Parameters Identification for a Composite Piezoelectric Actuator Dynamics

This work presents an approach for identifying the model of a composite piezoelectric (PZT) bimorph actuator dynamics, with the objective of creating a robust model that can be used under various operating conditions. This actuator exhibits nonlinear behavior that can be described using backlash and hysteresis. A linear dynamic model with a damping matrix that incorporates the Bouc–Wen hysteresis model and the backlash operators is developed. This work proposes identifying the actuator’s model parameters using the hybrid master-slave genetic algorithm neural network (HGANN). In this algorithm, the neural network exploits the ability of the genetic algorithm to search globally to optimize its structure, weights, biases and transfer functions to perform time series analysis efficiently. A total of nine datasets (cases) representing three different voltage amplitudes excited at three different frequencies are used to train and validate the model. Four cases are considered for training the NN architecture, connection weights, bias weights and learning rules. The remaining five cases are used to validate the model, which produced results that closely match the experimental ones. The analysis shows that damping parameters are inversely proportional to the excitation frequency. This indicates that the suggested hysteresis model is too general for the PZT model in this work. It also suggests that backlash appears only when dynamic forces become dominant

Training Graduate Engineering Students in Ethics

The Howard R. Hughes College of Engineering at the University of Nevada, Las Vegas embarked on providing ethics instruction to incoming graduate students in the form of a mandatory workshop. The College has a diverse graduate student population, including a sizable international component, who are enrolled in several M.S. and Ph.D. degree programs within four departments. Faculty felt that training in ethics was needed to better prepare incoming students for successful graduate studies and working professionally after graduation. Therefore, a standalone workshop was developed that covered four major topics: Research Ethics, Computer Coding Ethics, Publishing Ethics, and Intellectual Property. The last topic covered copyright law, patent law, and trade secrets. To develop this ethics workshop, some ethics instruction programs at U.S. engineering colleges were investigated

A Refreshable and Portable E-Braille System for the Blind and Visually Impaired

Braille is a communication system to assist the blind and visually impaired. Present an approach to measure fingertip forces while identifying Braille characters. Implement a force sensory feedback in the device to measure the force developed on the fingertip. Introduce a preliminary design for the device. Build a prototype for the device and evaluate its functionality and integrate its component

Modeling, Fabrication, and Optimization of Niobium Cavities – Phase I: Quarterly Progress Report November 20, 2001 - February 20, 2002

Multipacting is one of the major loss mechanisms in RF superconductivity cavities for accelerators. This loss mechanism limits the maximum amount of energy/power supported by the cavities. Optimal designs have been identified in others’ studies. In practice, these designs are not easily manufactured. Chemical etching processes used to polish the cavity walls result in a nonuniform surface etch. A nonuniform surface etch will leave some unclean areas with contaminants and micron size particles. These significantly affect multipacting. Further, a nonuniform etch will leave areas with damaged grain structure, which is not good for superconducting properties. Typically, the depth of chemical polishing etch ranges between 10 to 150 microns. It is the purpose of this study to examine the chemical etching process in the design of niobium cavities so to maximize the surface quality of the cavity walls while minimizing the multipacting losses. Single and multiple cavity cell geometries are to be investigated. Optimization techniques will be applied in search of the chemical etching processes, which will lead to cavity walls with near ideal properties

Modeling, Fabrication, and Optimization of Niobium Cavities: Final Phase

Niobium cavities are important parts of the integrated NC/SC high-power linacs. Over the years, researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells are the most appropriate shape for superconducting cavities. The need for very clean surfaces lead to the use of a buffered chemical polishing produce for surface cleaning to get good performance of the cavities. This is the third and final phase of the study. The first phase has resulted in improving the basic understanding of multipacting and the process of chemical etching. The second phase has resulted in an experimental setup of a fluid flow experiment with experimentation to be completed in the third year. Other experimental activities include the evaluation of a vacuum system and various vacuum equipment purchases and modifications. An optimization code for a five cell niobium cavity based on resonant frequency and mode number was developed. Based on our conclusions so far, as well as our interaction with personnel at Los Alamos National Laboratory (LANL), we propose to focus on the following topics in the third phase of this project: 1. Optimize the cavity shape based on the desired resonant frequency and examine multipacting of that structure. 2. Studying secondary electronic emission from a niobium test piece under cryogenic conditions. 3. Experimental study of the etching process using flow visualization techniques. 4. Redesign the etching process to maximize surface uniformity

