bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of Planar Microtoroid Cavities Using High-Power Laser
Authors: Yan Ying Zhan , Yan Shu Bin , Jiang Guo Qin , Ji Zhe , Wang Shao Hui , Xiong Ji Jun , Zhang Wen Dong
Published: March 2009

Planar Microtoroid cavities have important application in many researching and application domains due to their ultrahigh quality factor (Q). But the special toroid structure can not be fabricated through traditional technology. In this paper, a novel processing method for fabricating microtoroid cavities using high-power CO2 laser after a series of traditional processing steps is introduced. The processing details are discussed including light path, focusing system and other important parameters. Test using scanning electronic microscope and laser-Raman spectrum shows that fabrication of planar microtoroid cavity using CO2 laser is feasible. The final microtoroid cavity is fabricated with slight impact to the silicon strut-beam, ensuring excellent optical performance in Planar Microtoroid cavity.
A In Situ Measuring Method for Stress Gradient of a MEMS Film
Authors: Chen Han , Rong Hua , Wang Ming
Published: March 2009

The stress gradient of a deposited thin-film is a mechanical parameter that affects the performance of MEMS devices, so in-situ measuring stress gradient of a thin-film is great significant. A new in-situ measuring method based on a center-anchored circular plate is presented. The Mirau interferometer has been used to measure the out-of-plane height at the edge of circular plate, then the curvature radius of the plate and the stress gradient of the film can be calculated. The measuring method has been verified by CoventorWare. The accuracy of the presented measuring method is ideal. The advantages of the method also have been discussed.
Electrical Trimming of Boron-Doped Polysilicon Nanofilm Resistors Deposited at Different Temperatures
Authors: Shi Chang Zhi , Liu Xiao Wei , Chuai Rong Yan
Published: March 2009

The previous research showed that highly doped polysilicon nanofilms (PSNFs) have a high gauge factor and stable temperature characteristics, promoting their applications in piezoresistive sensors. For correcting the resistance deviation and improving the resistance matching of sensing elements, the electrical trimming (ET) characteristics of PSNFs deposited by LPCVD at different temperatures were studied. By the interstitial-vacancy (IV) model, the resistance falloff in trimming phenomenon is considered as a result of the decrease of scattering centers caused by the recombination of IV pairs. By modeling grain boundaries (GBs) as the accumulation of IV pairs (basic defects), it is believed that IV pairs can recombine layer-by-layer under the energy excitation of joule heat generated by high current conduction. The experiment results show that the threshold current density for ET of PSNFs is an order of magnitude lower than that of polysilicon common films, while the trimming accuracy and stability of directly deposited PSNFs are superior to the recrystallized ones. Finally, it is gained that reducing amorphous phases at GBs by optimizing deposition temperature can improve ET characteristics of PSNFs.
Preparation and Characterization of Micro Polypyrrole Electrodes for Supercapacitor
Authors: Sun Wei , San Hai Sheng , Duo Ying Xian , Chen Xu Yuan
Published: March 2009

A novel electrode of supercapacitor was developed with a three dimensional (3D) structure which results in a significant increase of the electrode area per unit capacitor volume. An area of 2.58 times the area of corresponding planar design was obtained. The process flow for fabricating the 3D electrode was developed compatible with microelectromechanical system technology. The key processes were high-aspect-ratio Deep Reactive Ion Etching, electroless plating and electropolymerization. Ni as the current collector was deposited on Si/SiO2 substrate by using electroless plating, Polypyrrole was galvanostatically polymerized as electroactive film. The capacitance properties of the 3D electrode were investigated. Cyclic voltammetry tests show that the specific capacitance of the 3D electrode at 100 mV/s was 0.014 F/cm2 which is comparable with the 0.013 F/cm2 for the planar design. Electrochemical impedance spectroscopy plot of the 3D electrode is well fitted by equivalent circuit, we found the specific capacitance is 0.011 F/cm2 which is slightly larger than 0.0094 F/cm2 for similarly planar design. From the gavanostatic charge/discharge tests, the specific capacitance of the 3D electrode at 2 mA/cm2 is 0.011 F/cm2 while for planar design the corresponding value is 0.010 F/cm2. The results indicate the continuous and homogeneous Polypyrrole film with 3D structure was obtained as we designed.
Research on Side-Insulation of Tool Electrode for Micro Electrochemical Machining
Authors: Liu Gai Hong , Li Yong , Chen Xu Peng , Lv Shan Jin
Published: March 2009

