Iranian students’ measurement estimation performance involving linear and area attributes of real-world objects

This article reports on an exploratory investigation of the measurement estimation performance of ten Iranian high school students on a set of real-world length and area measurement tasks. The results of a qualitative analysis of the data indicate that the students employed a variety of either mental or physically present Individual Frames of Reference as the non-tool units of measure in various estimation tasks. The analysis also found that a range of types of frames of reference was used across students in response to particular tasks and to the physical environments in which the tasks were situated. These results suggest that there is a complex interaction among a student’s individual preference for a particular type of Individual Frame of Reference, the nature of the estimation activity, and the physical context in which the activity takes place. These findings, which contribute to an understanding of the nature of the measurement unit that is employed during an estimation process, provide a different perspective from other studies that focus on categorizing estimation strategies, or processes.     

Effect of flow and physical parameters on the wax deposition of Middle East crude oil under subsea condition: heat transfer viewpoint

Change in pressure, temperature, flow rate and concentration of oil causes precipitation and deposition of wax particles in the pipelines which has become a major problem for oil industries. By decreasing the capacity and economic efficiency of land oil reserves, demand for offshore reserves increases. Change in temperature in subsea pipelines is more possible and so the wax deposition happens under this condition more. Low water temperature and subsea condition change overall heat transfer coefficient and heat transfer rate in pipe cross-section which affects the wax transportation from bulk fluid to the wall. In this study, the effects of temperature, flow rate and oil characteristic in different pipeline diameters on Middle East oil which covers the most oil reserves of the world have been investigated under Persian Gulf water condition. Higher inlet temperature postpone the wax deposition to far locations and higher flow rate causes lower wax thickness in first stages of pipe and higher wax thickness after passing the first stage.