1 |
Author(s):
Gonoh, B. A., Sabo, M.L..
Page No : 1-6
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STEADY STATE PERFORMANCE OF SPWM-FED SINGLE-PHASE INDUCTION GENERATOR
Abstract
The steady state performance of a wind-driven, sinusoidal-pulse-width-modulated inverter- fed, single-phase induction generator is presented in this paper. The scheme provides a control (or regulation) of the induction generator’s load angular frequency and voltage, by connecting sinusoidal-pulse-width-modulated inverter in the auxiliary winding of the generator. The inverter also provides real and reactive power requirements of the generator. The system of equations used for the computer simulation is the same as those considered in transient analysis, except that, the rate of change of system variables are equated to zero. Harmonics balance technique was used in the steady state analysis. A laboratory model of the system was implemented and the experimental results obtained agreed very well with computer simulated results.
2 |
Author(s):
GARBA, I., YAHAYA, D.B..
Page No : 7-13
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SIMULATION STUDIES OF HEAT EXCHANGERS IN UNTL KADUNA
Abstract
Process simulation is a critical step in the identification of areas of energy inefficiencies in industrial facilities. The result of simulation if properly carried out should aid in identifying points of intolerable energy losses in the system. This paper investigated the heat losses through computer simulations. Strategic plans for energy systems efficiency improvement were presented and opportunities for energy savings were also identified. The exact value of heat losses for the heat exchanger is 2720000Kj/h. The adiabatic and polytropic efficiencies of the heat exchanger were found to be 0.86% and 0.79%. A computer software package in Hysys version 3.1 was used for the simulation. From the simulation carried out, it was discovered that the simulation model developed satisfied all the conditions of the empirical model.
3 |
Author(s):
ALIYU, M. M..
Page No : 14-20
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ASSESSMENT OF QUALITY-RELATED ATTRIBUTES OF PROJECT MANAGERS FOR SUCCESSEFUL CONSTRUCTION PROJECT EXECUTION IN NIGERIA
Abstract
The paper traces the qualities required by a project manager to execute construction projects successfully. It also examines the perception of three significant actors in the construction industry (that is the clients, the consultants and the contractors) regarding the desirable qualities of an effective project manager. The research is limited to the views of a convenient sample of construction and property professionals who are employed or engaged by client’s organizations, consultancy firms or contracting companies. The total sample used for the study is 185 returned questionnaires answered by 50 clients, 70 consultants and 65 contractors. The individual desirable qualities were categorized into six main groups: personal qualities, problem-solving, administration, supervision/project management, interpersonal relation and technical expertise. The practitioners rated each of these qualities according to their perception of the degree of importance. The statistical tools such as frequency count, mean item score and spearman correlation were used in the analysis. The results revealed that the three groups perceived the desirable qualities differently. To the clients the most important attribute was personal qualities, the consultant rated problem solving to be the most important quality, while to the contractors it was technical expertise. However, when the three groups were combined, personal quality was rated as the most important desirable quality of an effective project manager.
4 |
Author(s):
Yusuf, A.O., Abdullahi, I..
Page No : 21-28
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DEVELOPMENT AND EVALUATION OF A POTATO SLICING MACHINE
Abstract
Large quantiiesy of potatoes are being produced and consumed annually in Nigeria. This work presents design and development of a potato slicing machine using appropriate technology. Various components of the machine were designed and locally available materials like mild steel, stainless steel, brass and aluminium alloy were used in the fabrication. The machine can be adjusted to slice potatoes to varying thicknesses, ranging from 4mm to 10mm. The capacity of the machine is 184kg of potato per hour and its performance efficiency is 68%. The production cost of the machine is Twenty Five thousand Two hundred and Eighty Two Naira, Fifty kobo only (N25, 282.50).
5 |
Author(s):
ABUBAKAR, N., YAHAYA, D.B.
