bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eigenvalue Inclusion Principles for Distributed Gyroscopic Systems
Authors: Yang B. 
Published: April 2021

Abstract
This paper presents several eigenvalue inclusion principles for a class of distributed gyroscopic systems under pointwise constraints. A transfer function formulation is proposed to describe the constrained system. Five types of non-dissipative constraints and their effects on the system natural frequencies are studied It is shown that the natural frequencies of the constrained gyroscopic system alternate with those of the unconstrained system.
A New Method of Time Series Analysis and its Application to Identifying Modal Parameters
Authors: He Yusheng , Deng Zhaoxiang 
Published: April 2021

Abstract
In the paper, the attention concentrates on the time domain modal analysis. A new method of time series analysis, which is formed mainly by an ideal modeling strategy and a new COR-IV method, is developed. In addition, an interesting parameter called as modal energy ratio, which is available for design reference, is defined and its identification algorithm is given. The new method presented in this paper and Frequency Domain Method (FDM) are performed on a frame of SG120 vehicle. It is shown by comparison between these two methods that the new method of time series analysis is practical.
Cyclic Transition Through Combination Resonances of Parametric Laminated Angle-Ply Composite Columns
Authors: Evan-lwanowski R. M. , Jia Hong-Yu , Lu Chu-Ho 
Published: April 2021

Abstract
Cyclic transitions through combination resonances of a laminated angle-ply, three-degrees-of-freedom column subjected to a parametric (periodic axial) load have been studied using the asymptotic method. The study included the effects of the coupling stiffnesses, fiber orientations, ply-angles, geometrical nonlinearities, load eccentricities, initial (stationary) conditions, types of the temporal modes.
Investigation of Parametric Resonance Instability in a Flexible Rod Slider Crank Mechanism
Authors: Beale David G. , Lee Shyr-Wen 
Published: April 2021

Abstract
A direct variational approach with a floating frame is presented to derive the ordinary differential equations of motion of a flexible rod, constant crank speed slider crank mechanism. Potential energy terms contained in the derivation include beam bending energy and energy in foreshortening of the rod tip (which were selected because of the importance of these terms in a pinned-pinned rod parametric resonance). A symbolic manipulator code is used to reduce the constrained equations of motion to unconstrained nonlinear equations. A linearized version of these equations is used to explore parametric resonance stability-instability zones at low crank speeds and small deflections by a monodromy matrix technique.
Static and Dynamic Analyses of Beam-Columns on Winkler Foundation
Authors: Lee T. W. , Cleghorn W. L. , Tabarrok B. 
Published: April 2021

Abstract
A finite element model is developed for static, free and forced vibration analyses of a compressed beam resting on a Winkler-type elastic foundation and subjected to transverse loads. The homogeneous solution of the governing differential equation of static equilibrium is used as shape functions when deriving the load vector, the stiffness and mass matrices. For the static case, a procedure is outlined for improving the internal distributions of deflections, rotations, bending moments and shear forces of the structure. In this procedure, exact results are obtained for concentrated, uniform and ramp distributed loads with a minimum number of elements. When considering free vibrations, natural frequencies converge rapidly with increasing numbers of elements, and are shown to agree with results obtained by other analytical methods. The effects of the axial load and elastic foundation on the natural frequencies are also illustrated. For forced vibrations, the Newmark β Method is employed for obtaining the time history response of a beam-column on an elastic foundation subjected to lateral time-dependent excitations and constant axial load.
Forced, Nonlinear, Nonplanar Oscillations of a Cantilevered Beam During Transition Through Resonance
Authors: Shyu In-Ming K. , Mook Dean T. , Plaut Raymond H. 
Published: April 2021

