Fully Compressible Hydrodynamic Simulation of Non-Equidiffusive Premixed Flames Propagation in Channels

Premixed combustion remains of fundamental interest in energy generation and propulsion systems as well as in implementation of safety measures for residential and industrial accidental fire explosions. While the fast pace and complex nature of the combustion process has previously necessitated the analytical and computational studies to employ the simplifying assumption of equidiffusivity, when the Lewis number defined as the thermal-to-mass diffusivities ratio is unity , the ongoing advancements in technology and the requirements for efficiently operating combustors over a wide range of conditions make the combustion process more non-equdiffusive ( ) than ever. The impact of non-equidiffusivity on the dynamics and morphology of a flame, and thereby on the combustion efficiency, becomes aggravated by the interactions with combustor geometric parameters as well as thermochemical properties of the fuel mixture. Therefore, by representing combustors as channels with various extreme conditions (open channels, when both ends are open, or semi-open, when one end is closed, while the other one remains open), boundary conditions (non-slip or free slip, adiabatic or isothermal walls) and internal structures (obstructed or unobstructed), the current work addresses the effects of non-equidiffusivity and its interplays with other parameters on flame propagation in channels. Specifically, propagation of non-equidiffusive flames in channels is investigated by means of the computational simulations of the reacting flow equations with fully-compressible hydrodynamics and Arrhenius chemical kinetics. A detailed parametric study is performed for the Lewis numbers in the range ; the channel half-width , where is the thermal flame thickness; the blockage ratios, , being from to ; and the spacing between the obstacles being . The diffusional-thermal combustion instability, associated with , and the flame thickening at are found to play a major role in determining the flame dynamics in a channel. Regarding finger flame acceleration in semi-open channels with adiabatic slip walls, it is shown that the flames accelerate slower than equidiffusive ones. In contrast, the flames acquire stronger distortion, associated with the diffusional-thermal combustion instability, and thereby accelerate much faster than at . Increased surface area of the flame front and thus, a higher burning rate and stronger acceleration is also obtained in wider channels. Presence of equally spaced obstacles in such channel produced higher acceleration, with the increase being more significant at and high blockage ratio. When both ends of the channels are open, the flames show oscillations, acceleration or a sequence of both, depending on other parameters. For a channel with adiabatic non-slip walls, the oscillation amplitude and frequency decreases with , and the low- flames exhibiting different morphologies. A drastic change in flame dynamics is however seen for channel with isothermal wall. In narrow channels with small blockage ratios, the oscillations amplitude and frequency changes with , with the frequency decreasing and the amplitude increasing as grows from 0.3 to 2. In other conditions, a transition from flame oscillations to its sudden acceleration or propagation at constant velocity, is singularly influenced by the Lewis number, or by coupling to the geometric parameters. The delay time before the onset of flame acceleration, especially at , also varies as channel width and the blockage ratio changes. In all cases, the Lewis number shows both quantitative and qualitative effects on flame propagation in obstructed channel

HCME: An Environment-Friendly I.C. Engine Fuel

The study revealed that Hura crepitans oil is a good candidate for Hura crepitans methyl ester (HCME) production. Two steps (esterification and transesterification) production stages influenced the high yield of HCME. Three possible experimental runs were performed in each step, the best of the three conditions were 1.45 (% v/v) for H2SO4 conc., 5:1 for methanol/oil molar ratio, 40 min for reaction time which gave 1.06 % for FFA in the first step, in the second step, 92.70 %(w/w) of HCME was obtained at 0.55% KOH, 5:1 methanol/oil molar ratio, 60 oC temperature and 30 min reaction time. The produced HCME had fuel properties which satisfied both ASTME D6751 and EN 1424 standards. The fatty acid profile of the HCME revealed the dominant fatty acids were linoleic (64.50%), oleic (17.54%) and palmitic (12.70%). Exhaust emissions from an internal combustion (I.C.) engine revealed that there is 60% decreased in CO, 58% decreased in NOx, 60% decreased in HC, 39% decrease in smoke opacity and 42% decreased in BSFC at B20, respectively. Flue gas temperature increased by 12% at B20, 45% increased in BTE at B50 when compared to pure diesel (AGO). Hence, it can be concluded that B20 (20% HCME + 80% AGO) will provides the best emission reduction at the lowest cost

