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Dynamics and Dynamical Systems Commons

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Articles 1 - 18 of 18

Full-Text Articles in Dynamics and Dynamical Systems

Principal Component Neural Networks For Modeling, Prediction, And Optimization Of Hot Mix Asphalt Dynamics Modulus, Parnian Ghasemi, Mohamad Aslani, Derrick K. Rollins, R. Christopher Williams Aug 2019

Principal Component Neural Networks For Modeling, Prediction, And Optimization Of Hot Mix Asphalt Dynamics Modulus, Parnian Ghasemi, Mohamad Aslani, Derrick K. Rollins, R. Christopher Williams

Chemical and Biological Engineering Publications

The dynamic modulus of hot mix asphalt (HMA) is a fundamental material property that defines the stress-strain relationship based on viscoelastic principles and is a function of HMA properties, loading rate, and temperature. Because of the large number of efficacious predictors (factors) and their nonlinear interrelationships, developing predictive models for dynamic modulus can be a challenging task. In this research, results obtained from a series of laboratory tests including mixture dynamic modulus, aggregate gradation, dynamic shear rheometer (on asphalt binder), and mixture volumetric are used to create a database. The created database is used to develop a model for estimating ...


A Lagrangian Probability-Density-Function Model For Collisional Turbulent Fluid–Particle Flows, Alessio Innocenti, Rodney O. Fox, Maria Vittoria Salvetti, Sergio Chibbaro Mar 2019

A Lagrangian Probability-Density-Function Model For Collisional Turbulent Fluid–Particle Flows, Alessio Innocenti, Rodney O. Fox, Maria Vittoria Salvetti, Sergio Chibbaro

Chemical and Biological Engineering Publications

Inertial particles in turbulent flows are characterised by preferential concentration and segregation and, at sufficient mass loading, dense particle clusters may spontaneously arise due to momentum coupling between the phases. These clusters, in turn, can generate and sustain turbulence in the fluid phase, which we refer to as cluster-induced turbulence (CIT). In the present work, we tackle the problem of developing a framework for the stochastic modelling of moderately dense particle-laden flows, based on a Lagrangian probability-density-function formalism. This framework includes the Eulerian approach, and hence can be useful also for the development of two-fluid models. A rigorous formalism and ...


Predicting Dynamic Modulus Of Asphalt Mixture Using Data Obtained From Indirect Tension Mode Of Testing, Parnian Ghasemi, Shibin Lin, Derrick K. Rollins, R. Christopher Williams Jan 2019

Predicting Dynamic Modulus Of Asphalt Mixture Using Data Obtained From Indirect Tension Mode Of Testing, Parnian Ghasemi, Shibin Lin, Derrick K. Rollins, R. Christopher Williams

Chemical and Biological Engineering Publications

Understanding stress-strain behavior of asphalt pavement under repetitive traffic loading is of critical importance to predict pavement performance and service life. For viscoelastic materials, the stress-strain relationship can be represented by the dynamic modulus. The dynamic modulus test in indirect tension mode can be used to measure the modulus of each specific layer of asphalt pavements using representative samples. Dynamic modulus is a function of material properties, loading, and environmental conditions. Developing predictive models for dynamic modulus is efficient and cost effective. This article focuses on developing an accurate Finite Element (FE) model using mixture elastic modulus and asphalt binder ...


Life Cycle Cost Evaluation Strategy For High Performance Control Systems Under Uncertainties, Laura Micheli, Ling Cao, Simon Laflamme, Alice Alipour Jan 2019

Life Cycle Cost Evaluation Strategy For High Performance Control Systems Under Uncertainties, Laura Micheli, Ling Cao, Simon Laflamme, Alice Alipour

Civil, Construction and Environmental Engineering Publications

High-performance control systems (HPCSs), including active, hybrid, and semi-active control strategies, can perform over a wide excitation bandwidth and are therefore good candidates for multi-hazard mitigation. However, the number of HPCS applications in the field is very limited. This is likely due the perceived high costs of installation, maintenance, possible malfunction, and lack of tools to financially justify their implementation. Such financial justifications could be conducted through life cycle cost (LCC) analysis, but would result in a computationally demanding task due to the very large number of simulations required given the large number of uncertainties. In this paper, two sets ...


