32,379 research outputs found
Policy issues and data communications for NASA earth observation missions until 1985
The series of LANDSAT sensors with the highest potential data rates of the missions were examined. An examination of LANDSAT imagery uses shows that relatively few require transmission of the full resolution data on a repetitive quasi real time basis. Accuracy of global crop size forecasting can possibly be improved through information derived from LANDSAT imagery. A current forecasting experiment uses the imagery for crop area estimation only, yield being derived from other data sources
Controlling the accuracy of unconditionally stable algorithms in Cahn-Hilliard Equation
Given an unconditionally stable algorithm for solving the Cahn-Hilliard
equation, we present a general calculation for an analytic time step \d \tau
in terms of an algorithmic time step \dt. By studying the accumulative
multi-step error in Fourier space and controlling the error with arbitrary
accuracy, we determine an improved driving scheme \dt=At^{2/3} and confirm
the numerical results observed in a previous study \cite{Cheng1}.Comment: 4 pages, late
Irreversible thermodynamics of creep in crystalline solids
We develop an irreversible thermodynamics framework for the description of
creep deformation in crystalline solids by mechanisms that involve vacancy
diffusion and lattice site generation and annihilation. The material undergoing
the creep deformation is treated as a non-hydrostatically stressed
multi-component solid medium with non-conserved lattice sites and
inhomogeneities handled by employing gradient thermodynamics. Phase fields
describe microstructure evolution which gives rise to redistribution of vacancy
sinks and sources in the material during the creep process. We derive a general
expression for the entropy production rate and use it to identify of the
relevant fluxes and driving forces and to formulate phenomenological relations
among them taking into account symmetry properties of the material. As a simple
application, we analyze a one-dimensional model of a bicrystal in which the
grain boundary acts as a sink and source of vacancies. The kinetic equations of
the model describe a creep deformation process accompanied by grain boundary
migration and relative rigid translations of the grains. They also demonstrate
the effect of grain boundary migration induced by a vacancy concentration
gradient across the boundary
Use of the Pyramid Model for Supporting Preschool Refugees
Response to Intervention (RtI) is being applied to early childhood settings for the support of positive behavior and social development through the Pyramid Model (Fox, Carta, Strain, Dunlap & Hemmeter, 2010). This qualitative study assessed the use of the Pyramid Model for preschool aged refugee children living in a refugee resettlement community. Many young refugee children have experienced trauma (George, 2010) and some experience behavior and social challenges (Almqvist & Brandell-Forsberg, 1997). Twenty-five preschool service providers were interviewed about their use of the Pyramid Model for the support of preschool refugee students. Themes to be shared include how ECEs are implementing the practices outlined in the Pyramid Model along with strategies for adapting recommended practices to meet the needs of refugee families
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