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Effect of Coolant Temperature on Machining Characteristics of High Carbon Steel
Get PDFThis paper reports on the effect of coolant temperature on
machining of high carbon steels. The development of a cooling system to
reduce the temperature of water soluble coolant to 7.9oC from ambient
temperature was employed in this work to improve the machining
performance. The experiments were performed using cooled and ambient
temperatures by employing Taguchi L18 orthogonal array to design the
experimental runs. The cutting speed, feed rate and depth of cut were the
machining parameters used; while the tool-work piece interface
temperature was monitored using a digital thermometer with k-type
thermocouple wire. The selected control factors are material removal rate
and surface roughness. The experimental results were analyzed using
Minitab 16. The main effects and percentage contributions of various
parameters affecting surface roughness and material removal rate were
discussed, and the optimal cutting conditions were determined. It was
observed that surface finish improved by 65% with the use of the
developed cooled system. The reduction in coolant temperature played a
vital role in improving surface finish during machining high carbon
steels
Assessment of the Strength of Conventionally Produced Sandcrete Blocks and Burnt Bricks
Get PDFThe fact remains that housing has been universally acknowledged as the second most important
human need after food. It has been of perennial interest to the world at large since its availability touches on one
of the widest spectrum of human existence. Sandcrete blocks as building materials have become so popular in
many parts of Africa that although similar to bricks in many respects, they both deserve to be treated separately.
It is therefore worthy of note that for an engineer to select one of these materials (block and brick), the fitness or
suitability of the chosen materials for the purposed structure must be considered.Tests carried out in this
research include sieve analysis, Atterberg’s limit tests (Liquid limit and plastic limit) were carried out on the
materials (sand andlaterite)to be able to ascertain certain of their properties for their intended use. About ten
pieces each of sandcrete block and burnt bricks were prepared for the study and density and compressive
strength tests were carried out on them. Findings of the study shows the samples Liquid Limit to be 32%, Plastic
Limit of 16.7%, density of the sandcrete block is 1947.47kg/m3 while the density of the burnt brick is
1823.58kg/m3
.The average compressive strength of burnt brick (5.20N/mm2
) was found to be higher than that of
sandcrete block (3.15N/mm2
).This shows that the compressive strength is directly proportional to the crushing
load on the specimens and this is shown by the regression equation y = 0.2129x+1.5;R² = 0.9817 for the burnt
bricks and y = 0.14x + 0.7; R² = 0.9942 for the sandcrete blocks.The study therefore concludes that burnt bricks
just like sandcrete blocks is a good construction material and can be used for sustainable building construction
Revisiting the tourism-economic growth nexus: the case of economic community of West African States
Get PDFThis article investigates the relationship between the level of tourism expenditures and economic growth using a short time panel dataset covering 15 West African Countries from 2007 to 2015. The fixed effects results show that tourism expenditures and tourism receipts are insignificant to explain ECOWAS per capita Gross Domestic Product (GDP) growth. The paper finds that gross capital formation (physical capital) and labour force are positive and significant mechanisms for growth in the per capita income of ECOWAS economy. The paper recommends that ECOWAS should sell all the unused buildings, equipment, machineries and other viable governments’ assets to raise capital for investment which may boost gross domestic product if the proceeds from the sales of the assets are well utilised
Optimization of CO2 production rate for firefighting robot applications using response surface methodology
Get PDFA carbon dioxide gas-powered pneumatic actuation has been proposed
as a suitable power source for an autonomous firefighting robot (CAFFR), which is
designed to operate in an indoor fire environment in our earlier study. Considering
the consumption rate of the pneumatic motor, the gas-powered actuation that is
based on the theory of phase change material requires optimal determination of
not only the sublimation rate of carbon dioxide but also the sizing of dry ice
granules. Previous studies that have used the same theory are limited to generating
a high volume of carbon dioxide without reference to neither the production rate of
the gas nor the size of the granules of the dry ice. However, such consideration
remains a design requirement for efficient driving of a carbon dioxide-powered
firefighting robot. This paper investigates the effects of influencing design parameters on the sublimation rate of dry ice for powering a pneumatic motor. The
