scholarly journals A Ball-Type Passive Tuned Mass Vibration Absorber for Response Control of Structures under Harmonic Loading

2021 ◽  
Author(s):  
Jiří Náprstek ◽  
Cyril Fischer
Keyword(s):  
Linear Structure ◽  
Random Excitation ◽  
Harmonic Loading ◽  
Directional Effect ◽  
Linear Character ◽  
System Parameters ◽  
Autoparametric Resonance ◽  
Non Linear ◽  
Practical Engineering ◽  
Structure And Design

Ball-type tuned mass absorbers are growing in popularity. They combine a multi-directional effect with compact dimensions, properties that make them attractive for use at slender structures prone to wind excitation. Their main drawback lies in limited adjustability of damping level to a prescribed value. Insufficient damping makes ball-type absorbers more prone than pendula to objectionable effects stemming from the non-linear character of the system. Thus, the structure and design of the damping device have to be made so that the autoparametric resonance states, occurrence of which depends on system parameters and properties of possible excitation, are avoided for safety reasons. This chapter summarises available 3D mathematical models of a ball-pendulum and introduces the non-linear approach based on the Appell–Gibbs function. Efficiency of the models is then illustrated for the case of kinematic and random excitation. Interaction of the absorber and the harmonically forced simple linear structure is numerically analysed. Finally, the chapter provides examples of typical patterns of the autoparametric response and outlines possibilities of applications in practical engineering.

A Systematic Approach to Estimate Non-Linear System Parameters using Particle Swarm Optimization and Bond Graph Methods

2021 ◽  
Author(s):  
Irfan Bahiuddin ◽  
Parsaulian I Siregar ◽  
Saiful Amri Mazlan ◽  
Rizki S Nugroho ◽  
Fitrian Imaduddin ◽  
...  
Keyword(s):  
Particle Swarm Optimization ◽  
Linear System ◽  
Systematic Approach ◽  
Particle Swarm ◽  
Bond Graph ◽  
Swarm Optimization ◽  
System Parameters ◽  
Non Linear ◽  
Non Linear System

On the Model Scaling of Polyester Mooring Lines for Offshore Applications

2002 ◽  
Author(s):  
Antonio Carlos Fernandes ◽  
Ronaldo Rosa Rossi
Keyword(s):  
Steel Wire ◽  
Random Excitation ◽  
Model Tests ◽  
Early Model ◽  
Random Waves ◽  
Mooring Lines ◽  
New Approach ◽  
Linear Behavior ◽  
Non Linear ◽  
Similarity Laws

With the introduction of the polyester ropes as mooring lines of large systems such as semi-submersibles, the need to simulate these lines in model tests became a necessity. Although the non-linear behavior is clear, depending on the type of cycling, the polyester rope responds in ways that may be considered linear as a steel wire rope. Because of that, the early model tests have been performed using a linear restoring capability, with different restoring coefficients. The use of equivalent springs seemed the proper way. However, with the help of fundamental investigation on the similarity laws, the present work shows that the use of very thin polyester lines in model scaling is feasible and will indeed allow a closer physical representation. By avoid using springs, but using the same material as in full scale, the same non-linear behavior is present during the tests and even the response to random excitation due to random waves is better represented. The paper closely describes the application of these ideas in a model test of a FPSO (Floating Production Storage and Offloading) comparing both the linear springs and new approach with the model scale equivalent polyester line.

Testing for non-linear structure in an artificial financial market

2001 ◽  
Vol 46 (3) ◽  
pp. 327-342 ◽  
Author(s):  
Shu-Heng Chen ◽  
Thomas Lux ◽  
Michele Marchesi
Keyword(s):  
Financial Market ◽  
Linear Structure ◽  
Non Linear

Evaluating Lateral Interactions of Motorized Two-Wheelers using Multi-Gene Symbolic Genetic Programming

2020 ◽  
Vol 2674 (9) ◽  
pp. 1120-1135 ◽  
Author(s):  
Sanhita Das ◽  
Narayana Raju ◽  
Akhilesh Kumar Maurya ◽  
Shriniwas Arkatkar
Keyword(s):  
Genetic Programming ◽  
Cognitive Architecture ◽  
Linear Structure ◽  
Symbolic Regression ◽  
Programming Algorithm ◽  
Lateral Interactions ◽  
Symbolic Model ◽  
Multigene Genetic Programming ◽  
Non Linear ◽  
Lateral Clearance

Complex maneuvering patterns are typical of motorized two-wheelers (MTWs), and their widespread adoption in many countries has spurred a growing response from transport researchers to model their dynamic behavior realistically. Considering the increased vulnerability of MTW drivers in dense urban mixed traffic systems, proper evaluation and modeling of lateral interactions between the drivers/riders moving abreast need to be addressed. A proper investigation can essentially help in understanding the behavioral aspects of riders in accepting shorter lateral clearances, design of exclusive motorcycle lanes, improved reliability of microsimulation models, and safety evaluation of the riders in a cognitive architecture. The current study therefore attempts to develop a novel symbolic regression model using a multigene genetic programming algorithm to generate and evaluate lateral clearance models naturally from field data for MTW interactions at mid-block sections, data being collected using video recorders. A binary logit model is initially developed to investigate the factors associated with the riders’ decisions to accept critical lateral clearances. Considering highly non-linear variations in data, the symbolic regression models were further developed and a comparison with the existing linear regression based lateral clearance models indicated that the symbolic model could generalize the non-linear structure of the data realistically and performed significantly better than the existing models.

