Ambient Excitation Based Model Updating for Structural Health Monitoring via Dynamic Strain Measurements

Structural health monitoring (SHM) technologies continue to be pursued for aerospace structures in the interests of increased safety and, when combined with prognosis, efficiency in life-cycle management. The current work is focused on developing and validating a method for in-situ health monitoring of aerospace structures. In particular, the current framework has been developed for use with response only vibration data using natural operating turbulence to provide the means of excitation. While the framework is general so as to work with a wide suite of sensor options, particular emphasis has been placed on fiber optic strain sensors as a lightweight, low cost, non-intrusive means of monitoring the vibration response. At its core, the developed SHM system actively monitors a network of fiber optic strain sensors and utilizes the transient response data to calculate their associated power spectral densities (PSD). These PSD serve as the fundamental input to the developed SHM algorithm presented in the dissertation whereby comparisons between previously correlated model PSD and the current measured PSD are made. If anomalies between the correlated model and the measured data sets are detected, the developed SHM algorithm seeks to minimize the difference via updating of structural parameters underlying the structural model of interest (in the case of the presented work, a finite element model of the structure). The SHM algorithm itself is an adaption of a statistical least-squares minimization based in concepts of non-linear parameter estimation and model correlation. The algorithm developed uses power spectra based residual error vectors derived from distributed vibration measurements to update a structural model through statistically weighted least-squares minimization. The output of the algorithm is a correlated finite element model which inherently produces estimates of the location, type, and severity of any detected damage as well as the uncertainty associated with these estimates. Throughout the dissertation the developed algorithm was shown, both analytically and experimentally, to successfully detect, locate, and quantify damage present in a structural system

A complete census of AGN and their hosts from optical surveys?

Large optical surveys provide an unprecedented census of galaxies in the local Universe, forming an invaluable framework into which more detailed studies of objects can be placed. But how useful are optical surveys for understanding the co-evolution of black holes and galaxies, given their limited wavelength coverage, selection criteria, and depth? In this conference paper I present work-in-progress comparing optical and mid-IR diagnostics of three "unusual" low redshift populations (luminous Seyferts, dusty Balmer-strong AGN, ULIRGs) with a set of ordinary star-forming galaxies from the SDSS. I address the questions: How well do the mid-infrared and optical diagnostics of star formation and AGN strength agree? To what extent do optical surveys allow us to include extreme, dusty, morphologically disturbed galaxies in our "complete" census of black hole-galaxy co-evolution?Comment: Proceedings of contributed talk at "Co-Evolution of Central Black Holes and Galaxies" (eds. B.M. Peterson, R.S. Somerville, and T. Storchi-Bergmann), IAU symposium 267, August 2009. 6 pages, 5 figure

Passive Aeroelastic Tailoring

The Passive Aeroelastic Tailoring (PAT) project was tasked with investigating novel methods to achieve passive aeroelastic tailoring on high aspect ratio wings. The goal of the project was to identify structural designs or topologies that can improve performance and/or reduce structural weight for high-aspect ratio wings. This project considered two unique approaches, which were pursued in parallel: through-thickness topology optimization and composite tow-steering

Relating Kleene algebras with pseudo uninorms

This paper explores a strict relation between two core notions of the semantics of programs and of fuzzy logics: Kleene Algebras and (pseudo) uninorms. It shows that every Kleene algebra induces a pseudo uninorm, and that some pseudo uninorms induce Kleene algebras. This connection establishes a new perspective on the theory of Kleene algebras and provides a way to build (new) Kleene algebras. The latter aspect is potentially useful as a source of formalism to capture and model programs acting with fuzzy behaviours and domains.publishe

High Levels of Oxidative Stress and Skin Microbiome are Critical for Initiation and Development of Chronic Wounds in Diabetic Mice.

A balanced redox state is critical for proper healing. Although human chronic wounds are characterized by high levels of oxidative stress (OS), whether OS levels are critical for chronic wound development is not known. For these studies, we used our chronic wound model in diabetic mice that has similar characteristics as human chronic wounds, including naturally developed biofilm. We hypothesize that OS levels in wound tissues are critical for chronic wound initiation and development. We show that increased OS levels in the wound correlate with increased chronicity. Moreover, without increased OS levels, biofilm taken from chronic wounds and placed in new excision wounds do not create chronic wounds. Similarly, high OS levels in the wound tissue in the absence of the skin microbiome do not lead to chronic wounds. These findings show that both high OS levels and bacteria are needed for chronic wound initiation and development. In conclusion, OS levels in the wound at time of injury are critical for biofilm formation and chronic wound development and may be a good predictor of the degree of wound chronicity. Treating such wounds might be accomplished by managing OS levels with antioxidants combined with manipulation of the skin microbiome after debridement

Active In-Flight Load Redistribution Utilizing Fiber-Optic Shape Sensing and Multiple Control Surfaces

Morphing wing technologies have gained research interest in recent years as technological advancements pave the way for such innovations. A key benefit of such a morphing wing concept is the ability of the wing to transition into an optimal configuration at multiple flight conditions. Such a morphing wing will have applications not only in drag reduction but also in flutter suppression and gust alleviation. By manipulating the wing geometry to match a given flight profile it is likely that the wing will yield increases in not just aerodynamic efficiency but also structural efficiency. These structurally efficient designs will likely rely on some type of structural sensing system which will ensure the wing maintains positive margins throughout its flight profile

