Abstract--Emerging cybersecurity vulnerabilities in supervisory control and data acquisition (SCADA) systems are becoming urgent engineering issues for modern substations. This paper proposes a novel intrusion detection system (IDS) tailored for cybersecurity of IEC 61850 based substations. The proposed IDS integrates physical knowledge, protocol specifications and logical behaviors to provide a comprehensive and effective solution that is able to mitigate various cyberattacks. The proposed approach comprises access control detection, protocol whitelisting, model-based detection, and multi-parameter based detection. This SCADA-specific IDS is implemented and validated using a comprehensive and realistic cyber-physical test-bed and data from a real 500kV smart substation.

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Fundamental understanding of complex FT synthesis is of great interest. We have employed X-ray photoelectron spectroscopy and temperature-programmed desorption to comparatively investigate CH 2 I 2 adsorption and reactions on clean, hydrogen-and CO-covered Co(0001) surfaces. Surface chemistry of CH 2 I 2 was demonstrated to sensitively depend on available vacant surface sites on Co(0001). Upon adsorption on clean Co(0001) surface at 110 K, CH 2 I 2 undergoes stepwise decomposition reactions to produce carbon adatoms, CH(a) and CH 2 (a) species at small coverages, and chemisorbs both dissociatively and molecularly at large coverages. Upon heating, CH 2 (a) species facilely undergoes surface reactions to produce CH 4 , C 3 H 6 , and C 2 H 4 in gas phase and CH(a) species on the surface at low temperatures. CH(a) species undergoes surface reactions to produce CH 4 in gas phase and C 2 H 2 (a) species on the surface at higher temperatures, and both CH(a) and C 2 H 2 (a) species undergo further surface reactions to produce H 2 in gas phase and carbon species on the surface. Coadsorbed H adatoms and CO molecules were found to strongly affect surface chemistry of CH 2 I 2 and the resulting CH x species on Co(0001) via suppressing the decomposition reactions and promoting the carbon− carbon bond coupling reactions. These results add novel insights in fundamental understanding of complex FT synthesis.

Investigating the surface chemistry of formaldehyde on the surface of TiO 2 is important in understanding the thermalcatalytic and photocatalytic reactions of formaldehyde on TiO 2involved catalysts. By combining thermal desorption spectroscopy and X-ray photoelectron spectroscopy, we studied the adsorption, thermo-induced surface reactions, and photo-induced surface reactions of formaldehyde on the rutile TiO 2 (011)-(2 × 1) surface. The dominant thermal-catalytic reaction is the formation of ethylene by a reductive carbon−carbon formation reaction of formaldehyde adsorbed at the oxygen vacancy sites, and the dominant photocatalytic reaction is the formation of formate, assisted by the bridge O 2c sites, followed by carbon monoxide formation at elevated temperatures. The surface intermediates of formaldehyde reactions to ethylene and carbon monoxide on the rutile TiO 2 (011)-(2 × 1) surface were identified. The effect of the surface structure of the rutile TiO 2 (011)-(2 × 1) surface, particularly the oxygen vacancy, on the thermal-catalytic and photocatalytic activity toward formaldehyde was revealed by studying the coadsorption of water and formaldehyde. These results broaden our fundamental comprehension on the reaction mechanism of formaldehyde on the TiO 2 surfaces.

Intermittent floodplain channels are low-relief conduits etched into the floodplain surface and remain dry much of the year. These channels comprise expansive systems and are important because during low-level inundation they facilitate lateral hydraulic connectivity throughout the floodplain. Nevertheless, few studies have focused on these floodplain channels due to uncertainty in how to identify and characterize these systems in digital elevation models (DEMs). In particular, their automatic extraction from widely available DEMs is challenging due to the characteristically low-relief and low-gradient topography of floodplains. We applied three channel extraction approaches to the Congaree River floodplain DEM and compared the results to a channel reference map created through numerous field excursions over the past 30 years. The methods that we tested are based on flow accumulation area, topographic curvature, and mathematical morphology, or the D8, Laplacian, and bottom-hat transform (BHT), respectively. Of the 198 km of reference channels the BHT, Laplacian, and D8 extracted 83%, 71%, and 23%, respectively, and the BHT consistently had the highest agreement with the reference network at the local (5 m) and regional (10 km) scales. The extraction results also include commission "error", augmenting the reference map with about 100 km of channel length. Overall, the BHT method provided the best results for channel extraction, giving over 298 km in 69 km 2 with a detrended regional relief of 1.9 m. Further, these analyses allow us to shed light on the meaning and use of the term "low-relief landscapes".

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