bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characteristics of Enhanced Active Constrained Layer Damping Treatments With Edge Elements: Part II — System Analysis
Authors: Liao W. H. , Wang K. W. 
Published: February 2021

Abstract
This paper presents some important characteristics of enhanced active constrained layer damping (EACL) treatments for vibration controls. Specific interests are on understanding how the edge elements will influence the active action authority, the passive damping ability, and their combined effects in EACL. Analysis results indicate that the edge elements can significantly improve the active action transmissibility of the current active constrained layer damping (ACL) treatment due to the bypass effect. Although the edge elements will slightly reduce the viscoelastic material (VEM) passive damping, the EACL will still have significant damping from the VEM. Combining the overall active and passive actions, the new EACL with sufficiently stiff edge elements not only could achieve better performance with less control effort compared to the current ACL system, but also could outperform the purely active system. With careful analysis, we can map out the required critical edge element stiffness for successful designs. In addition, analysis also shows that the EACL treatment is a more robust design. That is, it could outperform both the purely active and passive systems throughout a much broader design space than the current ACL configuration. With these desirable characteristics, the EACL could be used to realize an overall optimal active-passive hybrid system.
Design of Pendulum Absorbers for Transverse Vibration Attenuation of Rotating Beams
Authors: Wang Yenkai , Shaw Steven W. , Chao Chang-Po 
Published: February 2021

Abstract
This paper considers the placement, sizing and tuning of centrifugal pendulum vibration absorbers for the reduction of transverse vibrations in rotating beams. A simplified model describing the linearized dynamics of a rotating beam with external excitation and attached absorbers is used for the analysis. A design strategy is offered wherein individual absorbers are designed to reduce vibration amplitudes and stress levels caused by troublesome resonances. It is shown that this procedure offers significant reduction in vibratory stresses, even in the case of excitations composed of multiple harmonics.
Self-Excited Vibration Model of Dragonfly’s Wing Based on the Concept of Bionic Design for Small- or Micro-Sized Actuators
Authors: Ishimoto Sagiri , Hashimoto Hiromu 
Published: February 2021

Abstract
This paper describes a self-excited vibration model of dragonfly’s wing based on the concept of bionic design, which is expected as a technological hint to solve the scale effect problems in developing the small- or micro-sized actuators. From a morphological consideration of flight muscle of dragonfly, the nonlinear equation of motion for the wing considering the air drag force due to flapping of wing is formulated. In the model, the dry friction-type and Van der Pol-type driving forces are employed to power the flight muscles and to generate the stable self-excited wing vibration. Two typical Japanese dragonflies, “Anotogaster sieboldii Selys” and “Sympetrum frequens Selys”, are selected as examples, and the self-excited vibration analyses for these dragonfly’s wings are demonstrated. The linearized solutions for the nonlinear equation of motion are compared with the nonlinear solutions, and the vibration system parameters to generate the stable limit cycle of self-excited wing vibration are determined.
Dynamic Instability and Resonances of Geometrically Imperfect Plates
Authors: Ostiguy Germain L. , St-Georges Lyne 
Published: February 2021

Abstract
The parametric resonance and other dynamic instabilities of a rectangular plate with initial geometric imperfections acted upon by parametric excitation have been investigated. The temporal equations of motion describing the non-linear behavior of these plates for large oscillations are solved using a direct integration. Results are compared with those obtained from an approximate analytical method. For a structure with a sufficiently large initial imperfection, the soft-spring nature of parametric resonance is confirmed for small vibration amplitudes, followed by a hard-spring behavior for large vibration amplitudes. However, the temporal response of the imperfect structure displays a predominant inward deflection. This phenomenon increases with an augmentation of the imperfection amplitude. Moreover, some resonances not predicted by analytical methods are observed. Besides the possibility of principal parametric resonance, many internal resonances may be observed during a passage through a single parametric resonance.
Mean-Axis Conditions for Finite Elements Undergoing Large Rotations and Translations
Authors: Sonti Venkata R. , Agrawal Om P. 
Published: February 2021

