LAUTECH Journal of Engineering and Technology (LAUJET)
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A STUDY OF THE WATER CHARACTERISTICS AND PORE SIZE DISTRIBUTION OF A TROPICAL ALFISOL
Get PDFThe water characteristic of the an alfisol predominantly sandy loam in texture was measured with undisturbed core samples in a pressure plate apparatus at pressures of 5, 10, 33, 60, 100, 1000, and 1500 kPa. The core samples were obtained at 20 cm depth intervals to 100 cm soil depth. The pore size distribution and the matric pressure head (hB) defining the boundary between the structural and matrix domains were determined using a derivative curve technique. The pore size distribution varied from dominantly unimodal to essentially bimodal distribution as the soil clay content increased with soil depth. The values of hB ranged from 120 to 250 cm. However, at 0.05 level of significance, there was no difference between the respective structural and matrix domain porosities determined using the derivative curve technique and the corresponding ones by an empirical method which assumed and an arbitrary hB–value of 100 cm. Structural domain porosity comprised more than half of the total porosity in the upper soil depths indicating a preponderance of macropores in that region. The measured water characteristic fitted well to both the closed-form bimodal model of Seki (2007) and the unimodal one of Kosugi (1996). However, the model of Seki had higher coefficients of determination and showed better fit over the entire range of measured data
CONSOLIDATION SETTLEMENT OF RESIDUALLY-DERIVED LATERITIC SOILS FROM PART OF SW NIGERIA
No full textConsolidation of lateritic soils and related properties had been the subject of few investigations. Previous studies have evaluated the coefficients of compressibility and consolidation of lateritic soils. Initial results indicated that the soils have considerable strength despite the appreciable clay content. Another report revealed probable differential settlement of small magnitude if employed as foundation materials. As a result, there has been a growing interest to investigate settlement effects of lateritic soils. The present investigation focuses on the how total settlement is influenced by complexity and heterogeneity of lateritic soils. The studied soils were developed over the Precambrian, migmatised gneisses of the Basement Complex of Southwestern Nigeria.
Physical model tests out on 12 disturbed and 12 undisturbed soil samples were carried out following the BS Part 2 and Part 8, 1337, IS: 2720 Part 15 and ASTM Designation 4767-11. Results show that the soils contain a variety of particle sizes, with clay and sand being the dominant fractions. They also exhibit very low permeability, low to medium plasticity and cohesive strength range of 20 - 95 kN/m2. The total settlement values are not in any definite order with depth, but increases with increase in confining pressure. They range between 0.31 and 1.125mm at 800kN/m2. It is apparent that the tolerable settlements of different structures on the soils vary considerably, which may result to misalignment from foundation settlements causing structural damage to a building frame nuisance.  
MEMETIC ALGORITHM WITH MULTI-PARENT CROSSOVER (MA-MPC) FOR MULTI-OBJECTIVE NETWORK DESIGN
Get PDFIn many Evolutionary Algorithms (EAs), a crossover with two parents is commonly used to produce offsprings. Interestingly, we need not restrict ourselves to two-parent crossover since EA allows us to emulate natural evolution in a more flexible fashion. There are experimental results in the literature which show that multi-parent crossover operators can achieve better performance than traditional two-parent versions. However, most of these experimental results are based on common test functions. Experimental studies involving real-life, NP-hard problems such as network design problem are very rare. This paper presents Memetic Algorithm with Multi-Parent Crossover (MA-MPC) with a view to providing a case study of multi-parent crossover within the framework of MA for network topology design problem. Results show that MA-MPC does not always outperform MA. It depends on the size of the problem and the number parents (be it 3, 5, 7, or any other
ACCELERATING DECOMPOSITION RATE OF FRESH FAECAL MATERIALS FROM A FARROW-TO-FINISH SWINE FARM WITH BLACK SOLDIER FLY LARVAE (Hermetia illucens)