Abstract
A slender, elastic, inextensible, cantilevered beam is considered. The principal moments of inertia of the beam cross section are equal (e.g., the cross section may be circular or square). The beam is subjected to a uniformly distributed vertical force which has a static component (e.g., just the weight of the beam) and a dynamic component with constant amplitude and varying frequency Ω(t). Planar and nonplanar motions are analyzed.
The governing equations of motion are an extension of those derived by Crespo da Silva and Glynn [1,2], taking into account the static deflection. Nonlinear curvature, nonlinear inertia, torsional displacements, and viscous damping are included in the formulation. A perturbation method is applied, and quadratic and cubic terms are retained in the equations. Torsional inertia is neglected, and with the use of the inextensibility condition, the longitudinal motion is written in terms of the horizontal and vertical motions, which are then represented in terms of three vibration modes in the application of Galerkin’s method. In some cases, the time histories of the modal amplitudes are determined by numerical integration; in others, the method of multiple scales is used to obtain approximate solutions for the response.
When the forcing frequency Ω is fixed, the system exhibits primary resonance when Ω is close to a natural frequency of the beam, subharmonic resonance when Ω is close to twice or three times a natural frequency, and superharmonic resonance when Ω is close to one-half or one-third of a natural frequency. Under these resonance conditions, the planar (vertical) steady-state motion of the beam may be unstable and a non-planar (whirling) motion may occur. These stationary conditions have been examined previously [3]. Here, nonstationary conditions are studied, in which the forcing frequency Ω(t) either increases or decreases slowly through a resonance.
The time histories of the vertical and horizontal motions are determined. For the various resonances, the magnitude and form of the response depends on many factors, including the rate of change of Ω(t), the static component of the force, the amplitude of the dynamic component of the force, the amount of damping, and the initial conditions (at the beginning of the acceleration or deceleration). Attention is focused on cases that lead to nonplanar motions, and some interesting types of dynamic behavior are exhibited by the beam.
Simple Models for Periodic Lattices
Authors: Abrate Serge 
Published: April 2021

Abstract
In many applications, the dynamic behavior of large periodic structures must be modeled accurately, thus requiring the determination of a significant number of natural frequencies and mode shapes. In order to perform that task most efficiently, a continuum modeling approach can be adopted. The discrete structure is then replaced by a continuum model which can be analyzed more efficiently. Therefore, at the design stage many analyses can be performed while searching for the optimal solution.
Known structural models are usually used as continuum models, and several methods are available to determine the equivalent properties from the properties of the original structure. This task is usually cumbersome, and in addition, in certain cases, continuum models cannot represent all modes of deformation.
In this article, a simple approach to develop continuum models without explicit reference to an existing structural theory is presented. Very accurate results are obtained, and all vibration modes can now be handled easily.
A Method of On-Line Analysis for Mechanical Dynamic Characteristic
Authors: Wang Fengquan , Wu Huixin , Han Xiaolin , Fu Haomin 
Published: April 2021

Abstract
In this paper, a method of multipoint pseudorandom combined excitation with the orthogonal reciprocal repeated sequences (ORRS) is presented on the background of the on-line identification of the multivariate rotor system. The capacaty of the restraint to the identification error caused by the non-random D. C. drift of the multi-input excitation with the ORRS in the rotor system is also discussed. The validity of the method described in this paper is proved by the modelling tests of the multi-plate rotor system.
Identification of Viscously Damped Distributed Structural Dynamic Systems
Authors: Chander R. , Meyyappa M. , Hanagud S. 
Published: April 2021

Abstract
A frequency domain identification technique applicable to damped distributed structural dynamic systems is presented. The technique is developed for beams whose behavior can be modeled using the Euler-Bernoulli beam theory. External damping of the system is included by means of a linear viscous damping model. Parameters to be identified, mass, stiffness and damping distributions are assumed to be continuous functions over the beam. The response at a discrete number of points along the length of the beam for a given forcing function is used as the data for identification. The identification scheme involves approximating the infinite dimensional response and parameter spaces by using quintic B-splines and cubic cardinal splines, respectively. A Galerkin type weighted residual procedure, in conjunction with the least squares technique, is employed to determine the unknown parameters. Numerically simulated response data for an applied impulse load are utilized to validate the developed technique. Estimated values for the mass, stiffness and damping distributions are discussed.
The Principle of Cepstrum and its Application in Quantitative Fault Diagnostics of Gears
Authors: Tang He , Cha Jian-Zhong , Wang Yuanhui , Zhang Ce 
Published: April 2021