Shape-Design For Stabilizing Micro-Particles In Inertial Microfluidic Flows, Aditya Kommajosula, Daniel Stoecklein, Dino Di Carlo, Baskar Ganapathysubramanian Jan 2019

Shape-Design For Stabilizing Micro-Particles In Inertial Microfluidic Flows, Aditya Kommajosula, Daniel Stoecklein, Dino Di Carlo, Baskar Ganapathysubramanian

Mechanical Engineering Publications

Design of microparticles which stabilize at the centerline of a channel flow when part of a dilute suspension is examined numerically for moderate Reynolds numbers (10≤Re≤80). Stability metrics for particles with arbitrary shapes are formulated based on linear-stability theory. Particle shape is parametrized by a compact, Non-Uniform Rational B-Spline (NURBS)-based representation. Shape-design is posed as an optimization problem and solved using adaptive Bayesian optimization. We focus on designing particles for maximal stability at the channel-centerline robust to perturbations. Our results indicate that centerline-focusing particles are families of characteristic "fish"/"bottle"/"dumbbell"-like shapes, exhibiting fore-aft asymmetry. A ...


Characterization Of A Novel Variable Friction Connection For Semi-Active Cladding System, Yongqiang Gong, Liang Cao, Simon Laflamme, Spencer Quiel, James Ricles, Douglas Taylor Jun 2018

Characterization Of A Novel Variable Friction Connection For Semi-Active Cladding System, Yongqiang Gong, Liang Cao, Simon Laflamme, Spencer Quiel, James Ricles, Douglas Taylor

Civil, Construction and Environmental Engineering Publications

Cladding systems are conventionally designed to serve architectural purposes and protect occupants from the environment. Some research has been conducted in altering the cladding system in order to provide additional protection against natural and man‐made hazards. The vast majority of these solutions are passive energy dissipators, applicable to the mitigation of single types of hazards. In this paper, we propose a novel semiactive variable friction device that could act as a connector linking a cladding panel to the structural system. Because of its semiactive capabilities, the device, here termed variable friction cladding connection (VFCC), could be utilized to mitigate ...


Study Of Input Space For State Estimation Of High-Rate Dynamics, Jonathan Hong, Simon Laflamme, Jacob Dodson Jun 2018

Study Of Input Space For State Estimation Of High-Rate Dynamics, Jonathan Hong, Simon Laflamme, Jacob Dodson

Civil, Construction and Environmental Engineering Publications

High‐rate dynamic systems are defined as systems being exposed to highly dynamic environments that comprise high‐rate and high‐amplitude events. Examples of such systems include civil structures exposed to blast, space shuttles prone to debris strikes, and aerial vehicles experiencing in‐flight changes. The high‐rate dynamic characteristics of these systems provides several possibilities for state estimators to improve performance, including a high potential to reduce injuries and save lives. In this paper, opportunities and challenges that are specific to state estimation of high‐rate dynamic systems are presented and discussed. It is argued that a possible path ...


Adaptive Observers For Structural Health Monitoring Of High-Rate, Time-Varying Dynamic Systems, B. S. Joyce, J. Hong, J. C. Dodson, J. C. Wolfson, Simon Laflamme May 2018

Adaptive Observers For Structural Health Monitoring Of High-Rate, Time-Varying Dynamic Systems, B. S. Joyce, J. Hong, J. C. Dodson, J. C. Wolfson, Simon Laflamme

Civil, Construction and Environmental Engineering Conference Presentations and Proceedings

Safe and reliable operation of hypersonic aircraft, space structures, advanced weapon systems, and other high-rate dynamic systems depends on advances in state estimators and damage detection algorithms. High-rate dynamic systems have rapidly changing input forces, rate-dependent and time-varying structural parameters, and uncertainties in material and structural properties. While current structural health monitoring (SHM) techniques can assess damage on the order of seconds to minutes, complex high-rate structures require SHM methods that detect, locate, and quantify damage or changes in the structure’s configuration on the microsecond timescale.

This paper discusses the importance of microsecond structural health monitoring (μSHM) and some ...


Variable Input Observer For State Estimation Of High-Rate Dynamics, Jonathan Hong, Liang Cao, Simon Laflamme, Jacob Dodson Apr 2017

Variable Input Observer For State Estimation Of High-Rate Dynamics, Jonathan Hong, Liang Cao, Simon Laflamme, Jacob Dodson

Civil, Construction and Environmental Engineering Conference Presentations and Proceedings

High-rate systems operating in the 10 μs to 10 ms timescale are likely to experience damaging effects due to rapid environmental changes (e.g., turbulence, ballistic impact). Some of these systems could benefit from real-time state estimation to enable their full potential. Examples of such systems include blast mitigation strategies, automotive airbag technologies, and hypersonic vehicles. Particular challenges in high-rate state estimation include: 1) complex time varying nonlinearities of system (e.g. noise, uncertainty, and disturbance); 2) rapid environmental changes; 3) requirement of high convergence rate. Here, we propose using a Variable Input Observer (VIO) concept to vary the ...


