nigerian defence academy
journal of science and engineering (ajse)
ROLE OF MIXED SURFACTANTS ON THE OXIDATION OF MALACHITE GREEN BY NITRITE IONS
The oxidation of malachite green with nitrite ions in aqueous solutions of sodium dodecyl sulphate (SDS), Triton X-100 (TX-100), and their mixtures at 25oC has been used as a probe for investigating the catalytic/inhibitive property of SDS/TX-100 mixed systems. The results showed that the composition of the mixed surfactants has quite significant influence on the rate constant of the oxidation reaction when compared with the reaction in the single surfactant system and the effect of SDS was found crucial. The results indicated 62-85% lower reactivity as the mole fraction increased and a higher pseudo-first order rate constant in aqueous solution than in the surfactants or their mixtures were also observed with a rapid decrease until saturation was reached in pure SDS indicating an overall inhibition. The kinetic mechanism of the micellar effects was probed and rationalized using existing Clint’s, Menger and Portnoy, Rubingh’s and Maeda’s theories for mixed micellar systems. Strong electrostatic attraction between the protonated species and the anionic surfactant aggregates was important in the reaction process..
STRUCTURAL BEHAVIOR OF REINFORCED CONCRETE BEAMS WITH CRUSHED PALM KERNEL SHELL AS COARSE AGGREGATES
Fapohunda, Christopher, Ikponmwosa, Efe, and Osekita, Ifeoluwa
Any waste material that is found to be appropriate for use for structural concrete will not only serve as efficient means of waste disposal but also an innovative way of converting waste to wealth. This paper presents the results of the investigation conducted to assess the structural behaviour of reinforced concrete beams made with palm kernel shell as replacement for coarse aggregates. The properties investigated are: workability, density and mechanical properties of concrete specimens containing palm kernel shell as partial replacement of coarse aggregates using a mix ratio of 1:2:4 and water cement ratio of 0.65. The percentage replacement of coarse aggregates was varied from 0% to 100% by weight at intervals of 25%. For the density and compressive strength tests, 150 x 150 ×150 mm cube specimens were used, while 2370 x 225 x 225 mm reinforced beam specimens were cast for the flexural strength test according to BS EN 12350:2000. The test specimens were moist and air cured for 28 days. The findings of the study showed that the increase in the percentage replacement of coarse aggregates with PKS in concrete resulted in: (i) reduction in the workability to 95% at 100% PKS replacement with coarse aggregates (ii) varying densities with no particular trend but fall within the normal weight concrete and lightweight concrete classifications of between 1368.89 and 2586.67 kg/m3 (iii) reduction in the compressive strength of the specimens of up to 73.75% at 100% replacement level, and (iv) increase in the ratio of tensile to compressive strength from 0.08 - 0.15 respectively from 0 – 100% replacement levels, and (v) also the beam specimens containing PKS as partial replacement of coarse aggregates exhibited flexural failure.
EVALUATION OF BIOETHANOL PRODUCTION POTENTIAL FROM EUCALYPTUS TERETICORNIS BIO WASTE USING: Bacillus subtilis, Escherichia coli and Sacharomyces cerevisae
UsmanYahaya, Umar Yahaya Abdullahi, Denwe Samuel Dangmwan, Muhammad Muktar Namadi, Mohammad Sani
The use of bark and leaves of Eucalyptus tereticornis (forestry waste with no appreciable value to industries or competitive use as food) as alternative and cost effective feedstock for bioethanol production was examined. Eucalyptus tereticornis biomass (bark and leaves) were pretreated with microwave irradiation (250V, 50Hz) prior to fermentation with Bacillus subtilis and E.coli isolated from soil, and Saccharomyces cerevisae purchased from market. The highest reducing sugar yield of 43.5 % and 40 % were obtained from bark and leaves of Eucalyptus tereticornis pretreated with microwave irradiation as compared to untreated biomass. Bioethanol production concentration of 0.52% was higher in microwave irradiated bark of E .tereticornis during 21 days of fermentation while the least concentration of 0.13% was obtained from combination of bark and leaves of E .tereticornis at 21 days when B. subtilis and E. coli were used in synergy. The study concludes that synergy between B. subtilis and E. coli may be a better combination for bioethanol production from E. tereticornis Bio waste.
COMPARATIVE QUALITY EVALUATION OF CEMENT BRANDS USED IN SOUTH WEST NIGERIA
Olonade, K.A., Jaji, M.B., Rasak, S.A. and Ojo, B.A
The quality of common cement brands in Southwest Nigeria was investigated. This is with a view to comparing their properties. Cement brands considered in this study were labeled A, B, C, D and E. Fineness, setting times, chemical composition, compressive and flexural strengths of each of the cement brands were determined in accordance with the relevant BSand ASTM standards. The results showed that all the cement brands contained major oxides in amounts within the acceptable range of valuesas compared to BS EN 196-2 except that the sulphite content of cement E fell outside the range.Strength comparison indicated that cement brand A had the highest flexural and compressive strengths of 7.98 and 35.35 N/mm2respectively, followed by C(6.58 and 33.8 N/mm2) and then B(6.37 and 31.60 N/mm2) while D had the lowest compressive strength at 28 days (31.09 N/mm2). The study has shown that both cements A and C could be adjudged to have met the standard having strength above minimum of 32.5 N/mm2, while others were marginally below the minimum strength. It was concluded that the choice of cement brand to be used should be based on the expected strength requirements.
