48,926 research outputs found
Choked flow analogy for very low quality two-phase flows Technical report no. 18
Choked flow analogy for very low quality two-phase flows - homogeneous flow and hydraulic jump theoretical models for predicting axial pressure distributio
Cavitation damage characteristics in water and mercury from studies in a cavitating Venturi Technical report no. 17
Cavitating damage characteristics in water and mercury studied in cavitating Ventur
Gas Content, Size, Temperature and Velocity Effects on Cavitation Inception Internal Report No. 31
Gas content, size temperature, and velocity effects on Venturi cavity inceptio
Positivity and strong ellipticity
We consider second-order partial differential operators in divergence
form on \Ri^d with a positive-semidefinite, symmetric, matrix of real
-coefficients and establish that is strongly elliptic if and only
if the associated semigroup kernel satisfies local lower bounds, or, if and
only if the kernel satisfies Gaussian upper and lower bounds.Comment: 9 page
Comparative analysis of techniques for evaluating the effectiveness of aircraft computing systems
Performability analysis is a technique developed for evaluating the effectiveness of fault-tolerant computing systems in multiphase missions. Performability was evaluated for its accuracy, practical usefulness, and relative cost. The evaluation was performed by applying performability and the fault tree method to a set of sample problems ranging from simple to moderately complex. The problems involved as many as five outcomes, two to five mission phases, permanent faults, and some functional dependencies. Transient faults and software errors were not considered. A different analyst was responsible for each technique. Significantly more time and effort were required to learn performability analysis than the fault tree method. Performability is inherently as accurate as fault tree analysis. For the sample problems, fault trees were more practical and less time consuming to apply, while performability required less ingenuity and was more checkable. Performability offers some advantages for evaluating very complex problems
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