Modeling the Loading-Rate Dependency of the Hysteretic Dynamics of Magnetorheological Dampers

2011 ◽  
Vol 55-57 ◽  
pp. 807-812
Author(s):  
Cheng Zhang ◽  
Lin Xiang Wang
Keyword(s):  
Phase Transition ◽  
Nonlinear System ◽  
Loading Rate ◽  
Experimental Results ◽  
Transition Theory ◽  
Current Paper ◽  
Magnetorheological Dampers ◽  
Rate Dependency ◽  
Mr Dampers ◽  
Proposed Model

The loading rate dependency of the hysteretic dynamics of Magnetorheological (MR) dampers is investigated in the current paper. The model is constructed on the basis of a phenomenological phase-transition theory. The hysteretic dynamics is treated as the responses of a nonlinear system upon external loadings. With appropriately chosen coefficients, the proposed model is able to capture the loading-rate dependency feature of the hysteretic dynamics. Comparisons between the numerical and experimental results are presented, and perfect agreements are obtained.

Dynamic Models for Magnetorheological Dampers and its Feedback Linearization

2009 ◽  
Vol 79-82 ◽  
pp. 1205-1208 ◽  
Author(s):  
Cheng Zhang ◽  
Lin Xiang Wang
Keyword(s):  
Differential Equation ◽  
Phase Transition ◽  
Ordinary Differential Equation ◽  
Feedback Linearization ◽  
Dynamic Models ◽  
Nonlinear Ordinary Differential Equation ◽  
Transition Theory ◽  
Magnetorheological Dampers ◽  
Differential Model ◽  
Mr Dampers

In the current paper, the hysteretic dynamics of magnetorheological dampers is modeled by a differential model. The differential model is constructed on the basis of a phenomenological phase transition theory. The model is expressed as a second order nonlinear ordinary differential equation with bifurcations embedded in. Due to the differential nature of the model, the hysteretic dynamics of the MR dampers can be linearized and controlled by introducing a feedback linearization strategy.

Connected-Tube MPP Model for Unsupervised 3D Fiber Detection

2020 ◽  
Vol 2020 (14) ◽  
pp. 305-1-305-6
Author(s):  
Tianyu Li ◽  
Camilo G. Aguilar ◽  
Ronald F. Agyei ◽  
Imad A. Hanhan ◽  
Michael D. Sangid ◽  
...  
Keyword(s):  
Composite Material ◽  
Point Process ◽  
Marked Point ◽  
Experimental Results ◽  
Marked Point Process ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite ◽  
Proposed Model ◽  
Cylinder Model ◽  
Reinforced Composite Material

In this paper, we extend our previous 2D connected-tube marked point process (MPP) model to a 3D connected-tube MPP model for fiber detection. In the 3D case, a tube is represented by a cylinder model with two spherical areas at its ends. The spherical area is used to define connection priors that encourage connection of tubes that belong to the same fiber. Since each long fiber can be fitted by a series of connected short tubes, the proposed model is capable of detecting curved long tubes. We present experimental results on fiber-reinforced composite material images to show the performance of our method.

Dynamic changes in spatial microbial distribution in mixed-population biofilms: experimental results and model simulation

1995 ◽  
Vol 32 (8) ◽  
pp. 67-74 ◽  
Author(s):  
Satoshi Okabe ◽  
Kikuko Hirata ◽  
Yoshimasa Watanabe
Keyword(s):  
Oxygen Diffusion ◽  
Loading Rate ◽  
Model Simulation ◽  
Mixed Population ◽  
Experimental Results ◽  
Synthetic Wastewater ◽  
Diffusion Limitation ◽  
Dynamic Changes ◽  
Microbial Distribution ◽  
Rotating Biological Contactors

