Antonio Palacios

International conference on theory and application in nonlinear dynamics : (ICAND 2012)

Effect of voltage oscillations on response.- Properties in a model of sensory hair cell.- Enhancing signal resolution in a noisy nonlinear sensor via biomimetic processing.

Symmetry‐based Design and Fabrication of Novel Sensor Systems

Coupled systems of differential equations are often used as models of physical systems. For example they have been used by Hadley and Aronson to model arrays of Josephson junctions, by Kopell and Ermentrout and Rand to model coupled oscillators and central pattern generators (CPGs) in biological systems, by Pecora and Caroll to investigate synchronization of chaotic oscillators, and, more recently, by Susuki, Takatsuji, and Hikihara to study power grid systems. In these works the symmetry of the network is important in determining the patterns of collective behavior that the system can support. One particular pattern of behavior that is commonly found in symmetric coupled systems is cycling behavior, in which solution trajectories can linger around steady states and periodic solutions for increasingly longer periods of time. In this paper we discuss the existence and stability of heteroclinic cycles in coupled systems and show how they can be exploited to design and fabricate a new generation of highly‐se...

Dynamics and Noise in dc-SQUID Magnetometer Arrays

The natural behavior of most processes is that whenever they are effected by an external phenomenon the outcome of the system is changed. Hence the output of a process can be changed by the input of the system. Many of these processes have the capability of either being in a steady state while at others times they may be induced into a periodic or oscillating state. This type of behavior is common in a system of equations which is used to detect and measure an external phenomena which will change the state of the system. These systems are generally referred to as sensors. Quite often a sensor’s effectiveness is increased once it is in a region where it is oscillating. This, however, is not the only way to enhance effectiveness. If one is to connect the sensors in one of many different ways, generally referred to as a coupling, the sensitivity may be increased. In this work we will demonstrate the behavior of a particular type of sensor, known as dc-SQUID (Superconducting Quantum Interference Device) coupled in a nearest-neighboring scheme. We show that the response of the coupled system to an external magnetic field is greatly increased compared to that of a single SQUID element. Applications of this work include: geological equipment, biomedical equipment such as MRI machines, and applications to homeland defense such as mine detection.

Torus Bifurcation in Uni-Directional Coupled Gyroscopes

Nowadays, the global positioning system (GPS) is popularly used by the U.S. Navy in navigation systems to gain precise position, velocity, and time information. One of the biggest issues for using GPS is its susceptibility to jamming and other inferences. The received GPS signal is approximately 20 dB below the thermal noise level from a distance 11,000 miles away. Because of these weakness and vulnerability, many other alternative navigation methods are needed to improve performance and reduce the dependency on GPS. One of the main alternative methods is the Inertial Guidance System (IGS) that can operate wherever GPS signals are jammed or denied. A prototypical IGS is composed of three accelerometers to measure linear movement and three angular rate sensors (gyroscopes) to gauge the rotational movement. The main benefit of IGS is its low cost relatively to other methods. Current MEMS (Micro-Electro-Mechanical Systems) gyroscopes are compact and inexpensive, but their performance does not meet the requirements for an inertial grade guidance system. In this work, a difference approach was examined on the dynamics of coupled gyroscopes to improve performance through synchronization referred as vibratory coupled gyroscopes with drive amplitudes’ coupling. One of the main discoveries from the coupled gyroscopes’ mathematical model is a Torus bifurcation, which leads to synchronized behavior in and array of three gyroscopes uni-directionally coupled.

Applications of Nonlinear and Reconfigurable Electronic Circuits

In the search for small, fast and low power electronic circuits the microelectronic engineering community is increasingly faced with understanding the physical and non-ideal properties of the circuit at the transistor level. This is especially true with regard to the use of modern fabrication processes where transistor gate length is measured in tens of nanometers and physical properties such as leakage current and non-ideal sub-threshold behavior become more prevalent. The purpose of this work is to present the construction of some simple electronic circuits that possess nonlinear and dynamical properties and to illustrate their utility in a few applications. Specifically, the construction of oscillating, pattern forming and mixed signal reconfigurable circuits is discussed. In these examples, the nonlinear and dynamical properties of the circuits play a critical role in their operation. Experimental results from fabricated circuits are presented. Useful analytical tools are also discussed in the context of constructing and understanding the operation of the circuits. Similarities in the construction of several circuits lead to the development of a generic analog and nonlinear electronic fabric, similar to field-programmable gate arrays. Experimental results demonstrating configurability are shown. The array is constructed using non-volatile floating-gate based transistors. This type of proposed circuit construction and operation takes advantage of the nonlinear properties of the circuit and illustrates how many undesirable properties can actually provide utility.