Microsecond State Monitoring Of Nonlinear Time-Varying Dynamic Systems, Jacob Dodson, Bryan Joyce, Applied Research Associates Inc., Simon Laflamme, Janet Wolfson Jan 2017

Microsecond State Monitoring Of Nonlinear Time-Varying Dynamic Systems, Jacob Dodson, Bryan Joyce, Applied Research Associates Inc., Simon Laflamme, Janet Wolfson

Civil, Construction and Environmental Engineering Conference Presentations and Proceedings

Reliable operation of next generation high-speed complex structures (e.g. hypersonic air vehicles, space structures, and weapons) relies on the development of microsecond structural health monitoring (μSHM) systems. High amplitude impacts may damage or alter the structure, and therefore change the underlying system configuration and the dynamic response of these systems. While state-of-the-art structural health monitoring (SHM) systems can measure structures which change on the order of seconds to minutes, there are no real-time methods for detection and characterization of damage in the microsecond timescales.

This paper presents preliminary analysis addressing the need for microsecond detection of state and parameter ...


Robust Variable Input Observer For Structural Health Monitoring Of Systems Experiencing Harsh Extreme Environments, Jonathan Hong, Liang Cao, Simon Laflamme, Jacob Dodson Jan 2017

Robust Variable Input Observer For Structural Health Monitoring Of Systems Experiencing Harsh Extreme Environments, Jonathan Hong, Liang Cao, Simon Laflamme, Jacob Dodson

Civil, Construction and Environmental Engineering Conference Presentations and Proceedings

Systems experiencing events in the order of 10μs-10ms timescales, for instance highrate dynamics or harsh extreme environments, may encounter rapid damaging effects. If the structural health of such systems could be accurately estimated in a timely manner, preventative measures could be employed to minimize adverse effects. Previously, a Variable Input Observer (VIO) coupled with a neuro-observer was proposed by the authors as a potential solution in monitoring their structural health. The objective of the VIO is to provide state estimation based on an optimal input space allowed to vary as a function of time. The VIO incorporates the use of ...


Full-Field Structural Dynamics By Video Motion Manipulations, Yongchao Yang, Charles Farrara, David Mascarenasa Jan 2016

Full-Field Structural Dynamics By Video Motion Manipulations, Yongchao Yang, Charles Farrara, David Mascarenasa

Review of Progress in Quantitative Nondestructive Evaluation

Structures with complex geometries, material properties, and boundary conditions, exhibit spatially local, temporally transient, dynamic behaviors. High spatial and temporal resolution vibration measurements and modeling are thus required for high-fidelity characterization, analysis, and prediction of the structure’s dynamic phenomena. For example, high spatial resolution mode shapes are needed for accurate vibration-based damage localization. Also, higher order vibration modes typically contain local structural features that are essential for high-fidelity dynamic modeling of the structure. In addition, while it is possible to build a highly- refined mathematical model (e.g., a finite element model) of the structure, it needs to be ...


A Collocated C0 Finite Element Method: Reduced Quadrature Perspective, Cost Comparison With Standard Finite Elements, And Explicit Structural Dynamics, Dominik Schillinger, John A. Evans, Felix Frischmann, René R. Hiemstra, Ming-Chen Hsu, Thomas J.R. Hughes Apr 2015

A Collocated C0 Finite Element Method: Reduced Quadrature Perspective, Cost Comparison With Standard Finite Elements, And Explicit Structural Dynamics, Dominik Schillinger, John A. Evans, Felix Frischmann, René R. Hiemstra, Ming-Chen Hsu, Thomas J.R. Hughes

Mechanical Engineering Publications

We demonstrate the potential of collocation methods for efficient higher-order analysis on standard nodal finite element meshes. We focus on a collocation method that is variationally consistent and geometrically flexible, converges optimally, embraces concepts of reduced quadrature, and leads to symmetric stiffness and diagonal consistent mass matrices. At the same time, it minimizes the evaluation cost per quadrature point, thus reducing formation and assembly effort significantly with respect to standard Galerkin finite element methods. We provide a detailed review of all components of the technology in the context of elastodynamics, that is, weighted residual formulation, nodal basis functions on Gauss ...


