On the use of inexact, pruned hardware in atmospheric modelling.

Inexact hardware design, which advocates trading the accuracy of computations in exchange for significant savings in area, power and/or performance of computing hardware, has received increasing prominence in several error-tolerant application domains, particularly those involving perceptual or statistical end-users. In this paper, we evaluate inexact hardware for its applicability in weather and climate modelling. We expand previous studies on inexact techniques, in particular probabilistic pruning, to floating point arithmetic units and derive several simulated set-ups of pruned hardware with reasonable levels of error for applications in atmospheric modelling. The set-up is tested on the Lorenz '96 model, a toy model for atmospheric dynamics, using software emulation for the proposed hardware. The results show that large parts of the computation tolerate the use of pruned hardware blocks without major changes in the quality of short- and long-time diagnostics, such as forecast errors and probability density functions. This could open the door to significant savings in computational cost and to higher resolution simulations with weather and climate models.

Swelling of ionic and nonionic surfactant micelles by high pressure gases.

The influence of different solvent environments on the size, shape, and characteristics of surfactant micelles of Pluronic F127 and CTAB was investigated by small-angle neutron scattering (SANS). SANS experiments were undertaken on dilute micellar surfactant solutions of F127 and CTAB that between them were exposed to liquid and supercritical carbon dioxide, liquid propane, ethane, and heptane under various pressures and temperatures. Swelling of the surfactant micelles could be directly related to the solubility of the solvents within the micelles, especially within their cores. Carbon dioxide produced the largest swelling of the Pluronic F127 micelles, compared to propane and ethane, which mirrors the solubility of the gases in the PPO core of the micelles. Conversely, the extent of swelling of the cores of CTAB micelles was greater with propane compared to carbon dioxide, which again relates to the solubility of the solvents in the alkane core of the CTAB micelles.