Browsing by Author "Wang, Xuguang"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Additive and Multiplicative Mixture Trees for Network Traffic Modeling
    (2002-05-01) Sarvotham, Shriram; Wang, Xuguang; Riedi, Rudolf H.; Baraniuk, Richard G.; Digital Signal Processing (http://dsp.rice.edu/)
    Network traffic exhibits drastically different statistics, ranging from nearly Gaussian marginals and long range dependence at very large time scales to highly non-Gaussian marginals and multifractal scaling on small scales. This behavior can be explained by forming two components of the traffic according to the speed of connections, one component absorbing most traffic and being mostly Gaussian, the other constituting virtually all the small scale bursts. Towards a better understanding of this phenomenon, we propose a novel tree-based model which is flexible enough to accommodate Gaussian as well as bursty behavior on different scales in a parsimonious way.
  • Thumbnail Image
    Item
    Electrical characterizations of lithium niobate thin films in a metal-ferroelectric-semiconductor capacitor
    (2002) Wang, Xuguang; Rabson, Thomas A.
    A LiNbO3 thin film Metal-Ferroelectric-Semiconductor capacitor is analyzed with various electrical characterization methods for studying the polarization switching and the thin film conduction behavior. The polarization density vs. electric field (P-E) curve shows that the remnant polarization is 16.85muC/cm2 and the coercive field is 117.25 KV/cm when maximum applied field is 286.2KV/cm for a sinusoidal input waveform. The capacitance vs. voltage bias (C-V) curve further demonstrates that the polarization charge is the dominant charge in controlling the ferroelectric semiconductor interface property. The switching transient current curve from a dual polarity four pulses chain study (P-S) gives the switching time of the sample about 80--100ns. Current vs. voltage (I--V) curve is explained with a back-to-back Schottky barrier controlled conduction mechanism. These electrical characterization results demonstrate that LiNbO3 is a promising candidate for a Metal-Ferroelectric-Semiconductor-Field-Effect-Transistor (MFSFET) non-volatile non-destructive memory application.
  • Thumbnail Image
    Item
    VLSI Implementation of Mallat's Fast Discrete Wavelet
    (2001-11-20) Guo, Yuanbin; Zhang, Hongzhou; Wang, Xuguang; Cavallaro, Joseph R.; Center for Multimedia Communications (http://cmc.rice.edu/)
    This paper proposes a novel VLSI architecture to compute the DWT (discrete wavelet transform) coefficients using Mallat's algorithm with reduced complexity. We studied the commonality embedded in the mirror filters of the algorithm and use a PLA as an Address Generator (PAG) to load the data for cascaded FIR computation. By using an embedded downsampling process in the control signal design, we reduced the complexity by saving storage and computation. The prototyping design is implemented and fabricated using AMI 1.5 micron CMOS process through MOSIS.