Analysis of Vehicle Longitudinal Dynamics for Longitudinal Ride Comfort

2006 ◽  
Author(s):  
Shiang-Lung Koo ◽  
Han-Shue Tan ◽  
Masayoshi Tomizuka
Keyword(s):  
Time Domain ◽  
Ride Comfort ◽  
Vehicle Control ◽  
Switching Behavior ◽  
Mode Switching ◽  
Longitudinal Motion ◽  
Analytical Prediction ◽  
Longitudinal Model ◽  
The Time Domain ◽  
The Impact

Longitudinal ride comfort is one of the most crucial features to most advanced vehicle control systems. Literature review shows that the ride comfort analysis in vehicle longitudinal motion can be divided into two categories: time domain and frequency domain. Most vehicle longitudinal control designs incorporate jerk and acceleration constraints from the time-domain comfort criterion. However, the vehicle longitudinal characteristics in the frequency range important to passenger ride comfort are rarely discussed in the vehicle control literature. This paper proposes an improved vehicle longitudinal model that captures tire and suspension modes accurately and investigates the impact of these often-ignored vehicle resonant modes to ride comfort. This study shows that the "tire-mode switching behavior" affects longitudinal ride comfort of a stopping vehicle rather than the suspension. A passenger car was tested as an example, and the collected data verified the analytical prediction from the improved vehicle longitudinal model.

Selection of random vibration theory procedures for the NGA-East project and ground-motion modeling

2021 ◽  
Vol 37 (1_suppl) ◽  
pp. 1420-1439
Author(s):  
Albert R Kottke ◽  
Norman A Abrahamson ◽  
David M Boore ◽  
Yousef Bozorgnia ◽  
Christine A Goulet ◽  
...  
Keyword(s):  
Ground Motion ◽  
Time Domain ◽  
Random Vibration ◽  
Amplitude Spectrum ◽  
Motion Modeling ◽  
Peak Response ◽  
Vibration Theory ◽  
Random Vibration Theory ◽  
The Time Domain ◽  
The Impact

Traditional ground-motion models (GMMs) are used to compute pseudo-spectral acceleration (PSA) from future earthquakes and are generally developed by regression of PSA using a physics-based functional form. PSA is a relatively simple metric that correlates well with the response of several engineering systems and is a metric commonly used in engineering evaluations; however, characteristics of the PSA calculation make application of scaling factors dependent on the frequency content of the input motion, complicating the development and adaptability of GMMs. By comparison, Fourier amplitude spectrum (FAS) represents ground-motion amplitudes that are completely independent from the amplitudes at other frequencies, making them an attractive alternative for GMM development. Random vibration theory (RVT) predicts the peak response of motion in the time domain based on the FAS and a duration, and thus can be used to relate FAS to PSA. Using RVT to compute the expected peak response in the time domain for given FAS therefore presents a significant advantage that is gaining traction in the GMM field. This article provides recommended RVT procedures relevant to GMM development, which were developed for the Next Generation Attenuation (NGA)-East project. In addition, an orientation-independent FAS metric—called the effective amplitude spectrum (EAS)—is developed for use in conjunction with RVT to preserve the mean power of the corresponding two horizontal components considered in traditional PSA-based modeling (i.e., RotD50). The EAS uses a standardized smoothing approach to provide a practical representation of the FAS for ground-motion modeling, while minimizing the impact on the four RVT properties ( zeroth moment, [Formula: see text]; bandwidth parameter, [Formula: see text]; frequency of zero crossings, [Formula: see text]; and frequency of extrema, [Formula: see text]). Although the recommendations were originally developed for NGA-East, they and the methodology they are based on can be adapted to become portable to other GMM and engineering problems requiring the computation of PSA from FAS.

scholarly journals Calibration of ultrasonic hardware for enhanced total focusing method imaging

2020 ◽  
Vol 62 (7) ◽  
pp. 408-415
Author(s):  
M Ingram ◽  
A Gachagan ◽  
A Nordon ◽  
A J Mulholland ◽  
M Hegarty
Keyword(s):  
Time Domain ◽  
Pressure Profile ◽  
Side Lobe ◽  
Destructive Testing ◽  
Experimental Variation ◽  
Focal Position ◽  
Measured Time ◽  
The Time Domain ◽  
Ray Path ◽  
The Impact

Experimental variation from ultrasonic hardware is one source of uncertainty in measured ultrasonic data. This uncertainty leads to a reduction in the accuracy of images generated from these data. In this paper, a quick, easy-to-use and robust methodology is proposed to reduce this uncertainty in images generated using the total focusing method (TFM). Using a 128-element linear phased array, multiple full matrix capture (FMC) datasets of a planar reflection are used to characterise the experimental variation associated with each element index in the aperture. Following this, a methodology to decouple the time-domain error associated with transmission and reception at each element index is presented. These time-domain errors are then introduced into a simulated array model used to generate the two-way pressure profile from the array. The side-lobe-to-main-lobe energy ratio (SMER) and beam offset are used to quantify the impact of these measured time-domain errors on the pressure profile. This analysis shows that the SMER is raised by more than 6 dB and the beam is offset by more than 1 mm from its programmed focal position. This calibration methodology is then demonstrated using a steel non-destructive testing (NDT) sample with three side-drilled holes (SDHs). The time delay errors from transmission and reception are introduced into the time-of-flight (TOF) calculation for each ray path in the TFM. This results in an enhancement in the accuracy of defect localisation in the TFM image.

