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Detecting defects within reinforced concrete is vital to the safety and durability of our built infrastructure upon which we heavily rely. In this work a noninvasive technique, ElectroMagnetic Anomaly Detection (EMAD), is used which provides information into the electromagnetic properties of the reinforcing steel and for which data analysis is currently performed visually: an undesirable process. This article investigates the first use of two neural network approaches to automate the analysis of this data: Echo State Networks (ESNs) and Extreme Learning Machines (ELMs) where fast and efficient training procedures allow networks to be trained and evaluated in less time than traditional neural network approaches. Data collected from real-world concrete structures have been analyzed using these two approaches as well as using a simple threshold measure and a standard recurrent neural network. The ELM approach offers a significant improvement in performance for a single tendon-reinforced structure, while two ESN architectures provided best performance for a meshreinforced concrete structure. C 2013 Computer-Aided Civil and Infrastructure Engineering.

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A series of undoped Sn02 films was grown by metallorganic chemical vapor deposition (MOCVD) from an Sn(OtBu)4 precursor. The characterization of their CO-and H20-gas sensing properties is reported. The films were very sensitive to low levels of CO at elevated temperatures (200 to 400°C), although a significant cross-sensitivity to relative humidity was found. Response and recovery times were very short in comparison with a Pt-doped thick film Sn02 pellet. The optimum working temperature was found to be 300 to 350°C, where linear responses to CO concentration and to relative humidity were seen once drift had been taken into account. All MOCVD films tested showed superior responses to a sputtered film. InfroductionThe metal oxide semiconductor tin oxide (Sn02) has a range of important applications, such as in transparent and conducting coatings on glass,1 and in gas-sensing devices used in a variety of applications.2 The require-

Cobalt thin films were produced by metal-organic CVD from C 5 H 5 Co(CO) 2 , at various temperatures and for various deposition times. The films have been grown onto glass substrates with no buffer. The crystalline structure, morphology, and composition of the films were analyzed by X-ray diffractometry (XRD), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and Auger electron spectroscopy (AES). Routine XRD patterns were collected in symmetric geometry for phase identification and the sin 2 w diffraction technique was employed to calculate the average in-plane stress. Structural studies indicate that the films tend to grow in island mode, as predicted by theory, and have a structure between that of face-centered cubic (fcc) and hexagonal close-packed (hcp) cobalt. There is significant in-plane tensile stress at the interface with the substrate, which relaxes to a compressive stress an order of magnitude lower at the surface. The films have a relatively low impurity content, as determined by AES, except near the surface.