Get PDFThere is need to generate information required for the development of facilities for reducing environmental pollution caused by careless dumping of raw faecal materials from swine production facilities into streams, channels, ponds and other water bodies in developing countries. The objectives of this work were to:(1) use a simple bio-decomposer to study the decomposition rate and waste reduction index (or efficiency of decomposition) of fresh solid faecal materials obtained from a farrow- to- finish swine production unit when treated with Black Soldier Fly Larvae (BSFL) (2) fit a regression curve with acceptable R-squared value to the decomposition rate data generated in the study. With the use of the bio-decomposer, four batches of the Black Soldier Fly Larvae (BSFL) that developed from the hatched eggs were carefully collected and decanted from the faecal materials, after which they were weighed and mixed with four weighed samples of fresh solid swine faecal materials with three replications at an average inclusion rate of 94.3, 81.4, 61.4, and 59.04 gm of BSFL/kg of fresh solid swine faecal materials respectively in a Complete Randomized Design; the fifth sample of fresh solid faecal materials was used as the control. The average decomposition rates for the four samples treated at three treatment levels and control were 0.046, 0.041, 0.040, 0.040 and 0.0 kg/day, respectively translating to an average of 0.042 kg/day. These results depict a mean waste reduction index of 8.74 %/day indicating that high waste reduction efficiency has been obtained as attested to by the computed R-Squared value of 0.919. The fitted regression curve showed that the decomposition rate increased with increase in BSFL inclusion rate up to maximum limit of 42.85 g/day and inclusion rate of 63.27 g/kg for a 0.8 kg initial mass of fresh swine faecal materials. It was, therefore, concluded in the study that incorporation of BSFL is very effective for accelerated decomposition of fresh solid swine faecal materials from a farrow-to-finish production facility.  
THE COMBINED EFFECTS OF SOIL, WATER AND SURCHARGE LOADS ON THE STRUCTURAL BEHAVIOURS OF CANTILEVER RETAINING WALL
Get PDFRetaining walls are engineering structures constructed to resist lateral forces imposed by soil movement and water pressure; they are used as protection against the erosive forces of water and as a method of slope stabilization along highways, railroads and construction sites. This Study modeled the combined effects of soil, Surcharge loads and Hydrostatic pressure on the structural behaviours of cantilever retaining wall under varying geometric conditions. The limit state requirements for overturning, sliding and bearing pressure were studied under different geometric properties. The use of computer programming (Java) was employed for quick analyses of the conditions. This research therefore minimized the stress associated with the iterative process of design and analyses of these structures. The deductions gave range of satisfactory dimensions with respect to the height of the wall for the preliminary dimensioning state of design. This study also answered the remained unanswered question of the effects of an increasing load being supported by retaining wall. The results revealed that Cantilever retaining wall will perform satisfactorily based on the factors of safety of and as against sliding and overturning respectively if soil is ignored in front of the wall with following values of Base width: For wall supporting full submerged soil, the Base width, ; wall supporting submerge soil up to 0.6 of its Height, Base width, and for wall with submerge soil up to 0.2 of wall height, Base width, . Results also showed that safety factors against sliding and overturning increase at a decreasing rate with constant decrease in water level. This gives an indication that water level greatly affects the stability of the retaining wall, that is, the higher the water level the greater the sliding and overturning effects. Results also revealed that sliding safety factor increases constantly with Base width while factor of safety against overturning increases at an increasing rate. This also shows the severity of sliding as against overturning. Both safety factors also increase at a decreasing rate with Wall height giving an indication that the stability of cantilever retaining wall increases with its Height under the same load. For an increasing surcharge values, sliding safety factor decreases constantly while overturning decreases at a decreasing rate. This also explains why overturning is less critical as compared to sliding effect
PRODUCTION OF BIO-DIESEL FROM JATROPHA CURCAS SEED USING IN-SITU TECHNIQUE: EFFECT OF CATALYST AMOUNT AND ALCOHOL-SEED RATIO