Abstract
This paper has studied the principle of cepstrum and introduced a new method which can be used to quantitatively diagnose gear-wear through cepstrum analysis of gear noise. The amplitude value of the peak in cepstrum, which represents gear mesh-harmonics in spectrum, is independent of the intensity of gear noise signal. The value can indicate quantitatively the existence of gear-wear. In the paper, the further interpretation on physical meanings of other peaks in cepstrum has been done. Based on analysing the results of experiments with gearboxes, the thresholds of the gear wear by cepstrum diagnosis have been obtained. The theoretical analysis has agreed with the experimental results very well.
Trouble Diagnosis of Diesel Valves by Sound Intensity and Vibration Signals
Authors: Sun Zhonglang , Wang Hong , Xu Xiaoling 
Published: April 2021

Abstract
In this paper, we study the trouble diagnosis of diesel valve train by sound intensity, especially by the technique of the Gated Spectrum Analysis. To check the efficiency and reliability of our sound intensity measurement, we record vibration signals and sound intensity simultaneously to diagnose the valve train troubles of the 290-QN diesel. Some typical troubles with the valve train are analogued, the frequency spectrum plots of the vibration signals and sound intensity signals are gotten with the help of the tape recorder which record the signals in situ, so we could identify the troubles of the valve train from these frequency spectrum plots directly.
Optimum Design of Structure by Sensitivity Analysis
Authors: Kajiwara I. , Nagamatsu A. 
Published: April 2021

Abstract
A series of researches by the authors on structural optimum design by sensitivity analysis is introduced. First, the sensitivity of the anti-resonance frequency is defined, and an approach to eliminate the resonance peak from the frequency response function is proposed using this sensitivity. Next, an experimental approach for structural optimization based on a vibration test is introduced. An approach for optimum design combined with substructure synthesis method is proposed, in which the objective function is an impulse response function. The proposed methods are illustrated by some examples.
An Active Vibration Control Approach for Isolating General Base Vibration
Authors: Chen Anning , Batta George R. 
Published: April 2021

Abstract
This paper presents an approach for active vibration control in which translational vibration and rotational vibration can be controlled jointly or separately. By doing so, the flexibility of either partially isolating or totally isolating the vibration is achieved; this flexibility can be useful in a variety of engineering applications. A generic two degree-of-freedom vibration system is analyzed and modelled as a multivariable system. The control (isolation) approach is based on multivariable feedback decoupling design. The design scheme and simulation results are presented.
Quantification of the Eigenfrequency Extraction Advantages of the Riccati Transfer Matrix Method Over the Standard Transfer Matrix Method
Authors: Zeng Xiandi , Mitchell Larry D. , Li William Xinzuo 
Published: April 2021

Abstract
In this paper the Riccati transfer matrix method is implemented with a goal of studying its ability to expand eigenextraction capability. A pin-pin uniform beam is used as a numerical example to demonstrate the numerical stability of the Riccati transfer matrix method in finding higher natural frequencies. The results are compared with those from analytical solution and those from the standard transfer matrix method. It is shown that the number of frequency that can be found with the Riccati transfer matrix method is dependent on the number of segments into which the beam is evenly divided. It is also shown that the Riccati transfer matrix method exhibits the infinite wrap problem, i.e, the determinant has a number of infinite wrap points, where the determinant goes from +∞ to −∞. A simple method is suggested to take care of this problem when determinant search is used to find the natural frequencies. The mathematical demonstration of the numerical stability and infinite wrap associated with the Riccati transfer matrix method is provided.
Noninvasive Evaluation of the Prosthetic Hip Joint Using the Acousto-Ultrasonic Technique
Authors: Vaidya U. K. , Raju P. K. 
Published: April 2021