Stellar tracers of the Cygnus Arm. II: A young open cluster in Cam OB3

Cam OB3 is the only defined OB association believed to belong to the Outer Galactic Arm or Cygnus Arm. Very few members have been observed and the distance modulus to the association is not well known. We attempt a more complete description of the population of Cam OB3 and a better determination of its distance modulus. We present uvby photometry of the area surrounding the O-type stars BD +56 864 and LS I +57 138, finding a clear sequence of early-type stars that define an uncatalogued open cluster, which we call Alicante 1. We also present spectroscopy of stars in this cluster and the surrounding association. From the spectral types for 18 very likely members of the association and UBV photometry found in the literature, we derive individual reddenings, finding a extinction law close to standard and an average distance modulus DM=13.0+-0.4. This value is in excellent agreement with the distance modulus to the new cluster Alicante 1 found by fitting the photometric sequence to the ZAMS. In spite of the presence of several O-type stars, Alicante 1 is a very sparsely populated open cluster, with an almost total absence of early B-type stars. Our results definitely confirm Cam OB3 to be located on the Cygnus Arm and identify the first open cluster known to belong to the association.Comment: Accepted for publication in Astronomy & Astrophysics. Tables 7 & 8 to appear only in electronic forma

The infrared dust bubble N22: an expanding HII region and the star formation around it

Aims. To increase the observational samples of star formation around expanding Hii regions, we analyzed the interstellar medium and star formation around N22. Methods. We used data extracted from the seven large-scale surveys from infrared to radio wavelengths. In addition we used the JCMT observations of the J = 3-2 line of 12CO emission data released on CADC and the 12CO J = 2-1 and J =3-2 lines observed by the KOSMA 3 m telescope. We performed a multiwavelength study of bubble N22. Results. A molecular shell composed of several clumps agrees very well with the border of N22, suggesting that its expansion is collecting the surrounding material. The high integrated 12CO line intensity ratio (ranging from 0.7 to 1.14) implies that shocks have driven into the molecular clouds. We identify eleven possible O-type stars inside the Hii region, five of which are located in projection inside the cavity of the 20 cm radio continuum emission and are probably the exciting-star candidates of N22. Twenty-nine YSOs (young stellar objects) are distributed close to the dense cores of N22. We conclude that star formation is indeed active around N22; the formation of most of YSOs may have been triggered by the expanding of the Hii region. After comparing the dynamical age of N22 and the fragmentation time of the molecular shell, we suggest that radiation-driven compression of pre-existing dense clumps may be ongoing.Comment: accepted in A&A 30/05/2012. arXiv admin note: text overlap with arXiv:1010.5430 by other author

DEVELOPMENT OF A FIRE DANGER INDEX FOR EUCALYPT PLANTATIONS IN THE NORTHERN COAST OF BAHIA, BRAZIL

Economic losses caused by fires in commercial plantations of eucalypt forest has led to the development of new fire-fighting systems and methodologies. This study aimed to develop a fire danger index for eucalypt plantations in the Copener Forestal Ltda. areas located in the north coast of Bahia, Brazil, in order to improve fire control efforts. For this purpose, eight years of meteorological data were collected and correlated to forest fire occurrence through multivariate logistic regression. The proposed model (White Model) presented a better statistical performance than other models generally used in Brazil, recommended for operational use in focused area.Keywords: Fire danger rating; fire prevention; fire suppression; fire safety. ResumoDesenvolvimento de um índice de perigo de ocorrência de incêndios florestais para plantações de eucalipto no litoral norte da Bahia, Brasil. Em função das perdas econômicas causadas pelo fogo em plantações comerciais de eucalipto, novas metodologias e sistemas de prevenção e combate ao fogo têm sido criados. Este estudo buscou desenvolver um índice de perigo de ocorrência de incêndio florestal em plantações de eucalipto da empresa Copener Florestal Ltda., localizada no litoral norte da Bahia, Brasil, a fim de aprimorar os sistemas de prevenção e combate ao fogo. Para tal, oito anos de dados meteorológicos foram coletados e correlacionados com a ocorrência de incêndios florestais através da regressão logística multivariada. O modelo proposto neste trabalho (Modelo White) obteve um melhor desempenho estatístico que outros modelos comumente utilizados no Brasil e, portanto, é recomendado para utilização operacional na área de estudo.Palavras-chave: Índice de perigo; prevenção e combate ao fogo; segurança florestal.Economic losses caused by fires in commercial plantations of eucalypt forest has led to the development of new fire-fighting systems and methodologies. This study aimed to develop a fire danger index for eucalypt plantations in the Copener Forestal Ltda. areas located in the north coast of Bahia, Brazil, in order to improve fire control efforts. For this purpose, eight years of meteorological data were collected and correlated to forest fire occurrence through multivariate logistic regression. The proposed model (White Model) presented a better statistical performance than other models generally used in Brazil, recommended for operational use in focused area.Keywords: Fire danger rating; fire prevention; fire suppression; fire safety