scholarly journals Uncertainty Analysis of Quasi-Zero Stiffness Air Suspension based on Polynomial Chaos Method

2021 ◽  
Author(s):  
Xing Xu ◽  
Huan Liu ◽  
Xinwei Jiang ◽  
Akolbire Vincent Atindana
Keyword(s):  
Vibration Isolation ◽  
Polynomial Chaos ◽  
Structural Parameters ◽  
Practical Importance ◽  
Structural Complexity ◽  
Structural Parameter ◽  
Strong Nonlinearity ◽  
Performance Parameters ◽  
Air Suspension ◽  
Suspension Performance

Abstract In order to improve the vibration isolation performance of suspensions, various new structural forms of suspensions have been proposed. In this paper, a quasi-zero stiffness isolator is used in automotive suspensions to form a new suspension-quasi-zero stiffness air suspension(QZSAS).Due to the strong nonlinearity and structural complexity of quasi-zero stiffness suspensions, changes in structural parameters may cause dramatic changes in suspension performance, so it is of practical importance to study the effect of structural parameter uncertainty on the performance of such suspensions. In order to solve this problem, three suspension structural parameters d0,L0,Pc0 are selected as random variables in this paper, and the polynomial chaos expansion(PCE) theory is used to solve the suspension performance parameters such as body acceleration, suspension dynamic deflection, and wheel relative dynamic load response under different excitation. The sensitivity of the performance parameters to different structural parameters was discussed and analysed in the frequency domain. This paper verifies the feasibility of the PCE method for solving the uncertainty problem of complex nonlinear systems, and the research in this paper can provide a reference for the future structural design and optimization of such suspension systems.

scholarly journals Modeling and Dynamics of a MDOF Isolation System

2017 ◽  
Author(s):  
Youshuo Song ◽  
Xiuting Sun
Keyword(s):  
Vibration Isolation ◽  
Vibration Suppression ◽  
Structural Parameters ◽  
Structural Parameter ◽  
Isolation System ◽  
Passive Components ◽  
Vibration Isolation System ◽  
Joint Friction ◽  
Engineering Practices ◽  
Stiffness And Damping

This study analyzes the modeling and dynamics of a novel passive in Multi-Degree-of-Freedom (MDOF) vibration isolation platform which can achieve significant isolation effect. Symmetrical Scissor-Like structures (SLSs) are utilized in the proposed MDOF isolation platform as the supporting and isolation elastic components. Based on the mathematical modeling and theoretical analysis of the MDOF vibration isolation system with SLSs, the effect of structural parameter and joint friction on stiffness and damping properties is investigated. It is shown that due to geometric relations within the SLSs, the natural frequencies can be reduced via adjusting structural parameters of the SLS for different direction vibration isolation. Theoretical and experimental results show that the SLS isolation platform can achieve much better loading capacity and vibration isolation performance simultaneously by only using linear passive components because of the MDOF adjustable stiffness property. Therefore, with low costing and energy consumption, the proposed novel isolation platform can provide the improvement of vibration suppression in various engineering practices.

Dispersion properties of single-mode optical fibers in telecommunication region: poly (methyl methacrylate) (PMMA) versus silica

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hassan Pakarzadeh ◽  
Seyed Mostafa Rezaei ◽  
Mostafa Taghizadeh ◽  
Forough Bozorgzadeh
Keyword(s):  
Methyl Methacrylate ◽  
Optical Fibers ◽  
Spectral Range ◽  
Structural Parameters ◽  
Practical Importance ◽  
Single Mode ◽  
Dispersion Characteristics ◽  
Poly Methyl Methacrylate ◽  
Dispersion Wavelength ◽  
Zero Dispersion Wavelength

