Hybrid Artificial Root Foraging Optimizer Based Multilevel Threshold for Image Segmentation

This paper proposes a new plant-inspired optimization algorithm for multilevel threshold image segmentation, namely, hybrid artificial root foraging optimizer (HARFO), which essentially mimics the iterative root foraging behaviors. In this algorithm the new growth operators of branching, regrowing, and shrinkage are initially designed to optimize continuous space search by combining root-to-root communication and coevolution mechanism. With the auxin-regulated scheme, various root growth operators are guided systematically. With root-to-root communication, individuals exchange information in different efficient topologies, which essentially improve the exploration ability. With coevolution mechanism, the hierarchical spatial population driven by evolutionary pressure of multiple subpopulations is structured, which ensure that the diversity of root population is well maintained. The comparative results on a suit of benchmarks show the superiority of the proposed algorithm. Finally, the proposed HARFO algorithm is applied to handle the complex image segmentation problem based on multilevel threshold. Computational results of this approach on a set of tested images show the outperformance of the proposed algorithm in terms of optimization accuracy computation efficiency

Factors contributing to the unnaturally low water table of Moanatuatua Scientific Reserve, Waikato, New Zealand

Water table regime in peatlands (depth below the peat surface) is an important driver in biochemical processes. A deep water table can lead to increased rates of peat decomposition resulting in surface subsidence, release of carbon and changes to the vegetation cover. This study focused on the factors responsible for the unnaturally deep and highly fluctuating water table regime at Moanatuatua, a remnant peat bog, in contrast to the hydrologically pristine Kopuatai bog, with a shallow, more stable water table. Moanatuatua Scientific Reserve in the Hamilton basin is the 1.1 km2 remnant of a former 75 km2 raised peat bog, and Kopuatai bog covers an area of 96 km2 on the Hauraki plains. Native bog vegetation in the Waikato is dominated by two species from the Restionaceae family of vascular plants, Empodisma robustum and Sporadanthus ferrugineus. Water table measurements at Moanatuatua were obtained from nine pressure transducers across an east to west transect of the bog. At Kopuatai, water table measurements were taken from a single reference site. At both bogs evaporation and rainfall were measured by eddy covariance towers. Three years of measurements (1 September 2015 – 31 August 2018) were used to compare the two sites. The water table at Moanatuatua was consistently very deep for a peat bog and had a strong seasonal cycle resulting in a deeper water table in summer and a shallower water table in winter, with a mean depth of -601 mm below the surface for the three-year study period. Kopuatai also showed a seasonal pattern although the water table did not reach the same extreme depths with a mean water table depth of -25 mm. The water table at Moanatuatua followed the domed shape of the peat surface, but remained well below the peat surface for the duration of the study. The pattern of water table depth across Moanatuatua indicated that the border drains do not cause a drawdown effect on the water table across the entire transect of the bog. Similar water table depths were found 18 years ago suggesting that the hydrological regime at Moanatuatua has not altered much in this time. Evaporation rates from Moanatuatua were higher than Kopuatai. Mean daily evaporation from Moanatuatua was 2.2 mm and Kopuatai 1.8 mm for the entire study period. Eliminating wet canopy influences the evaporation rate at Moanatuatua was 2.0 mm day-1 and at Kopuatai of 1.45 mm day-1. Mean annual water balance inputs into the bog (rainfall – evaporation) were 587 mm at Moanatuatua and 872 mm at Kopuatai. If the late successional vegetation at Moanatuatua were replaced with early successional vegetation as present at Kopuatai, it is estimated that an average water balance would have been of 741 mm, resulting in more water available for potential water table recharge

Fractional Calculus and the Future of Science

Newton foresaw the limitations of geometry’s description of planetary behavior and developed fluxions (differentials) as the new language for celestial mechanics and as the way to implement his laws of mechanics. Two hundred years later Mandelbrot introduced the notion of fractals into the scientific lexicon of geometry, dynamics, and statistics and in so doing suggested ways to see beyond the limitations of Newton’s laws. Mandelbrot’s mathematical essays suggest how fractals may lead to the understanding of turbulence, viscoelasticity, and ultimately to end of dominance of the Newton’s macroscopic world view.Fractional Calculus and the Future of Science examines the nexus of these two game-changing contributions to our scientific understanding of the world. It addresses how non-integer differential equations replace Newton’s laws to describe the many guises of complexity, most of which lay beyond Newton’s experience, and many had even eluded Mandelbrot’s powerful intuition. The book’s authors look behind the mathematics and examine what must be true about a phenomenon’s behavior to justify the replacement of an integer-order with a noninteger-order (fractional) derivative. This window into the future of specific science disciplines using the fractional calculus lens suggests how what is seen entails a difference in scientific thinking and understanding