Showing papers in "Nigerian Journal of Technology in 2009"

Effects of Rice Husk Ash on Some Geotechnical Properties of Lateritic Soil

Abstract: The study is an investigation into the effect of rice husk ash (RHA) on some geotechnical properties of a lateritic soil classified as A-2-6 (0) or SW for sub-grade purposes The investigation includes evaluation of properties such as compaction, consistency limits and strength of the soil with RHA content of 5%, 75%, 10% and 125% by weight of the dry soil The results obtained show that the increase in RHA content increased the optimum moisture content but decreased the maximum dry density It was also observed that increase in RHA content, reduced plasticity and increased volume stability as well as the strength of the soil 10% RHA content was also observed to be the optimum content

Effects of eggshells ash (esa) on the setting time of cement

Abstract: Admixture properties of eggshells ash (ESA), with a focus on the setting time, were investigated. ESA was obtained by incinerating fowls’ eggshells to ash. The ash was sieved through 75μm sieve. The ash passing the 75 μm sieve was used in the investigation. Consistency test was carried out to establish the quantity of water required to constitute a standard cement paste of normal consistency in accordance to BS 12: 1991 [1]. Cement-eggshells ash (CESA) paste was constituted using 0%, 0.1%, 0.5%, 1%, 1.5%, 2.0% and 2.5% of ESA by weight of cement. Setting time test was conducted on the CESA paste in accordance to BS 12:1991 n[1]. Results show that the addition of ESA to the ordinary Portland cement (OPC) decreases the setting time of the cement. Conclusions drawn are that ESA is an accelerator; the higher the ESA content, the faster the rate of setting; all contents of the of the ESA employed in this investigation satisfy the setting time requirements of BS 12:1991 [1] for both the initial and final setting times. Thus, it is recommended that ESA can be used as an accelerator in concrete.

Optimization of drinking water treatment processes using artificial neural network

Abstract: Drinking water treatment is the process of removing microorganisms and solid from water through different methods such as coagulation and filtration. Artificial neural network (ANN) was developed for process and cost optimization of drinking water treatment processes. Results obtained from ANN model showed that ANN is a suitable tool for the improvement of overall process performance and cost effectiveness in drinking water treatment. There was cost reduction, process safety improvement, and high stability in ANN application of water treatment.

Wireless Fidelity (Wi-Fi) Broadband Network Technology: An Overview with Other Broadband Wireless Networks

Abstract: Wireless Fidelity (Wi-Fi) broadband network technology has made tremendous impact in the growth of broadband wireless networks. There exists today several Wi-Fi access points that allow employees, partners and customers to access corporate data from almost anywhere and anytime. Wireless broadband networks are expected to grow in terms of broadband speed and coverage, while Wi-Fi can be integrated with WiMAX networks to provide Internet connectivity to mobile Wi-Fi users. This paper explores the Wi-Fi broadband wireless network technology, its uses, advantages and disadvantages, comparison with other broadband wireless networks and integration with WiMAX network.

Effects of Compaction Delay on the Properties of Cement-Bound Lateritic Soils

Abstract: This study is an investigation into the effect of 0 to 3 hours compaction delay with half an hour intervals on soil-cement mixes 3,5,8; and 1, 3, 5 percent cement contents by weight of dry soils, for yellow and red lateritic soils respectively. The tests carried out on the cement stabilized soils were the Compaction test (Standard Proctor), the Unconfined Compressive Strength (UCS), the California Bearing Ratio (CBR) test and Durability test. The results obtained indicated that compaction and strength characteristics decreased with increase in compaction delay for both lateritic soils. For yellow and red lateritic soils 5% and 3% cement content respectively were sufficient and compaction delay must not be more than 2 hours. They are good in stabilized form for sub-base and base of light trafficked ro ads with red lateritic soil more economical.

Safety of Premature Loading on Reinforced Concrete Slabs

Abstract: The provision of safe structural systems has always been the object of any structural design formulation and practice. This paper investigates the safety of premature loading on reinforced concrete slabs in a more rational manner. The slab was designed to BS8110 (1985; 1997) provisions. The moment of resistance of a prematurely loaded slab was simulated and safety indices corresponding to the probability of failure of the slab were determined. From results obtained, it was observed that a reinforced concrete slab may be safely loaded prematurely if it has attained at least two-thirds of its characteristic strength. The reliability indices of a prematurely loaded reinforced concrete slab in flexure are directly proportional to the characteristic strength of concrete. Therefore in practice, due consideration must be given to early-age strength development in reinforced concrete slabs before loading.