Authoring Effective Embedded Tutors: An Overview Of The Extensible Problem Specific Tutor (Xpst) System, Stephen B. Gilbert, Stephen B. Blessing, Enruo Guo Jan 2015

Authoring Effective Embedded Tutors: An Overview Of The Extensible Problem Specific Tutor (Xpst) System, Stephen B. Gilbert, Stephen B. Blessing, Enruo Guo

Industrial and Manufacturing Systems Engineering Publications

The Extensible Problem Specific Tutor (xPST) allows authors who are not cognitive scientists and not programmers to quickly create an intelligent tutoring system that provides instruction akin to a model-tracing tutor. Furthermore, this instruction is overlaid on existing software, so that the learner’s interface does not have to be made from scratch. The xPST architecture allows for extending its capabilities by the addition of plug-ins that communicate with additional third-party software. After reviewing this general architecture, we describe three major implementations that we have created using the xPST system, each using different third-party software as the learner’s interface ...


Using Conceptgrid As An Easy Authoring Technique To Check Natural Language Responses, Stephen B. Blessing, Shrenik Devasani, Stephen B. Gilbert, Jivko Sinapov Jan 2015

Using Conceptgrid As An Easy Authoring Technique To Check Natural Language Responses, Stephen B. Blessing, Shrenik Devasani, Stephen B. Gilbert, Jivko Sinapov

Industrial and Manufacturing Systems Engineering Publications

ConceptGrid provides a template-style approach to check natural language responses by students using a model-tracing style intelligent tutoring system. The tutor-author creates, using a web-based authoring system, a latticestyle structure that contains the set of required concepts that need to be in a student response. The author can also create just-in-time feedback based on the concepts present or absent in the student's response. ConceptGrid is integrated within the xPST authoring tool and was tested in two experiments, both of which show the efficacy of the technique to check student answers. The first study tested the tutor's effectiveness overall ...


Adaptive Structural Control Using Dynamic Hyperspace, Simon Laflamme Jan 2015

Adaptive Structural Control Using Dynamic Hyperspace, Simon Laflamme

Civil, Construction and Environmental Engineering Publications

The design of closed-loop structural control systems necessitates a certain level of robustness to cope with system uncertainties. Neurocontrollers, a type of adaptive control system, have been proposed to cope with those uncertainties. However, the performance of neural networks can be substantially influenced by the choice of the input space, or the hyperspace in which the representation lies. For instance, input selection may influence computation time, adaptation speed, effects of the curse of dimensionality, understanding of the representation, and model complexity. Input space selection is often overlooked in literature, and inputs are traditionally determined offline for an optimized performance of ...


Dynamic Characterization Of A Soft Elastomeric Capacitor For Structural Health Monitoring Applications, Husaam Saleem, Simon Laflamme, Filippo Ubertini Mar 2014

Dynamic Characterization Of A Soft Elastomeric Capacitor For Structural Health Monitoring Applications, Husaam Saleem, Simon Laflamme, Filippo Ubertini

Civil, Construction and Environmental Engineering Conference Presentations and Proceedings

A novel thin film sensor consisting of a soft elastomeric capacitor (SEC) for meso-scale monitoring has been developed by the authors. Each SEC transduces surface strain into a measurable change in capacitance. In previous work, the authors have shown that the performance of the SEC compares well with conventional resistive strain gauges, providing a resolution of 25 με using an inexpensive off-the-shelf data acquisition system for capacitance measurements. Here, we further the understanding of the thin film sensor by characterizing its dynamic behavior. The SEC is subjected to dynamic loads in bending mode. The study of Fourier and wavelet transforms ...


Human Differences In Navigational Approaches During Tele-Robotic Search, Richard Stone, Michael Dorneich, Stephen Gilbert, Elease Mclaurin Sep 2013

Human Differences In Navigational Approaches During Tele-Robotic Search, Richard Stone, Michael Dorneich, Stephen Gilbert, Elease Mclaurin

Industrial and Manufacturing Systems Engineering Conference Proceedings and Posters

This study investigated the navigational approaches used by humans when operating a simple tele-robot in a simulated search and rescue operation. Tele-robots are being increasingly used in safety-critical operations. During tele-operation, the situational awareness of tele-robot operators needs to be supported. Navigation depends on psychological skills of perception and cognition, and can utlize different problem solving strategies. However, there is limited knowledge of how operators develop situational awareness while navigating tele-robots. The study was conducted to understand if there were distinctive, identifiable strategies in the way operators navigated. When participants manually tele-operated a robot in a remote physical environment, two ...