Page No : 29-33
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AN OVERVIEW OF THERMAL HYDRAULIC BEHAVIOUR OF THE FIRST NIGERIA NUCLEAR RESEARCH REACTOR (NIRR-1) MANIFESTING TO ITS INHERENT SAFETY
Abstract
Measurements were performed to verify the thermal hydraulic behaviour of NIRR-1 under normal and transient conditions. The reactor thermal power and neutron flux parameters that result from changes in the core coolant temperatures were measured and the analysis of the data recorded showed inverse relation of the reactor power to coolant temperature. During normal operation at 31 kW (neutron flux of 1.0×1012 n cm-2s-1), the control rod gradually pulled out of the core as the inlet temperature rose from 24.8oC to 37.7oC with the corresponding outlet temperature rising from 45.1oC to 57.2oC respectively. When operated at self restraint (with control rod fully withdrawn from the core), the reactor power rose to a maximum of 75.8 kW (neutron flux of 2.59×1012 n cm-2s-1) with the corresponding inlet and outlet temperatures of 27.3oC to 62.9oC respectively and then began to drop. In both cases rise in coolant temperature results in power suppression and subsequent self shutdown which ascertained that NIRR-1 thermal hydraulic design agrees with its designed safety.
6 |
Author(s):
Mukhtar, M.M., Bala, K., Zubairu, I.K..
Page No : 34-38
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AN APPRAISAL OF COST CONTINGENCY MANAGEMENT PRACTICES FOR BUILDING PROJECTS IN NIGERIA
Abstract
Contingency funds are included in project estimates to manage risks and uncertainties so as to achieve project objectives. This paper presents results of a research work on management of contingency fund for building projects in Nigeria. A total of 100 questionnaires on projects cost contingency were randomly distributed to project managers. Sixty seven (67) completed questionnaires were returned. Analysis of the responses indicates that, in many organizations, there is a lack of formal policy or guidelines for the management of project cost contingency. Furthermore, 12% of the respondents do not monitor the use of contingency fund; also 37% do not review the accuracy of contingency allowance at the completion of projects. The study also shows that, the major problem encountered in the management of contingency fund is that, more often the fund is inadequate to cater for all the risks and uncertainties associated with projects. To improve cost contingency management practice, it is recommended that, organizations should establish a policy or guideline for management of contingency fund.
7 |
Author(s):
Adedokun, T.A, Uche, O.A.U, Abdulkadir, S.
Page No : 39-44
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EVALUATION CRITERIA FOR HAND-GUIDED VIBRATORY ROLLERS IN COMPACTION OF LATERITES FOR ROAD MAINTENANCE WORKS’
Abstract
This paper reports the results of an investigation aimed at evolving criteria for the use of Hand-guided vibratory rollers in the compaction of laterite for road maintenance works such as shoulder repairs and re-instatement of base course materials in failed sections. Samples of lateritic soil were collected from existing borrow pits in Tsamiya Babba and Chalawa areas of Kano State, Nigeria and classified using American Association of State Highway Officials (AASTHO) method as A-6, A-2-4 (sub-base) and A-2-6 (base) materials. Rolling tests were carried out with hand guided vibratory roller in six number bays prepared with 100 mm and 150 mm thick lateritic soil. This was to determine the economic number of passes required to achieve the maximum dry density (MDD) of the samples. It was found that for a base course, the number of passes required in compacting 100 mm and 150 mm thick layers of lateritic soil with a hand-guided rollers of weight 1015 kg were 14 and 16 respectively, while that of sub-base were 16 and 18 passes. In comparison with the rolling tests on similar materials in active earth works construction site using 10,000 kg self propelled roller, the number of passes is reduced to 4-6 and 5-8 passes for 100 mm and 150 mm base and sub base materials respectively. The number of passes required to achieve maximum dry density (MDD) depends on weight or size of compaction plant, layer thickness and material type. The hand-guided vibratory roller with 16-18 passes is recommended for maintenance work for economic base and sub-base lateritic soil material compaction.
8 |
Author(s):
Abdulfatah, A. Y., Adedokun, T.A., Umar, M., Yunusa, G.H..
