535 research outputs found
Input–Output Linearization of a Boost Converter With Mixed Load (Constant Voltage Load and Constant Power Load)
No full textDue to copyright restrictions and/or publisher's policy full text access from Treasures at UT Dallas is limited to current UTD affiliates (use the provided Link to Article).Power converters and electric motor drives when tightly regulated behave as constant power loads. These loads are different from resistive loads and have destabilizing negative impedance characteristics, which impact a system's stability. A boost converter is intrinsically nonlinear and is a nonminimum phase system at the output voltage with respect to the control input. The linear approximation of this boost converter loaded with a constant power load has a zero and poles in the right half of the s-plane, making the system unstable and very difficult to control. Control techniques that employ some form of system inversion cannot be implemented for a nonminimum phase system. This paper describes a technique to modify the nonminimum phase boost converter to a minimum phase for a constant power load, further implementing the input-output linearization technique to stabilize the system. This paper also provides a methodological analysis of the problem followed by the proposed solution. Furthermore, it verifies the analysis of the proposed solution through simulation and experimental results.Erik Jonsson School of Engineering and Computer Scienc
Preparation and characterization of Poly(vinylidenefluoride)-CdSiO3 nanocomposite thin films
Get PDFThe state of art behavior of PVDF-CdSiO3 nano-composite has been reported in context to their crystal structure, morphology and optical bandgap. Nanocomposites of varying concentration (1, 3 and 5 wt %) were prepared by spin coating method. The thickness of the film was measured by using Elecro Physik instrument and was found to be ~40µm. Peaks in the X-ray diffraction pattern indicate the presence of CdSiO3 nanoparticles in PVDF matrices and absence of any extra peak in the pattern shows that there is no new phase formation. The scanning electron microscope (SEM) images showed that nano inclusions are uniformly distributed in PVDF matrix. It is also observed that the granular structure PVDF disappears with the increase in the concentration of CdSiO3. The shift in the optical edges as observed by UV-Vis spectra of the developed composites has been correlated to optical band gap using Tauc’s expression. The composite showed an increasing trend in the optical band gap from 3.6eV to 5.2eV with the increase in the concentration of the nanofillers. The present study finds potential applications in the design of microsensors and actuator
Nonlinear Phenomenon and Efficient Nonlinear Control Techniques for DC-DC Power Converters
No full textThe increase in the energy demands and high-performance systems has led to an increase
in number power electronic devices. To achieve high efficiency, it has become necessary to
explore more efficient control methods and techniques to meet modern quality standards
and device specifications. This dissertation addresses issues in regards to the nonlinear
phenomenon and nonlinear control techniques for switching power converters. This research
address the issues with the following contribution.
This dissertation first characterizes DC-DC converters targeting non-minimum phase systems
with the change in sampling instant of the switch. Further, to validate the analysis
experimentally, a practical frequency response function measurement device is implemented
called as the Gain and Phase (GAP) measurement device. The GAP device has the ability to
measure system response as a function of sampling time/sampling instant and is integrated
with a graphical user interface which can be used to design a linear controller and measure
important system parameters.
Further, this dissertation explores efficient two nonlinear control algorithms. The proposed
algorithms targets non-minimum phase DC-DC converters like the boost DC-DC converter.
The boost converter intrinsically has unstable internal dynamics and is unstable when loaded
with a nonlinear constant power load. The dissertation proposes a nonlinear control technique
to stabilize the overall closed loop boost converter when loaded with constant power
load. Further, the dissertation extends to another non-linear control technique for a boost
converter for direct voltage regulation when loaded by resistive loads.