scholarly journals Spillover effects from news to travel and leisure stocks during the COVID-19 pandemic: Evidence from the time and frequency domains

2021 ◽  
pp. 135481662110584
Author(s):  
Ying Wang ◽  
Hongwei Zhang ◽  
Wang Gao ◽  
Cai Yang
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Spillover Effects ◽  
Short Term ◽  
Time Frequency ◽  
Frequency Domains ◽  
Media Hype ◽  
The Time Domain ◽  
The Impact

The impact of the COVID-19 pandemic on tourism has received general attention in the literature, while the role of news during the pandemic has been ignored. Using a time-frequency connectedness approach, this paper focuses on the spillover effects of COVID-19-related news on the return and volatility of four regional travel and leisure (T&L) stocks. The results in the time domain reveal significant spillovers from news to T&L stocks. Specifically, in the return system, T&L stocks are mainly affected by media hype, while in the volatility system, they are mainly affected by panic sentiment. This paper also finds two risk contagion paths. The contagion index and Global T&L stock are the sources of these paths. The results in the frequency domain indicate that the shocks in the T&L industry are mainly driven by short-term fluctuations. The spillovers from news to T&L stocks and among these T&L stocks are stronger within 1 month.

Compensation Scheme of a 50 Ω Bond Wire Interconnect Using Time Domain Reflectometry

2011 ◽  
Vol 8 (3) ◽  
pp. 114-120
Author(s):  
K. Webb ◽  
H. Song
Keyword(s):  
Time Domain ◽  
Integrated Circuit ◽  
Negative Impact ◽  
Time Domain Reflectometry ◽  
Physical Models ◽  
High Signal ◽  
Compensation Scheme ◽  
Bond Wires ◽  
The Time Domain ◽  
The Impact

A compensation scheme that reduces the impact of the excess reactance of bond wires is introduced. From the 3D finite element code and the time domain reflectometry (TDR), physical models were evaluated and the excess reactance of the signal path was determined to optimize the compensation structure. The presented method can be employed to reduce the negative impact caused by the excess reactances in bond wires for high signal integrity integrated circuit (IC) packaging applications.

Analysis of the Dielectric Loss in the Transmission Line Based on Time Domain BLT Equation

2013 ◽  
Vol 756-759 ◽  
pp. 4287-4291 ◽  
Author(s):  
Wan Jin Wang ◽  
Zhi Wu Xuan
Keyword(s):  
Dielectric Loss ◽  
Transmission Line ◽  
Time Domain ◽  
Transient Signal ◽  
Signal Source ◽  
Response Voltage ◽  
Calculation Results ◽  
The Time Domain ◽  
The Impact ◽  
Dielectric Insulation

Dielectric loss is caused due to imperfect dielectric insulation, in order to study the impact of the dielectric loss consider a uniform loss transmission line with leak conductance. The BLT equation from the frequency domain to time domain is derived to improve the time domain BLT equation, and the aim of using the time domain BLT equation to calculate load voltage of the transmission line with transient signal source, through the calculation results to analyze the impact of the dielectric loss. The results showed that the attenuation of the terminal load transient response voltage occurred when the dielectric loss exists, and this effect is nonlinear.

Ferroresonance in Power and Instrument Transformers

2013 ◽  
pp. 184-237 ◽  
Author(s):  
Afshin Rezaei-Zare ◽  
Reza Iravani
Keyword(s):  
Power Systems ◽  
Time Domain ◽  
Iron Core ◽  
Time Domain Simulation ◽  
Instrument Transformers ◽  
The Time Domain ◽  
System Configurations ◽  
The Impact ◽  
Analytical Approaches ◽  
Nonlinear Nature

This chapter describes the fundamental concepts of ferroresonance phenomenon and analyzes its symptoms and the consequences in transformers and power systems. Due to its nonlinear nature, the ferroresonance phenomenon can result in multiple oscillating modes which can be characterized based on the concepts of the nonlinear dynamic systems, e.g., Poincare map. Among numerous system configurations which can experience the phenomena, a few typical systems scenarios, which cover the majority of the observed ferroresonance incidents in power systems, are introduced. This chapter also classifies the ferroresonance study methods into the analytical and the time-domain simulation approaches. A set of analytical approaches are presented, and the corresponding fundamentals, assumptions, and limitations are discussed. Furthermore, key parameters for accurate digital time-domain simulation of the ferroresonance phenomenon are introduced, and the impact of transformer models and the iron core representations on the ferroresonance behavior of transformers is investigated. The chapter also presents some of the ferroresonance mitigation approaches in power and instrument transformers.

