Data validation and reliability calculations in digital protection systems

Imperial Users onl

Lifting properties in operator ranges

Given a bounded positive linear operator A on a Hilbert space H we consider the semi-Hilbertian space (H, _A), where _A =. On the other hand, we consider the operator range R(A^1/2) with its canonical Hilbertian structure, denoted by R(A^1/2). In this paper we explore the relationship between different types of operators on (H, _A) with classical subsets of operators on R(A^1/2), like Hermitian, normal, contractions, projections, partial isometries and so on. We extend a theorem by M. G. Krein on symmetrizable operators and a result by M. Mbekhta on reduced minimum modulus.Fil: Arias, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Corach, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Gonzalez, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

Collisional Dynamics of Macroscopic Particles in a Viscous Fluid

This thesis presents experimental measurements of the approach and rebound of a particle colliding with a wall in a viscous fluid. Steel, glass, nylon, and Delrin particles were used, with diameters ranging from 3 to 12 mm. The experiments were performed using a thick Zerodur or Lucite wall with various mixtures of glycerol and water. Normal and tangential coefficients of restitution were defined from the ratios of the respective velocity components at the point of contact just prior to and after impact. These coefficients account for losses due to lubrication effects and inelasticity. The experiments clearly show that the rebound velocity depends strongly on the impact Stokes number and weakly on the elastic properties of the materials. Below a Stokes number of approximately 10, no rebound of the particle occurs. Above a Stokes number of approximately 500, the normal coefficient of restitution asymptotically approaches the value for a dry collision. The data collapse onto a single curve of restitution coefficient as a function of Stokes number when normalized by the dry coefficient of restitution. Oblique collisions in a fluid are qualitatively similar to oblique collisions in a dry system, with a lowered friction coefficient dependent on surface roughness. For smooth surfaces the friction coefficient is drastically reduced due to lubrication effects. Values for the friction coefficient are predicted based on elastohydrodynamic lubrication theory. The particle surface roughness was found to affect the repeatability of some measurements, especially for low impact velocities. A significant retardation of a particle approaching a target at a low Stokes number was observed and quantified. The distance at which the particle's trajectory varies due to the presence of the wall is dependent on the impact Stokes number. The observed slowdown can be predicted from hydrodynamic theory to a good approximation. An analysis of the erosion of ductile materials during immersed collisions is presented. The size of the crater formed by the impact of a single particle against a ductile target can be estimated from theory, and these estimates agree well with experimental measurements.</p

Effects of power ultrasound treatments on properties of Longissimus beef muscle

This study was conducted to determine the effects of power ultrasound treatments on properties of Longissimus beef muscle. Twenty pairs of loins from steer carcasses, USDA Choice, maturity A were obtained 24hrs after slaughter for this study. Two experiments will be conducted at different intensity/time levels: (1) Control, 1.5 w/cm2, 3 w/cm2, and 5 w/cm2 for 3 minutes/side. (2) Control, 20 w/cm2, 40 w/cm2, and 60 w/cm2 for 45s/side (at 20 kHz) under refrigerated conditions. Each steak (four pieces) will be randomly allotted among these two experiments. Each loin was divided into at least 12 steaks and each steak was divided into 4 pieces, labeled, vacuum packed individually, and divided into groups: Day 1 and Day 7. Ultrasound treatments were applied using a direct probe commercial ultrasonic system. Cooking yields, shear force (Warner-Bratzler), and ultrasonic power entering the samples was measured. In addition, microscopy and SDS PAGE tests were conducted on the samples. No difference in shear force was observed for day 1, however at day seven the 5 w/cm2 treatment required a lower force (P \u3c 0.05) to shear the sample. Histological cross-sectional samples for all treatments showed separation of the muscle bundles when compared with the control. SDS PAGE did not show any difference between treatments. Shear force values for day 1 were not significant, but showed a tendency toward lower shear values for the treated samples. At day 7, the shear force values were significant for the 40 w/cm2 treatment. The histological samples showed an evident separation of the muscle fibers. 5% gels indicated a possible degradation of titin at day 7

How to Improve Higher Education in Panama

Panama is a country with potential for economic growth. Its higher education system is internationally considered the second most problematic.A stronger focus on quality , access and resources are key to a competitive higher educational system in order to support the Panamanian economic growth