Get PDFThe effect of alcohol seed ratio(0.5,1.5 & 2.0) and initial catalyst amount(0.5,1.0 & 1.5%) on the in-situ production of biodiesel from raw Jatropha Curcas seed was studied at a reaction temperature of 600C and reaction time of 120min. Central composite experimental design was applied to evaluate effects of alcohol-seed weight ratio (0.5 – 2.0) and initial catalyst amount (0.5 – 1.5%). Initial catalyst amount and alcohol seed ratio was found to have significant (P<0.05) effects on the yield. Initial catalyst amount was the more important factor and had a positive influence on the yield than alcohol seed ratio which does not significantly affect the yield as a single factor. Due to formation of by-products (soaps) caused by excessive amount of catalyst and excess alcohol leading to difficult ester separation from glycerol, there was a general reduction in Jatropha Curcas ethyl-ester as levels of catalyst and alcohol seed ratio increased. A second-order model was obtained to predict the yield as a function of all factors. The model predicted well the observed data with a R2 value of 0.985 and a non-significant Lack-of-Fit (P<0.05). The biodiesel obtained, compared favorably with the ASTM D6751-02 standard for biodiesel but the viscosity
ASSESSING THE EFFECTIVE UTILIZATION OF EDUCATIONAL FACILITIES: STUDY OF NYAKROM SECONDARY TECHNICAL SCHOOL
Get PDFThe study was conducted in Nyakrom Secondary Technical School, sought to find out whether the teaching space facilities were being used efficiently. In other words, whether with facilities available the school had indeed reached their enrolment limit. Both structured and unstructured questionnaire items as well as interview sessions were used to elicit information from fifty (50) students in twelve (12) classes using stratified random sampling and ten (10) teachers using purposive non-sampling method. Data collected were analyzed by means of descriptive statistics, frequency distribution tables and simple percentages. The result of the study showed that Nyakrom Secondary Technical School had not exceeded its optimum enrolment. The school could comfortably accommodate over 560 students if teaching space facilities were efficiently utilized. There was the need to plan an effective timetable that would take into consideration the general classroom spaces, specialized spaces available, class size and class enrolment. Finally, it was revealed that, the classrooms needed to be adequately furnished, and the school should be provided with a well-equipped spacious assembly hall for meetings and examinations to withstand the test of time
ON EMPIRICAL COMPARISON OF CHECKLIST-BASED READING AND ADHOC READING FOR CODE INSPECTION
Get PDFSoftware inspection is a necessary tool for software quality assurance. To this end a number of inspection techniques have been proposed in the literature with the ad hoc and Checklist-Based Reading (CBR) being the most widely used. This paper investigates the performance of ad hoc and CBR techniques in a traditional paper-based environment. Seventeen undergraduate students of computer science most of whom are in their final year were used as subjects in the controlled experiment. Results of the experiment indicate that CBR is significantly superior to ad hoc reading in terms of effectiveness, efficiency, effort, and number of false positives. On the average, 4 faults were detected in 69 minutes using ad hoc reading while 11 faults were detected in 42.5 minutes using Checklist-based reading. Also the average number of false positive is about 3.13 in checklist-based approach as against about 6.44 in ad hoc approach. 
THRESHOLD-BASED BANDWIDTH ALLOCATION SCHEME FOR MULTISERVICE WIRELESS NETWORKS
Get PDFPriority Queuing with Buffer Management (PQBM) has been recently proposed in the literature. The protocol is acclaimed to be a very attractive candidate in current (2.5G and 3G) and next (4G) multiservice wireless networks. However, it suffers bandwidth monopolization by higher priority data packets. This paper proposes a new scheme namely Improved Priority Queuing with Buffer Management (IPQBM) with a view to redistributing service provision to the data classes optimally. In particular, the scheduling discipline of PQBM is modified so as to correct the monopoly problem. IPQBM is compared with PQBM vis-à-vis throughput and mean delay of data packets. Numerical results reveal that IPQBM offers improved throughput for lower priority data packets by ensuring that higher priority data class does not have a monopoly of bandwidth resources
VOLTAGE MAGNITUDE IMPROVEMENT: A CASE STUDY OF NIGERIAN 330kV TRANSMISSION SYSTEM
Get PDFVoltage magnitude improvement on power system is important for effective power delivery to consumers. In this study, voltage magnitudes of buses on Nigerian 330kV Transmission System were determined using the Newton-Raphson Power Flow solution method. Buses with low voltage magnitudes were identified. Appropriate shunt capacitor bank ratings in Mega-Volts Ampere (MVA) were determined and installed on the buses with voltage magnitudes that violate limits. It was discovered that the the injection of appropriate MVAr ratings on the buses improved the bus voltage magnitude to fall within acceptable range. Power system losses on the Nigerian 330kV Transmission System were also considerably reduced