Impact of Bathymetry on the Mooring Design of an Offshore Floating Unit

2016 ◽  
Author(s):  
Vivek Jaiswal ◽  
Srinivas Vishnubhotla ◽  
Sean Cole ◽  
Robert B. Gordon ◽  
Partha Sharma
Keyword(s):  
Time Domain ◽  
Previous Method ◽  
Mooring Line ◽  
Mooring System ◽  
Analysis Program ◽  
Design Assessment ◽  
True Representation ◽  
The Time Domain ◽  
Constant Slope ◽  
The Impact

Moored offshore floating units may operate in regions where the bathymetry changes significantly over the mooring spread. Traditional mooring analysis methods make the assumption that the seabed slope is constant along the azimuth direction of each mooring line. This assumption, while reasonable for a seabed with nearly constant slope, can lead to significant errors with respect to the line tensions and vessel offsets in the mooring design assessment when the seabed slope is variable. This paper demonstrates the impact of bathymetry changes on the mooring design with the help of numerical analysis examples. The floating vessel considered is a semi-submersible moored by an eight point all chain catenary mooring system. Two methods of analysis are compared. In the first method, a true representation of the seabed surface that accounts for all variations in the bathymetry is used. In the second method, the anchor depths and the seabed slopes at the anchor locations estimated in the previous method are used, however, with the assumption of constant seabed slopes along the line azimuth directions. The dynamic analysis program Orcaflex is used for performing the numerical analyses in the time domain for both the methods. Differences in the performance of the mooring system are demonstrated by comparing the static and the dynamic line tensions as well as the vessel offsets in different environmental conditions. The paper also discusses how maximum offsets and line tensions are estimated.

scholarly journals Direct Time Domain Numerical Analysis of Transient Behavior of a VLFS during Unsteady External Loads in Wave Condition

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Yong Cheng ◽  
Gang-jun Zhai ◽  
Jin-ping Ou
Keyword(s):  
Time Domain ◽  
Vertical Motion ◽  
Expansion Method ◽  
Transient Behavior ◽  
Boundary Integral ◽  
Wave Condition ◽  
Modal Expansion ◽  
Wave Conditions ◽  
The Time Domain ◽  
The Impact

The transient response of the VLFS subjected to arbitrary external load is systematically investigated by a direct time domain modal expansion method, in which the BEM solutions based on time domain Kelvin sources are used for hydrodynamic forces. In the analysis, the time domain free-surface Green functions with sufficient accuracy are rapidly evaluated in finite water depth by the interpolation-tabulation method, and the boundary integral equation with a quarter VLFS model is established taking advantage of symmetry of flow field and structure. The validity of the present method is verified by comparing with the time histories of vertical displacements of the VLFS during a mass drop and airplane landing and takeoff in still water conditions, respectively. Then the developed numerical scheme is used in wave conditions to study the combined action taking into account the mass drop/airplane landing/takeoff loads as well as incident wave action. It is found that the elevation of structural waves due to mass drop load can be significantly changed near the impact region, while the vertical motion of runway in wave conditions is dominant as compared with that only generated by airplane.

scholarly journals Causality between Oil Prices and Tourist Arrivals

Stats ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 134-154 ◽  
Author(s):  
Xu Huang ◽  
Emmanuel Silva ◽  
Hossein Hassani
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Price Volatility ◽  
Oil Prices ◽  
Oil Price ◽  
Economic Activities ◽  
Oil Price Volatility ◽  
Causality Tests ◽  
The Time Domain ◽  
The Impact

This paper investigates the causal relationship between oil price and tourist arrivals to further explain the impact of oil price volatility on tourism-related economic activities. The analysis itself considers the time domain, frequency domain, and information theory domain perspectives. Data relating to the US and nine European countries are exploited in this paper with causality tests which include the time domain, frequency domain, and Convergent Cross Mapping (CCM). The CCM approach is nonparametric and therefore not restricted by assumptions. We contribute to existing research through the successful and introductory application of an advanced method and via the uncovering of significant causal links from oil prices to tourist arrivals.

scholarly journals Time domain reflectometry model: analysis and characterization of a chafing defect in a coaxial cable

2018 ◽  
Vol 83 (3) ◽  
pp. 30601 ◽  
Author(s):  
Abelin Kameni ◽  
Florent Loete ◽  
Lionel Pichon
Keyword(s):  
Time Domain ◽  
Time Domain Reflectometry ◽  
Coaxial Cable ◽  
Network Analyzer ◽  
3D Numerical Modeling ◽  
Numerical Studies ◽  
A Chain ◽  
The Time Domain ◽  
The Impact

This paper presents experimental and numerical studies of a chafing soft defect realized by partially milling coaxial cables. The approach is based on the time domain reflectometry technique. The numerical model consists in solving Maxwell’s equations while an incident Gaussian pulse is injected on the faulty line. The experimental time domain measurements are performed with a vector network analyzer. To get the experimental results comparable to the numerical ones, a process to denoise the measured impulse responses is proposed. The reflection coefficients obtained are compared to those given by a classical approach based on a chain matrix model to show the impact of 3D numerical modeling in studying soft faults.

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