Dynamic changes in spatial microbial distribution in mixed-population biofilms were experimentally determined using a microslicer technique and simulated by a biofilm accumulation model (BAM). Experimental results were compared with the model simulation. The biofilms cultured in partially submerged rotating biological contactors (RBC) with synthetic wastewater were used as test materials. Experimental results showed that an increase of substrate loading rate (i.e., organic carbon and NH4-N) resulted in the microbial stratification in the biofilms. Heterotrophs defeated nitrifiers and dominated in the outer biofilm, whereas nitrifiers were diluted out in the outer biofilm and forced into the inner biofilm. At higher organic loading rates, a stronger stratified microbial spatial distribution was observed, which imposed a severe internal oxygen diffusion limitation on nitrifiers and resulted in the deterioration of nitrification efficiency. Model simulations described a general trend of the stratified biofilm structure. However, the actual stratification was stronger than the simulated results. For implication in the reactor design, when the specific carbon loading rate exceeds a certain limit, nitrification will be deteriorated or require a long start-up period due to the interspecies competition resulting in oxygen diffusion limitation. The extend of microbial stratification in the biofilm is especially important for determination of feasibility of nitrification in the presence of organic matters.

Aeration characteristics of a rectangular stepped cascade system

2010 ◽  
Vol 61 (2) ◽  
pp. 415-420 ◽  
Author(s):  
Sanjib Moulick ◽  
Naresh V. Tambada ◽  
Basant K. Singh ◽  
B. C. Mal
Keyword(s):  
Surface Area ◽  
Loading Rate ◽  
Experimental Results ◽  
Step Height ◽  
Optimum Number ◽  
Hydraulic Loading Rate ◽  
Hydraulic Loading ◽  
Aeration Efficiency ◽  
Stepped Cascade ◽  
Independent Parameters

Aeration experiments, maintaining nappe flow conditions, were carried out on a rectangular stepped cascade of total height 3.0 m to determine the total number of steps, slope of the entire cascade and hydraulic loading rate at which maximum overall aeration efficiency occurs, keeping the surface area of individual steps constant. Based on dimensional analysis, the overall aeration efficiency at standard conditions (E20) was expressed as a function of square of total number of steps (N2) and dimensionless discharge (dc/h), where dc and h represent critical depth in a rectangular prismatic channel and individual step height respectively. An empirical equation with E20 as the response and N2 and dc/h as the independent parameters was developed based on the experimental results subject to 36 ≤ N2 ≤ 196 and 0.009 ≤ dc/h ≤ 0.144. The experimental results showed that the overall aeration efficiency (E20) for a particular step height of stepped cascade increases with increase in dc/h up to a certain value and then decreases. This may be due to at higher dc/h, i.e., at higher hydraulic loading rate, the flow approaches the transition zone and thereby aeration efficiency decreases. E20 was also found to increase with number of steps at any hydraulic loading rate, because of the increased surface area of fall. The optimum number of steps, slope of the entire stepped cascade and hydraulic loading rate were found to be 14, 0.351 and 0.009 m2/s respectively producing the maximum value of overall aeration efficiency of 0.90.

Semi-Active Damping of Ground Resonance in Helicopters Using Magnetorheological Dampers

2000 ◽  
Author(s):  
Norman M. Wereley ◽  
Nicolas Costes
Keyword(s):  
Mr Damper ◽  
Active Damping ◽  
Rotor System ◽  
Magnetorheological Dampers ◽  
Resonance Analysis ◽  
Mr Dampers ◽  
Resonance Behavior ◽  
Ground Resonance ◽  
And Control

Abstract We will assess the capabilities of physically motivated MR dampers to mitigate ground resonance instability and control the damping level of rotor lag modes. The objectives of this research are threefold: (1) develop a methodology for the integration of the MR damper into a classic linear ground resonance analysis assuming an isotropic rotor hub (all dampers and blades similar) and an anisotropic rotor hub (due to lag damper dissimilarity due to damage, for example), (2) assess whether MR dampers can stabilize a rotor system that exhibits unstable ground resonance, (3) assess whether MR dampers can stabilize a rotor which exhibits unstable ground resonance behavior due to lag damper degradation or damage. The analyses developed in this study show that MR dampers are feasible for achieving these goals.

