song ◽  
Andy Muszynski
Keyword(s):  
Simultaneous Measurement ◽  
Single Frequency ◽  
Multiple Frequency ◽  
Simple Modification ◽  
Frequency Domains ◽  
Measurement Tools ◽  
Timing Measurement ◽  
Multiple Frequencies ◽  
On Chip

Abstract Commonly used timing measurement tools are often limited to probing a circuit running at one single frequency [1,2]. In reality, multiple frequencies may be present on chip, and that can lead to timing problems which render the chip inoperable within certain frequency ranges. We will describe a simple modification to a Picosecond Imaging Circuit Analysis (PICA [3]) instrumentation whih permits the simultaneous measurement of timing in multiple frequency domains.

Properties of pulse single-frequency laser and extra-cavity double frequency green laser

2015 ◽  
Vol 8 (5) ◽  
pp. 800-805
Author(s):  
董磊 DONG Lei ◽  
刘欣悦 LIU Xin-yue ◽  
陈浩 CHEN Hao
Keyword(s):  
Green Laser ◽  
Single Frequency ◽  
Double Frequency ◽  
Frequency Laser
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