Abstract
The need to identify the bond quality between the implant material and the bone is crucial in prosthetic orthopedic applications. When in service, there is a likelihood of loosening of the implant-bone interface which can result in loss of mechanical rigidity and stress concentration in the vicinity of the bone and the implant. Hence, noninvasive techniques are necessary to assess the bond quality in orthopedic implants. The purpose of the present work was to investigate the bond quality in a hip bone with a steel implant, using the acousto-ultrasonics technique in which two methods — acoustic emission and ultrasonics are used in combination. The acousto-ultrasonic technique was found to be sensitive to a loose joint when compared to a good one, indicating variation in terms of the ringdown counts and energy content of the acoustic emission events.
Two-Dimensional Velocity Data Smoothing and Structural Angular Velocity Extraction Using a DFT-IDFT Technique
Authors: Sun F. P. , Mitchell Larry D. 
Published: April 2021

Abstract
Structure dynamic imaging using a scanning Laser Doppler Velocimeter provides a feasible and efficient means for high-resolution rotational velocity extraction. It shifts the experimentalists’ ground from physical measurement of rotations to mathematical data manipulation and the differentiation of the experimental translational velocity. Consequently, the differentiability of velocity data becomes a major issue since such data are sequences of discrete numbers and are usually noise contaminated. This paper presents an effective method for two-dimensional data set smoothing using one-dimensional Discrete Fourier Transform-Inverse Discrete Fourier Transform (DFT-IDFT) process as a lowpass spatial filter. The angular velocities can then be defined analytically by differentiation in the spatial frequency domain. The technique is prototyped with several real experimental data sets from a steel plate excited at its resonance modes. Special attention is paid to the efforts on making 2-D data set periodic in the data frame as well as to the related error analysis. A preliminary criterion is suggested for determination of “spatial frequency truncation” in IDFT.
On Object-Oriented Databases, Materialized Views, and Concurrent Engineering
Authors: Hardwick Martin , Downie Blair R. 
Published: April 2021

Abstract
Concurrent engineering seeks to reduce the length of the design life cycle by allowing multiple engineers to work on a design concurrently using their different design tools. A major stumbling block in achieving this goal is that most design tools use different file formats. Emerging standards such as STEP/PDES/EXPRESS reduce this barrier, but conformance to standards is not enough. One reason design tools have different file formats is because each tool requires a different perspective or view of the design. Engineering databases must provide designers with the ability to define application specific views of design data, and the ability to propagate changes among those related views. In this paper, we examine how an object-oriented database system can support the definition of application views using a class hierarchy and multiple inheritance.
Numerical Research on the Interaction of Multidirectional Random Waves With a Large-Scale Offshore Wind Turbine Foundation
Authors: Ji Xinran , Wang Daoru 
Published: April 2021

Abstract
Real sea waves are multidirectional, but most of researches are focused on the unidirectional wave. Special to the numerical wave basin based on OpenFOAM to simulate the propagation of multidirectional random wave and its interaction with structure has the insufficient of large amount of calculation, to overcome this problem, a one-way coupling model is established based on the potential theory and OpenFOAM wave basin, and the amount of calculation is reduced and the computational efficiency is improved. Base on the coupling model, the multidirectional random waves and its interaction with a large-scale offshore wind turbine foundation are simulated. In the outer domain, the multidirectional random wave is generated by the potential theory quickly. The interaction of multidirectional waves with the offshore wind turbine foundation is simulated in the inner domain by solving the Navier-Stokes equation. The result shows that the wave directionality has a significant effect on the interaction of multidirectional irregular waves with cylinder.
A Reduced-Order Mathematical Model for the Current-Induced Motion of a Floating Offshore Wind Turbine
Authors: de Oliveira Éverton L. , Pesce Celso P. , Mendes Bruno , Orsino Renato M. M. , Franzini Guilherme R. 
Published: April 2021