In micro electrochemical machining (micro ECM), side-insulation of tool electrode can significantly improve the machining accuracy, especially for high aspect ratio structures. This paper presented a new side-insulation approach for not only micro single electrodes but also micro array electrodes, in which spin-coating and room curing are used to coat the micro tool electrodes with a very thin film of polymer, followed by an end-rubbing process to remove the insulation material from the electrode end surfaces. Processing parameters of spin-coating were optimized experimentally, and side-insulated micro single electrodes with a double-layer epoxy coating of 3m thickness were prepared. Experiments were made to test the performance of the side-insulation film under simulated micro ECM conditions. And the results demonstrated good insulativity and high adherence strength in a 6-hour durability test. Also side-insulation for micro array electrodes was performed using this approach.
Influence of Electrolytic Products in Machining Gap on Micro ECM
Authors: Ma Xiao Yu , Li Yong , Lv Shan Jin
Published: March 2009

Electrolytic products are hard to be removed from the machining gap in micro ECM (electrochemical machining) process, which may lower the machining speed or even stop the machining process. Intermittent withdrawal of electrode is an effective way to cleanse electrolytic products, renew electrolyte in the gap, and promote the continuance of machining process. The influence of electrolytic products’ removal rate upon machining speed is analyzed in the case of intermittent withdrawal of electrode. Results show that the machining speed does not increase monotonously with the decrease of inter-electrode distance. Considering machining efficiency and accuracy, machining gap should be the corresponding gap value when the machining speed reaches its maximum.
Molecular Dynamics Modeling and Effects of Cutting Parameters on Nanometric Cutting Process
Authors: Wang Jia Chun , Zhang Ji Min , Wu Feng He , Li Na
Published: March 2009

In nanometric cutting process, the actual material removal can take place at atomic level, which makes the observation of machining phenomena and the measurement of cutting parameters difficult or impossible in experiments. However, it is crucial to investigate the cutting process in nanoscale. In this work, molecular dynamics (MD) is used to study effects of cutting parameters on nanometric cutting process with the aid of EAM potential. The result of the simulation shows that higher cutting speed leads to a rough machined surface with a relative large deformation in workpiece. It is found that a smaller cutting depth results in less plastic deformation and fewer dislocations in workpiece, and also results in a smoother machined surface. Rake angle has big effect on the chip formation, potential energy and the machined surface.
Numerical Simulation of Viscous Jet for Near-Field Electrospinning
Authors: Zhong Yuan Yuan , Zheng Gao Feng , Sun Dao Heng
Published: March 2009

Near-Field Electrospinning (NFES) is a newly developed method to fabricate continuous and ordered solid nanofibers, with smaller spinneret-to-collector-distance the behavior of viscous jet would play a more prominent effect on the deposition and morphology of nanofiber. In this paper, a 2-dimentional physical model based on electrohydrodynamics and rheology was set up to discuss the morphology of viscous jet for NFES. The profile of the jet along z direction can be predicted by this model, and the impact of process parameters on the jet radius is analyzed. Radius of jet decreases with spinneret-to-substrate-distance decreasing; jet radius decreases with applied voltage and electric field strength increasing; jet electrospun from PEO solution is thinner than that from PVA solution with the same solution concentration; solution concentration has insignificant influence on the radius of jet from solution of the same polymer (PVA or PEO). This numerical simulation would improve the control of electrospinning process in NFES.
Study on Excitation Voltage Effects of the Thermal Excitation Resonant Pressure Sensor
Authors: Li Xiao Wei , Zhang Zheng Yuan
Published: March 2009