Effects of flexural rigidity of reinforcement bars on the fundamental natural frequency of reinforced concrete slabs

Abstract: An understanding of the orthotropic plates' behavior in their dynamic regime is essential because the loading can cause severe damage in the plates, such as: - cracking, loss of aesthetic, fear to the occupants, etc. To this end, a new set of stress - strain relations for. Orthotropic plates were derived. The principle of force of inertia was introduced, yielding the corresponding dynamic governing equation of orthotropic plate. The solution of the equation was obtained by numerical method, and the results show that the flexural rigidity of the bars has significant effect on the fundamental natural frequency of heavily reinforced concrete sections.

Effect of Data Traffic Patterns on QoS Parameters

Abstract: In the design and management of data communication networks the appropriate choice of traffic model that would reflect the exact pattern of the users’ traffic has always been an issue of study. In the literatures different models have been presented. This work presents the comparison of several data traffic models (most popularly used in the literatures) on the basis of their influence on the quality of service (QoS) parameters. It is intended that this comparison would place at the disposal of researchers the data traffic models that would assist in making effective worse-case or best-case analysis of data communication systems. Object oriented computer simulation modeling technique provided the general platform necessary for such level of comparison. In this work MATLAB simulink simevent simulation environment was employed. The results present exponential distribution as the traffic model to be employed for worst-case analysis while Gamma distribution is for best-case communication systems analysis.

Credit Risk Evaluation System: An Artificial Neural Network Approach

Abstract: Decisions concerning credits granting are one of the most crucial issues in an everyday banks’ policy. Well-allocated credits may become one of the biggest sources of profits for any financial organizations. On the other hand, this kind of bank’s activity is connected with high risk as big amount of bad decisions may even cause bankruptcy. The key problem consists of distinguishing good (that surely repay) and bad (that likely default) credit applicants. Credit risk evaluation is an important and interesting management science problem in financial analysis. The main idea in credit risk evaluation investigations consists of building classification rules that properly assess bank customers as good or bad. In this paper, we proposed an architecture which uses the theory of artificial neural networks and business rules to correctly determine whether a customer is good or bad. In the first step, by using clustering algorithm, clients are segmented into groups with similar features. In the second step, decision trees are built based on classification rules defined for each group of clients. To avoid redundancy, different attributes are taken into consideration during each phase of classification. The proposed approach allows for using different rules within the same data set, and for defining more accurately clients with high risk. Preliminary result indicates that the model presented is promising and reasonable.

Automatic Data Collection Design for Real-Time Detection of Oil-Spillage Disasters in Nigeria

Abstract: Oil-spillage disaster is a phenomenon that has thrived and come to stay especially in the Niger Delta region in Nigeria where crude oil is produced both on-shored and off-shored resulting in the loss of billions of crude oils and corresponding loss of income every year. Such disasters can occur at any point within the entire oil-pipeline topology, which is geographically dispersed across the country spanning from the extreme south-south through south-east and south-west to the north central. A major cause of oil spillage disaster is oil-pipeline vandalism, which has recently become one of the primary means of defrauding the Nation by oil bunkers and even angry youths of the host communities. Currently in Nigeria oil spillage disaster is monitored manually under the auspices of the National Emergency Management Agency (NEMA) and involves huge human labor as gathering of useful data has proven to be difficult and untimely using traditional data collection methods given the peculiarity of the operational terrain. An automated data collection design (ADCD) for real-time data collection on oil spillages in the on-shore, mangrove, thick forest and off-shore areas of the Nation offers the much needed solution. This paper examined some current procedures for data collection and highlighted inherent pitfalls. It further presented a robust architecture and model for real-time detection of oil-spillage and discussed incorporated contemporary technological requirements. The major advantages and disadvantages of the proposed system were also discussed.

Scheduling of Solid Waste Collection Routes

Abstract: Routing of solid waste collection vehicles in Nigeria poses a challenging task because of attitudinal and haphazard infrastructure problems to contend with. The objective is to minimize the overall cost, which was essentially based on the distance travelled by collection vehicles. The study proposes heuristic methods to generate feasible solution to an extended capacitated Chinese Postman Problem (CCPP) in undirected network. The heuristic procedure consist of “route first, cluster second” and “cluster first, route second” and was applied to scheduling solid waste collection problems in two cities – Abuja and Onitsha. The two techniques were compared and with the existing schedule with respect to cost, efficiency, and distance travelled. A cost model was developed to compare the quality of solution derived. The adoption of the proposed heuristics in Onitsha resulted in reduction of the number of existing vehicles by three, $325.90 (or 7.65%) in refuse collection cost and 28.17km (or 6.03%) in vehicle distance travelled per day. In Abuja, the heuristics produced routes which could save about 19.08km travel per day and $31.10 (or 21.09%) of collection cost per day. Efficiency in refuse collection was increased from 86% to 98% in Abuja and 75% to 95% in Onitsha. The results revealed a good performance of the proposed heuristic methods which will find useful applications in other areas of vehicle scheduling.