scholarly journals Cosmology with galaxy–galaxy lensing on non-perturbative scales: emulation method and application to BOSS LOWZ

2019 ◽  
Vol 492 (2) ◽  
pp. 2872-2896 ◽  
Author(s):  
Benjamin D Wibking ◽  
David H Weinberg ◽  
Andrés N Salcedo ◽  
Hao-Yi Wu ◽  
Sukhdeep Singh ◽  
...  
Keyword(s):  
Cosmological Parameters ◽  
Linear Structure ◽  
Sloan Digital Sky Survey ◽  
Projected Clustering ◽  
True Value ◽  
Data Release ◽  
Non Linear ◽  
Galaxy Sample ◽  
Galaxy Bias ◽  
Red Galaxies

ABSTRACT We describe our non-linear emulation (i.e. interpolation) framework that combines the halo occupation distribution (HOD) galaxy bias model with N-body simulations of non-linear structure formation, designed to accurately predict the projected clustering and galaxy–galaxy lensing signals from luminous red galaxies in the redshift range 0.16 < z < 0.36 on comoving scales 0.6 < rp < 30 $h^{-1} \, \text{Mpc}$. The interpolation accuracy is ≲ 1–2 per cent across the entire physically plausible range of parameters for all scales considered. We correctly recover the true value of the cosmological parameter S8 = (σ8/0.8228)(Ωm/0.3107)0.6 from mock measurements produced via subhalo abundance matching (SHAM)-based light-cones designed to approximately match the properties of the SDSS LOWZ galaxy sample. Applying our model to Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 14 (DR14) LOWZ galaxy clustering and galaxy-shear cross-correlation measurements made with Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8) imaging, we perform a prototype cosmological analysis marginalizing over wCDM cosmological parameters and galaxy HOD parameters. We obtain a 4.4 per cent measurement of S8 = 0.847 ± 0.037, in 3.5σ tension with the Planck cosmological results of 1.00 ± 0.02. We discuss the possibility of underestimated systematic uncertainties or astrophysical effects that could explain this discrepancy.

Evidence concerning non-linear structure in Canadian provincial unemployment rates

1993 ◽  
Vol 4 (2) ◽  
pp. 333-343 ◽  
Author(s):  
Murray Frank ◽  
Chera Sayers ◽  
Thanasis Stengos
Keyword(s):  
Linear Structure ◽  
Unemployment Rates ◽  
Non Linear

Integrating Constructionism and Instructionism in Educational Hypermedia Programs

1997 ◽  
Vol 17 (3) ◽  
pp. 231-247 ◽  
Author(s):  
Amnon Shabo
Keyword(s):  
Subject Matter ◽  
Linear Structure ◽  
Learning Objectives ◽  
Pedagogical Approach ◽  
Original Meaning ◽  
Learning Path ◽  
Non Linear ◽  
The Subject ◽  
Linear Instruction ◽  
Educational Hypermedia

In many educational hypermedia programs, the original meaning of hypertext influenced the entire pedagogical approach underlying the programs. This meant that learners were free to navigate, construct, and choose their learning path. In addition, no learning objectives were mandatory, and the processes of hypertext navigation and artifact constructions were emphasized. The problem of this trend was that learners received little feedback to guide them on how to use the non-linear structure, and not all could acquire important skills and knowledge of the subject matter. This article deals with an attempt to integrate linear instruction elements into hypermedia programs in order for learners to benefit from the advantages of both approaches. It offers feedback as a connecting unit in such an integration and suggests a model of feedback that fades in and out, based on the fading-out model of scaffolding traditionally used in the apprenticeship approach. A few projects are described to illustrate these ideas.

scholarly journals Using large-scale structure data and a halo model to constrain generalized dark matter

2019 ◽  
Vol 490 (1) ◽  
pp. 813-831 ◽  
Author(s):  
Daniel B Thomas ◽  
Michael Kopp ◽  
Katarina Markovič
Keyword(s):  
Dark Matter ◽  
Gravitational Lensing ◽  
Large Scale ◽  
Linear Structure ◽  
Microwave Background ◽  
Wavenumber Range ◽  
Significant Difference ◽  
Linear Modelling ◽  
Non Linear ◽  
Order Of Magnitude

ABSTRACT Constraints on the properties of the cosmological dark matter have previously been obtained in a model-independent fashion using the generalized dark matter (GDM) framework. Here we extend that work in several directions: We consider the inclusion of WiggleZ matter power spectrum data (MPS), and show that this improves the constraints on the two perturbative GDM parameters, $c^2_\mathrm{ s}$ and $c^2_\text{vis}$, by a factor of 3, for a conservative choice of wavenumber range. A less conservative choice can yield an improvement of up to an order of magnitude compared to previous constraints. In order to examine the robustness of this result we develop a GDM halo model (HM) to explore how non-linear structure formation could proceed in this framework, since currently GDM has only been defined perturbatively and only linear theory has been used when generating constraints. We then examine how the HM affects the constraints obtained from the MPS data. The less-conservative wavenumber range shows a significant difference between linear and non-linear modelling, with the latter favouring GDM parameters inconsistent with ΛCDM, underlining the importance of careful non-linear modelling when using this data. We also use this HM to establish the robustness of previously obtained constraints, particularly those that involve weak gravitational lensing of the cosmic microwave background. Additionally, we show how the inclusion of neutrino mass as a free parameter affects previous constraints on the GDM parameters.

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