Resonant pressure sensor, whose thermal gradient field is changed by variations in electro-thermal excitation, then influences the resonant frequency of the sensor, so different thermal excitation will produce different thermal stress, and then influences the characteristic of the sensor. For the thermal excitation resonant pressure sensor at different voltages excitant will produce different thermal gradient field, then influences the frequency of the sensor. Taking the advantage of lock-in amplifier, which can detect weak signal, an open-loop test experiment about the resonance output signal is carried out by using the method of alternating current excitation and pick-up with two-octave component. The results show the relational about thermal excitant virtual value and resonant frequency of this silicon microstructure resonant pressure sensor. Analysis about the result of the experiment is given, which can provide certain theories basis for the optimum design of the related parameter of this sensor, and have an important advice for the peripheral circuit design.
Design, Construction and Performance Evaluation of a Low Cost Electric Arc Welding Machine
Authors: Igbinovia S.O. , Onuoha M.C. , Olaogun O.K.
Published: March 2009

Apart from woodwork, brickwork, all other formworks are of metalwork. Thus engineering devices, equipment, machineries and infrastructures are made possible with the use of welding machines, be it carbide or arc – welding type. In Nigeria, where the cost of imported goods rises astronomically in accordance with the foreign exchange rates, the need to fabricate this very important equipment became of important necessity. In this paper, a single-phase 6KVA, 240VAC/30-70 VDC electric arc welding machine was designed and constructed using locally available materials. The different operating current required, arcing time, the heat generated by the arc, the minimum arc gap, the fluxite coated electrode, oxidation of the molten materials by the surrounding air where some of the designed parameters that determined the auto-transformer specific magnetic loading and specific electric loading. Cooling medium, integral switch, the rectifier circuits and the tanking of the transformer designed determined the equipment production. The locally fabricated AC/DC air cooled electric arc welding machine capable of withstanding 200A, when subjected to insulation resistance test, no – load test, short circuit test and on-load test to ascertain its performance characteristics were very satisfactory.
Comparative Analysis of Electric Field Measurement in Zaria
Authors: Akinsanmi Olaitan , Bajoga B.G. , Dajab D.D.
Published: March 2009

This paper presents the comparative analysis of the measurement of static electric field within and outside the test location in Zaria, Nigeria, based on the measurement carried out using a data acquisition system, interfaced with a digital electrostatic field strength meter (model 257D). The acquired electric field data are captured by a computer using the Microsoft Office Excel Program. The focus of the analysis is determining the effect of environmental factors such as temperature, pressure and relative humidity on the static electric field during the harmattan (March) and non-harmattan period (April – May). The plots of the average electric field against the variation of the environmental factors were used as the qualitative analytical tools and conclusion was drawn to the fact that the relative variation in the measurement of the electric field within and outside the test location is averagely 0.06KV/cm and dependent on the environmental factors.
An Investigation of Microwave Link Degradation due to Atmospheric Conditions (A Case Study of Akure-Owo Digital Microwave Link)
Authors: Otasowie P.O. , Edeko F.O.
Published: March 2009

This work investigates the microwave link degradation due to atmospheric conditions on the Akure-Owo Digital Microwave Link. Microwave line of sight measurements were carried out between January and December 2005 with a data acquisition software (PROCOMM PLUS SOFTWARE). The data collected were analyzed using MATLAB 7.0 SOFTWARE program to determine the months of the year that has the highest degradation due to atmospheric conditions and also the months of the year that has the highest bit error rates. The result showed that the months of January, June, July, August and September have the worst signal degradation of -0.97dbm, -2.0dbm, -3.97dbm, -3.97dbm, -1.97dbm. respectively. The result also showed that the bit error rates are good and acceptable throughout the months of the year. A model equation was developed to predict the signal strength received and the bit error rate in the microwave link investigated, when atmospheric conditions are taken into consideration. The results of the predicted model were validated by field data and the results obtained showed an error of -0.2% for the received signal level and zero error for the bit error rate which means that the developed model equations can be used to accurately predict the link degradation parameters.
Electricity Network Planning: The Key to Efficient and Reliable Power Supply to Consumers
Authors: Onohaebi S.O. , Apeh S.T.
Published: March 2009

