The demo, BeepBeep, shows a high-accuracy acousticbased ranging system without relaying on any pre-planned infrastructure or inter-device time synchronization. Moreover, the BeepBeep is a pure software-based solution and readily applicable to many low-cost sensor platforms and to most commercial-off-the-shelf mobile devices. Our demo using two common cell phones shows that BeepBeep can achieve average two centimeters accuracy within a range of more than ten meters.
The TCP end-to-end congestion control plus RED router queue management can be modeled as a discrete-time dynamical system, which can create complex bifurcating and chaotic behavior. Based on the basic features of the TCP-RED model, we investigate the possibility of controlling bifurcation and chaos in the system via several time-delayed feedback control strategies. Two adaptive parameter-tuning algorithms are proposed and evaluated.
Epoxy shape memory polymers (SMPs) were preparation and their mechanical properties are focused on. Full shape recovery is observed at 150 °C for each polymer, and the SMP with lower hardener content shows a quicker shape recovery speed. In addition to a good thermal stability, glass transition temperature of the polymers increases with increasing hardener content. Of particular attention of DMA test is that the epoxy SMPs show a high storage modulus not only in glass state but also in rubber state. The tension test indicates that both stress at break and corresponding elastic modulus vary with a peak value for the polymers.
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