Abstract
The mean-axis conditions for three types of finite elements that undergo large rotation and translation are derived. The cases include two Lagrangian planar elements (linear triangle and linear rectangle) and a three dimensional rectangular plate element. Each case includes two elements connected at the nodes. Three separate coordinate systems are used in describing the systems. The numerical values of different matrices including the mass matrix are presented for specific cases. It may be seen that the non-linear mass matrix is expressed in terms of a set of time-invariand matrices. The total mass matrix of the body i is obtained by assembling the individual mass matrices of the finite elements of body i.
A Fully Symbolic Model of Multibody Systems Containing Flexible Plates
Authors: Ouatouati A. El , Fisette P. , Johnson D. A. 
Published: February 2021

Abstract
The modelling of flexible elements in mechanical systems has been investigated through several methods issuing from both the field of multi-body dynamics and the area of structural mechanics and vibration theory. Concerning the multibody approach, recursive formulations in relative coordinates have been widely claimed to be most suitable and efficient for a large variety of applications. Such a formalism is developed here for a general multibody system containing flexible plates and in such a way that its full symbolic generation is possible within the ROBOTRAN program (Maes et al. 1989).
On the Use of Virtual Work in a Graph-Theoretic Formulation for Multibody Dynamics
Authors: Shi Pengfei , McPhee John 
Published: February 2021

Abstract
In this paper, graph-theoretic and virtual work methods are combined in a new formulation of the equations of motion for rigid and flexible multibody systems. In addition to extending the theory for existing graph-theoretic approaches, this new formulation offers two distinct improvements. First, the set of differential-algebraic dynamic equations are smaller in number than those obtained using conventional formulations. Secondly, the equations of motion for rigid and flexible multibody systems can be generated using a consistent graph-theoretic approach, thereby leading to an efficient and modular computer implementation.
Recursive Dynamics and Adaptive Control for Animating Articulated Figures
Authors: Kokkevis Evangelos , Metaxas Dimitris 
Published: February 2021

Abstract
We present a dynamic system for the guided animation of articulated figures. Based on an efficient forward dynamics simulator, we introduce a robust feedback control scheme and a fast two-stage collision response algorithm. A user of our system provides kinematic trajectories for selected degrees of freedom (DOFs) of the figure. The output motion is fully generated using forward dynamics. The specified motion trajectories are the input to a control system which computes the forces and torques that should be exerted to achieve the desired motion. The dynamic controllers, designed based on the Model Reference Adaptive Control paradigm, continuously self-adjust for optimal performance in trajectory following. Moreover, the user is given a handle on the type and speed of reaction of the figure’s controlled DOFs to sudden changes in their desired motion. The overall goal of our system is to provide a platform for generating and studying realistic, user controlled motion at interactive rates. We require minimal user involvement in specifying non-intuitive parameters.
Small Vibrations Superimposed on Non-Linear Rigid Body Motion
Authors: Schwab A. L. , Meijaard J. P. 
Published: February 2021

Abstract
In the case of small elastic deformations in a flexible multi-body system, the periodic motion of the system can be modelled as a superposition of a small linear vibration and a non-linear rigid body motion. For the small deformations this analysis results in a set of linear differential equations with periodic coefficients. These equations give more insight in the vibration phenomena and are computationally more efficient than a direct non-linear analysis by numeric integration. The realization of the method in a program for flexible multibody systems is discussed which requires, besides the determination of the periodic rigid motion, the determination of the linearized equations of motion. The periodic solutions for the linear equations are determined with a harmonic balance method, while transient solutions are obtained by averaging. The stability of the periodic solution is considered. The method is applied to a pendulum with a circular motion of its support point and a slider-crank mechanism with flexible connecting rod. A comparison is made with previous non-linear results.
A Study on the Simulation of Flexible Link Mechanics Based on FEM
Authors: Honke Koichi , Inoue Yoshio , Hirooka Eiko , Sugano Naoki 
Published: February 2021