This paper focuses on the need and procedure for the planning of electrical engineering infrastructure for any district/community in order to enhance reliability and efficiency of power supply to consumers. Almost all the towns/cities in Nigeria are unplanned and this has resulted in haphazard approach to Electricity Network Planning and implementation. A detailed theory, methodology and technical considerations, in compliance with both National and International standards are discussed in this paper. A proposed University campus was used to demonstrate the procedures involved in electricity network planning in order to achieve an efficient power supply. This involves the electric power supply, design concepts, load estimates and analysis, network distribution/equipment and sizing of cables and electrical panels taking into account the various modes of distribution. This paper also drew a simple analogy between Benin City and the Federal Capital Territory, Abuja, to illustrate the objective of the paper while highlighting the merits associated with planned electrical engineering infrastructure and suggested the ways to remedy the unplanned networks in Nigeria.
Dehydrated Cassava Chips Utilization in Starch and "Garri" Production
Authors: Ikujenlola A.V. , Omosuli S.V.
Published: March 2009

Fresh cassava roots were processed to chips by peeling, washing,chipping, dehydration, and packaging. The dehydrated chips were thereafter processed to starch and garri by rehydrating the chips to 50-60% moisture. The products were compared with the ones produced from fresh cassava roots by evaluating the organoleptic properties, chemical compositions, and pasting characteristics. The garri from the dehydrated chips was ranked better in terms of particle size and aroma; while garri from fresh roots was ranked better in colour, and mouth feel. Both garri were generally acceptable to the panelists. The cyanide level, titrable acidity, protein, ash, crude fibre and moisture contents of garri from dehydrated cassava chips were 2.36mg/kg, 1.06%,3.35%, 2.14%, 2.02%,and 11.24% respectively. The viscosities of the starches from the dehydrated cassava chips and fresh roots were 3.33 and 129.58 RVU respectively. The yield of starch from the dehydrated chip was higher than that of the fresh roots however, it was easier to process fresh roots to starch than using the dehydrated chips. This study has established the fact that using dehydrated cassava chips( which provide a good form of storage for cassava) could be processed to both garri and starch of good and acceptable qualities.
Field Comparison of Irrigation Scheduling of Tomato (Lycopersicon Esculentum)
Authors: Okoli C.S.
Published: March 2009

This study of Field Comparison of Irrigation Scheduling of Tomato (Lycopersicon Esculentum) was conducted to determine the response of Tomato plant to water stress from three irrigation schedules, viz: daily irrigation, irrigation at 3- days interval and irrigation at 5-days interval. The water use of the three irrigation schedules for tomato plant was determined using the water balance method. The maximum evapotranspiration for treatments occurred between the 3rd week after planting to the 5th week after planting. Water use efficiency was also highest in irrigation treatment T1 (Daily irrigation) than other treatments. Analysis of variance showed that there were significant differences in the yield at the 5% level among the three treatments. However, the highest biomass yield and fruit yield were observed in irrigation treatment T1. This may be due to increased vegetative growth in treatment T1. The lower yield in irrigation treatment T2 and T3 could be associated with moisture stress which affected the plant at fruiting stage. The result of this study is useful in designing effective irrigation scheduling for Tomato production.
Lime Stabilization of Black Cotton Soil Using Bagasse Ash as Admixture
Authors: Osinubi K.J. , Ijimdiya Thomas Stephen , Nmadu I.
Published: March 2009