The Politics of Conflict and Internal Displacement: An Assessment of the Internal and External causes of The Liberian Civil War

The perennial status of peace and conflict dialogue in Africa has been very consistent. There is hardly any African States today that is not ridden with one form of internal conflict or the other. Some actions and inactions still have the possibility of generating more conflict in Africa. The possible missing link is that most African States (the leaders and the led) have not learnt the value of learning from history especially the causes and the effects of the Liberian Civil War on its economy, politics, social and citizenry. The Liberian Civil War, which was one of Africa's bloodiest, claimed the lives of more than 200,000 Liberians and further displaced a million others into refugee camps in neighboring countries. Thus, this paper takes a critical look at the incidents of the Liberian Civil War with the intention of critically reflecting on both the internal and the external causes of the war and the countless number of internally displaced people. The paper, dwelling on extensive secondary data, exposes some hidden trajectory to the historical Liberian Civil War with the intention of providing the rest of the African States enough “food for thought” and also provide a comprehensive understanding of the causes and the background of displacement in Liberi

Performance Analysis of ANN on Dataset Allocations for Pattern Recognition of Bivariate Process

Several approaches to identifying the out-of-control variables after the detection of abnormal pattern has been most intensively studied and used in practice. One of the several approaches is the Artificial Neural Network (ANN) based model for diagnosis of out-of-control signal of multivariate process mean shift. In spite of the number of years of research in neural network, limited research (if any) have been done on the effect of dataset allocations in percentages for training and testing on the performance of ANN. In this paper, we investigate the use of different percentages of dataset allocation into training, validation and testing on the performance of ANN in pattern recognition of bivariate process using six selected training algorithms. The result of study showed that large allocation of dataset for training was found suitable, having higher recognition accuracy for ANN learning and perform better for pattern recognition of bivariate process. Keywords: Bivariate Process; Pattern Recognition; Recognition accuracy; Multivariate quality control charts, training algorith

A Comparative Study of the Engagement of Migrant and Indigenous Artisans on the Construction Sites in Lagos Metropolis and Benin City, Nigeria

It is gradually becoming a norm to find some construction trades in project sites in Nigeria being dominated by migrant artisans from other West African countries, despite the high unemployment rate in Nigeria. The magnitude and spread of these migrants in Nigerian cities deserves research attention in the effort to understand the demographic settings that encourage their influx, and the reasons why contractors often employ them. This research carried out comparative study of the factors responsible for the engagement of migrant artisans in Lagos Metropolis and Benin City, South-West and South-South Nigeria respectively. Based on data from 40 randomly selected construction sites, 20 from each of the cities; it was found that indigenous artisans were dominant on construction sites in the study area with migrant artisans constituting 19.93% in Lagos and 15.67% in Benin City. Contractors in Lagos Metropolis engage the services of migrant artisans more frequently than those in Benin City. The study further revealed that migrant artisans are mainly engaged for tiling, P.O.P. installation and plastering works in Lagos and Benin City. The migrant artisans’ ability to work for longer hours (MS= 4.03), achieve better quality of workmanship (MS= 3.94) and reduction in cost (MS= 3.92) were the most important factors accounting for their engagement in Lagos. In Benin City, better quality of workmanship (MS= 4.30), reduction in cost (MS= 4.10) and migrant artisans’ ability to work for longer hours (MS= 3.82) were the most highly rated factors. Collaboration for trade test certification between the Federal Ministry of Labour and Productivity and Polytechnics in Nigeria was recommended as a means of achieving adequate training of Nigerian artisans in order to check the increasing engagement of nationals of other countries in construction trades in Nigeria

Assessment of Municipal Waste Disposal Methods: A Case Study of Ibadan, Nigeria.

