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Now showing items 11-20 of 87
Development Of High Strength Lime Pozzolana Pastes
(University of Nairobi,, 2014)
Non - hydraulic hydrated lime is a binder obtained by heating rocks, sand or shells containing calcite to temperature between 900 °C an d 950 °C to produce CaO, which is then slaked with water to produce Ca(OH) 2 . It sets ...
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, ...
Rainwater Harvesting And Management For Improving Agricultural Productivity In Arid And Semi-arid Areas Of Kenya
(22-06-13)
Kenya Rainwater Association (KRA) has been working to implement rainwater harvesting and management
systems (RHM) and complementary technologies across Kenya since 1994. A founder member of the Greater
Horn of Africa ...
Development Of Technical Capabilities For Sustainable Radiation And Waste Safety; - Status of resources and services in Kenya: A stakeholder's view
(2003)
Provision of radiation services and acquisition of radiation detection and measurement equipment in the country has been generally lacking dating as far back as 1995.
During the period 1995 to present, Kenya's Regulatory ...
Land Development Options for Coastal Islands of Mombasa and Lamu
(2001)
This paper discusses land-sourced pollution with an emphasis on domestic sewage in the Caribbean in relation to similar issues in the Indian Ocean and Pacific. Starting on a large-scale in the 1980s, tropical Atlantic ...
Sampling in research
(2002)
The Dynamics and Implications of Sustaining Urban Spatial Segregation in Kenya: Experiences from Nairobi Metropolis
(2001)
Urban spatial segregation is not a recent phenomenon in Kenya. Its origin in the Kenyan towns
can be traced way back to the emergence of colonization. Initially, the attitude and response of
national governments towards ...
Residents' Participation in Neighbourhood Management and Maintenance-Experiences and Lessons from Nairobi, Kenya
(07-08-13)
Kenya has been faced with challenges of planning, development and management of its urban residential neighbourhoods. Any residential neighbourhood should have a well-defined spatial and social entity so as to give meaning ...