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Hāgere Hiywet, Ethiopia

Krishnaraj R.,Ambo University
Ecotoxicology and Environmental Safety | Year: 2015

Foundry practices are used in contemporary world to produce large volume of components and products. Foundry practices involve the melting of metals and pouring the molten metal into the cavities called molds. On solidification, the metals which assume the shape of molds are removed as castings. Foundries that employ these practices were growing in large number till the middle part of the twentieth century in the world. After the middle part of the twentieth century, the world community begun to realize that, foundries were emitting pollutants which were affecting the health of humans. In order to overcome this situation, several countries in the world promulgated laws stipulating the maximum level of pollutants that can emit by foundries. These laws affected the functioning and growth of foundries. In order to sustain amidst these constraints, foundries begun to install energy efficient melting technologies and pollution control devices (PCDs). In this back ground, this paper reports to assess the contemporary scenario and project the future needs for sustaining the foundries. During the conduct of this literature review, it was discernable that, research papers have reported three categories of researches. In the first category of research papers, the researches reporting the achievement of cleaner production technologies in foundries using PCDs have appeared. In the second category of research papers, the application of cleaner production technology in foundries located in different countries has been examined. In the third category of research papers, the application of efficient melting technologies and PCDs in different clusters of foundries located in different parts of world has been explored. Subsequently implementation technics of Environmental Management System in cleaner production technics in foundries has been described the analysis of the information and knowledge drawn from these three categories of papers has revealed that, researches exploring the sustenance of foundries situated in different parts of world are required to be carried out intensively in future. The outcome of these researchers will be useful to apply the cleaner production technologies that would be suitable for implementation in different foundry clusters to suit the different conditions prevailing with regard to the adoption of efficient melting technologies and PCDs. © 2015 Elsevier Inc. Source

Krishnaraj R.,Ambo University
Environmental Chemistry Letters | Year: 2015

Research has made considerable attempt to decrease the emission of harmful gaseous pollutants to the atmosphere. This report reviews hazards due to foundry air pollution, measurement of pollution emission, pollution control devices and policies of pollution control. The pollutants discussed are polycyclic aromatic hydrocarbon, 1-hydroxypyrene, polychlorinated-p-dibenzodioxins and dibenzofurans and polychlorinated biphenyls. © 2015, Springer International Publishing Switzerland. Source

The study scrutinizes the effect of convective heating on magnetohydrodynamic (MHD) stagnation point flow and heat transfer of upper-convected Maxell fluid past a stretching sheet in the presence o f nanoparticles. The model used in the study includes the effect o f Brownian motion and thermophoresis parameters. The non-linear governing equations and their boundary conditions are initially cast into dimensionless forms by similarity transformation. The resulting system of equations is then solved numerically using fourth order Runge-Kutta method along with shooting technique. Numerical results are obtained for velocity, temperature, concentration profiles, skin friction coefficient, local Nusselt number and Sherwood number. It is found that the skin friction coefficient, the local Nusselt number and Sherwood number increase with an increase in A and β and decreases as the values of M increase. Moreover, the local Nusselt number-θ′(0) and local Sherwood number-ϕ′(0) increases with an increase in Bi. © 2016, Global Digital Central. All Rights Reserved. Source

Gebremedhin E.Z.,Ambo University
Tropical Animal Health and Production | Year: 2011

A study was carried out to estimate the prevalence, larval burden and risk factors of ovine and caprine oestrosis from December 2007 to May 2008 on 554 heads of randomly selected sheep and goat slaughtered at Ambo town, Western Shoa, Ethiopia. The results show an overall prevalence of 59.9% with infection rate of 69.8% and 47.3% in sheep and goats respectively. No statistically significant difference in the prevalence was noted with regard to the assumed risk factors like sex, nose color, face color, horned versus polled, origin, and months (p > 0.05). Sheep were nearly twice more likely to be infected as compared to goats (p = 0.0001, odds ratio (OR) = 1.975). Age of the animals was found to be protective (OR = 0.579; 95% confidence interval = 0.393, 0.853; p = 0.006). As compared to very fat animals, poor (p = 0.040, OR = 4.834), medium (p = 0.049, OR = 4.198), and fat (p = 0.022, OR = 5.795) body condition animals are more likely to be infected by Oestrus ovis larvae. Nasal and sinus cavity pathology is positively correlated with the total larval count (r = 0.56, p < 0.0001). Out of a total of 3,770 larvae collected, 57.5% were L1, 30.8% L2, and 11.7% L3 larvae. All the three larval instars were seen throughout the study months. It is concluded that oestrosis is a common problem in the study area and more prevalent in sheep than goats, in adult than young, and in animals with poor body condition. © 2010 Springer Science+Business Media B.V. Source

In this analysis, the boundary layer flow and heat transfer over a permeable stretching sheet due to a nanofluid with the effects of magnetic field, slip boundary condition and thermal radiation have been investigated. The transport equations used in the analysis took into account the effect of Brownian motion and thermophoresis parameters. The solution for the velocity, temperature and nanoparticle concentration depends on parameters viz. thermal radiation parameter R, Prandtl number Pr, Lewis number Le, Brownian motion parameter Nb, thermophoresis parameter Nt, Eckert number Ec, magnetic parameter M and slip parameters. Similarity transformation is used to convert the governing non-linear boundary-layer equations into coupled higher order non-linear ordinary differential equations. These equations are numerically solved using fourth order Runge-Kutta method along with shooting technique. An analysis has been carried out to elucidate the effects of governing parameters corresponding to various physical conditions. Numerical results are obtained for distributions of velocity, temperature and concentration, as well as, for the skin friction, local Nusselt number and local Sherwood number for several values of governing parameters. The results indicate that the local Nusselt number decreases with an increase in both Brownian motion parameter Nb and thermophoresis parameter Nt. However, the local Sherwood number increases with an increase in both thermophoresis parameter Nt and Lewis number Le, but it decreases as the values of Nb increase. Besides, it was found that the surface temperature of a sheet increases with an increase in the Eckert number Ec. A comparison with previous studies available in the literature has been done and we found an excellent agreement with it. © 2013 Elsevier Ltd. Source

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