A coupled interannual oscillation system

2000 ◽  
Vol 18 (3) ◽  
pp. 216-220 ◽  
Author(s):  
Wang Qi ◽  
Liu Qin-yu ◽  
Li Li
Keyword(s):  
Oscillation System ◽  
Interannual Oscillation

Belousov–Zhabotinskii type oscillation reaction with glycerol and kinetics of reactions between the system components

1987 ◽  
Vol 52 (10) ◽  
pp. 2375-2382 ◽  
Author(s):  
Ľubica Adamčíková ◽  
Peter Ševčík
Keyword(s):  
Oscillation System ◽  
Chemical Oscillations ◽  
Oscillation Reaction ◽  
Reaction Solution ◽  
System Components ◽  
Probable Source ◽  
Belousov Zhabotinskii Reaction ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Type Oscillation

Glycerol causes chemical oscillations in Belousov-Zhabotinskii reaction in a closed system as well as in a reaction solution bubbled with nitrogen. Since the oxidation of glycerol with bromate ions does not proceed autocatalytically and bromine in the oxidation state 0 or +1 in the absence of light does not react with glycerol, hydrolysis of bromine is the probable source of bromide ions in the studied oscillation system.

scholarly journals Acoustic Modeling and Vibration Characteristics of Supersonic Inlet Buzz

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2048
Author(s):  
Jianfeng Zhu ◽  
Wenguo Luo ◽  
Yuqing Wei ◽  
Cheng Yan ◽  
Yancheng You
Keyword(s):  
Numerical Simulations ◽  
Pressure Oscillation ◽  
Resonant Mode ◽  
Acoustic Model ◽  
Oscillation System ◽  
Nonlinear Simulation ◽  
Supersonic Inlet ◽  
Nonlinear Amplification ◽  
Oscillation Damping ◽  
The Ideal

The buzz phenomenon of a typical supersonic inlet is analyzed on the basis of numerical simulations and duct acoustic theory. Considering that the choked inlet could be treated as a duct with one end closed, a one-dimensional (1D) mathematical model based on the duct acoustic theory is proposed to describe the periodic pressure oscillation of the little buzz and the big buzz. The results of the acoustic model agree well with that of the numerical simulations and the experimental data. It could verify that the dominated oscillation patterns of the little buzz and the big buzz are closely related to the first and second resonant mode of the standing wave, respectively. The discrepancies between the numerical simulation and the ideal acoustic model might be attributed to the viscous damping in the fluid oscillation system. In order to explore the damping, a small perturbation jet is introduced to trigger the resonance of the buzz system and the nonlinear amplification effect of resonance might be helpful to estimate the damping. Through the comparison between the linear acoustic model and the nonlinear simulation, the calculated pressure oscillation damping of the little buzz and the big buzz are 0.33 and 0.16, which could be regarded as an estimation of real damping.

Aspects Regarding the Achievement of Vertical Welding Joints

2015 ◽  
Vol 1128 ◽  
pp. 254-260 ◽  
Author(s):  
Radu Cristian Seculin ◽  
Barna Fazakas ◽  
Teodor Machedon Pisu ◽  
Mihai Alin Pop
Keyword(s):  
Point Of View ◽  
Steel Plates ◽  
Welding Parameters ◽  
Welding Wire ◽  
Oscillation System ◽  
Welded Steel ◽  
Welding Torch ◽  
Welding Joints ◽  
Protective Gas ◽  
Welding Procedure

The vertical MAG welding procedure is a difficult position to be executed because the trend of the molten bath flowing. This article aims to present the achievement of vertical welding joints with a linear device with a radial oscillation system that should achieve automatic vertical welds and the correlation of the welding parameters with the movement of the welding torch in order to obtain these, using the MAG procedure, protective gas M 21 (82% argon + 18% CO2), welding wire SG2, the material of the welded pieces S 355 JR. Samples will be cut from the welded steel plates and they will be characterized from the mechanical point of view (hardness, microstructure and macrostructure).

A purely mechanical forced oscillation system

1972 ◽  
Vol 7 (6) ◽  
pp. 391-394 ◽  
Author(s):  
P P Ong
Keyword(s):  
Forced Oscillation ◽  
Oscillation System

scholarly journals Continuous Hydrothermal Liquefaction of Biomass in a Novel Pilot Plant with Heat Recovery and Hydraulic Oscillation

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2695 ◽  
Author(s):  
Konstantinos Anastasakis ◽  
Patrick Biller ◽  
René Madsen ◽  
Marianne Glasius ◽  
Ib Johannsen
Keyword(s):  
Heat Exchanger ◽  
Sewage Sludge ◽  
Palmitic Acid ◽  
Pilot Plant ◽  
Heat Recovery ◽  
Hydrothermal Liquefaction ◽  
Dry Matter Content ◽  
Oscillation System ◽  
Run Time ◽  
Hydraulic Oscillation

Hydrothermal liquefaction (HTL) is regarded as a promising technology for the production of biofuels from biomass and wastes. As such, there is a drive towards continuous-flow processing systems to aid process scale-up and eventually commercialization. The current study presents results from a novel pilot-scale HTL reactor with a feed capacity of up to 100 L/h and a process volume of approximately 20 L. The pilot plant employs a heat exchanger for heat recovery and a novel hydraulic oscillation system to increase the turbulence in the tubular reactor. The energy grass Miscanthus and the microalgae Spirulina, both representing advanced dedicated energy crops, as well as sewage sludge as high-potential waste stream were selected to assess the reactor performance. Biomass slurries with up to 16 wt% dry matter content were successfully processed. The heat recovery of the heat exchanger is found to increase with reactor run time, reaching 80% within 5–6 h of operation. The hydraulic oscillation system is shown to improve mixing and enhance heat transfer. Bio-crudes with average yields of 26 wt%, 33 wt% and 25 wt% were produced from Miscanthus, Spirulina and sewage sludge, respectively. The yields also appeared to increase with reactor run time. Bio-crude from HTL of Spirulina was mainly composed of palmitic acid, glycerol, heptadecane and linolelaidic acid, while biocrude from sewage sludge contained mainly palmitic acid, oleic acid and stearic acid. In contrast, biocrude from HTL of Miscanthus consisted of a large number of different phenolics. An energetic comparison between the three feedstocks revealed a thermal efficiency of 47%, 47% and 33% and energy return on investment (EROI) of 2.8, 3.3 and 0.5 for HTL of Miscanthus, Spirulina and sewage sludge, respectively.