AbstractIn this paper, the dispersion characteristics of two standard single-mode optical fibers (SMFs), fabricated with silica and poly (methyl methacrylate) (PMMA) are studied in telecommunication spectral regions. The effect of structural parameters, such as the radius of the fiber core and the relative core-cladding index difference, is numerically investigated. It is found that over whole spectral range, the PMMA-based SMF shows lower dispersion than the silica SMF. Also, the zero-dispersion wavelength (ZDW) of PMMA-based SMF is longer than that of silica fiber. The results may be of practical importance for the telecommunication applications.

scholarly journals Electromagnetic and Mechanical Characteristics Analysis of a Flat-Type Vertical-Gap Passive Magnetic Levitation Vibration Isolator

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Baoquan Kou ◽  
Yiheng Zhou ◽  
Xiaobao Yang ◽  
Feng Xing ◽  
He Zhang
Keyword(s):  
Vibration Isolation ◽  
Mechanical Characteristics ◽  
Magnetic Levitation ◽  
Structural Parameters ◽  
Force Density ◽  
Vibration Isolator ◽  
Isolation System ◽  
Flat Type ◽  
Characteristics Analysis ◽  
Vertical Gap

In this paper, we describe a flat-type vertical-gap passive magnetic levitation vibration isolator (FVPMLVI) for active vibration isolation system (AVIS). A dual-stator scheme and a special stator magnet array are adopted in the proposed FVPMLVI, which has the effect of decreasing its natural frequency, and this enhances the vibration isolation capability of the FVPMLVI. The structure, operating principle, analytical model, and electromagnetic and mechanical characteristics of the FVPMLVI are investigated. The relationship between the force characteristics (levitation force, horizontal force, force ripple, and force density) and major structural parameters (width and thickness of stator and mover magnets) is analyzed by finite element method. The experiment result is in good agreement with the theoretical analysis.

scholarly journals Wavelet multi-resolution approximation of time-varying frame structure

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401879559 ◽  
Author(s):  
Min Xiang ◽  
Feng Xiong ◽  
Yuanfeng Shi ◽  
Kaoshan Dai ◽  
Zhibin Ding
Keyword(s):  
Parameter Estimation ◽  
Degrees Of Freedom ◽  
Structural Parameters ◽  
Identification Problem ◽  
Frame Structure ◽  
Structural Parameter ◽  
Time Varying ◽  
Engineering Structures ◽  
Time Frequency ◽  
Non Parametric

Engineering structures usually exhibit time-varying behavior when subjected to strong excitation or due to material deterioration. This behavior is one of the key properties affecting the structural performance. Hence, reasonable description and timely tracking of time-varying characteristics of engineering structures are necessary for their safety assessment and life-cycle management. Due to its powerful ability of approximating functions in the time–frequency domain, wavelet multi-resolution approximation has been widely applied in the field of parameter estimation. Considering that the damage levels of beams and columns are usually different, identification of time-varying structural parameters of frame structure under seismic excitation using wavelet multi-resolution approximation is studied in this article. A time-varying dynamical model including both the translational and rotational degrees of freedom is established so as to estimate the stiffness coefficients of beams and columns separately. By decomposing each time-varying structural parameter using one wavelet multi-resolution approximation, the time-varying parametric identification problem is transformed into a time-invariant non-parametric one. In solving the high number of regressors in the non-parametric regression program, the modified orthogonal forward regression algorithm is proposed for significant term selection and parameter estimation. This work is demonstrated through numerical examples which consider both gradual variation and abrupt changes in the structural parameters.

The Experimental Research of Vibration Isolation Performance of MR Isolator at High Temperature

2012 ◽  
Vol 184-185 ◽  
pp. 525-528 ◽  
Author(s):  
Hui Yan ◽  
Liang Chen ◽  
Hong Rui Ao ◽  
Hong Yuan Jiang
Keyword(s):  
Vibration Isolation ◽  
Evaluation Index ◽  
Structural Parameter ◽  
Sweep Frequency ◽  
Frequency Test ◽  
Metal Rubber ◽  
Performance Evaluation Index ◽  
Vibration Isolation Performance ◽  
Isolation Performance ◽  
Sine Sweep