Page No : 45-55
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REACTIONS OF COPPER AND CHROMIUM WITH EXTERNAL SURFACE OF WATER PIPELINES IN SOIL
Abstract
Water companies are facing problems of leakages and breakage of water pipelines that result into an increasing loss of water in the tune of Mega litres daily. Corrosion of metallic pipelines is one of the major causes of weakening the strength of water pipeline, which subsequently results into water leakage. In the wake of ever growing environmental pollution, this paper focuses on the reactions of soil contaminants; Copper (Cu) and Chromium (Cr) with external surface of buried water pipeline systems. Study of the behavior of the two metals in soil reveals that up to 7.852 mg/l of iron in solution was produced as a result of the pipeline’s interaction with the two metals.
9 |
Author(s):
Ijimdiya, T.S., Onwude, L.U..
Page No : 56-61
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EFFECT OF RICE HUSK ASH STABILIZATION ON THE COMPRESSIVE STRENGTH OF OIL CONTAMINATED SOILS
Abstract
The paper presents the results of a laboratory study carried out on oil contaminated soil samples treated with Rice Husk Ash (RHA) contents at the Standard Proctor compaction energy. The results obtained showed improvements in the properties of the RHA treated oil contaminated soil samples. The Atterberg limits decreased with higher RHA content and maximum Unconfined Compressive Strength (UCS) value of 405 kN/m2 at 2 % oil/ 2 % RHA content was obtained.
10 |
Author(s):
Gonoh, B.A., Sabo, M.L..
Page No : 62-70
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MODELING AN INVERTER FOR USE AS A SINGLE PHASE INDUCTION GENERATOR
Abstract
This paper presents Simulink implementation of an Insulated Gate Bipolar Transistor (IGBT) Sinusoidal Pulse Width Modulation (SPWM) DC/AC inverter for induction generator as a static VAR (variable) source. Connected to an induction generator, the inverter provides reactive power, which is needed for self excitation and load voltage, frequency regulation. A DC source (Battery) feeding the PWM inverter supplied (reactive) power to (from) the generator when the load demand is greater (lesser) than the power supplies from the prime mover (wind). Based on the design, the inverter was implemented with IGBTs as the switching elements. The simulation results of different modulation indexes compared favorably with experimental waveforms as fed to the auxiliary winding of the generator and shows good agreement, even though the laboratory waveforms were a bit distorted by harmonics and vibration from both inverter and generator respectively. The battery inverter single phase induction generator can be used as a source of regulated voltage and frequency for isolated application such as commercial and industrial uses. The system will find application for battery charging purpose and controllable single phase ac voltage source.
11 |
Author(s):
Ejeh, S.P., Musa, N.M..
Page No : 71-74
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PHYSICO – CHEMICAL CHARACTERISTICS OF NEEM SEED HUSK ASH CONCRETE
Abstract
The effect of Neem Seed husk on the physico-chemical properties of Neem seed husk ash concrete was investigated. Neem Seed husk is a by-product obtained during industrial processing of Neem Seed to extract oil and produce fertilizer. Neem seed husk ash was used in replacing cement in the proportions of 0%, 5%, 10%, 15%, 20% and 25% by weight of cement. The phyisico-chemical properties of cement at anhydrous state and the hydrated state (chemical composition, specific gravity, fineness, consistency of the cement paste and setting times) were studied. The experimental results obtained showed that Neem seed husk ash is a principal parameter which has influences on the physico-chemical properties of the Neem seed husk ash concrete.
12 |
Author(s):
Aliyu, M.M., Abdullahi, Y.I..