Laboratory studies to investigate the effect of Bagasse Ash (BA) admixture on the engineering properties of lime treated black cotton soil was carried out. Black cotton soil is classified as A-7-6 or CH respectively. Bagasse ash is obtained from burning the fibrous residue from the extraction of sugar juice from sugarcane. The results obtained show that the moisture density relationship follows a trend of increasing optimum moisture content (OMC)/decreasing maximum dry density (MDD) at the Standard Proctor compaction energy. California bearing ratio (CBR) values obtained are lower than the 80% CBR criterion for untreated base course materials. The peak CBR value obtained was 31% at 8 %lime/ 4%BA. This value meets the recommended criteria for subgrade materials. The Unconfined compressive strength (UCS) at 7 days is lower than the 1034.25kN/m2 evaluation criterion for adequate lime stabilization. On the basis of the soaked CBR and durability values, it is recommended that black cotton soil can be stabilized for road construction using a 8 % lime/ 4 % BA blend of admixture at standard proctor compaction. However, due to the relative high cost of lime and large quantity that shall be required to achieve stabilization, further study and consideration should therefore be given to the use another additive such as cement to augment and lower the percentage of lime and thus the cost of stabilization.
Effects of Selected Media on Corrosion Behaviour of Mild Steel
Authors: Kareem B.
Published: March 2009

In this study, investigations were carried out on the corrosion behaviour of low carbon steel (mild steel) in the selected media which are cassava extracts, sodium chloride solution (brine), lubricating oil, distilled water and atmospheric air. The test pieces, after chemical analysis were machined to similar dimensions. Each of the specimens was immersed into equal volumes of the selected media except one for the atmospheric air which was placed in the open air. The weight and hardness measurements were carried out every five days for a period of twenty-five days and loss in weight and hardness of the specimens were determined in succession. The results obtained showed that mild steel was more susceptible to corrosion in cassava extracts, sodium chloride and distilled water, than in lubricating oil and atmospheric air. Follow up statistical test results showed that loss in weight is significant for cassava extracts when compared with other media.
Accuracy of Static Differential GPS Techniques; Implications for Structural Deformation Monitoring
Authors: Ehiorobo J.O.
Published: March 2009

In recent years, the need to monitor for Deformation in Engineering Structures such as Dams, Bridges and Tall buildings have become more necessary as a result of reported failures of many of these structures with catastrophic consequences globally. Global Positioning System (GPS) is highly automated and less labour intensive than other conventional techniques used in structural deformation monitoring. For most applications, such as National Geodetic Control Network, Urban Control Network and other Engineering Control Network, an accuracy in the cm level for most GPS work is quite adequate. For Structural deformation monitoring however, the required accuracy is in millimeters. In this paper, the use of Static Differential GPS method with multiple receivers for high precision measurement was investigated using the monitoring Stations at Ikpoba Dam as case study Scenerio. Four units of LEICA 300 Dual Frequency GPS receivers were deployed for code and carrier phase measurements with observation session of 1hr at a sampling rate of 15 sec. Baseline Processing and Least Squares Adjustment of observation was carried out in WGS 84 and NTM reference frames using the LEICA SKI-PRO Processing software and Move. Analysis of the results revealed that the number of outliers in the observation were <5% and the accuracy of horizontal and vertical coordinates were 4mm maximum for horizontal and 2mm maximum for vertical. The study revealed that in areas with favourable satellite constellation and appropriate reduction or elimination of multipath and other noise like errors, Static Differential GPS techniques with a combination of code and carrier phase measurement gives good results for structural deformation monitoring.
Evaluating Microstructural and Hardness Variations in Time Dependent Multipass Welded Mild Steel
Authors: Amuda Muhammed Olawale Hakeem , Oladoye A.M. , Ojemeni K. , Agunsoye Johnson Olumuyiwa , Subair W.
Published: March 2009

This paper investigates the microstructural induced hardness variation in multirun welded plain carbon steel at different interpass time. Beveled 16mm thick mild steel samples were welded in 2 and 4 passes at interpass time of 90, 120 and 240s respectively via manual metal arc. The result showed that the differences in hardness values of the fusion zone and heat affected zone reduce as interpass time increases for both 2 and 4 runs. The effect was however quite distinct in the 4 runs welding cycle. In the 2 run cycle, the fusion zone and heat affected zone merge at 100 seconds; while in the 4 runs cycle, the merging occurred at 25 seconds; indicating that the higher the multipass, the shorter the time required to produce uniformity in hardness and structural homogeneity. Thereby increasing the resistance of the weld to crack susceptibility and failure. At these instances, the microstructure revealed fine grained pearlite interpassed in martensite.
Permeability Characteristics and Classification of Coal Seams in Nigeria
Authors: Olaleye B.M. , Onyemaobi O.O. , Akande J.M.
Published: March 2009

