System Integration of Flexible and Multifunctional Thin Film Sensors for Structural Health Monitoring

Greater information is needed on the state of civil infrastructure to ensure public safety and cost-efficient management. Lack of infrastructure investment and foreseeable funding challenges mandate a more intelligent approach to future maintenance of infrastructure systems. Much of the technology currently utilized to assess structural performance is based on discrete sensors. While such sensors can provide valuable data, they can lack sufficient resolution to accurately identify damage through inverse methods. Alternatively, technologies have shown promise for distributed, direct damage detection with flexible thin film and multifunctional polymer-nanocomposite materials. However, challenges remain as significant past work has focused on material optimization as opposed to sensing systems for damage detection. This dissertation offers novel methods for direct and distributed strain sensing by providing a fabrication methodology for broadly enabling thin film sensing technologies in structural health monitoring (SHM) applications. This fabrication methodology is presented initially as a set of materials and processes which are illustrated in analog circuit primitive forms including flexible, thin film capacitors, resistors, and inductors. Three sensing systems addressing specific SHM challenges are developed from this base of components and processes as specific illustrations of the broader fabrication approach. The first system developed is a fully integrated strain sensing system designed to enable the use of multifunctional materials in sensing applications. This is achieved through the development of an optimized fabrication approach applicable to many multifunctional materials. A layer-by-layer (LbL) deposited nanocomposite is incorporated with a lithography process to produce a sensing system. To illustrate the process, a strain sensing platform consisting of a nanocomposite film within an amplified Wheatstone bridge circuit is presented. The study reveals the material process is highly repeatable to produce fully integrated strain sensors with high linearity and sensitivity. The thin film strain sensors are robust and are capable of high strain measurements beyond 3,000 μϵ. The second system developed is an array of resistive distributed strain sensors and an associated algorithm to provide an alternative to electrical impedance tomography for spatial strain sensing. An LbL deposited polymer composite thin film is utilized as the piezoresistive sensing material. An inverse algorithm is presented and utilized for determining the resistance of array elements by electrically stimulating boundary nodes. Two polymer nanocomposite arrays are strain tested under cyclic loading. Both arrays functioned as networks of strain sensors confirming the viability of the approach and computational benefits for SHM. The third system developed is a thin film wireless threshold strain sensor for measuring strain in implanted and embedded applications. The wireless sensing system is comprised of two thin film, inductor-capacitor circuits, one of which included a fuse element. The sensor is fabricated on polyimide with metal layers used to pattern inductive antennas and a strain sensitive parallel plate capacitor. A titanium thin film fuse is designed to fail, or have a large resistance increase, when a strain threshold is exceeded. Three prototype systems are interrogated wirelessly while under increasing tensile strain. One of two sensor resonant peaks disappear at a strain threshold as designed, validating the sensing approach and thin film form for use in SHM systems. The fuse approach provides a platform for various systems and sensing elements. The reference peak remains intact and is used for continuous real-time strain sensing with a sensitivity of 0.5 and a noise floor below 50 microstrain.PHDCivil EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/144183/1/arburt_1.pd

The Great Commission is Binding Upon Every Christian

A 5-page pamphlet of quotations regarding the topic of proselytization sent out by Mr. and Mrs. A. M. Burton with Season\u27s Greetings.https://digitalcommons.acu.edu/crs_books/1462/thumbnail.jp

Interdependencies between people and information systems in organizations

This article argues that while people and information systems (ISs) represent the two single largest areas of investment for many organizations and are increasingly interconnected resources, there has been very little research on the nature of their interdependencies and how these interdependencies affect their functioning and complementarity. It discusses how a better understanding of the dynamics of interdependencies between people and ISs can help researchers study organizations and help organizations improve the interoperation of their human and technological assets, and thus returns on investments in them. The article begins by reviewing the concept of capital and its application to people - human capital - and information systems: ISs capital. Next, it surveys past literature on interdependencies and recent literature relating to interdependencies between people and information systems. Based on the analysis, the article proposes an agenda for future research aiming to conceptualize interdependencies between people and ISs in a richer fashion

What have we learned from the Smart Machine?

Zuboff's (1988) book In the Age of the Smart Machine: The Future of Work and Power is one of the most celebrated texts among Information Systems researchers. Despite its significant influence, I suggest that it may have a richer story to tell than has been told to date. Motivated by this potential, my essay has two aims: to explicate the theory developed in Zuboff's text, and to determine how fully it has been used and extended by Information Systems researchers, through an analysis of papers citing her text. My findings show that the theory developed in Zuboff's text has been used in a fairly limited and piecemeal fashion. I discuss how this presents a significant opportunity for research because the theory appears to be just as relevant now as it was when the text was published

Doctor of Philosophy

dissertationThe aim of the research reported in this dissertation was to define and quantify the contribution of recent photosynthetic carbon uptake to spatial and temporal patterns respiration of CO2 I conducted a multiyear analysis of soil CO from soils. Carbon dioxide is produced in soils primarily by roots and heterotrophic bacteria and fungi. Roots use carbon from recent photosynthesis or storage for growth, maintenance, and nutrient uptake, and a large fraction of soil microorganisms live in close proximity to roots and consume short-lived tissues and root exudates. Thus, both of these components largely depend on carbon that has been assimilated only hours to months before. Therefore, it was expected that seasonal patterns of uptake and use of carbon associated with particular vegetation types would be primary drivers of spatial and temporal variability in soil respiration. However, it was also expected that these general patterns would be mediated by environmental conditions

New Perspectives on the System Usage Construct

Information systems are designed to support human and organizational purposes. To achieve their ends, information systems must be used. Although this may seem to be self-evident, there are many aspects of systems usage that are not so, and yet, in spite of this, there has been little intense conceptual scrutiny of this construct in past research. The objective of this thesis, therefore, is to develop new in-depth perspectives for studying system usage. Drawing on critical realist assumptions and studies of research diversity, I explain how epistemological factors enable while ontological factors constrain the diversity of meanings of system usage, and I build on this reasoning to advance a systematic approach for conceptualizing and measuring system usage in an appropriate way for a given research context. To demonstrate the approach and judge its usefulness, I carry out three empirical studies to test whether measures of system usage that are selected according to the proposed approach provide more explanatory power and lead to more coherent results in specific research contexts than other measures of system usage. Exploring the relationship between system usage and user task performance among 804 users of spreadsheet software, the experiments reveal support for the usefulness of the approach and demonstrate how it can enable researchers to conceptualize and measure system usage in an appropriate manner for a given research context. Together, the conceptual approach and empirical studies contribute by: (1) providing a systematic way to conceptualize and measure system usage for a given study context, (2) revealing rich new directions for research on the nature of system usage, its antecedents, and its consequences, and (3) suggesting a new approach for construct development and investigation in IS research