W. Xu

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The Carnegie Mellon Communicator system helps users create complex travel itineraries through a conversational interface. Itineraries consist of (multi-leg) flights, hotel and car reservations and are built from actual travel information for North America, obtained from the Web. The system manages dialog using a schema-based approach. Schemas correspond to(More)
The high peak-to-average-power ratio (PAPR) of orthogonal frequency-division multiplexing (OFDM) degrades the performance in optical wireless communication systems. This paper proposes a modified asymmetrically clipped optical OFDM (ACO-OFDM) with low PAPR via introducing a recoverable upper-clipping (RoC) procedure. Although some information is clipped by(More)
We describe the initial work of the PASS Project which uses techniques from distributed object manag-ment to analyze experimental data from high energy physics. A t this time, we have designed two prototypes to analyze high energy physics data from the CDF experiment at Fermi Lab. The data from this experiment consists of ((events " which describe particle(More)
Spatial joins and spatial index creation are two of the most expensive operations in Oracle Spatial. Since spatial indexing is implemented in extensible indexing framework where queries only return rows from a single table, spatial joins could not be effectively and efficiently implemented in Oracle8i and prior releases. On the other hand, spatial index(More)
BACKGROUND O(6)-methylguanine-DNA methyltransferase (MGMT) is one of most important DNA repair enzyme against common carcinogens such as alkylate and tobacco. Aberrant promoter methylation of the gene is frequently observed in non-small cell lung cancer (NSCLC). However, the importance of epigenetic inactivation of the gene in NSCLC published in the(More)
We demonstrate theoretically that it is possible to realize terahertz (THz) fundamental band-gap between the electron mini-band in the InAs layer and the heavy-hole mini-band in the GaSb layer in InAs/GaSb based type II superlattices (SLs). The THz band-gap can be tuned by varying the sample growth parameters such as the well widths of the InAs and/or GaSb(More)