METHODOLOGY FOR COST ESTIMATION AND MANUFACTURING FRAMEWORK FOR THE MODIFICATION OF ABT-18 AIRCRAFT TO AN UNMANNED AERIAL VEHICLE
DA Olawuyi, S Thomas, PO Jemitola, AG Udu, DS Nyitamen
The ABT-18 Air Beetle has been the ab-initio trainer of the Nigerian Air Force (NAF) since 1993. As the aircraft reaches the end of its service life, the service seeks to modify the aircraft into an Unmanned Aerial Vehicle (UAV) as a life extension programme. This study examined the various costs involved in the modification and remanufacturing of the ABT-18 and its modification to an Unmanned Aerial Vehicle as well the various manufacturing methodologies involved. This study used various cost analysis models to predict the likely costs of various possible programme components of developing the UAV. It was determined that the avionics components particularly the sensor payload constitute 84% of the total cost of the modification and therefore cost reduction efforts should be aimed in this direction. A basic programme workflow and staffing template was designed which can be further developed as the project advances.
EFFICACY OF SOME SPICES AS MAIZE GRAIN PROTECTANTS AGAINST SITOPHILUS ZEAMAIS MOTSCH Ameerah Muhammad and Babatunde M.M.
Studies were carried out to determine the efficacy of three spices (Allium sativum L., Capsicum frutescens L., and Zingiber officinale Rosc.) against Sitophilus zeamais reared on maize grains. Application rates of 0.5, 1.0 and 1.5 g of each of A. sativum, C. frutescens and Z. officinale and 0.12 g of Permethrin were applied to 20 g of maize grains infested with S. zeamais under controlled conditions of 30 ± 2°C and 65 ± 5% R.H. In all the treatments, 100% mortality of adult S. zeamais reared on maize was obtained. The effect of the spices on adult mortality was significantly different (p<0.05) between the powdered spices and the control. The effect of the different spices applied at varying rates on grain damage caused by S. zeamais was significantly (p<0.05) different with the highest difference (23.22%) in the 1.5 g treatment of C. frutescens and Z. officinale and the least (10.00%) from treatments of 0.5 g of Z. officinale and A. sativum respectively. The findings of this study indicate that the selected spices showed potential in reducing maize grain damage caused by S. zeamais.
APPLICATION OF QUEUING THEORY IN CADET MESS ADMINISTRATION: A CASE STUDY OF NIGERIAN DEFENCE ACADEMY, KADUNA NIGERIA
H.N. Kama and I.M. Mankilik
ABSTRACTThe application of Queuing models as a Technique of Queue solution in Mess System was carried out in Nigerian Defence Academy, Kaduna. Specifically, this study attempts to look at the problem of long queues in cadet mess, why mess managers find it difficult to eliminate queues and the effect of queuing model as a technique of queue solution in Mess System. The variables measured include arrival rate (?) and service rate (µ). They were analyzed for simultaneous efficiency in cadet satisfaction and cost minimization through the use of a multichannel queuing model, which were compared for a number of queue performances. It was discovered that, using a six-server (six-channel) system was better than a 3-server, 4-server or 5-server systems in terms of the performance criteria used and the study inter-alia recommended that, the management should maintain a six-server model to increase cadet satisfaction.
EFFECTS OF COMBINING METAKAOLIN AND CEMENT KILN DUST AS CEMENT REPLACEMENT MATERIAL IN CONCRETE
Oriola F.O.P, G. Moses and J. O. Afolayan
ABSTRACTResults of Compressive strength test and slump test of concrete containing Metakaolin and CKD at varying replacement levels are discussed and are compared with those obtained with the control (pure Portland cement concrete). The total partial replacement was considered in the range of 0% (i.e. control) to 50% by weight in steps of 10%. The combination for each replacement level apart from 0% are as follows: 10% (8%CKD and 2%MK), 20% (l6%CKD and 4%MK), 30% (24%CKD & 6%MK), 40% (32%CKD & 8%MK) and 50% (40% CKD and 10% MK). Cubes were cast with three mixes with varying water cement ratio; 0.55/1:1.5:3, 0.6/1:1.5/3 and 0.65/1:/1.5/3 with the aim of achieving medium strength structural grade concrete. Cubes were cured in water and tested at 7, 14 and 28 days respectively, to appreciate the strength development at each replacement value. It was observed that workability decreased with increase in replacement and that strength also decreased with increase in replacement, the best result for replacement was obtained at 10% replacement with at least 95% of the control strength. It was also observed that more than 90% of the compression strength at 28days had been attained at 14days.