Page No : 75-80
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PROPERTIES OF RICE HUSK-LIME-CEMENT CONCRETE
Abstract
This paper presents a research work on the effect of rice husk ash (RHA)/lime (CaO) as a partial replacement of cement in concrete production. A total number of ninety (90) cubes were cast, thirty (30) cubes for trial mix to obtain optimum water cement ratio (W/C) for the actual mix and another sixty (60) cubes were cast for actual mix on the percentage replacement group of 0%, 2.5%, 5.0%, 7.5% and 10% of both rice husk ash and lime respectively. The setting times of RHA/Lime and ordinary Portland cement (OPC) paste, workability, saturated surface density, chemical composition of RHA and compressive strength of the concrete were determined. Results showed that RHA/lime has influence on the setting times because both initial and final setting times of the cement paste with RHA/lime have higher setting times. The initial setting time ranges from 140 mins to 159 mins at 2.5% to 10% of RHA/ Lime respectively, as compared with the control specimen, which has 95 mins. The steady increase in the initial setting time is also reflected in the final setting times, and ranges between 216 mins – 261 mins. Slump decreased from 18 mm to 0 mm.Compacting factor test ranges between 0.89 – 0.81, the specific gravity of rice husk ash was found to be 2.13, and the bulk density 530 kg/m3. Lime (CaO) content of RHA 1.36%, silica (SiO2) content 67.30% and loss on ignition (L.O.I) 17.78%.The average compressive strength at 2.5% replacement level of RHA/lime was 25.3 N/mm2 at 21days which decreased to 18.7 N/mm2 at 28days with other replacement level of RHA/CaO, respectively. This is initially closer to the strength of the control concrete specimen which has average compressive strength of 25.6 N/mm2 at 21days but behaves differently later by increasing to 27.8N/mm2 at 28 days. The decrease in the RHA/CaO replacement situation could be attributed to the variation of the chemical composition of RHA/CaO.
13 |
Author(s):
Jibia, A.U..
Page No : 81-87
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A REVIEW OF THE TIME DOMAIN METHODS FOR MULTICOMPONENT TRANSIENT SIGNAL ANALYSIS
Abstract
The problem of estimating time constant of a sum of damped exponentials has been a major area of research
in many fields in science and engineering. Several methods have been reported all of which can be grouped
into time-domain and frequency-domain techniques. Time-domain analysis predated frequency domain
analysis but the latter has taken the centre stage due to the ease with which signals can be analyzed in the
frequency domain. Nonetheless, time-domain analysis is still widely used and time-domain methods are still
being investigated and refined. This paper investigates time-domain approach to transient multiexponential
data analysis. Although no claim is being made that time-domain methods are exhausted, it can be truly
asserted that major methods of time-domain analysis are reviewed in this paper. The paper attempts to give a
detailed summary of each method and shows its limitations. Of all time-domain methods, Prony has undergone
the most modifications. However, a more recent method (METS) has been more successfully applied especially
in Chemical Engineering. The peeling technique is obsolete and only significant because it serves as the basis
for nonlinear least squares method. IMOM was applied only by its originator in Fluorescence decay analysis
and its applicability in other areas has not been proven.
14 |
Author(s):
Sadiq, A.S., Adisa, A.B..
Page No : 88-92
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INVESTIGATION ON THE SUITABILITY OF SAWDUST FOR IMPROVING THE COMPRESSIVE STRENGTH OF FIBRE REINFORCED POLYESTER COMPOSITE
Abstract
Fibre-reinforced composite materials are synthetic or man-made materials. These materials are used for many engineering applications especially automobile structures and components. One of the mechanical properties that constitute the central focus in usage is the compressive strength. The central focus of this work is to determine the degree of effectiveness of sawdust in the improvement of the compressive strength of continuous strand mat reinforced polyester composite using hand lay-up technique of production. Composites consisting of the continuous strand mat glass fibre and polyester resin were produced using hand-lay up open mould technique. Five other composites consisting of varying masses (between 4-20g) of sawdust, fixed mass (45g) of continuous strand mat glass fibre and varying masses of polyester resin (between 75-95g) were produced using hand-lay up open mould technique respectively. These composite specimens were subjected to compressive tests using universal testing machine. An efficiency of 84.4% improvement on the compressive strength of the non sawdust composite was obtained via strength to weight ratio criteria. The results indicated that sawdust is a very good material that may be used for improving the compressive strength of Fibre-reinforced polyester composite.
15 |
Author(s):
ABUBAKAR, I..