Lastly, this dissertation proposed a higher resolution Direct Digital Synthesis (DDS) based
DPWM architecture to eliminate a nonlinear phenomenon called steady-state limit cycle
oscillation (LCO) which commonly exist in digitally controlled SMPS. The proposed
architecture addresses numerous application with numerous advantage
Nyateism vs teism-debatten : En analys av Dinesh D'Souza's argumentation
No full textDuring the last few years the western world has seen an increasing interest in the topic of atheism, with bestselling books by writers like Richard Dawkins, Sam Harris and Christopher Hitchens. The critic of religions that these writers have brought to the table have not gone unmet, with writers like Dinesh D'Souza rushing to the defence of Chrisianity. Taking on the arguments of New York Times bestselling author Dinesh D'Souza in the current debate on the existece of God and the usefullness of religion, I here examine the claim by D'Souza that atheism, in fact, is responsible for the worst mass murders of history. In taking D'Souza's arguments and analyzing them on its own philosophical merits, with methods like the process of elimination and information evaluation (i.e source criticism), I will here show just exactly how persuasive these arguments prove to be. In the following pages we will not only discuss the role of atheism in 20th centuary totalitarianism, but also answer questions like ”Was Hitler an atheist or a theist?”, ”Is atheism responsible for the worst crimes of history?” and ”Are people who believe in God in fact more moral the those who do not?
Determinig the efficacy of mathematical programming approaches for multi-group classification:
No full textManagers have been grappling with the problem of extracting patterns out of the vast database generated by their systems. The advent of powerful information systems in organizations and the consequent agglomeration of vast pool of data since the mid-1980s have created renewed interest in the usefulness of discriminant analysis (DA). Expert systems have come to the aid of managers in their day-to-day decision making with many successful applications in financial planning, sales management, and other areas of business operations (Erenguc and Koehler 1990).
Currently, no comprehensive research study exists that tests the robustness of multi-group classification analysis. Our research aims to bridge the gaps in the existing works and take a step further by extending our study to four-group classification problems. The main purpose of this research is to determine the efficacy of mathematical programming classification models, more specifically, LP methods vis-à-vis statistical approaches such as discriminant analysis (Mahalanobis) and logistic regression, an artificial intelligence (AI) technique such as a neural network, and a non-parametric technique such as k-nearest neighborhood (k-NN) for four-group classification problems. This research also proposes an integrated (hybrid) model that combines a non-parametric classification technique and a LP approach to enhance the overall classification performance. Furthermore, the study extends an existing two-group LP model (Bal et al. 2006) based on the work of (Lam and Moy 1996b) and apply it to four-group classification problems. These models are tested through robust computational experiments under varying data conditions using a financial product example. The characteristics of a real dataset are used to simulate (Monte Carlo method) multiple sample runs for four group classification problems with three continuous independent variables.
The experimental results show that LP approaches in general and the proposed integrated method in particular consistently have lower misclassification rates for most data characteristics. Furthermore, the integrated method utilizes the strengths of both the methods: k-NN and linear programming, thereby considerably improving the classification accuracy.Ph.D.Includes bibliographical references (p. 83-97)by Dinesh R. Pa
Conservative Author Dinesh D’Souza Celebrates America’s Greatness in Lawrence University Appearance
Get PDFNoted conservative author Dinesh D’Souza takes on the critics and defends America’s unique standing as the “freest and most decent society in existence” in an address Thursday, May 20 at Lawrence University.
Based on his 2002 book of the same name, D’Souza presents “What’s So Great About America” at 7:30 p.m. in the Lawrence Memorial Chapel.
Written in the wake of the September 11 terrorist attacks, “What’s So Great About America” celebrates the United States, in D’Souza’s view as, “the best life our world has to offer” while taking on those who hate America, including radical Muslims.
Born and raised in India, D’Souza, 43, immigrated to the United States in 1978. After earning a degree from Dartmouth University, he served as the editor of Prospect magazine and spent a year as managing editor of the conservative magazine Policy Review. In 1987, D’Souza joined the Reagan administration as a senior domestic policy analyst.
