The authors consider the link scheduling problem for packet radio networks which is assigning channels to the connecting links so that transmission may proceed on all links assigned the same channel simultaneously without collisions. This problem can be cast as the distance-2 edge coloring problem, a variant of proper edge coloring, on the graph with transceivers as vertices and links as edges. They present efficient approximation algorithms for the distance-2 edge coloring problem for various classes of graphs.

Abstract: A trigger track processor, called the eXtremely Fast Tracker (XFT), has been designed for the CDF upgrade. This processor identifies high transverse momentum (> 1.5 GeV/c) charged particles in the new central outer tracking chamber for CDF II. The XFT design is highly parallel to handle the input rate of 183 Gbits/s and output rate of 44 Gbits/s. The processor is pipelined and reports the result for a new event every 132 ns. The processor uses three stages: hit classification, segment finding, and segment linking. The pattern recognition algorithms for the three stages are implemented in programmable logic devices (PLDs) which allow in-situ modification of the algorithm at any time. The PLDs reside on three different types of modules. The complete system has been installed and commissioned at CDF II. An overview of the track processor and performance in CDF Run II are presented.

The high spectral brilliance of x-rays produced at the Basic Energy Sciences Synchrotron Radiation Center of Argonne's Advanced Photon Source allows us to perform small-angle x-ray scattering (SAXS) measurements of the distributions of soot particles in flames. SAXS provides an in situ probe of the size and distribution of particles in the region between 1 and 100 nm. Detailed measurements on a propylene/air diffusion flame allow us to extract a spatially dependent background, which occurs in gas-phase combustion systems, and to perform Abel inversions, which provide the radial dependence of the scattering intensity. A bimodal distribution of soot particles is needed to describe our results. The radial behavior of the two modes of this distribution implies that the chemistry and fluid dynamics are strongly coupled in this simple diffusion flame. The larger particles of this distribution correspond to the previously observed primary particles, which have a relatively complex radial dependence. Midway between the fuel source and the widest part of the flame the primary particles have a mean radius of 6 nm or less and their concentration is symmetrically distributed about the flame front. At the widest part of the flame, two distinct distributions of primary particles are observed. Near …