32,266 research outputs found
Initial stages of cavitation damage and erosion on copper and brass tested in a rotating disk device
In view of the differences in flow and experimental conditions, there has been a continuing debate as to whether or not the ultrasonic method of producing cavitation damage is similar to the damage occurring in cavitating flow systems, namely, venturi and rotating disk devices. In this paper, the progress of cavitation damage during incubation periods on polycrystalline copper and brass tested in a rotating disk device is presented. The results indicate several similarities and differences in the damage mechanism encountered in a rotating disk device (which simulates field rotary devices) and a magnetostriction apparatus. The macroscopic erosion appears similar to that in the vibratory device except for nonuniform erosion and apparent plastic flow during the initial damage phase
Magnetocaloric effect and nature of magnetic transition in nanoscale Pr0.5Ca0.5MnO3
Systematic measurements pertinent to the magnetocaloric effect and nature of
magnetic transition around the transition temperature are performed in the 10
nm Pr0.5Ca0.5MnO3 nanoparticles (PCMO10) . Maxwell relation is employed to
estimate the change in magnetic entropy. At Curie temperature TC, 83.5 K, the
change in magnetic entropy discloses a typical variation with a value 0.57 J/kg
K, and is found to be magnetic field dependent. From the area under the curve
Delta S vs T, the refrigeration capacity is calculated at TC, 83.5 K and it is
found to be 7.01 J/kg. Arrott plots infer that due to the competition between
the ferromagnetic and anti ferromagnetic interactions, the magnetic phase
transition in PCMO10 is broadly spread over both in temperature as well as in
magnetic field coordinates. Upon tuning the particle size, size distribution,
morphology, and relative fraction of magnetic phases, it may be possible to
enhance the magnetocalorific effect further in PCMO10.Comment: Accepted (Journal of Applied Physics) (In press
Quantitative mapping of rainfall rates over the oceans utilizing Nimbus-5 ESMR data
The electrically scanning microwave radiometer (ESMR) data from the Nimbus 5 satellite was used to deduce estimates of precipitation amount over the oceans. An atlas of the global oceanic rainfall was prepared and the global rainfall maps analyzed and related to available ground truth information as well as to large scale processes in the atmosphere. It was concluded that the ESMR system provides the most reliable and direct approach yet known for the estimation of rainfall over sparsely documented, wide oceanic regions
Periodic variations of precipitation in the tropical Atlantic Ocean
Statistical analysis of the satellite-borne Electrically Scanning Microwave Radiometer data in the tropical Atlantic region reveals that the rainfall near local noon is higher both in frequency of occurrence and intensity than the rainfall in the same area near local midnight. Another striking feature that stands out from the analysis is an oscillation with a period of 3.3. days in rainfall occurrence and intensity. This periodicty is consistent with easterly waves traveling from the African continent to the region under study
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