MEMS-Based Atomic Force Microscope: Nonlinear Dynamics Analysis and Its Control

In this chapter, we explore a mathematical modelling that describes the nonlinear dynamic behavior of atomic force microscopy (AFM). We propose two control techniques for suppressing the chaotic motion of the system. The proposed model considers the interatomic interactions between the analyzed sample and the cantilever. These acting forces are van der Waals type, and we add a mathematical term that is a simple approximation to the viscoelasticity that possibly occurs in biological samples. We analyzed the behavior of the initial conditions of the proposed mathematical model, which showed a degree of complexity of the basins of attraction that were detected by entropy and uncertainty parameter, both detect if the basins have a fractal behavior. Numerical results showed that the nonlinear dynamic behavior has chaotic regions with the Lyapunov exponent, bifurcation diagram, and the Poincaré map. And, we propose two control techniques to suppress the chaotic movement of the AFM cantilever. First technique is the optimal linear feedback control (OLFC), which does not consider the nonlinearities of mathematical model. On the other hand, the control state dependent Riccati equation (SDRE) considers the nonlinearities of mathematical model. Both control techniques for a desired periodic orbit proved to be efficient

Dementia in Latin America : paving the way towards a regional action plan

Regional challenges faced by Latin American and Caribbean countries (LACs) to fight dementia, such as heterogeneity, diversity, political instabilities, and socioeconomic disparities, can be addressed more effectively grounded in a collaborative setting based on the open exchange of knowledge. In this work, the Latin American and Caribbean Consortium on Dementia (LAC-CD) proposes an agenda for integration to deliver a Knowledge to Action Framework (KtAF). First, we summarize evidence-based strategies (epidemiology, genetics, biomarkers, clinical trials, nonpharmacological interventions, networking and translational research) and align them to current global strategies to translate regional knowledge into actions with transformative power. Then, by characterizing genetic isolates, admixture in populations, environmental factors, and barriers to effective interventions and mapping these to the above challenges, we provide the basic mosaics of knowledge that will pave the way towards a KtAF. We describe strategies supporting the knowledge creation stage that underpins the translational impact of KtAF

5th Symposium on Mechanics of Slender Structures 2015 (MoSS2015)

This issue of Journal of Physics: Conference Series contains sixteen selected technical papers that were presented at the 5th Symposium on the Mechanics of Slender Structures (MoSS2015) and show a range of different approaches used in the analysis of slender structures. The meeting was held in Northampton, UK, from 21st to 22nd September 2015. This conference runs under the auspices of the Institute of Physics Applied Mechanics Group and forms a continuation of a successful meeting series on the Mechanics of Slender Structures first held in Northampton, UK, in 2006, followed by the event hosted in Baltimore, USA in 2008, in San Sebastian, Spain in 2010, and in Harbin, China in 2013

Bifurcational Phenomena In A Nonideal System

In this paper, a particular system is studied consisting of a pendulum whose support point is vibrated along a horizontal guide through two bar linkage driven by a DC motor, considered as a limited power supply. In this condition the parameters as external force and frequency are not arbitrary constants, but they are defined by a differential equation increasing the degrees of freedom of the system. Also, the motor's parameters are chosen in a way that the energy source be of limited power (nonideal condition). We will analyze the system behavior numerically through the bifurcation diagram, showing the main characteristics of its microscopic dynamics close to fundamental resonance.228628

Dynamic analysis of the non-linear behavior of an ocean buoy for energy harvesting

We investigated the nonlinear dynamic behavior of the system for energy harvesting using ocean wave motion. The system consists of a linear electromagnetic system coupled to a float to move with ocean waves. We define the mathematical modeling of a structure together with the parameters for energy harvesting. In this way, we analyzed average power for the parameters linked to the wave profile, the resistance load of the electromechanical motor, and the nonlinear parameters of spring cubic. Therefore, we also analyze the nonlinear dynamic behavior with Maximum Lyapunov exponent, bifurcation diagrams, phase portraits, and Poincaré maps

