Controlling the Size of Popcorn

We present a thermo-statistical model of popcorn production and propose a way to control the final size of the popcorn by monitoring only the chamber pressure.Comment: 6 pages; revision (typo and minor content corrections

Density Functional Theory of Hard Sphere Condensation Under Gravity

The onset of condensation of hard spheres in a gravitational field is studied using density functional theory. In particular, we find that the local density approximation yields results identical to those obtained previously using the kinetic theory [Physica A 271, 192, (1999)], and a weighted density functional theory gives qualitatively similar results, namely, that the temperature at which condensation begins at the bottom scales linearly with weight, diameter, and number of layers of particles.Comment: 17 pages, 4 figure

Increasing the Size of a Piece of Popcorn

Popcorn is an extremely popular snack food in the world today. Thermodynamics can be used to analyze how popcorn is produced. By treating the popping mechanism of the corn as a thermodynamic expansion, a method of increasing the volume or size of a kernel of popcorn can be studied. By lowering the pressure surrounding the unpopped kernel, one can use a thermodynamic argument to show that the expanded volume of the kernel when it pops must increase. In this project, a variety of experiments are run to test the validity of this theory. The results show that there is a significant increase in the average kernel size when the pressure of the surroundings is reduced.Comment: Latex document, 14 pages, 4 figures, 1 page of table

Escola ambiental: transferência de tecnologias geradas pela Embrapa para a segurança alimentar e a valorização da agricultura urbana nas escolas da cidade de Belém, Pará.

Organizar e qualificar os conhecimentos e tecnologias sobre educação ambiental, segurança alimentar, cultivo de hortas, formação de pomares e a criação de abelhas sem ferrão adaptáveis ao cultivo em escolas; Implantar módulos de cultivos de hortifrutigrangeiros, de pomares e de criação de abelhas sem ferrão para demonstração de tecnologias visando contribuir para a formação educacional sobre educação ambiental e segurança alimentar; Desenvolver ações de comunicação para disseminar as iniciativas e os resultados do projeto; Capacitar agentes multiplicadores (professores, funcionários, alunos, familiares de alunos e etc.) para desenvolvimento da agricultura urbana através de ação educativa e melhoria de hábitos alimentares; Monitorar e avaliar os resultados e impactos das ações de TT

Variational Approach to Hard Sphere Segregation Under Gravity

It is demonstrated that the minimization of the free energy functional for hard spheres and hard disks yields the result that excited granular materials under gravity segregate not only in the widely known "Brazil nut" fashion, i.e. with the larger particles rising to the top, but also in reverse "Brazil nut" fashion. Specifically, the local density approximation is used to investigate the crossover between the two types of segregation occurring in the liquid state, and the results are found to agree qualitatively with previously published results of simulation and of a simple model based on condensation.Comment: 10 pages, 3 figure

Surface Instability in Windblown Sand

We investigate the formation of ripples on the surface of windblown sand based on the one-dimensional model of Nishimori and Ouchi [Phys. Rev. Lett. 71, 197 (1993)], which contains the processes of saltation and grain relaxation. We carry out a nonlinear analysis to determine the propagation speed of the restabilized ripple patterns, and the amplitudes and phases of their first, second, and third harmonics. The agreement between the theory and our numerical simulations is excellent near the onset of instability. We also determine the Eckhaus boundary, outside which the steady ripple patterns are unstable.Comment: 23 pages, 8 figure