Abstract
The dynamics analysis of link structure, including elastic vibrations, is presented. The two nodes element including large displacement is developed. This element is based on the theory of finite rotation, and includes geometric stiffness. The stiffness matrix and the inertia matrix are obtained from the FEM model by the theory of Guyan’s reduction including large displacement motion. In this paper, we explain the theory of this element and show some examples of analysis.
A Theoretical and Experimental Study of the Vibratory Behavior of a High-Precision Optical Positioning Table
Authors: Basdogan Ipek , Royston Thomas J. , Barraza Juan , Shu Deming , Kuzay Tuncer M. 
Published: February 2021

Abstract
At the Advanced Photon Source (APS), a state-of-the-art synchrotron radiation facility at Argonne National Laboratory (ANL), high-precision optical positioning systems are needed to conduct a wide range of experiments utilizing the high-brilliance x-ray beam. The high-precision, multi-dimensional positioning capability required for these positioning systems may be compromised by vibratory motion. The vibratory dynamics of the complex kinematic joints and components that comprise these multibody structures are not easily described by simple theoretical models. A combined experimental and theoretical approach has been developed to predict the dynamic properties of the individual components and joints and of the assembled multibody system. A prototypical optical table has been analyzed as an example case.
Controlling a Dynamic System With Open and Closed Loops: Application to Ladder Climbing
Authors: Lo Janzen , Metaxas Dimitris , Badler Norman I. 
Published: February 2021

Abstract
We develop a method for animating systems with open and closed loops and in particular ladder climbing for virtual world applications. Ladder climbing requires the modeling of dynamic open and closed-loop chains. We model the stance phase and the associated closed-loop dynamics, through the use of the Lagrange multiplier method which results in a system of differential algebraic equations (DAE). We use the Lagrange method for the dynamic formulation of the swing phase. The input to the algorithm is a given forward velocity, step length, step frequency and a chosen gait. The algorithm then determines the initial and final positions for each phase of ladder climbing. We use the Newton-Ralphson method to find the vector of joint torques that drives the dynamic system from the initial position to the final position. We use the Baumgarte stabilization method to achieve stability of the numerical integration. We present a series of real-time animations involving ladder climbing.
Fatigue Life Predictions by Coupling Finite Element and Multibody Systems Calculations
Authors: Dietz Stefan , Netter Helmuth , Sachau Delf 
Published: February 2021

Abstract
The dynamic loads and accelerations acting on a railway bogie are predicted by multibody simulation. The bogie frame is considered as an elastic body of the MBS-model, in which elastic displacements are represented by eigen and staticmodes. Stresses are calculated for the most stressed locations of a bogie in the MBS-postprocessor. Based on these a fatigue life prediction is carried out.
Monitoring Fault Condition During Manufacturing Using the Karhunen-Loève Transform
Authors: Turner Irem Y. , Wood Kristin L. , Busch-Vishniac Ilene J. 
Published: February 2021

Abstract
Monitoring the condition of parts and machine components is a crucial task in ensuring fault-free manufacturing. In this work, we propose an alternative condition monitoring technique, with great potential in extracting and isolating individual fault patterns from manufacturing signals. We propose that the Karhunen-Loève transform provides the ability to decompose measured signals into decorrelated fault patterns, in the form of fundamental eigenvectors. These fundamental eigenvectors can then be monitored by means of coefficient vectors, which indicate any changes in the fault patterns. The technique can provide accurate fault information, whether the manufacturing signals are deterministic, stochastic, stationary, or nonstationary.
This paper presents the fundamentals of the proposed technique and its extension to condition monitoring. The outputs of the Karhunen-Loève transform are studied to interpret their physical significance. Then, a subset of general manufacturing signals is used to understand the mathematical foundations of the technique. Extensions to general functions are investigated by means of numerical simulations. The technique proposed in this paper has great potential in providing a robust condition monitoring tool.
Multivariable Feedback Relevant System Identification of a Wafer Stepper System
Authors: de Callafon Raymond A. , Van den Hof Paul M. J. 
Published: February 2021