optimal settings of these parameters that maximize the sublimation rate at the
minimal time and dry ice mass are presented. In the experimental design and
analysis, we employed full-factorial design and response surface methodology to fit
an acceptable model for the relationship between the design factors and the
response variables. Predictive models of the sublimation rate were examined viaANOVA, and the suitability of the linear model is confirmed. Further, an optimal
sublimation rate value of 0.1025 g/s is obtained at a temperature of 80°C, the mass
of 16.1683 g, and sublimation time of 159.375 s
3D Geomechanical reservoir model for Appraisal and Development of Emi-003 field In Niger Delta, Nigeria
Get PDFIn this paper, geomechanical parameters were effectively integrated in 3-D geostatic model of Emi-003 reservoir in the Niger Delta basin, Nigeria for
deformability and rock strength appraisal using well logs and 3D seismic volume. Unconsolidated sandstone and compacted shale were delineated
and evaluated by determined elastic moduli (Poisson ratio, Young modulus, Bulk modulus, Shear modulus and Compressibility) and the Unconfined
compressive strength (UCS) using sonic logs and petrophysical analysis, correlations and cross plots for comparison of the evaluated reservoir
strength, physical properties (such as modulus, porosity, velocity) of the five mapped zones from five vertical wells in the studied reservoir for
validation were done. Finally, incorporation of elastic properties, unconfined compressive strength in 3D static model of the studied reservoir was
carried out to capture strong lateral variance of rock elastic moduli and strength into areas where well control may not exist. especially off the well
points. The results show average parameters of the weakly cemented sand to have lower Poisson ratio, Young, Bulk, Shear modulus and Unconfined
compressive strength (0.27, 2.3GPa, 10.8GPa, 6.91GPa, 14.21MPa respectively,) high compressibility and porosity (0.13 GPa-1, 0.26) conversely
the compacted shale have higher Poisson ratio, Young, Bulk, Shear modulus and rock strength as (0.36, 8.91GPa, 18.05GPa, 21.09GPa, 56.44MPa
respectively) lower compressibility and porosity (0.05 GPa-1, 0.05 respectively). There is a marked increase of rock strength and elastic moduli with
relative decrease in porosity. The mechanical failure in the NNW direction of the reservoir will be relatively lower than other areas as analyse using
the 3D earth model. The information gathered will help manage reservoir stress and strain induced during development and maximize reservoir
performance, while mitigating risk
Haematological and Pathological Effects of Bacteria from Vegetable Wastes in Ilara-Mokin, Ondo State
Get PDFAims: Different selling points or markets in Ilara-Mokin town were visited after the market session
and a day after to collect vegetable wastes. This research aimed to isolate bacteria and fungi from
selected waste vegetables, to infect laboratory animals with the bacterial isolates and to study the
effect of the isolated bacteria on the laboratory animals.
Methodology: Three major vegetable wastes were commonly found in the markets and they are
Amaranthus cruentus (Arowojeja), Senecio biafrae (Worowo) and Spinacia oleracea (Amunututu).
Sufficient quantity of these decaying wastes were collected and sterile crucible was used to grind
the waste samples. On each sample, serial dilution was done using 2g. Nutrient Agar and potato
dextrose agar were used for isolation of bacteria and fungi respectively. Standard Microbiological
methods were used for the identification of the microorganisms. Results: Five bacteria were isolated from the waste, which are: Salmonella spp, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Proteus mirabilis. Also six fungi were isolated from the waste vegetable. They are: Aspergillus niger, Aspergillus fumigatus, Aspergillus
flavus, Penicillium chrysogenum, Geotrichum spp. and Articularia quercina. All of the bacteria were
sensitive to commercial antibiotics like ciprofloxacin and gentamicin, except Salmonella spp that
showed resistance to Tetracycline, Augmentin and Ceftriaxone. The bacterial isolates were then
used to infect Albino rats and haematogical analysis was performed on the animals’ blood. The
result showed that Proteus, and Pseudomonas reduced the PCV from 45.55±1.67% (in control
group) to 36.75±0.55% and 37.25±0.33% respectively. The haemoglobin concentration was
decreased from 15.00±0.00 (in control group) to 12.33±0.67 in the group infected with Pseudomonas. The white blood cell count was highest on the group infected with Salmonella with a count of 12.2±0.96×105 mm-3
. Histopathological Analysis of the liver and intestine of the rats showed that the pathogenic microorganisms cause negative pathological effects such as the absence of sinusoid in the liver hepatocytes, hepatocellular drainage and necrosis, while only necrosis and haemorrhage were prominent in their intestine.
