497 research outputs found

    Woven Graph Codes: Asymptotic Performances and Examples

    Full text link
    Constructions of woven graph codes based on constituent block and convolutional codes are studied. It is shown that within the random ensemble of such codes based on ss-partite, ss-uniform hypergraphs, where ss depends only on the code rate, there exist codes satisfying the Varshamov-Gilbert (VG) and the Costello lower bound on the minimum distance and the free distance, respectively. A connection between regular bipartite graphs and tailbiting codes is shown. Some examples of woven graph codes are presented. Among them an example of a rate Rwg=1/3R_{\rm wg}=1/3 woven graph code with dfree=32d_{\rm free}=32 based on Heawood's bipartite graph and containing n=7n=7 constituent rate Rc=2/3R^{c}=2/3 convolutional codes with overall constraint lengths νc=5\nu^{c}=5 is given. An encoding procedure for woven graph codes with complexity proportional to the number of constituent codes and their overall constraint length νc\nu^{c} is presented.Comment: Submitted to IEEE Trans. Inform. Theor

    Submicrosecond Dynamics of Water Explosive Boiling and Lift-Off from Laser-Heated Silicon Surfaces

    Get PDF
    Explosive boiling and lift-off of a thin layer of micron-sized transparent water droplets from an absorbing Si substrate heated by a nanosecond KrF laser were studied using a contact photoacoustic technique. The compressive photoacoustic response increases steeply to an asymptotic value on the order of the water critical pressure starting at a threshold laser fluence of 0.20 J cm2, where lift-off of the water layer also occurs. Above this threshold, several reproducible discrete multimegahertz components are revealed in Fourier spectra of the acoustic transients, corresponding to nanosecond oscillations of steam bubbles inside the water droplets on the microsecond time scale of the lift-off process. The acoustic pressure buildup, bubble dynamics, and the subsequent lift-off of the thin water layer are interpreted as relaxation stages after near-spinodal explosive boiling of the superheated interfacial water. © 2006 American Institute of Physics

    Optical Transmission Measurements of Explosive Boiling and Liftoff of a Layer of Micron-Scale Water Droplets from a KrF Laser-Heated Si Substrate

    Get PDF
    Water plume velocities were measured in air by optical transmission as a function of laser fluence using a KrF laser for explosive boiling and liftoff of a layer of micron-scale waterdroplets from a laser-heated Si substrate of interest for laser particle removal. The thickness of the superheated water layer near the water/Si interface determines acceleration and removal of the waterdroplets from the Si substrate. © 2003 American Institute of Physic
    • …
    corecore