Abstract
This paper discusses the approximate and feedback relevant parametric identification of a positioning mechanism present in a wafer stepper. The positioning mechanism in a wafer stepper is used in chip manufacturing processes for accurate positioning of the silicon wafer on which the chips are to be produced. The accurate positioning requires a robust and high performance feedback controller that enables a fast through put of silicon wafers. A set of multivariable finite dimensional linear time invariant discrete time models will be estimated, that is suitable for model-based robust control design of the positioning mechanism.
Frequency and Time Signal Analysis in Source Identification of Vibration and Noise in Cylindrical Cam Mechanisms
Authors: Ge Song Lin , Nerli Giovanni , Pierini Marco 
Published: February 2021

Abstract
It is vitally important to identify sources from which unwanted noise and vibration are emitted before further research work can commence on the design optimization of the cylindrical cam mechanism. Acoustic microphone and vibration accelerometer measurement systems were used to analyze the system characteristics in both the time and frequency domains. We have succeeded in identifying the sources of noise and vibration and distinguishing the signals between the regions of the groove junctions and the groove inversions in terms of the relative values of their instantaneous powers. Some of the problems encountered were impossible to resolve using only frequency analysis techniques due to the characteristics of the rectilinear reciprocating motions of the cam mechanism follower. The results obtained from the cam analyzed show that the structure of the groove inversion has a greater influence on the noise levels emitted from the mechanism than the structure of the groove junction. The emitted noise level from the former is generally twice that emitted from the latter.
Identification of System and Periodic Disturbances
Authors: Phan Minh Q. , Goodzeit Neil E. , Juang Jer-Nan 
Published: February 2021

Abstract
This paper addresses the problem of system identification in the presence of unknown periodic disturbances. Available for identification is a set of excitation input and the disturbance-corrupted response. This paper shows that the excitation-to-output system dynamics can still be identified successfully with disturbance-corrupted data in a manner analogous to the case when there is no disturbance present. This input-output domain derivation is in agreement with a similar result previously derived in the state-space domain. Criteria to distinguish the disturbances from system dynamics are discussed. A detailed analysis of experimental data obtained from a structural acoustic test setup is used to support the theoretical results.
On Frequency-Domain System Identification
Authors: Blades Eric L. , Craig Roy R. 
Published: February 2021

Abstract
Over the past three decades vibration tests have frequently been conducted on structures and machines for the purpose of validating (updating) finite element models. Such testing is usually referred to as experimental modal analysis. The results of the vibration test are generally presented as a modal model consisting of natural frequencies, mode shapes, and modal damping factors, and the algorithms most frequently used to reduce the test data to modal-model form are time-domain algorithms. Alternatively, direct-parameter system identification may be performed, in which case the direct-parameter model consists of system mass, damping, and stiffness matrices. This paper discusses several features of a new frequency-domain direct-parameter system identification algorithm. Simulations based on a 52-DOF “payload simulator” are used to illustrate the performance of this algorithm.
Mass Transfer Influence on the Rollover Threshold for a Vehicle With Nonlinear Suspension
Authors: Gonzalez Oscar M. , Jauregui Juan C. 
Published: February 2021

Abstract
A dynamic model for a two-axle vehicle equipped with different types of suspensions is presented in this paper. The model is formulated considering the roll and pitch moments acting on the vehicle’s body and the roll moments on each of the axles during cornering.
The pitch-roll model is preferred to a single-roll plane model in order to analyze the mass transfer caused by the vertical displacements of each axle. These displacements usually have a negative effect in the rollover threshold of the vehicle. The model is solved numerically in the time domain for a steady state cornering in order to obtain the rollover threshold of the vehicle and for a sinusoidal steering input.
The formulation includes non-linear terms due to the weight transfer between the axles and the suspension behavior for the non-linear spring rate case.
Results are analyzed and compared with those obtained from quasi-static.
Characterization and Identification of Damping and Nonlinear Systems Parameters With Bispectral Analysis
Authors: Nayfeh A. H. , Hajj M. R. , Fung J. , Fahey S. O’F. 
Published: February 2021