Overview of Fuzzy Logic

The presentation includes a brief introduction to fuzzy logic and fuzzy logic controllers. These concepts are illustrated by an example of an autonomous vehicle controller

Modeling, Fabrication, and Optimization of Niobium Cavities – Phase I: Quarterly Progress Report May 15, 2001 - August 15, 2001

Multipacting is one of the major loss mechanisms in rf superconductivity cavities for accelerators. This loss mechanism limits the maximum amount of energy/power supported by the cavities. Optimal designs have been identified in others’ studies. In practice, these designs are not easily manufactured. Chemical etching processes used to polish the cavity walls result in a nonuniform surface etch compromising the optimal geometrical design. Past multipacting studies have not examined the impact of wall perturbations. It is the purpose of this study to examine the chemical etching process in the design of niobium cavities so to maximize the surface quality of the cavity walls while minimizing the multipacting losses. Single and multiple cavity cell geometries are to be investigated. Optimization techniques will be applied in search of the chemical etching processes, which will lead to cavity walls with near ideal properties

Modeling, Fabrication, and Optimization of Niobium Cavities: Phase III Second Quarterly Report

Niobium cavities are important parts of the integrated NC/SC high-power linacs. Over the years, researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells are the most appropriate shape for superconducting cavities. The need for very clean surfaces lead to the use of a buffered chemical polishing produce for surface cleaning to get good performance of the cavities. The third phase concludes the experimental a fluid flow study and optimization study. The first quarter and second quarter of phase three also begins the experimental set-up of secondary emission studies from niobium in superconducting mode. This study is to be completed by the end of the third year

Modeling, Fabrication, and Optimization of Niobium Cavities: Phase II Quarterly Report

Multipacting is one of the major loss mechanisms in rf superconductivity cavities for accelerators. This loss mechanism limits the maximum amount of energy/power supported by the cavities. Optimal designs have been identified in others’ studies. In practice, these designs are not easily manufactured. Chemical etching processes used to polish the cavity walls result in a nonuniform surface etch. A nonuniform surface etch will leave some unclean areas with contaminants and micron size particles. These significantly affect mutipacting. Further, a nonuniform etch will leave areas with damaged grain structure, which is not good for superconducting properties. Typically, the depth of chemical polishing etch ranges between 10 to 150 microns. It is the purpose of this study to experimentally model the fluid flow resulting in the chemical etching of a niobium cavities with the aid of a baffle. Numerical tend to show that the current etching process with baffle does not uniformly etch the cavity surface. Multiple cavity cell geometries are to be investigated. Optimization techniques will be applied in search of the chemical etching processes, which will lead to cavity walls with near ideal properties

Optimization of the Seating Position in a Human-Powered Vehicle

Until recently, most of the human-powered vehicles (HPV) were designed focusing solely on its aerodynamics characteristic. In many of these HPV designs, the rider seating position was arbitrarily chosen without consideration of its effect on the rider\u27s comfort and cycling effectiveness. Also, there is no guarantee that the seating position is related to maximum power output. Too (1991) used an experimental approach to determine that the rider will produce the maximum anaerobic power when the seat tube angle of a bicycle is at 75° whereas Hull and Gonzalez (1990) used an engineering approach to optimize the cycling biomechanics. However several factors. including aerodynamic effects, were not considered in both studies. The objective of this study was, therefore, to find the optimal rider\u27s seating position in HPV for either aerobic or anaerobic performance. The method is based on modeling a mechanism equivalent to the hip, knee, and ankle joints. All physical constraints on the motion of these three joints as well as the HPV design constraints are mathematically described. Nonlinear programming techniques were used to reach an optimal solution for either aerobic or anaerobic designs. To test the validity of the model, it was compared to the experimental results of the anaerobic cycling power test presented by Too (1991)