In addition to “What’s So Great About America,” D’Souza is the author of six other books, including 1991′s bestseller “Illiberal Education,” in which he casts a critical eye on the state of contemporary American higher education. He has also written a biography of Jerry Falwell, “Falwell: Before the Millennium,” provided a controversial view of the role of race in American society in “The End of Racism” and argues the case why Ronald Reagan should be considered among the nation’s greatest presidents in his 1997 book “Ronald Reagan: How an Ordinary Man Became an Extraordinary Leader.”
Hailed by Investor’s Business Daily as one of the “top young public-policy makers in the country,” D’Souza’s writing also has appeared in the Wall Street Journal, the New York Times, the Washington Post, Vanity Fair, Forbes, Harper’s and the Atlantic Monthly.
He currently serves as the Robert and Karen Rishwain Research Fellow at Stanford University’s Hoover Institution, specializing in issues of social and individual responsibility, civil rights and affirmative action, economics and society and higher education.
D’Souza is speaking at the invitation of the Lawrence College Republicans, and his appearance is sponsored by the Class of ’65 Student Activity Fund, the Young America’s Foundation, and the Outagamie County Republican Party
Thematic Analysis of Discussion Board Posts from a Self-Management Program for People With Systemic Sclerosis
No full textAbstract
Date Presented 3/31/2017
This session discusses the themes that emerged from discussion boards that were part of a self-management program for people with systemic sclerosis. Themes revealed more positive than negative strategies, thus supporting the inclusion of social interactions in self-management programs.
Primary Author and Speaker: Janet Poole
Additional Authors and Speakers: Sharon Newbill, Jennifer Serrano, Pedro Cuencas, Dinesh Khanna</jats:p
Non-typeable Haemophilus influenzae–Moraxella catarrhalis vaccine for the prevention of exacerbations in chronic obstructive pulmonary disease: a multicentre, randomised, placebo-controlled, observer-blinded, proof-of-concept, phase 2b trial
No full textMeasuring effectiveness and value of email advertisements in relationship-oriented email messages
Get PDFThesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 63-70).This thesis explores the value of email advertisements in relationship-based communication by measuring click-through rates. Advertisements were embedded within standard electronic mail messages in a template. The results are discussed in aggregate to better understand this medium and value in an advertising context, but the analysis also breaks down how six factors affect click behavior by recipients. The factors include the impact of a privacy statement, type of organizational recipients, click timing, recent advertisements, advertisement frequency, and advertisement relevance. The results are also analyzed using a chi-squared statistical test to determine whether the individual factor is significant in this analysis. This paper also discusses the privacy implications of advertising in a social-medium with comparisons to social ads using Facebook's Beacon as a benchmark. A discussion of how these results apply in an email environment where anti-SPAM infrastructure is a large part of the overall system is evaluated as well. Results show that internal recipients are an effective target market for relationship messaging and that emails often generate clicks days or weeks after the original message was delivered. The research is very relevant to email and targeted advertising, but also applies in a broader context to social advertising where there is a existing relationship between a sender and recipient.by Dinesh Shenoy.S.M
RT-DEFORM: Interactive Ray Tracing of Dynamic Scenes using BVHs
Get PDFPart of this work was performed while the primary author was
working at Intel corporation. We would like to thank Ingo Wald,
Alexander Reshetov, Gordon Stoll and UNC's GAMMA group for
helpful discussions and feedback, as well as the anonymous reviewers
for their comments. The model used for the dress simulation
is courtesy of Walt Disney Feature Animation and the
Bunny and Buddha models are courtesy of the 3D scanning repository
at Stanford University. This work was supported in part
by ARO Contracts DAAD19-02-1-0390 and W911NF-04-1-0088,
NSF awards 0400134 and 0118743, ONR Contract N00014-01-1-
0496, DARPA/RDECOM Contract N61339-04-C-0043, Intel, and
LOCAL LLNL LDRD project (05-ERD-018) and was performed
under the auspices of the U.S. Department of Energy by the University
of California, Lawrence Livermore National Laboratory under
Contract No. W-7405-Eng-48
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