American Proverb: Two’s company, three’s a crowd. Genetic Algorithm Proverb: One’s a hill climber and a thousand’s random search. Population size is one of the key parameters affecting the success of genetic algorithms (GAs). Assuming a limited number of fitness evaluations (the most time-intensive factor in virtually all optimization problems), there exists an optimal population size for a gen...

The origin of a recently discovered close-in Neptune-mass planet around GJ436 poses a challenge to the current theories of planet formation. Based on the sequential accretion hypothesis and the standard theory of gap formation and orbital migration, we show that around M dwarf stars, close-in Neptune-mass ice-giant planets may be relatively common, while close-in Jupiter-mass gas-giant planets ...

Biogeography is the study of distribution of biological species, over space and time, among random habitats. Recently developed Biogeography-Based Optimization (BBO) is a technique, where solutions of the problem under consideration are named as habitats; similar to chromosome in Genetic Algorithms (GAs) and particles in Particle Swarm Optimization (PSO). Feature sharing among various habitats,...

Although Osborn et al. (1) provided important geochemical measurements of dissolved methane in a portion of the Appalachian basin, their report does not fully appreciate the geologic history of this region and misrepresents potential risks of modern drilling and completion techniques used to develop shale-gas resources. The fear that hydraulic fracturing is responsible for methane migration fro...

This paper presents a systematic methodology for design of landfill methane migration control systems. The key to the methodology is that it tests for deficiencies in the conceptual model (working hypothesis) of methane migration, correcting potential design flaws in the landfill methane control system before commencing design and construction. The testing is accomplished by (1) a field investi...

Context. Our previous models of a giant planet migrating through an inner protoplanet/planetesimal disk find that the giant shepherds a portion of the material it encounters into interior orbits, whilst scattering the rest into external orbits. Scattering tends to dominate, leaving behind abundant material that can accrete into terrestrial planets. Aims. We add to the possible realism of our mo...

The growth of Jovian mass planets during migration in their protoplanetary disks is one of the most important problems that needs to be solved in light of observations of the small orbital radii of exosolar planets. Studies of the migration of planets in standard gas disk models routinely show that the migration speeds are too high to form Jovian planets, and that such migrating planetary cores...