Staff members at Los Alamos National Laboratory (LANL) produced a summary of the structural health monitoring literature in 1995. This presentation will summarize the outcome of an updated review covering the years 1996 2001. The updated review follows the LANL statistical pattern recognition paradigm for SHM, which addresses four topics: 1. Operational Evaluation; 2. Data Acquisition and Cleansing; 3. Feature Extraction; and 4. Statistical Modeling for Feature Discrimination. The literature has been reviewed based on how a particular study addresses these four topics. A significant observation from this review is that although there are many more SHM studies being reported, the investigators, in general, have not yet fully embraced the well-developed tools from statistical pattern recognition. As such, the discrimination procedures employed are often lacking the appropriate rigor necessary for this technology to evolve beyond demonstration problems carried out in laboratory setting.

A review of structural health monitoring literature 1996-2001

This book focuses on structural health monitoring in the context of machine learning. The authors review the technical literature and include case studies. Chapters include: operational evaluation, sensing and data acquisition, introduction to probability and statistics, machine learning and statistical pattern recognition, and data prognosis.

Structural Health Monitoring: A Machine Learning Perspective

A review of recent research on mechanics of multifunctional composite materials and structures

In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques.

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Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications.

Since the discovery of high Tc iron-based superconductors in early 2008, more than 15,000 papers have been published as a result of intensive research. This paper describes the current status of iron-based superconductors (IBSC) covering most up-to-date research progress along with the some background research, focusing on materials (bulk and thin film) and pairing mechanism.

Iron-based superconductors: Current status of materials and pairing mechanism

We found that hot alcoholic beverages were effective in inducing superconductivity in FeTe$_{0.8}$S0$_{.2}$. Heating FeTe$_{0.8}$S0$_{.2}$ compound in various alcoholic beverages enhances the superconducting properties compared to pure water-ethanol mixture as a control. Heating with red wine for 24 hours leads to the largest shielding volume fraction of 62.4% and the highest zero resistivity temperature of 7.8 K. Some components present in alcoholic beverages, other than water and ethanol, have the ability to induce superconductivity in FeTe$_{0.8}$S0$_{.2}$ compound.

Alcoholic beverages induce superconductivity in FeTe$_{1-x}$S$_x$

FeTe0.5Se0.5 superconducting wires have been fabricated using ex-situ PIT method with an Fe sheath. Among the other FeAs-based superconductors, FeTe0.5Se0.5 has great advantage for applications due to its binary composition and less toxicity. Surprisingly, superconducting current was observed in the as-fabricated wire without any heat treatments. The zero- resistivity critical temperature (Tczero) and transport critical current density (Jc) at 2 K were 3.2 K and 2.8 A/cm2, respectively. In addition, by annealing at 200°C for 2 h, Tczero and Jc were enhanced up to 9.1 K, and 64.1 A/cm2 , respectively. This suggests that the inter-grain connectivity was improved by heat treatment, and superconducting properties of FeTe0.5Se0.5 wire were enhanced.

Transport Properties of Iron-Based $\hbox{FeTe}_{0.5}\hbox{Se}_{0.5}$ Superconducting Wire

To elucidate the mechanism as to why alcoholic beverages can induce superconductivity in Fe_{1+d}Te_{1-x}S_x samples, we performed component analysis and found that weak acid such as organic acid has the ability to induce superconductivity. Inductively-coupled plasma spectroscopy was performed on weak acid solutions post annealing. We found that the mechanism of inducement of superconductivity in Fe_{1+d}Te_{1-x}S_x is the deintercalation of excess Fe from the interlayer sites.

Clarification as to why alcoholic beverages have the ability to induce superconductivity in Fe_{1+d}Te_{1-x}S_x

Recent satellites, growing in size and electrical power capacity, require sophisticated technology in terms of thermal and structural design. On the other hand, reducing their lifecycle cost while maintaining their reliability remains a definite necessity. From this point of view, a health monitoring system, designed to monitor the thermal and structural condition of a satellite during all its life stages, is expected to be a very useful tool. The authors are developing a health monitoring system for satellites utilizing a FBG (fiber Bragg grating) sensor. This paper first reports on a newly developed optical fiber connector that is used to install FBG sensors in satellite structures. Then, the assessment of a FBG sensor system in a space environment simulated in a thermal vacuum chamber is described. Finally, the results of an experimental study are presented in which damage due to thermal stress, that is typical in satellite structure, is detected by investigating the reflection spectrum from the embedded FBG sensor.

Structural health monitoring using FBG sensor in space environment

The authors focus on the construction of a structural health monitoring (SHM) system with an advanced grid structure (AGS) made of carbon-fiber reinforced plastic (CFRP). AGS is often applied to aerospace structures because the ribs carry only axial forces in the carbon fiber direction, making AGS structurally effective and lightweight, and because the repetition of many ribs in the AGS composition results in damage tolerance. The failure of a single rib hardly affects the fracture of the whole structure, making AGS a fail-safe structure. In this research, the authors have embedded multiplexed-fiber Bragg grating (FBG) sensors into an AGS rib in the longitudinal direction to measure mechanical strains of all ribs in order to detect the existence and regions of AGS rib fractures. Monitoring the change in rib-longitudinal strains is the most effective SHM system for AGS. To confirm the proposal, the authors explore the following. First, various damage characteristics under low-velocity impact loading are in...

Tsuyoshi Ozaki

Papers

Alcoholic beverages induce superconductivity in FeTe$_{1-x}$S$_x$

Transport Properties of Iron-Based $\hbox{FeTe}_{0.5}\hbox{Se}_{0.5}$ Superconducting Wire

Clarification as to why alcoholic beverages have the ability to induce superconductivity in Fe_{1+d}Te_{1-x}S_x

Structural health monitoring using FBG sensor in space environment

Structural Health Monitoring of an Advanced Grid Structure with Embedded Fiber Bragg Grating Sensors