scholarly journals Research on Precise Control of a Cylinder Delay Oscillation System Based on Response Surface and Genetic Algorithm

2021 ◽  
Vol 2083 (4) ◽  
pp. 042060
Author(s):  
Zhongfu Bao ◽  
Dejiang Zeng ◽  
Runxi Gu
Keyword(s):  
Genetic Algorithm ◽  
Time Delay ◽  
Response Surface ◽  
Dwell Time ◽  
Simulation Analysis ◽  
Oscillation System ◽  
Precise Control ◽  
Throttle Valve ◽  
Air Bag ◽  
Main Component

Abstract A cylinder time-delay oscillation system can be constructed by using air bag and throttle valve. The air bag and throttle valve are used to realize the time-delay transmission of pressure in the feedback circuit, and the feedback pressure is used to promote the reversing of two position five-way valve, so as to realize the reciprocating action of the cylinder. The experimental design is carried out based on the simulation analysis, and the response surface is constructed based on the experimental data to clarify the relationship between the cylinder dwell time and the main component parameters. Based on response surface, genetic algorithm is used to search for the best control parameters to realize the accurate control of cylinder dwell time.

Nonlinearity and periodic solution of a standard-beam balance oscillation system

2012 ◽  
Vol 21 (6) ◽  
pp. 064601 ◽  
Author(s):  
Shi-Song Li ◽  
Jiang Lan ◽  
Bing Han ◽  
Hong Tan ◽  
Zheng-Kun Li
Keyword(s):  
Periodic Solution ◽  
Oscillation System ◽  
Beam Balance

Operational modal analysis of a nonlinear oscillation system under a harmonic excitation

2020 ◽  
pp. 095440622097755
Author(s):  
Xuchu Jiang ◽  
Feng Jiang ◽  
Biao Zhang
Keyword(s):  
Modal Analysis ◽  
Nonlinear Oscillation ◽  
Normal Modes ◽  
Nonlinear Normal Modes ◽  
Harmonic Excitation ◽  
Forced Response ◽  
Operational Modal Analysis ◽  
Single Frequency ◽  
Modal Parameters ◽  
Oscillation System

Operational modal analysis (OMA) is a procedure that allows the modal parameters of a structure to be extracted from the measured response to an unknown excitation generated during operation. Nonlinearity is inevitably and frequently encountered in OMA. The problem: The traditional OMA method based on linear modal theory cannot be applied to a nonlinear oscillation system. The solution: This paper aims to propose a nonlinear OMA method for nonlinear oscillation systems. The new OMA method is based on the following: (1) a self-excitation phenomenon is caused by nonlinear components; (2) the nonlinear normal modes (NNMs) of the system appear under a single-frequency harmonic excitation; and (3) using forced response data, the symbolic regression method (SR) can be used to automatically search for the NNMs of the system, whose modal parameters are implicit in the expression structure expressing each NNM. The simulation result of a three-degree-of-freedom (3-DOF) nonlinear system verifies the correctness of the proposed OMA method. Then, a disc-rod rotor model is considered, and the proposed OMA method’s capability is further evaluated.

Theoretical and experimental studies of a novel nested oscillator with a high-damping characteristic

2020 ◽  
pp. 107754632094378
Author(s):  
Haiping Liu ◽  
Kaili Xiao ◽  
PengPeng Zhao ◽  
Dongmei Zhu
Keyword(s):  
Resonant Frequency ◽  
Vibration Suppression ◽  
Damping Ratio ◽  
Experimental Studies ◽  
Harmonic Balance Method ◽  
Design Parameters ◽  
Base Excitation ◽  
Oscillation System ◽  
Equivalent Damping ◽  
Vibration Transmissibility

Stiffness and damping of a structure usually show the opposite change so that the resonant frequency and the static load bearing capacity of a mechanical system often exhibit contradiction. To solve this dilemma, a novel high-damping oscillator which is constructed by a nested diamond structure with the purpose of enhancing the damping property is proposed in this study without reducing the overall systematic stiffness. The mathematical model and geometrical relationships are established at first. And then, the steady-state solutions under base excitation are derived by using the harmonic balance method and further verified by numerical simulation. In addition, the effects of some design parameters on the equivalent damping ratio for the high-damping oscillator are studied to reveal the nonlinear characteristic. Besides, the natural frequency of the nonlinear oscillator is also presented and investigated. By using the displacement transmissibility and comparing with the traditional linear isolator with the same overall stiffness, the vibration suppression performance of the high-damping oscillator is addressed. The obtained calculating results demonstrate that the vibration control performance of the high-damping oscillator outperforms the linear counterpart around resonant frequency. Moreover, the influences of systematic parameters of the high-damping oscillator for the base excitation case on the vibration transmissibility are also discussed, respectively. Finally, an experimental campaign is conducted on an in-house-built test rig to corroborate the accuracy of the analytical solutions of the high-damping oscillation system. The results discussed in this study provide a useful guideline, which can help to design this class of high-damping oscillation system.

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