Showing 3 results for Atefi
A. Heydari, S. Hatefi-Pour and A.a. Ahangar,
Volume 16, Issue 2 (1-1998)
Abstract
In the last quarter of the century, a substantial amount of research work has been conducted on optimization of energy consumption by refrigeration systems and on proper design and construction of household refrigerator-freezers. The importance of such energy optimization schemes stems from the environmental impacts of Freon (R-12) used as the working refrigerant in household refrigerator – freezers as well as the enormous energy consumed by such appliances. International regulations for the replacement of Ozone-depleting refrigerants, such as the Montreal Protocol, as well as the Iranian regulations regarding reduced energy consumption of energy consuming products have motivated research on the optimum design of household refrigerator-freezers. In this paper, research works aimed at analytical modeling and also the experimental works conducted to determine design methods of energy efficient refrigerator- freezers in Iran will be presented. Using the numerical method developed for this purpose, a parametric analysis of the components of a refrigerator-freezer manufactured in Iran will be presented and the reduced energy consumption by the selected appliance and its increased efficiency will be discussed. The influence of replacing R-12 with its substitute refrigerant (R-134a) on the energy consumption and efficiency of the typical refrigerator is also presented.
A. Shams Nateri, S. H. Amirshahi and M. Latefi,
Volume 21, Issue 2 (1-2003)
Abstract
In the present work the reflection behavior and the color appearance of acrylic yarns, as pile yarns used in carpet and pilled fabrics, are considered along their lengths as well as their cross- sections. Differences between longitudinal and cross-sectional reflection behaviors of yarns are measured in different yarn densities and hues and explained by the geometric model. The results of experimental work show that the average of reflectance and lightness values along yarns' length, with identical hue, are higher than values obtained from their cross-section. Besides, the lightness values of cross-sectional of samples, with identical hue, increase when the density of yarns in holder cell increases. The metric chromas as well as the hue angles of samples, dyed with the same dyestuff are different in two directions and lead to color difference values between 3.35 and 27.84 under D65 Illumination and CIE 1964 standard observer in CIELAB color difference formula. The reflection differences between two directions are analyzed using the geometric model and it is found that they originated from different optical passes through the fibers in the mentioned modes.
Keywords: Reflection behavior, Geometric model, Acrylic yarn
F. Shahriari Nogorani, M. Afari, M. A. Taghipoor, A. Atefi,
Volume 39, Issue 1 (Journal of Advanced Materials-Spring 2020)
Abstract
Practical applications of thermal barrier coatings with aluminide bond-coats are limited due to oxide scale spallation of the aluminide coating under applied thermal stresses. Considering the positive effects of oxygen-active elements or their oxides on the high temperature oxidation behavior, in this research zirconia was introduced into an aluminide coating. For this purpose, a Watts type bath was used to electroplate a layer of Ni-ZrO2 composite on a Ni-based substrate. Aluminizing was performed using the conventional two-step process at 760 and 1080 °C. Microstructural characterization of coatings in the as-coated conditions and after cyclic oxidation via 5-hour cycles at 1050 °C was performed using electron microscopy, energy dispersive spectroscopy and X-ray diffractometry. The results showed that the general three-zone microstructure of the simple high activity aluminide coatings develops below the pre-deposited nickel-zirconia layer and latter converts to a nearly un-alloyed porous NiAl. In spite of its porous surface layer, the zirconia modified coating has a higher oxidation resistance than the unmodified aluminide coating.