The Effects of Off Take Angle on the Velocity Distribution and Rate of Siltation of Canals

Abstract: The problem of excessive siltation in canals (navigation, irrigation, water supply, etc) was tackled by the Schwarz-Christoffel transformation, neglecting gravity and assuming a constant depth of flow. This implies that large off take angles will encourage more intake of sediments by the canal. In addition, it was also observed that large off take angles exhibit higher and lower (wider range) velocities. That is, near the stagnation point, a large off take angle will posses lower velocities than small off take angles thus encouraging siltation, while near the point of infinite velocity, a large off take angle will posses higher velocities thereby increasing sediment intake by canal. It is therefore recommended that canals off take angles should be as small as possible but not too small. If the off take angle is too small, the bank between the branch canal and the main canal will be eroded gradually leading to flooding and eventual destruction of the canal. The results obtained can be applied to navigation, irrigation and water supply canals. The results obtained show that the larger the off take angle, the higher will be the off take discharge as well as the off take entrance velocity distribution. The results were found to agree with both laboratory data obtained using a model and field data, giving correlation coefficients of 0.76, 0.77 and 0.62.

Algorithm for concrete mix design based on british method

Abstract: Most of the methods of concrete mix design developed over the years were geared towards manual approach. Apart from being characterized by rigorous complication in computation, manual concrete mix design is prone to errors and mistakes inherent in the calculation during interpolations and reading of charts. Useful time is also wasted in the processes involved in the manual method. This paper presents the result of a study aimed at solving the above problems through the development of a mathematical algorithm based on the British Method of concrete mix design. The tables used in this algorithm are the same as those used in the British Method, however, Charts or figures in the British method were converted into polynomial equations. QBASIC program was written to ease the use of the algorithm, and was also used in solving two examples. The results obtained from the algorithm were compared with those obtained based on the British method and the differences between them were found to be less than 10% in each example. Hence, the algorithm developed in this paper is working with minimum error. It is recommended for use in obtaining good results for normal weight concrete mix design.

The impact of ict in rural education: case study - enugu state

Abstract: Rural areas are geographically dispersed and if educational programs for such rural areas are to provide equitable coverage, accessibility technological means must be considered. Indeed there has to be an existing or proposed infrastructure that would enable these programs to be conveyed. This paper looks into the information and communication needs for the vast majority of rural areas in Enugu State so as to build mechanisms to support ICT in order to increase the rate of development and economic growth. The paper shows, through data collected from Secondary schools in Enugu State, why there is a pressing need to primarily finance ICT projects focusing on the needs, aspirations, capacities and perspectives of the vast majority of people in rural areas. Choices for communication infrastructure are detailed.

Formula for Forced Vibration Analysis of Structures Using Static Factored Response as Equivalent Dynamic Response

Abstract: This Paper proposed and examined a formula for forced vibration analysis of structures using static factored response as equivalent dynamic response. Some methods of dynamic analysis are based on using static factored response as equivalent dynamic response thereby excluding the formulation of the equations of motion for forced vibration. These methods obtain dynamic response by the magnification of static response using the dynamic magnification factor or a modified form of the dynamic magnification factor. Dynamic response obtained by such methods give stress values which differ greatly from the actual. The flaw of these methods consist in magnifying stress values with factors obtained from displacement consideration on a false assumption of direct linear variation in the stress-displacement relationship. Based on the flexible frame model and stiffness formulation a formula for forced vibration analysis of structures using static factored response as equivalent dynamic response was developed with forced vibration equations and appropriate stress-displacement relationship. Though the use of this formula excludes the formulation of the equation of motion for forced vibration, the results obtained by its application to an MDOF Frame agree with that of the exact method using the flexible frame model. The formula can be used in practice for forced vibration analysis of structures or serve as control for the exact methods.