In this work, the permeability characteristics of Nigerian coal seams were determined and these properties were used to investigation the applicability of water infusion in the coal seams to solve coal-mining problems. The experimental work was conducted with Triaxial Compression Machine adapted for the permeability test comprising of Hoek cell, a self- developed water piston, pressure gauge and an overhead water tank. The results of the investigation showed that the permeability measurements of the coals were consistent at the different sites and locations of the coalmines. It also revealed that the difference in coal seam permeability was relatively small in Nigeria.
Effect of Particle Sizes on the Reinforcing Properties of Locally Sourced Filler in Rubber Vulcanisate
Authors: Aluyor E.O. , Oboh I.O.
Published: March 2009

The effect of particle sizes on the reinforcing properties of locally sourced filler (P.K.S) on rubber compound (foot mat) was investigated. This was also compared with the characteristics of kaolin filled vulcanisate. Various particle sizes of kaolin and palm kernel shell (P.K.S); 75µm, 150µm, 212µm and 300µm were used. Different physical tests relating to the required service conditions (hardness and compression set) were carried out on the vulcanisate. From the results, it was observed that P.K.S (pH of 6.25 and moisture content of 10.9%) at particle sizes 75µm and 212µm had better hardness and compression set resistance and this could be recommended for products where these properties are desired.
The Study of Biogeoavailability of Calcium in Ashaka Cement Industry Environs of North Eastern Zone of Nigeria
Authors: Inegbenebor A.I.
Published: March 2009

The samples in the study of Ashaka cement environs were collected on both mineralized and unmineralized ground. These were analyzed to determine the amounts of the elements absorbed by the plants in the area under study using analytical methods (IR, AAS). The observations and prediction of the results show that secondary carbonate minerals, especially those of the common base metals such as magnesium, lead and zinc may be found in Gombe-Bauchi ore bodies include associate minerals. The associate minerals that may be found are hydrozincite, Zn5(CO3)2(OH)6, hydrocerussite, Pb3 (CO3)2 (OH)2 and the very rare mineral plumbonacrite, PbOO(OH)6(CO3)2, Dypingite, Mg5(CO3)4(OH)2.5H2O etc. This is in accordance with the statistical interpretation of the results. The standard deviation were identified as action line , which is equivalent to 59.16 and 49.84 , while two standard error as warning lines, that is resulting in 58.91 . The expectation of these minerals in abundance depends on the ratio of a(Ca2+)/a(Mg2+), a(Ca2+)/a(Zn2+) and a(Ca2+)/a(Pb2+). The technological importances of these associate and very rare minerals are discussed.
Pressure Derivative Studies of a Laterally Infinite Reservoir with a Horizontal Well
Authors: Ovwigho K. , Adewole E. Steve
Published: March 2009

Dimensionless pressure derivatives of a laterally infinite reservoir drained with a horizontal well are studied. The effect of anisotropy on the derivative response is also studied. It is revealed that anisotropy mainly affects the start of the late radial flow regime, and for cases where LD is small (<0.5), affects the end of the first radial flow regime. Time criteria equations were also developed to delineate flow periods and have been shown to give good results for the range 0.00005 ≤ rwD ≤ 0.01 and 0.1 ≤ LD ≤ 100.
Assessing the Rate of Remediation of Polycyclic Aromatic Hydrocarbon Contaminated Soil Using Redox Parameters
Authors: Owabor C.N. , Obahiagbon K.O.
Published: March 2009

