835 research outputs found
Petrology alteration and mineralization of the Poorman Creek-Silver Bell stock porphyry Cu-Mo deposit
Soil fertility and plant nutrition research in southeast Missouri, 1961
Cover title.This report summarized the soil fertility and plant nutrition experiments conducted by the Agricultural Experiment Station in southeast Missouri during 1961
Soils research in southeast Missouri 1960
Cover title.This report summarized the soil fertility experiments conducted by the Agricultural Experiment Station in southeast Missouri during 1960
Probing the Local Interstellar Medium with Scintillometry of the Bright Pulsar B1133+16
The interstellar medium hosts a population of scattering screens, most of unknown origin. Scintillation studies of pulsars provide a sensitive tool for resolving these scattering screens and a means of measuring their properties. In this paper, we report our analysis of 34 yr of Arecibo observations of PSR B1133 + 16, from which we have obtained high-quality dynamic spectra and their associated scintillation arcs, arising from the scattering screens located along the line of sight to the pulsar. We have identified six individual scattering screens that are responsible for the observed scintillation arcs, which persist for decades. Using the assumption that the scattering screens have not changed significantly in this time, we have modeled the variations in arc curvature throughout the Earth's orbit and extracted information about the placement, orientation, and velocity of five of the six screens, with the highest-precision distance measurement placing a screen at just pc from the Earth. We associate the more distant of these screens with an underdense region of the Local Bubble
ECLSS advanced automation preliminary requirements
A description of the total Environmental Control and Life Support System (ECLSS) is presented. The description of the hardware is given in a top down format, the lowest level of which is a functional description of each candidate implementation. For each candidate implementation, both its advantages and disadvantages are presented. From this knowledge, it was suggested where expert systems could be used in the diagnosis and control of specific portions of the ECLSS. A process to determine if expert systems are applicable and how to select the expert system is also presented. The consideration of possible problems or inconsistencies in the knowledge or workings in the subsystems is described
Images in Emergency Medicine: Splenic Infarction Due to Sickle Cell Trait after Climbing Mt. Fuji
A diagnostic prototype of the potable water subsystem of the Space Station Freedom ECLSS
In analyzing the baseline Environmental Control and Life Support System (ECLSS) command and control architecture, various processes are found which would be enhanced by the use of knowledge based system methods of implementation. The most suitable process for prototyping using rule based methods are documented, while domain knowledge resources and other practical considerations are examined. Requirements for a prototype rule based software system are documented. These requirements reflect Space Station Freedom ECLSS software and hardware development efforts, and knowledge based system requirements. A quick prototype knowledge based system environment is researched and developed
A New Way to Conserve Total Energy for Eulerian Hydrodynamic Simulations with Self-Gravity
We propose a new method to conserve the total energy to round-off error in
grid-based codes for hydrodynamic simulations with self-gravity. A formula for
the energy flux due to the work done by the the self-gravitational force is
given, so the change in total energy can be written in conservative form.
Numerical experiments with the code Athena show that the total energy is indeed
conserved with our new algorithm and the new algorithm is second order
accurate. We have performed a set of tests that show the numerical errors in
the traditional, non-conservative algorithm can affect the dynamics of the
system. The new algorithm only requires one extra solution of the Poisson
equation, as compared to the traditional algorithm which includes self-gravity
as a source term. If the Poisson solver takes a negligible fraction of the
total simulation time, such as when FFTs are used, the new algorithm is almost
as efficient as the original method. This new algorithm is useful in Eulerian
hydrodynamic simulations with self-gravity, especially when results are
sensitive to small energy errors, as for radiation pressure dominated flow.Comment: 19 pages, 8 figures, 2 tables, add journal information in New
Astronom
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