Conclusion: The result obtained has shown that pathogenic microorganisms from these vegetable
wastes can cause serious health problem for the public if not disposed adequately, especially when
these vegetable vendors place freshly harvested ones on the same ground the next market day;
and when such is bought and not properly washed or cooked
Partial Purification, Characterization and Application of Bacteriocin from Bacteria Isolated Parkia biglobosa Seeds
Get PDFStaff PublicationBacteriocins are proteinaceous toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strains. Fermented Parkia biglobosa seeds (African locust bean) were screened for bacteriocin-producing lactic acid bacteria (LAB) with the characterization of putative bacteriocins. Bacteriocin-producing lactic acid bacteria (LAB) were identified by 16s rDNA sequencing. Molecular sizes of the bacteriocins were determined using the tricine-sodium dodecyl sulphate-polyacrylamide gel electrophoresis (tricine-SDS–PAGE) and effects of enzymes, pH, detergents and temperature on bacteriocin activity investigated, using standard procedures. Bacteriocins production and activities were measured by spectrophotometric analysis. Statistical analysis was carried out using student t-test and Analyses of Variance. Bacteriocigenic LAB isolated were Lactobacillus plantarum Z1116, Enterococcus faecium AU02 and Leuconostoc lactis PKT0003. They inhibited the growth of both Gram-positive and Gram-negative bacteria. The sizes of bacteriocins Z1116, AU02 and PKT0003 were 3.2 kDa, 10 kDa and 10 kDa, respectively. The synergistic effects of characterized bacteriocins and rifampicin tested on organisms showed significant differences (P < 0.05), as compared with the effects of only one of the two. The antimicrobial activity of the three bacteriocins was deactivated after treatment of the cell-free supernatants with proteinase K, papain, pepsin and trypsin. Parkia biglobosa seeds are, therefore, rich in LAB bacteriocins which could be explored. The biosynthetic mechanisms of LAB bacteriocins could be employed in food safety and security, preservation, peptide design, infection control and pharmacotherapy. This should help in the control of undesirable bacteria and in designing more potent and selective antimicrobial peptides
Tropospheric delay in microwave propagation in Nigeria
Get PDFSatellite communication systems suffer from the systematic error of tropospheric delay. Accurate estimation of this delay is essential for communication budget and planning. This study investigates the tropospheric delay in three Nigeria cities: Abuja, Lagos, Port-Harcourt using two different models (Saastominen and Hopfield). Three year atmospheric data for surface pressure, relative humidity and temperature obtained at 5-mins interval were acquired from the Tropospheric Data Acquisition Network (TRODAN) archives. Computed radio refractivity values showed distinct seasonal dependence in Abuja with low and high values during the dry and wet season respectively. The Hopfield model predicts higher hydrostatic delay values than the Saastominen model. In the non-hydrostatic delay, the two models converge to a single values at high temperature. Theorems were proposed with proofs to explain the relationship observed between the two models
Addressing the energy consumption-economic growth nexus: The Nigerian case
Get PDFEnergy is critical to the survival and expansion of any economy. In Nigeria, energy consumption has been skewed towards household use, and below thresholds for sector-driven growth. The article updates, in time and methodology, those studies highlighting the significance of energy use for economic growth, using the Bound test and the Auto Regression Distributed Lag (ARDL) to establish the long- and short-run relationships between disaggregated energy consumption and economic growth in Nigeria from 1990 to 2016. The variables considered are real GDP, energy consumption decomposed into electricity and petroleum consumption, labour and capital. The findings show that, in the short and long run, petroleum consumption and labour have a significant positive relationship with GDP. Furthermore, the causality results show that feedback causation between economic growth and energy consumption as well as labour exists, while one-way causation runs from labour to economic growth. The study recommends diversification of the power-generation portfolio in the country, as this will improve energy consumption. Also, full deregulating policies in the energy sector would encourage industrialization and move energy demand towards increasingly productive uses. Finally, a strong institutional framework is needed to ensure energy policies achieve their objectives and target
Open Access/Open Science and the Humanities on a Cross-regional Basis
Get PDFThe first Visiting Library Lecture delivered at the closing ceremony of the Summer Course in Digital Library Management (SCDLM) in Elizade University by Prof Daniel Paul O'Donnell of the University of Lethbridge, Canada on September 28, 2018