Overhead cost ratios are easy to compare across charities relative to other metrics. Many third-party rating agencies rely on overhead cost ratios when evaluating charities, at least in part. Many donors report relying heavily on overhead cost metrics when choosing among charities. Donors exhibit strong distaste for charities that report high overhead costs, even when there is no relationship w...

in this paper, second law analysis for calculations of the entropy generation due to the flow andheat transfer of water-al2o3 and ethylene glycol-al2o3 nanofluids inside annuli is presented. thephysical properties of the nanofluids are calculated using empirical correlations. constant heatfluxes at inner surface of the annuli are considered and fully developed condition for fluid flowand heat t...

We report the optical studies of nanohole arrays in metallic coatings on cleaved optical fibers and also on glass substrates. Nanoholes are produced using electron-beam lithography and range in size from 100 to 700 nm; the pitch is varied from 300 to 3000 nm. Transmission properties are examined using visible 632.8 nm and infrared 1550 nm laser light. The observed interference patterns are dete...

In this paper, a novel design of all-solid photonic bandgap fiber with ultra-low confinement loss is proposed. The confinement loss is reduced remarkably by managing the number of rods rings, up-doping level, pitch value, and rods diameters. Moreover, the designed PCF shows ultra-flattened dispersion in L- and U-band. Furthermore, a new design, based on introducing of an extra ring of air h...

this paper presents a k- turbulence model for simulation of steady current and itsinduced vortex shedding caused by the presence of an offshore pipeline. performance of the modelaround a circular cylinder above a wall with gap to diameter ratios of 0.1, 0.35 and 0.5 underdifferent flow regimes with reynolds numbers of 1500, 2500 and 7000 is studied. the flow field iscomputed with solving the re...

Outer-arm dynein is the main engine providing the motive force in cilia. Using three-dimensional tracking microscopy, we found that contrary to previous reports Tetrahymena ciliary three-headed outer-arm dynein (αβγ) as well as proteolytically generated two-headed (βγ) and one-headed (α) subparticles showed clockwise rotation of each sliding microtubule around its longitudinal axis in microtubu...

Dynamic behavior of ground supported cylindrical storage tanks (CST) is of crucial importance because of its applications in industrial complexes. Seismic behavior of tanks is greatly affected by the height to diameter ratio, fluid height and fluid type. Five CSTs with different height to diameter ratios, three CSTs with the same height and diameters but various fluid heights and one CST with t...

this study aims to investigate the effects of geometric imperfections on buckling of thin cylindrical shells due to global shear. to this end, more than 320 finite element models of cylindrical shells with different diameter to thickness ratios were prepared. random imperfections with different amplitudes were applied to numerical models. the results revealed that global buckling of cylindrical...

The interturbine transition duct (ITD), located between the high-pressure (HP) and low-pressure (LP) turbines of aeroengines, tends to be designed as an aggressive ITD integrated with wide-chord struts meet requirements civil aeroengines for high bypass ratios thrust–weight ratios. This paper presents a detailed unsteady numerical investigation effects HP rotor trailing-edge radius on flow char...