12 research outputs found
The Putative Liquid-Liquid Transition is a Liquid-Solid Transition in Atomistic Models of Water
We use numerical simulation to examine the possibility of a reversible
liquid-liquid transition in supercooled water and related systems. In
particular, for two atomistic models of water, we have computed free energies
as functions of multiple order parameters, where one is density and another
distinguishes crystal from liquid. For a range of temperatures and pressures,
separate free energy basins for liquid and crystal are found, conditions of
phase coexistence between these phases are demonstrated, and time scales for
equilibration are determined. We find that at no range of temperatures and
pressures is there more than a single liquid basin, even at conditions where
amorphous behavior is unstable with respect to the crystal. We find a similar
result for a related model of silicon. This result excludes the possibility of
the proposed liquid-liquid critical point for the models we have studied.
Further, we argue that behaviors others have attributed to a liquid-liquid
transition in water and related systems are in fact reflections of transitions
between liquid and crystal
Design of variable bandwidth symmetric/anti-symmetric FIR single-band PCLS lowpass and highpass filters
© 2014, Springer-Verlag London. This paper proposes a reconfiguration design of variable bandwidth symmetric/anti-symmetric finite impulse response single-band peak-constrained least squares (PCLS) lowpass and highpass filters. When the bandwidth of the filter changes, a new set of filter coefficients is derived based on the old set of filter coefficients via a modified method of bisection. Since the proposed algorithm is very efficient, the new set of filter coefficients can be obtained in real time. Also, the new set of filter coefficients can be arbitrarily close to the globally optimal solution of the new PCLS optimization problem