A.6.7 MIS Software to Generate Homogeneous and Heterogeneous DUs

The homogeneous and heterogeneous DUs in the M3 series of maps considered in this appendix are generated using the DU generation program, MIS (Singh, Maichle, and Armbya 2009). The detailed description of the DU simulation procedure used to generate homogeneous and heterogeneous DUs can be found in Singh, Singh, and Murphy (2009).

The MIS software package is used to collect ISM samples using the three sampling patterns: simple random sampling, serpentine (Hewitt et al. 2007, 2009) sampling, and systematic random within grid. A schematic of the sampling patterns used is given in Figures A-21 to A-23. For systematic random sampling pattern, increments are collected randomly from each grid (one increment per grid).

In a bulk material DU, not all sample locations are accessible due to the presence of bushes, trees, rocks, boulders, trash, and building structures. These locations are represented by empty spots in a simulated DU. While sampling, if one comes across an inaccessible spot (empty space), an increment of the same sample support is collected from a neighboring accessible spot (as commonly done in field).

The ISM sampling process incorporated in the MIS software mimics the sampling process used by CRREL scientists (e.g., Hewitt et al. 2007, 2009). Specifically, all points (material) collected from all increments making an ISM sample are put into a bag. The average of that bag (points in the ISM) represents the analytical value of material (particles) contained in that ISM replicate. The MIS program collects r (≥1, specified by the user) ISM replicates based up 16, 25, 36, 64, and 100 increments. The MIS program can collect ISM samples with increments based up the user-specified sample support (e.g., of radius 0.05 units). For a sample support of 0.05 units, all points (particles) included in a circle of radius 0.05 units are included in each increment making the ISM sample.

For heterogeneous bulk material DUs, not all sampling locations have exactly the same mass or the same number of particulates. Similarly, in simulated hypothetical DUs modeling heterogeneities (CH and small-scale DH), not all increments of the same sample support (radius 0.05 units) consist of the same number of particles/points.