A method for delivering spatio-temporally focused energy to a dynamically adjustable target along a waveguiding structure

It is possible to exploit the frequency-dependent velocity dispersion inherent to waveguiding structures to deliver spatio-temporally focused energy to a spatial target anywhere along the longitudinal extent of a waveguide. Such focusing of energy may have application to technologies as varied as nerve stimulation or chemical etching. A waveguide signal that effects this focused energy is conceptualized and derived. The spatial location of the target acted upon by the waveguide signal is demonstrated to be dynamically adjustable with a linear filtering step. Optimal parameters for waveguide signal generation are derived in the general case, allowing for application to a cross section of homogeneous waveguides. Performance is also considered in non-ideal, absorptive media. Numerical simulations are presented that indicate agreement with analytic results, and an evaluation of possible reduction to practice is presented

Information theoretic evaluation of a noiseband-based cochlear implant simulator

Noise-band vocoders are often used to simulate the signal processing algorithms used in cochlear implants (CIs), producing acoustic stimuli that may be presented to normal hearing (NH) subjects. Such evaluations may obviate the heterogeneity of CI user populations, achieving greater experimental control than when testing on CI subjects. However, it remains an open question whether advancements in algorithms developed on NH subjects using a simulator will necessarily improve performance in CI users. This study assessed the similarity in vowel identification of CI subjects and NH subjects using an 8-channel noise-band vocoder simulator configured to match input and output frequencies or to mimic output after a basalward shift of input frequencies. Under each stimulus condition, NH subjects performed the task both with and without feedback/training. Similarity of NH subjects to CI users was evaluated using correct identification rates and information theoretic approaches. Feedback/training produced higher rates of correct identification, as expected, but also resulted in error patterns that were closer to those of the CI users. Further evaluation remains necessary to determine how patterns of confusion at the token level are affected by the various parameters in CI simulators, providing insight into how a true CI simulation may be developed to facilitate more rapid prototyping and testing of novel CI signal processing and electrical stimulation strategies

Sediment Delivery on Rill and Interrill Areas

Equations which relate sediment delivery to a power function of flow rate and slope gradient were calculated in this study. The data used to parameterize the calculations were obtained from sites where crop residues had been removed. and moldboard plowing and disking had occurred. Measurements of sediment delivery resulting from simulated rainfall were obtained from preformed rills and interrill areas. The equations provided reliable sediment delivery estimates for selected soils located throughout the United States. To use the sediment delivery equations, soil-related parameter values must be identified. Multiple regression analyses were performed to relate parameter values used in the equations to selected soil properties. Equations were also developed for estimating rill sediment delivery under rainfall conditions from rill soil loss and discharge data collected without the addition of rainfall. The equations identified in this study, and appropriate soils information, can be used to predict sediment delivery on both rill and interrill area