Intercritical heat treatment effects on low carbon steels quenched from intermediate temperature austenitization

Abstract: Six low carbon steels containing carbon in the range 0.13-0.18wt%C were studied after intercritical quenching, intercritical quenching with low temperature tempering, intercritical annealing and intercritical normalizing using specimens originally quenched from intermediate austenitizing temperature (950 0 C). The studies also examined the microstructure of the intermediate austenitizing temperature (950 0 C) quenched specimens. The intercritical and tempering temperatures were 740 0 C and 180 0 C respectively. Comparison of the mechanical properties of the intercritically heat treated specimens with those of the intermediate austenitizing temperature specimens showed that intercritical quenching with low temperature tempering reduced the ultimate tensile strength and hardness and increased the percentage reduction in area and the notch impact toughness. Intercritical annealing and intercritical normalizing increased the yield strength, ductility and toughness but decreased the ultimate tensile strength and hardness.

Flexural, Torsional and Distortional Buckling of Single-Cell Thin-Walled Box Columns

Abstract: Instability is an important branch of structural mechanics which examines alternate equilibrium states associated with large deformations. In this study, Varbanov's generalized strain fields and Vlasov's displacement equations were used to obtain a set of equations for neutral equilibrium of axially compressed single-cell box column with deformable cross-sections. The study involved a theoretical formulation based on Vlasov's theory as modified by Varbanov and implemented the associated displacement model in generating series of ordinary differential equations in distortional displacement V(x). The initial result of the formulation was in form of total potential energy functional, which was then minimized using Euler-Lagrange equation. Minimization of the total potential energy functional resulted to a set of governing equations of equilibrium in matrix form. The longitudinal warping displacement functions U (x) were eliminated from the governing equations of equilibrium in different forms to obtain the following equations: two fully uncoupled ordinary differential equations in V 1 and V 2 representing flexural buckling about the two axis of symmetry; a fully separated ordinary differential equation in V 4 representing distortional buckling about the longitudinal ox-axis; a pair of coupled simultaneous ordinary differential equations in V 3 and V 4 representing torsional – distortional buckling mode. This study has resulted in better understanding and separation of distortional mode from the other stability modes. The results show that the effect of deformation can be substantial and should not be disregarded by assuming rigid cross-sections. This present work has also simplified instability analysis and design of thin-walled box columns with deformable single-cell cross-sections on the basis of Vlasov's theory by deriving precise equations for all the possible buckling modes.

Stability of Axially Compressed Single-Cell Mono-Symmetric Thin-Walled Closed Column

Abstract: Compared with conventional structural columns, the pronounced role of instabilities complicates the behaviour and design of thin-walled columns. This study investigated the stability of axially compressed single-cell thin-walled column with mono-symmetric non-deformable cross-sections. The work involved a theoretical formulation based on Vlasov's theory with modification by Varbanov and implemented the associated displacement model in analysing flexural and flexural-torsional (FT) buckling modes. The initial result of the formulation was in form of total potential energy functional, which was then minimized using Euler-Lagrange equation to obtain a set of differential equations of equilibrium in matrix form. The elements of the coefficient matrices of the governing differential equations of equilibrium were determined for the mono-symmetric cross-section by first generating and plotting the generalized strain fields. Technique of diagram multiplication was then used in determining the elements of the coefficient matrices from the generalize strain mode diagrams. The substitution of the determined coefficients back into the governing equations of equilibrium resulted to one uncoupled ordinary differential equation representing flexural behaviour and a pair of two interactive (coupled) ordinary differential equations representing the flexural-torsional (FT) behaviour. These equations were then solved using direct closed-form approach for the uncoupled flexural behaviour and Varbanov's trigonometrical series with accelerated convergence (TSWAC) for the coupled flexural-torsional behaviour. The results are presented in form of stability matrices and the numerical results are presented on tables (1) and (2). Comparison of the two tables' results indicates that the flexural behaviour will control design.

Design, manufacture and characterization of a journal bearing demonstration unit

Abstract: The paper examines the potential for the indigenous design and manufacture of laboratory equipment used for demonstrating the engineering principles of taught courses in our Engineering Schools. Using the Demonstration Journal Bearing as a case-study it is shown that imaginative modifications to classical design could result to a prototype within the technical capability of our local skilled technicians and available machine-tools. It recommends that engineers in the private sector should work together with academia to popularize this potential, which, in addition to solving a chronic problem that holds ominous consequences for the survival of sound engineering practice for the nation in the years ahead, is going to be profitable in national image, even if not too lucrative, financially.