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Steel Square Hollow Sections Subjected To Transverse Blast Loads
(2012)
Thin-walled steel hollow sections are used extensively in the construction, offshore, mining and security industries. Such members subjected to blast loads are of interest due to increased security demands and the occurrence ...
A model based on reaction kinetics and elemental diffusion is proposed to account for the presence of double inflection in the hardness profiles of the heat-affected zone (HAZ) in weldments of AI-Li-X alloys tested without postweld heat treatment (PWHT). Such profiles are particularly evident when 1 ) the base metal is in the peak-aged (T8 or T6) temper condition prior to welding; 2) the welding process is a high-heat input process, i.e., gas tungsten arc (GTA), gas metal arc (GMA) or plasma arc (PA) welding; and 3) a filler alloy deficient in lithium (i.e., AA 2319)is used. In the first part of this paper, the theoretical mechanisms are presented. It is proposed that the double inflection appears due to complete or partial reversion of the semi-coherent, plate-like precipitates (i.e., 0% T 1 or S'); coarsening of the platelike precipitates at constant volume fraction; precipitation of ~5' as a result of natural aging; and diffusion of lithium from the HAZ into the weld pool due to the concentration gradient between the weld pool and the base metal. In the second part (to be published in next month's Welding Journal), experimental validation of the model is provided using weldments of the AI-Li-Cu Alloy 2095.
(2012)
Pt-based alloys for high-temperature applications in aggressive environments have been under
development for over 10 years, and are targeted to be used as either as bulk, or as coatings.
The alloys comprise Pt, Al, Cr, ...
An Improved Enhancement Of Degraded Binary Text Document Images Using Morphological And Single Scale Retinex Operations
(University of Nairobi, 2012-07)
This paper proposes a novel enhancement algorithm for degraded binary document images captured using a low end cell phone camera. The algorithm starts with colour to grey scale conversion followed by contrast stretching. ...
Radioactivity And Dose Assessment Of Rock And Soil Samples From Homa Mountain, Homa Bay County, Kenya
(University of Nairobi, 2012-11-28)
The in situ measured average outdoor ab
sorbed dose rate in air was found to
vary from 108.4 to 1596.4 nGy h
-1
at Homa Mountain area in southwestern
Kenya. Rock and soil samples collected gave average values of ...
Approaches to informal settlement upgrading in East Africa
(2012)
On nth July 201.2, the University of Nairobi, School of the Built Environment, in collaboration with partners organized a regional Conference to explore approaches and. share lessons on sustainable up-scaling of informal ...
Magnesium alloy AZ31 as a Potential Candidate for Automobile Weight Optimization
(2012)
Magnesium-alluminium-zinc alloy (Mg alloy AZ31) is among the five general classes of wrought alloys that are strength¬ened by annealing. This paper will highlight the possibilities of manipulating the mechanical properties ...