Page No : 93-99
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DIRECT CURRENT (DC) GENERATION FROM A REFURBISHED AUTOMOTIVE ALTERNATOR USING A STATIONARY BICYCLE
Abstract
The DC generator developed provides 12V power supply from a designed and constructed system consisting of a fabricated stationary bicycle, refurbished automotive alternator, a six diode rectifier and a 12V DC regulator. The alternator is driven by the rear wheel of a stationary bicycle through a V-belt to generate a 3-phase voltage that is then rectified by a three phase (six diodes) rectifier. The output voltage from the three phase rectifier was subsequently passed through a 7812 integrated circuit (IC) regulator for supplying a stable 12V supply. The system developed is intended to be used in fitness centres, where it will be used for physical exercise as well as a small DC generator. The performance of the generator was tested at open circuit voltage levels and at load test levels. The final result shows that using an excitation current of 1.22A, a regulated output of 12V could be obtained. The system developed and presented in this work can serve as an alternative source of power generation which can be used to charge hand set, batteries and for demonstration in laboratory to help the students understand generator principles.
16 |
Author(s):
Aliyu, A.B., Sambo, A.S..
Page No : 100-109
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POROSITY AND PERMEABILITY ANALYSIS OF RIVER-BED SAND FOR EVAPORATIVE COOLING STRUCTURE
Abstract
This paper reports an analysis of riverbed sand as heat exchange medium for use in evaporative cooling storage system in different climate characteristics. Evaporative cooling operates using water and air as working fluids. It consists in water evaporation, through the removal of water moisture from the skin outer wall surface of the structure by the adjacent dry air (flowing or stationary), thus decreasing the air temperature that is in immediate contact with the structure. It was found that sand with larger grading (size) discharges less amount of water and that the granulated limestone has the largest grading of between 0.3 mm and 5.0 mm and discharges less amount of water. This shows that the particles are much more compacted than for other sands tested. The fine sand range (0.063mm to 0.6 mm) registered large flow rate or discharge. It therefore has a high permeability, the highest concentration time of 265 seconds and is the best type of sand to be used. From thermal properties tables for sand, finer sands have less density than the sandstone (Challawa type) and lime stones of the same volume. This is an important parameter for design purposes. This system has a great potential to provide storage facilities for fruits and vegetables especially in places where air humidity is low or during periods of low humidity. This type of climatic condition is obtainable in most parts of Northern Nigeria.
17 |
Author(s):
Zakari, M.D, Maina, M.M, Abubakar, M.S, Shanono, N.J., Lawan, I., Tadda, M.A. and Nasidi, N.M..
Page No : 109-117
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DESIGN, CONSTRUCTION AND INSTALLATION OF SPRINKLER IRRIGATION SYSTEM
Abstract
The need to irrigate farms/gardens by a method that will replace the natural rainfall when not available led to the design and construction of the sprinkler irrigation system. In this study, a sprinkler irrigation system was designed, constructed and installed. The design was based on using a rotating sprinkler system to irrigate a small size plot which provides an acceptable scientific basis for proper water scheduling, evaluation of the system and minimizing water wastage and runoff. It was designed for four crops, but tomato (Lycopersicum esculentum spp) was considered with irrigation interval of five days. The result shows that the discharge of individual sprinkler was found to be 2.144 lit/sec and the rate of application of the sprinkler was 8.85 mm/hr, the pump required for the operation of the system is approximately 2 hp and a pressure at the inlet of the main pipe is 13.44 bar.
18 |
Author(s):
ABUBAKAR, M.S..
Page No : 118-123
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DETERMINATION OF THE SPRAY DROPLET SIZE SPECTRUM FROM DUAL-PURPOSE DISC AGROCHEMICAL APPLICATOR
Abstract
Application of liquid chemical on agricultural fields is mainly performed using hydraulic nozzle sprayers. However, in this study a dual-purpose disc agrochemical applicator for field crops was developed to boost agricultural mechanization in crop production and also to overcome the safety concern of hazardous spray drift during agrochemical application by the field crop farmers. The dual-purpose disc agrochemical applicator was tested with in order to determine the spray droplet size spectrum. The result shows that the average values of volume median diameter (VMD) range from 342-102 μm at 2000-5000 rpm rotational disc speed at different values of application rate for NASA glyphosate liquid chemical. The average value of the number median diameter (NMD) varies from 82 to 209 μm for NASA glyphosate liquid solution. The mean values of coefficient of uniformity for droplet sizes expressed as VMD/NMD found in this study were in the range of 1.25 to 1.63 for the liquid chemical.