Abstract: A computer-implemented inversion method for determining characteristics of a bottom roughness field using a numerical wave model is provided. Measured wave heights over an area of interest are compared to predicted wave heights calculated by a wave model using an estimated bottom roughness parameter. If the error between the measured wave heights and the predicted wave heights is within a specified tolerance level, the analysis ends and the value of the bottom roughness parameter used in the wave model is retrieved. If the error is not within the specified tolerance level, an Influence Matrix IM is used to obtain a revised estimated bottom roughness parameter. The wave model is re-run using the revised roughness parameter and the resulting predicted wave heights are compared to the measured wave heights. The inversion continues until the wave height error is within the specified tolerance level. When the inversion ends, the bottom roughness field that produced those predicted wave heights is retrieved.

Abstract: A sparsely populated array of antenna elements on a plane is provided such that the angle of arrival (AoA) measurement for a radiofrequency signal received by the array has high resolution and is non-ambiguous within a 360-degree azimuthal field of view. The array comprises a two-dimensional antenna array developed using fuzzy genetic logic based on specified criteria. In response to one specified set of criteria, the array comprises having a first large element formation combined with a second smaller element formation. The first large element formation supports high DF accuracy while the second smaller cluster facilitates ambiguity resolution.

Abstract: A method is provided for constructing a histogram to represent the root-mean-squared phase differences for a signal received at pairs of elements in an array. A pair-wise element phase difference (“PEP”) between a signal received at an angle of arrival ?1 and a signal received at an angle of arrival ?2 are determined. The difference ?? between the differential phase measurements at ?1 and ?2 is computed. The process is repeated for all unique pairs of angles (?1, ?2) from 0 to 359 degrees and the results are summed over all PEPs to calculate the root mean squared phase difference ?{square root over (??2(?1,?2))} between two different angles of arrival ?1 and ?2. A two-dimensional histogram is created by pairing the measurements ?{square root over (??2)} and ??, where ??=?2??1.

Abstract: The device includes two supports and a primary conductive strip. The primary conductive strip includes a neutral surface, a first side, and a second side. The primary conductive strip is connected one of directly and indirectly on the first side to the two supports such that the primary conductive strip is constrained in two dimensions and movable in one dimension. The device also includes a primary distributed feedback fiber laser. The primary distributed feedback fiber laser includes a fiber axis. The primary distributed feedback fiber laser is connected to the primary conductive strip along one of the first side and the second side such that there is a positive distance between the neutral surface of the primary conductive strip and the fiber axis of the primary distributed feedback fiber laser.