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Full-Text Articles in Engineering

Biogeography-Based Optimization, Daniel J. Simon Dec 2008

Biogeography-Based Optimization, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Biogeography is the study of the geographical distribution of biological organisms. Mathematical equations that govern the distribution of organisms were first discovered and developed during the 1960s. The mindset of the engineer is that we can learn from nature. This motivates the application of biogeography to optimization problems. Just as the mathematics of biological genetics inspired the development of genetic algorithms (GAs), and the mathematics of biological neurons inspired the development of artificial neural networks, this paper considers the mathematics of biogeography as the basis for the development of a new field: biogeography-based optimization (BBO). We discuss natural biogeography and …


On Control System Design For The Conventional Mode Of Operation Of Vibrational Gyroscopes, Lili Dong, Qing Zheng, Zhiqiang Gao Nov 2008

On Control System Design For The Conventional Mode Of Operation Of Vibrational Gyroscopes, Lili Dong, Qing Zheng, Zhiqiang Gao

Electrical and Computer Engineering Faculty Publications

This paper presents a novel control circuitry design for both vibrating axes (drive and sense) of vibrational gyroscopes, and a new sensing method for time-varying rotation rates. The control design is motivated to address the challenges posed by manufacturing imperfection and environment vibrations that are particularly pronounced in microelectromechanical systems (MEMS) gyroscopes. The method of choice is active disturbance rejection control that, unlike most existing control design methods, does not depend on an accurate model of the plant. The task of control design is simplified when the internal dynamics, such as mechanical cross coupling between the drive and sense axes, …


A Two-Degree-Of-Freedom Time-Optimal Solution For Hard Disk Drive Servo Problems, Shaohua Hu, Zhiqiang Gao May 2008

A Two-Degree-Of-Freedom Time-Optimal Solution For Hard Disk Drive Servo Problems, Shaohua Hu, Zhiqiang Gao

Electrical and Computer Engineering Faculty Publications

This paper deals with the hard disk drive (HDD) servo problems. A novel discrete time-optimal control solution is proposed in a two-degree-of-freedom (2DOF) structure, employing both the feedback and feedforward controllers. The time-optimal feedback controller, derived from a simple, double integral plant model, shows remarkable robustness and disturbance rejection in the presence of resonant modes, measurement noises and position and torque disturbances. It eliminates the needs for two separate controllers for track-seeking and track-following operations. The proposed feedforward controller in this 2DOF structure proves to be quite beneficial in reducing the …


Fluorescent Si Nanoparticle-Based Electrode For Sensing Biomedical Substances, Gang Wang, Siu-Tung Yau, Kevin Mantey, Munir H. Nayfeh Apr 2008

Fluorescent Si Nanoparticle-Based Electrode For Sensing Biomedical Substances, Gang Wang, Siu-Tung Yau, Kevin Mantey, Munir H. Nayfeh

Electrical and Computer Engineering Faculty Publications

We have been studying the miniaturization of silicon crystals and the transition from the solid state to the atomistic state. We demonstrated the existence of “sweet spots” in cluster size in the range 1–3nm that have enhanced chemical, structural, and photo stability. The particles are produced by an electrochemical etching process as dispersion in liquid, and they are reconstituted in films, patterns, alloys, or spread on chips to produce super chips. Unlike bulk, these Si nanoparticle configurations have a spectacular ability to glow in distinct RGB colors. In this paper we describe an electrode sensor built by decorating metal or …


A Reservation-Based Extended Transaction Protocol, Wenbing Zhao, Louise E. Moser, P. Michale Melliar-Smith Feb 2008

A Reservation-Based Extended Transaction Protocol, Wenbing Zhao, Louise E. Moser, P. Michale Melliar-Smith

Electrical and Computer Engineering Faculty Publications

With the advent of the new generation of Internet-based technology, in particular, web services, the automation of business activities that are distributed across multiple enterprises becomes possible. Business activities are different from traditional transactions in that they are typically asynchronous, loosely coupled, and long running. Therefore, extended transaction protocols are needed to coordinate business activities that span multiple enterprises. Existing extended transaction protocols typically rely on compensating transactions to handle exceptional conditions. In this paper, we identify a number of issues with compensation-based extended transaction protocols and describe a reservation-based extended transaction protocol that addresses those issues. Moreover, we define …


A Comparison Of Filtering Approaches For Aircraft Engine Health Estimation, Daniel J. Simon Jan 2008

A Comparison Of Filtering Approaches For Aircraft Engine Health Estimation, Daniel J. Simon

Electrical and Computer Engineering Faculty Publications

Different approaches for the estimation of the states of linear dynamic systems are commonly used, the most common being the Kalman filter. For nonlinear systems, variants of the Kalman filter are used. Some of these variants include the LKF (linearized Kalman filter), the EKF (extended Kalman filter), and the UKF (unscented Kalman filter). With the LKF and EKF, performance varies depending on how often Jacobians (partial derivative matrices) are updated. In other words, we see a tradeoff between computational effort and filtering performance. With the unscented Kalman filter, Jacobians are not calculated but computational effort is typically high due to …