Transmissibility is the main performance evaluation index of Metal Rubber (MR) isolator, which can be got by sine sweep frequency test. At different temperature, the sine sweep frequency test is done with different structural parameter MR isolator. The influence that relative density and pre-deformation have on transmissibility and natural frequency when temperature changed is analyzed. The changing regularity of MR isolator’s transmissibility at different temperature is explored. Research results provide the basis for designing MR isolator.

scholarly journals Influence of response time of magnetorheological valve in Skyhook controlled three-parameter damping system

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401881119 ◽  
Author(s):  
Zbyněk Strecker ◽  
Jakub Roupec ◽  
Ivan Mazůrek ◽  
Ondřej Macháček ◽  
Michal Kubík
Keyword(s):  
Response Time ◽  
Control Algorithm ◽  
Vibration Isolation ◽  
Suspension System ◽  
Magnetorheological Damper ◽  
Semiactive Control ◽  
Control Loop ◽  
Space Industry ◽  
Magnetorheological Valve ◽  
Suspension Performance

A three-parameter suspension system is often used for vibration isolation of sensitive devices especially in a space industry. This article describes the three-parameter suspension system with magnetorheological valve controlled by Skyhook algorithm. Simulations of such systems showed promising results. They, however, showed that the suspension performance is strongly influenced by magnetorheological valve response time. Results from simulations proved that the semiactive control of such system with response time of magnetorheological damper up to 4 ms outperforms any passive setting. The simulations were verified by an experiment on suspension system with magnetorheological valve with response time between 3.5 and 4.1 ms controlled by a Skyhook algorithm. Although the control algorithm was slightly modified in order to prevent instabilities of control loop caused by signal noise, the results from the experiment showed the same trends like the simulations.

Studies of molecular structure parameters of 20-piperidin-2-yl-5α-pregnan-3β,20-diol and its N-methyl derivative: two inhibitors of Δ24(25) sterol methyl transferase and Δ24(24′) sterol methyl reductase of Trypanosoma cruzi

2001 ◽  
Vol 57 (5) ◽  
pp. 714-721 ◽  
Author(s):  
Reinaldo Atencio ◽  
Gonzalo Visbal ◽  
Sara Pekerar ◽  
Jham Papale ◽  
Julio A. Urbina
Keyword(s):  
Trypanosoma Cruzi ◽  
Structural Parameters ◽  
Spectroscopic Characterization ◽  
Structural Parameter ◽  
Torsion Angles ◽  
Methyl Transferase ◽  
X Ray ◽  
The Family ◽  
Fused Ring ◽  
The Mean

Molecular structural parameters of two potential drugs against Trypanosoma cruzi epimastigotes, 20-piperidin-2-yl-5α-pregnan-3β,20-diol (1) and 20-N-methylpiperidin-2-yl-5α-pregnan-3β, 20-diol (2) were studied using a combination of a stereoselective synthetic route, spectroscopic characterization and single-crystal X-ray analysis. Both compounds were synthesized with an R configuration at C20. This chirality is a consequence of the stereoselectivity observed during the formation of the intermediate 20-pyridin-2-yl-5α-pregnan-3β,20R-diol (4). NMR data indicated that the six-membered aza ring of (2) is conformationally more restrained, in CDCl3 solution, than (1). X-ray studies showed that maximum deviations among structural molecular parameters of (1) and (2) correspond to torsion angles along the C20—C22 bonds, leading to a different relative orientation of the N atom; a critical structural parameter for the binding properties of aza-sterols to Δ24(25) sterol methyl transferase. Cremer–Pople parameters of the five-membered rings of (1) and (2) lie in the observed range for a family of tetracyclic fused ring systems retrieved from the CSD. The φ2 parameter of (1) lies just on the mean of the family, while φ2 of (2) deviates significantly towards the lower limit.