scholarly journals Multimedia Quality Integration Using Piecewise Function

2011 ◽  
Vol 1 ◽  
pp. 375-380
Author(s):  
Shu Ai Wan ◽  
Kai Fang Yang ◽  
Hai Yong Zhou
Keyword(s):  
Visual Quality ◽  
Experimental Results ◽  
Integration Model ◽  
Quality Performance ◽  
Piecewise Function ◽  
Proposed Model ◽  
Constant Coefficients ◽  
Theoretical Analyses ◽  
Different Levels

In this paper the important issue of multimedia quality evaluation is concerned, given the unimodal quality of audio and video. Firstly, the quality integration model recommended in G.1070 is evaluated using experimental results. Theoretical analyses aide empirical observations suggest that the constant coefficients used in the G.1070 model should actually be piecewise adjusted for different levels of audio and visual quality. Then a piecewise function is proposed to perform multimedia quality integration under different levels of the audio and visual quality. Performance gain observed from experimental results substantiates the effectiveness of the proposed model.

scholarly journals Experimental Study and Extended Finite Element Simulation of Fracture of Self-Compacting Rubberized Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xinquan Wang ◽  
Hongguo Diao ◽  
Yunliang Cui ◽  
Changguang Qi ◽  
Shangyu Han
Keyword(s):  
Finite Element ◽  
Loading Rate ◽  
High Performance Concrete ◽  
The Self ◽  
Experimental Results ◽  
Crack Mouth Opening Displacement ◽  
Displacement Curve ◽  
Rubberized Concrete ◽  
Extended Finite Element ◽  
Self Compacting Concrete

Self-compacting rubberized concrete (SCRC) is a high-performance concrete that can achieve compacting effect by self-gravity without vibration during pouring. Because of its excellent fluidity, homogeneity, and stability, the application of self-compacting concrete in engineering can improve work efficiency and reduce project cost. The effects of loading rate on the fracture behavior of self-compacting concrete were studied in this paper. Three-point bend (TPB) tests were carried out at five loading rates of 1, 0.1, 0.001, 0.0001, and 0.00001 mm/s. The dimensions of the specimens were 100  mm × 100 mm × 400 mm. A precast crack was set in the middle of the specimen with a notch-depth ratio of 0.4. The experimental results show that the peak load on the load-CMOD (crack mouth opening displacement) curve gradually increases with the increase of the loading rate. Although the fracture energy a presented greater dispersion under the loading rate of 1 mm/s, the overall changes were still rising with the increase of the loading rate. Besides studying the softening characteristics of the self-compacting concrete, the constitutive softening curve of the self-compacting concrete was obtained using the bilinear model. Finally, curved three-point bending beams were simulated by using the extended finite element method based on ABAQUS. The fracture process of the self-compacting concrete under different loading conditions was analyzed more intuitively. The simulation results were compared with the experimental results, and the same conclusions were obtained.

scholarly journals Ударно-волновой полиморфный переход в пористом графите

2021 ◽  
Vol 91 (11) ◽  
pp. 1707
Author(s):  
С.А. Кинеловский
Keyword(s):  
Phase Transition ◽  
Shock Wave ◽  
Elastic Energy ◽  
Polymorphic Transformation ◽  
Polymorphic Transition ◽  
Initial Structure ◽  
Graphite Phase ◽  
Proposed Model ◽  
Porous Graphite ◽  
Wide Range

For the polymorphic transformation of porous graphite in the shock, the previously proposed model linking the process of graphite phase transition with a change in the elastic energy of a substance has been tested. It is shown that the model plausibly describes the experimental results outside the transition zone in a fairly wide range of changes in the porosity of samples with their different initial structure. It is discussed how the model under consideration changes the currently existing ideas about the thermodynamics of the polymorphic transition of matter in a shock wave.

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