Abstract
Floating offshore platforms motions induced by currents are quite complex phenomena, in general. In particular, VIM, Vortex-Induced Motion, is a type often encountered in platforms with circular columns. Recently, VIM has been observed in towing tank tests with a small-scale model of a Floating Offshore Wind Turbine (FOWT), the OC4 Phase II floater, a 3+1 columns platform. The present paper proposes a reduced-order mathematical model (ROM) to assess VIM of a FOWT. The ROM is derived on the horizontal plane, including yaw motions and nonlinear mooring forces. Current forces are represented through ‘wake variables’, adapting phenomenological models firstly used for VIM of mono-column platforms. The ROM is built upon a set of eleven generalized coordinates, three for the rigid body motion on the horizontal plane and a pair of wake variables for each column, resulting in a system of eleven nonlinear second-order ODEs. The pairs of wake variables obey van der Pol equations, and use hydrodynamic coefficients and parameters obtained from previous experiments with small draught cylinders. Hydro-dynamic interferences among columns or heave plates effects on the flow are not considered, for simplicity. The validity of the proposed model is assessed having the mentioned small-scale experimental campaign as a case study. The simulations are carried out at three different current incidence angles, 0, 90 and 180 degrees, spanning a large range of reduced velocities. The simulations reproduce well the oscillations observed in the experimental tests. A good agreement in transverse oscillations is found, including lock-in regions. The simulations also depict a possibly important phenomenon: a resonant yaw motion emerging at high reduced velocities.
Experimental Validation of a Wave Elevation Observer on a Floating Wind Turbine Model
Authors: Di Carlo Simone , Fontanella Alessandro , Facchinetti Alan , Muggiasca Sara , Taruffi Federico , Belloli Marco 
Published: April 2021

Abstract
The scope of this work is to investigate if and how it is possible to estimate the incident wave elevation on a floating wind turbine, with the purpose of improved control strategies. A Kalman based algorithm is proposed, which receives as input the rigid motions of the floater and estimates the wave elevation hitting the floating platform. The structure of the observer is described and the estimator is tested numerically on the OC3-Hywind platform coupled with the 5-MW reference wind turbine from NREL. Limitations to the estimation procedure are discussed. Finally the algorithm is tested on experimental data coming from a wave basin experimental campaign on a floating wind turbine model. The algorithm still needs improvements, but results are encouraging in the development of this technology.
Study of Motion Performance of a Floating System With Four Moonpools and a VAWT
Authors: Tan Lei , Moritsu Satsuya , Ikoma Tomoki , Aida Yasuhiro , Masuda Koichi 
Published: April 2021

Abstract
In this paper the hydrodynamic performance of a barge-type floating foundation installed with four moonpools and a VAWT was investigated through model tests and theoretical calculations. The characteristics of wave-induced motion responses and tether tensions and the effects of turbine rotations were examined. Physical model tests were conducted in a wave tank using regular waves with the wave period ranging from 0.6 to 1.6 seconds and 0.01 or 0.02 meters in amplitude. A 2-MW-class VAWT was modelled with a scale ratio of 1/100 in the experiments. By varying the mass and the rotational speed of the turbine, gyroscopic moment effects were studied. In addition, numerical calculations based on the linear potential theory and Green function method were carried out to estimate motion responses and tether tensions.
The present results indicate that the gyroscopic effect due to turbine rotations can be profound. It was found that the first-order motions of the floating system were substantially reduced by the gyroscopic effect, while the second-order motions and tether tensions may be significantly increased. Moreover, the viscous damping of water motions in moonpools was found not negligible. As a result, theoretical models based on linear potential theory should be used with care in hydrodynamic analysis with regard to the floating systems with VAWT rotations. In addition, the present in-house program code was validated against WAMIT through comparing hydrodynamic predictions of a floating foundation with four moonpools, with reasonable agreement.