The deterioration of steel reinforced concrete caused by reinforcing bar corrosion is recognized as a major technical problem in the State of Florida and nationwide. This mode of failure is usually recognized in the final stages when surface cracking and spalling of the concrete occurs. The purpose of this study is to extend work previously reported on a nondestructive monitoring technique to detect, characterize, and locate corrosion induced structural damage. Acoustic emission technology is used to monitor and characterize the deterioration process in a series of controlled laboratory tests. By comparing measured acoustic emission characteristics, including counts and amplitude distributions, with physical examination of test specimens at various phases of corrosion induced damage, a relation between the observed damage and the attendant acoustic emission is developed. The study illustrates the sensitivity of the method to the ongoing deterioration process and explores its use as a corrosion damage monitoring technique. Various aspects of the experimental results are discussed.
The Ocean Voyager I1 is a small long-range AUV designed for coastal oceanography. A system overview and design constraints are given with reference to the specific mission of bottom classification through light reflectance and absorption measurement. This mission requires the AUV to fly above the sea floor at a constant altitude will measuring the albedo of the bottom and the absorption of certain light frequencies by plant life. Important navigation, sensing, power, computation, control, and configuration issues are discussed. The OVII has been developed by Florida Atlantic University's Ocean Engineering Dept. in cooperation with the University of South Florida's Marine Science Department to provide more efficient means of sampling the coastal ocean negions. Of great importance is ground-trutbing satellite spectrometry. Current measorements of bottom albedos are limited in density and scope. The O W provides a means of covering large areas of the ocean floor in an efficient manner. This paper will provide insights gained from the development effort and describe initial testing of the vehicle. The potential of AIJV's in coastal oceanographic missions will be discnssed in light of the experience gained from the initial testing of the OVII.
Undersampling of the coastal oceans remains a persistent problem for standard oceanographic measurement practice wherein an instrument package is tethered to a research vessel. The overhead costs associated with operating a large research vessel impose a strict minimum on the cost of data collected. Owing to the overheads, significant improvements in sampling technology on the tethered platform can only produce modest gains in the cost effectiveness. In contrast. untethered vehicles if operated simultaneously have the potential to increase cost effectiveness significantly by distributing the overhead costs over several sampling platforms. Furthermore, synoptic and pseudosynoptic data can be collected with multiple autonomous underwater vehicles (A UVs). thereby providing the type of information critical to dynamic process modeling unattainable with non-synoptic data. While the goal of simultaneous multiple-vehicle operation has been espoused over the last few years. A UV technology and practice have until recently been too immature to realize that potential. Recently, Florida Atlantic University (FA U) has developed a new series of modular A UVs with the express purpose of supporting multiple sensors and multiple-vehicle operation. This series of vehicle is called the Ocean Explorer of which three have been produced so far. This paper will explore some of the associated navigation, tracking, control and deployment problems associated with multiple-vehicle operation in coastal applications. In addition, the characteristics of the component level intelligent distributed control system. integrated data logger and vehicle control system will be discussed. In particular this paper will discuss how FA U has applied the concepts ofelastic constraint propagation and the symmetric fuzzy decision-making model /0 A UV control systems. Some results of early experiments ill synoptic data collection with a conductivity, temperature and depth (CTD) sensor using multiple A UVs for the determination of horizontal structure will be described.
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