Derivatives and Parameter Designs of Arbitrary Cross-Section Inhomogenous Beams’ Modes

2013 ◽  
Author(s):  
J. W. Xing ◽  
G. T. Zheng
Keyword(s):  
Cantilever Beam ◽  
Cross Section ◽  
Analytical Solutions ◽  
Structural Parameters ◽  
Arbitrary Cross Section ◽  
Mode Shapes ◽  
Design Parameters ◽  
Structural Parameter ◽  
Highly Sensitive ◽  
Sensitivity Analysis Method

As highly sensitive to structural parameter variations, it is necessary to study relations between derivatives of displacement modes and structural design parameters. This paper proposes an integral technique for obtaining the analytical solutions of slope and curvature modes of arbitrary cross-section inhomogeneous cantilever beam. The method is validated by comparing the computation results of modal frequencies and shapes with both numerical and analytical solutions. Furthermore, based on the presented method, we have established explicit expressions for the structural parameters sensitivity of the slope/curvature mode shapes. An example of parameter design is also presented for a cantilever beam with the proposed sensitivity analysis method.

Blood Pressure Parameters as Determinants of Small Artery Structure in Human Essential Hypertension

1997 ◽  
Vol 92 (6) ◽  
pp. 551-557 ◽  
Author(s):  
Anne Cooper ◽  
Anthony M. Heagerty
Keyword(s):  
Blood Pressure ◽  
Essential Hypertension ◽  
Pulse Pressure ◽  
Structural Parameters ◽  
Structural Parameter ◽  
Pressure Measurements ◽  
Significant Determinant ◽  
Small Artery ◽  
Small Arteries ◽  
Blood Pressures

1. Adaptive changes in small arteries may be more closely correlated with pulse pressure than with systolic, diastolic or mean blood pressures in human essential hypertension. 2. An analysis was performed on the structure of small arteries, age and blood pressure measurements obtained from 56 patients with untreated essential hypertension and 56 matched normotensive volunteers to examine the association between age, blood pressure and small artery structural parameters. 3. Essential hypertension was associated with an increase in media thickness and a decrease in lumen diameter, resulting in an increase in media/lumen ratio. 4. There was a significant correlation between age and media/lumen ratio in normotensive volunteers but not in patients with essential hypertension. 5. There was no correlation between any blood pressure and structural parameter in normotensive volunteers. 6. Both diastolic and mean blood pressures in essential hypertension correlated with media/lumen ratio (P < 0.01); systolic blood pressure correlated less well (P < 0.02). However, pulse pressure did not correlate with media/lumen ratio, suggesting that it is not a significant determinant of small artery structure in untreated essential hypertension.

Study on the Influences of the Structural Parameters of Hydraulic Engine Mounts on their Vibration Isolation Characteristics

2014 ◽  
Vol 620 ◽  
pp. 200-205
Author(s):  
Qian Li ◽  
Ying Sun ◽  
Ying Ya Huang ◽  
Gang He ◽  
Deng Lin Zhu
Keyword(s):  
Frequency Response ◽  
Analytical Methods ◽  
Vibration Isolation ◽  
Structural Parameters ◽  
Structure Parameters ◽  
Cross Sectional ◽  
Engine Mounts ◽  
Response Characteristics ◽  
Main Factors ◽  
Frequency Response Characteristics

Hydraulic engine mounts (HEMs) are important vibration isolation parts in vehicle powertrain mounting systems. The structural parameters of HEMs are the main factors which determine their vibration isolation characteristics. It is of great significance to discover the influences of the structure parameters on their vibration isolation characteristics in the design and study of HEMs. HEMs with different rubber materials, lengths and cross-sectional areas of the inertia tracks are designed and manufactured, and their frequency response characteristics are investigated by experimental and analytical methods. The influences of these structural parameters on the vibration isolation characteristics of HEMs are educed. The analytical methods and conclusions are instructive for the design and tuning of the vibration isolation characteristics of HEMs.

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