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Abstract. We present new radar-based techniques for efficient identification of surface changes generated by lava and pyroclastic flows, and apply these to the 1996 eruption of Manam Volcano, Papua New Guinea. Polarimetric L- and P-band airborne synthetic aperture radar (SAR) data, along with a C-band DEM, were acquired over the volcano on 17 November 1996 during a major eruption sequence. The L-band data are analyzed for dominant scattering mechanisms on a per pixel basis using radar target decomposition techniques. A classification method is presented, and when applied to the L-band polarimetry, it readily distinguishes bare surfaces from forest cover over Manam volcano. In particular, the classification scheme identifies a post-1992 lava flow in NE Valley of Manam Island as a mainly bare surface and the underlying 1992 flow units as mainly vegetated surfaces. The Smithsonian's Global Volcanism Network reports allow us to speculate whether the bare surface is a flow dating from October or November in the early part of the late-1996 eruption sequence. This work shows that fully polarimetric SAR is sensitive to scattering mechanism changes caused by volcanic resurfacing processes such as lava and pyroclastic flows. By extension, this technique should also prove useful in mapping debris flows, ash deposits and volcanic landslides associated with major eruptions.

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this record. ; Skyline queries identify skyline points, the minimal set of data points that dominate all other data points in a large dataset. The main challenge with skyline queries is executing the skyline query in the shortest possible time. To address and solve skyline query performance issues, we propose a decision tree-based method known as the decision tree-based comparator (DC). This method minimizes unnecessary dominance tests (i.e., pairwise comparisons) by constructing a decision tree based on the dominance testing. DC uses dominance relations that can be obtained from the decision rules of the decision tree to determine incomparability between data points. DC can also be easily applied to improve the performance of various existing skyline query methods. After describing the theoretical background of DC and applying it to existing skyline queries, we present the results of various experiments showing that DC can improve skyline query performance by up to 23.15 times. ; Institute of Information & communications Technology Planning & Evaluation (IITP) grant funded by the Korea government(MSIT) ; Industrial Strategic Technology Development Program funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea).

Tourism which is regarded as information intensive sector is the mostly affected sector by technology revolution and its traditional trading structures have been totally changed. The adoption and use of e-commerce in tourism sector is regarded as a tool to widen market reach and improve efficiency and effectiveness of business operations. The degree of impact of e-commerce use on business performance depends on the intensity of its usage in organization's key value-chain activities. However, the intensity of e-commerce use is influenced by technological, organizational and environmental (TOE) contextual factors. Based on TOE model and the existing literature on post-adoption use of e-commerce, a set of factors that affect the intensity of e-commerce use in Tanzanian tourism sector was identified. A survey was conducted with 181Tanzanian tourism firms that have already adopted e-commerce and structural equation modeling (SEM) was used to analyze the data. The findings indicated that the scope of e-commerce use has a positive impact on business performance in terms of improved internal processes, competitive position, customer service delivery, overall business performance and increased customer base. The scope of e-commerce use is affected positively by pressure intensity and perceived benefits and negatively by barriers to e-commerce use. The findings have highlighted key areas that require immediate actions from both the government and private sector in order to promote a successful growth of e commerce in the country.