Dynamical Analysis and Control of a Chaotic Microelectromechanical Resonator Model

The dynamic analysis and control of a nonlinear MEM resonator system are considered. Phase diagram, bifurcation diagram, and the 0-1 test are applied to the analysis of the influence of the parameters on the dynamics of the system, whose parameters are damping coefficient, polarization of the voltage, and nonlinear stiffness term. The bifurcation diagram is used to demonstrate the existence of the pull-in effect. Numerical results showed that the parameters, which were taken into account, were significant, indicating that the response can be either chaotic or periodic behavior. In order to bring the system from a chaotic state to a periodic orbit, two controls are considered: the time-delayed feedback control and the sliding mode control

SDRE and LQR Controls Comparison Applied in High-Performance Aircraft in a Longitudinal Flight

This paper presents the design of the LQR (Linear Quadratic Regulator) and SDRE (State-Dependent Riccati Equation) controllers for the flight control of the F-8 Crusader aircraft considering the nonlinear model of longitudinal movement of the aircraft.  Numerical results and analysis demonstrate that the designed controllers can lead to significant improvements in the aircraft's performance, ensuring stability in a large range of attack angle situations. When applied in flight conditions with an angle of attack above the stall situation and influenced by the gust model, it was demonstrated that the LQR and SDRE controllers were able to smooth the flight response maintaining conditions in balance for an angle of attack up to 56% above stall angle.  However, for even more difficult situations, with angles of attack up to 76% above the stall angle, only the SDRE controller proved to be efficient and reliable in recovering the aircraft to its stable flight configuration

Numerical analysis of fractional dynamical behavior of Atomic Force Microscopy

We investigate the nonlinear dynamic model of the Atomic Force Microscopy model (AFM) with the influence of a viscoelastic term. The mathematical model is based on non-resonant and almost linear responses, together with the deflection of the microcantilever, and also considers the interaction forces between the atoms of the analysis tip and the sample surface. Our results show the influence on the nonlinear dynamics of this model considering the term viscoelastic. We also analyzed the generalized model with the fractional calculus with the Riemann–Liouville operator derivative applied to the viscoelastic term and thus having the fractional nonlinear dynamics of the AFM system. For the analysis of the system, we used the classic tooling of nonlinear dynamics (Bifurcation diagram, 0–1 Test, and Poincaré maps, and the Maximum Lyapunov Exponent), however, the results showed the chaotic and periodic regions of the fractional system

Dynamic Model of a Robotic Manipulator with One Degree of Freedom with Friction Component

This research aims to develop a dynamic model of a robotic manipulator with one degree of freedom by incorporating the LuGre friction model. The study combines a mathematical model with experimental data analysis, using the Stribeck curve and Non-linear Least Square method for Parameter Identification. The purpose of the study is to improve the accuracy of the model and enhance the performance of robotic manipulators. The LuGre model is chosen for its ability to capture the nonlinear behavior of friction, which is a significant source of error in robot control systems. The effectiveness of the proposed representation is evaluated by comparing the simulation results of the dynamic model with experimental data obtained from a prototype. The results indicate that the model accurately captures the nonlinear behavior of friction, and the proposed approach can be used to develop more accurate models for control purposes

Instrumentation Of a Nonlinear Pendulum Using Arduino

Abstract. In this paper the Arduino microcontroller together with the gyroscopic sensor for measuring vibrations in mechanical systems are used. The objective is to present the Arduino platform as an alternative for low cost signal acquisition, easy use and good precision for educational purpose. In this application the system presents a nonlinear behavior for certain initial conditions. The characterization of the system’s nonlinearities are done by the comparison between the signal measured and a numerical solution of the classic equation of motion of the pendulum. It is also presented a scenario where the pendulum is excited by an magnetic interaction. The results showed in conformity with the literature. Keywords: Arduino microcontroller, sensor, vibrations, nonlinear, educatio