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Galvanized coating is used to prevent corrosion of reinforcing bars. Contrary to steel, this coating reacts with the surrounding aqueous phase of the cement paste and induces a delay in the hydration of the interfacial zone. This paper describes an experimental study of this effect on bond strength of the reinforcement. This effect is evaluated by testing specimens with smooth bars, ribbed bars placed in a horizontal or vertical position, or machined bars with different rib heights. The results indicate that the bond performance of galvanized bars depends on the failure zone of the concrete surrounding the reinforcement and on the time of testing. The type of bar and the rib height of the reinforcing bar are designated as the parameters affecting the bond failure of galvanized bars.

It is known that longitudinal ribs manufactured in a flat surface act to reduce (reduces) turbulent skin-friction drag, thus providing a moderate drag reduction of 4 to 8%. In this paper, nonconventional variable blades are used instead of uniform grooves. Numerical simulation of a turbulent flow over blade-covered surface is performed for three cases: uniform, increasing and decreasing spacing blades. All riblets have rectangular cross-section as well as the same wetted area. Results show that drag reduction is strongly depending on the spacing variation, showing a benefit over uniform riblets for regressive spacing, and an opposite trend for the progressive one. Different nature of the flow over the three cases of blades' surfaces is revealed by looking at transverse planes cross flow motion, mean streamwise velocity and Reynolds stresses. Results show cross flow turbulence intensity reduced for regressive riblets compared to progressive and uniform ones. [ABSTRACT FROM AUTHOR]

The current global COVID-19 pandemic is adversely affecting financial markets, including commodities, conventional stocks, and Islamic stocks. This paper empirically investigates the extent to which COVID-19 effects may drive interdependence in markets. We fit copulas to pairs of returns before and during the ongoing epidemic shock, analyze the observed changes in the dependence structure, and discuss asymmetries on the propagation of crisis. We also use the findings to construct portfolios possessing desirable expected behavior. We find that the dependence structure changes significantly during the global pandemic providing valuable information on how the COVID-19 crisis affects inter-dependencies. The selected portfolio, including gold and Islamic return indices, has the best performance outside the COVID-19 crisis, and slightly more performing during the bear markets validating gold's intrinsic characteristic to be a safe haven. However, the portfolio performances, when combining the Brent with Islamic or conventional indices, have the same trend for the whole period. Our findings contribute to help investors better adjust their investment strategies., (© 2022 Board of Trustees of the University of Illinois. Published by Elsevier Inc. All rights reserved.)

Using a drifting spillover index approach (Diebold and Yilmaz, 2012) and a continuous time-frequency tool (Torrence and Webster, 1999), this paper attempts an empirical investigation of the spillovers and co-movements among commodity and stock prices in the major oil-producing and consuming countries. While our results point to the existence of a significant interdependence among the markets considered, Chinese and Saudi Arabian stock markets seem to be weakly integrated into the world market. Moreover, the spillovers are time-varying and reached their highest levels during the COVID-19 medical shock., (© 2020 Elsevier Inc. All rights reserved.)