In order to prevent health hazards that can occur as a result of inappropriate waste disposal, this study was carried out to identify the various municipal waste disposal methods practiced, and present the methods that are mostly adopted in the South Sahara region. It also analyzed the effects of these methods practiced on individuals and environment, and proffered solutions to the problems facing the populace as a result of these inappropriate methods of waste disposal. The third largest city of Africa located in Nigeria, called Ibadan was used as a case study. Questionnaires of population size 5000 were administered to households in all Local Government Areas of Ibadan. 4500 questionnaires were completely filled and returned. The rating results derived from the survey revealed that the most practiced municipal waste disposal method is open burning. Keywords: Environmental Assessment, Health, Waste Disposal, Open Burning

Predictors of Sustainable Energy Technology Adoption Behavior in South-Western Nigeria

This study focuses on the predictors of sustainable energy technology (SET) adoption behavior in south-western Nigeria. Although the extant literature is gorged with plethora of studies on sustainable energy technology adoption, studies that were conducted in a typical emerging economy like Nigeria in general and south-west Nigeria in particular are grossly under-researched and under-reported. The main objective of this study is to empirically investigate the predicting factors that influence the adoption of sustainable energy technology in south-western Nigeria. Based on the foregoing, the study adopted quantitative design and quota sampling as the research design and sampling method respectively. Questionnaire was the research instrument. The validity and the reliability of the research instrument were tested using construct validity and composite validity respectively. Hypothesized relationships were tested using structural equation modeling. It was found that performance expectancy, perceived value and effort expectancy have significant effect on the intention to adopt sustainable energy technology, while social influence, facilitating condition and intrinsic motivation do not. Also, it was revealed that there is a positive and significant relationship between intention to adopt sustainable energy technology and the actual adoption of sustainable energy technology. It was concluded that the study provided empirical support that Unified theory of acceptance and use of technology (UTAUT) provides a robust and comprehensive theoretical framework to predict, explain and describe sustainable energy technology adoption behaviour in a typical developing country context like Nigeria. The marketers of SET products should use price as their unique selling proposition to attract customers. Also, the quality of the SET products should conform with the expected performance of the product. Also, the SET marketers should endeavour that expected efforts of the prospective SET products consumers are met adequately since social influence, facilitating conditions and intrinsic motivation did not have significant effect on adoption intentions for SET. Keywords: Sustainable energy technology, Adoption behavior, Intention to adopt, Unified theory of acceptance and use technology, Structural equation modeling, Nigeria. DOI: 10.7176/JESD/11-8-07 Publication date: April 30th 202

Short-Term Toxicological Evaluation of AnacardiumOccidentale Oil in Albino Rats

Anacardium occidentale L. nut oil was characterized after which 5% of it was incorporated in the feed formulation for albino rats. Two diets were formulated; one of these diets had 5 % A. occidentale oil (test diet) while the other had 5% of groundnut oil as a representative of conventional edible oil (control diet).  Proximate analysis result indicated that the nut comprises of 5.82 ± 0.16% moisture, 25.54 ± 0.25% protein, 6.28 ± 0.02% crude fibre, 42.52 ± 0.45% fat, 2.90 ± 0.09% ash and 16.97 ± 0.84% carbohydrate.  A. occidentale nut was found to be rich in potassium and magnesium.  Physicochemical analysis of cashew nut oil gave 22.03 ± 0.04 mgKOH/g acid value, 22.03 ± 0.40 g/100g iodine value, 1.96 ± 0.23 mgKOH/g free fatty acid, 97.98 ± 0.99 mgKOH/g saponification value, 2.96 ± 0.59 peroxide value and 1.64 ± 0.02 refractive index.  Fatty acid analysis of A. occidentale nut oil showed that it has high level of unsaturation (77.5754%).  This is evident from the values obtained for oleic acid (61.02%), linoleic acid (15.34%) and linolenic acid (0.13%). There was weight gain by the rats during the feeding period of eight weeks and no mortality was recorded. Haematological and biochemical parameters were investigated for in the test and control rats and the results obtained revealed no adverse effect on the rats’ blood.  The cholesterol level in the test and control rat tissues was not significantly different at p<0.05.  The result of the histopathology of some of  the rat tissues showed no visible lesion.  A. occidentale nut oil might be suitable for edible purposes. Key words:A. occidentale, fatty acid, proximate composition, toxicolog