Abstract
We propose a consistent methodology whereby perturbation techniques, complex Fourier amplitudes, and higher-order statistics can be combined to characterize and quantify the damping and parameters of nonlinear systems. The methodology is used to characterize and quantify the damping and parameters of the first mode of a three-beam two-mass frame. The frame is excited harmonically near twice the natural frequency of its first mode. The generalized coordinate of this mode is modeled with a second-order nonlinear equation with quadratic and cubic geometric nonlinearities, a cubic inertia nonlinearity, linear and quadratic damping, and parametric and external excitation terms. The method of multiple scales is used to obtain a second-order approximate solution of this equation. This solution shows how the response amplitude and frequency content and phase difference between that of the excitation and response depend on the damping, nonlinear system parameters, and excitation amplitude and frequency. Measurements of the response amplitude, “phase difference” obtained from the bispectrum, and complex Fourier amplitudes at the excitation frequency and its one-half, under different excitation levels are then used to determine the damping and nonlinear parameters.
Novel Speed and Position Estimation in Field-Oriented Control of Induction Machine Drive System
Authors: Khater Faeka M. H. , Abu-Elsebah Mohamed I. , Ahmed Farouk I. 
Published: February 2021

Abstract
This paper describes a novel technique which has been proposed to simplify field orientation control system. This technique depends on zero crossing detection of different waveform of stator fluxes using the comparator reference signal which control the inverter transistors. By using this technique it is available to update the position θ and current components in the rotational reference frame up to twelve times per cycle. As a result, the transformation from two phase stationary reference frame (SRF) to two phase rotating synchronously reference frame (RRF), has been canceled which leads to less consumption time in software. Thus control algorithm requires less time to be implemented via software for position detection and speed estimation.
Daily Myofibrillar Protein Synthesis Rates in Response to Low- and High-Frequency Resistance Exercise Training in Healthy, Young Men
Authors: Shad Brandon J. , Thompson Janice L. , Mckendry James , Holwerda Andrew M. , Elhassan Yasir S. , Breen Leigh , van Loon Luc J.C. , Wallis Gareth A. 
Published: February 2021

The impact of resistance exercise frequency on muscle protein synthesis rates remains unknown. The aim of this study was to compare daily myofibrillar protein synthesis rates over a 7-day period of low-frequency (LF) versus high-frequency (HF) resistance exercise training. Nine young men (21 ± 2 years) completed a 7-day period of habitual physical activity (BASAL). This was followed by a 7-day exercise period of volume-matched, LF (10 × 10 repetitions at 70% one-repetition maximum, once per week) or HF (2 × 10 repetitions at ∼70% one-repetition maximum, five times per week) resistance exercise training. The participants had one leg randomly allocated to LF and the other to HF. Skeletal muscle biopsies and daily saliva samples were collected to determine myofibrillar protein synthesis rates using 2H2O, with intracellular signaling determined using Western blotting. The myofibrillar protein synthesis rates did not differ between the LF (1.46 ± 0.26%/day) and HF (1.48 ± 0.33%/day) conditions over the 7-day exercise training period (p > .05). There were no significant differences between the LF and HF conditions over the first 2 days (1.45 ± 0.41%/day vs. 1.25 ± 0.46%/day) or last 5 days (1.47 ± 0.30%/day vs. 1.50 ± 0.41%/day) of the exercise training period (p > .05). Daily myofibrillar protein synthesis rates were not different from BASAL at any time point during LF or HF (p > .05). The phosphorylation status and total protein content of selected proteins implicated in skeletal muscle ribosomal biogenesis were not different between conditions (p > .05). Under the conditions of the present study, resistance exercise training frequency did not modulate daily myofibrillar protein synthesis rates in young men.