personal samplers or in general blunt body samplers are widely used in occupational hygiene for collecting air contaminants in the work environments. this work is part of an ongoing research into the performance evaluation of personal samplers, particularly in terms of their aerodynamic properties. velocity profiles have been measured around and within typical cylindrical sampling devices, plac...

in this research a flat plate solar air collector was investigated under direct solar radiation consisted of a slatted glass cover, perforated absorber aluminum sheets (porosity 0.0177, 0.0314 and absorber thickness of 2.5 mm). the effect of porosity on absorber efficiency of collector was evaluated. six levels of air mass flow rates (0.0056 to 0.0385 kg m-2 s-1) were adopted.average solar ener...

Solar water heaters are good tools for saving fuel. The main component of these water heaters is collectors, which are responsible for absorbing solar energy and transferring it to the working fluid with the least heat dissipation. The present study is an experimental study of the performance of the solar semispherical collector with 1 m2 of absorber area at different volumetric flow...

ABSTRACT: In this paper, the thermal characteristics of single and double flow plane solar heaters with radiating working gas were analyzed and compared by numerical analysis for the first time. The laminar mixed convection gas flow in the heaters was numerically simulated by the CFD method using the finite volume technique. The set of governing equations included the conservation of mass, mome...

Enhancing the species mixing in microfluidic applications is key to reducing analysis time and increasing device portability. The mixing in electroosmotic flow is usually diffusion-dominated. Recent numerical studies have indicated that the introduction of electrically charged surface heterogeneities may augment mixing efficiencies by creating localized regions of flow circulation. In this stud...

This study investigates whether the capital market values the efficiency of firms. After tracing stock returns and efficiency changes of 399 listed insurance firms in 52 countries during the 2002-2008 period, the paper reports a positive and statistically significant relationship between profit efficiency change and market adjusted stock returns. However, there is no robust evidence that cost e...

In this note we consider the cooperative linear quadratic control problem. That is, the problem where a number of players, all facing a (different) linear quadratic control problem, decide to cooperate in order to optimize their performance. It is well-known, in case the performance criteria are positive definite, how one can determine the set of Pareto efficient equilibria for these games. In ...