This paper investigates the use of redox parameters as a measure of the environmental impact assessment of soil contaminated with polycyclic aromatic hydrocarbons. The levels of naphthalene and anthracene which were used as model contaminants in the soil were periodically monitored along with ferric sulphate and nitrate at ambient conditions. The Brucine and Gelatin Barium methods were employed in estimating the nitrate and sulphate reductions. Experimental results revealed that the microbial utilization of nitrate was faster than that of sulphate; an indication that nitrate is the basic nutrient which provides nitrogen for the metabolic processes occurring during soil remediation. The percentage absorption for both nitrate and sulphate was comparatively higher for the soil unimpacted with polycyclic aromatic hydrocarbons, approximately 49.3% and 26.12% respectively. The percentage absorption of nitrate and sulphate for soil spiked independently with naphthalene and anthracene was found to be 42.18%; 31.21% and 22.93%; 19.74% respectively. The percentage reduction of naphthalene and anthracene in the nitrate and sulphate enhanced soil was 47.5%; 43.1% and 42.5%; 36.5% respectively. These results further affirm that the higher the molecular weight of the polycyclic aromatic hydrocarbon, the slower the rate of its degradation.
An Assessment of Torsional Parameters of Steel Reinforcement Used in the Nigerian Construction Industry
Authors: Orie O.U.
Published: March 2009

This paper determined the torsional strength of steel reinforcements used in the construction industry in Nigeria and compares their Modulus of Rigidity with available standards. Fifteen test specimens were examined from the reinforcing steel of various sizes ranging from 8mm to 20mm diameter which were sourced randomly. The samples were tested with the Torsion Testing Machine until failure. The initial parameters such as gauge length and diameter were considered before the application of torque. The failure torque for the 8mm, 10mm, 12mm, 16mm and 20mm steel reinforcements obtained from the test are 15Nm, 28.81Nm, 77.09Nm, 191.89Nm and 368.99Nm respectively. The result showed that the torsional strength of reinforcement available in the construction industry is below the standard modulus of rigidity of 21000N/mm2 by about 15%.
Sand Production Forecasts for Unconsolidated Gas Reservoirs
Authors: Oyeneyin Babs Mufutau , Moriwawon Babatunde
Published: March 2009

Development of appropriate strategy for the management of reservoirs with sanding problems is rather complex and requires an integrated approach to finding the optimum solution to solving the problem. This requires integration of key aspects of reservoir characterisation, drilling, completion and production technologies including sand tolerances (Seabed wellhead/flow lines, topside facilities. Providing an accurate forecast of the tolerance depends on accurate prediction of sand failure and the corresponding volume of produced sand. This is a transient phenomena further complicated by gas reservoir fluid flow. In this paper the results of a comprehensive Thick Wall Cylinder[TWC] experimental sand production studies carried out on synthetic sandstones are presented. The sand production prediction model for liquid flow are further calibrated and upscaled with field data for gas reservoirs. The prediction model developed is further validated with independent field data with good results. The results represent a first for sand production forecast for gas reservoirs. Mitigation of sanding requires reliable sanding prediction, precise well design, accurate technology selection as well as optimum completion strategy.
Equations for the Z-Factor and Compressibility of Nigerian Natural Gas
Authors: Ohirhian P.U.
Published: March 2009

New equations for calculating the Gas Deviation Factor (z) and the Compressibility of Nigerian Natural Gas have been developed. The equation for the Gas Deviation Factor was developed from a plot of the logarithm of the ratio of Pressure to Temperature versus the logarithm of the ratio of the Pressure to the Gas Deviation Factor.. The plot gave a linear relationship that gave the Gas Deviation Factor equation. A differentiation of the Gas Deviation Factor equation produced the new equation for calculating the Gas Compressibility. Values from the new equation for calculating the Gas Deviation Factor were compared with experimental Pressure, Volume, Temperature (PVT) measurements and the following statistical measurements of accuracy were obtained: Average percent error of 3.050, average absolute percent error of 3.649 and standard deviation of 3.910. Over 75% data tested showed error less than 5 %. A big advantage of the new equations is that they are simple and do not require pseudo critical pressure and pseudo critical temperature needed to obtain z from the current popular equations of state used in the Oil Industry. The data used to develop the model in this work came from Gas associated with produced oil in the Niger Delta. API gravity of the oil, ranged from 17.4 to 44. Pressure ranged from 15 psia to 4015 psia and Temperature ranged between 127 and 205 degree Fahrenheit. This range of data covers at least, ninety five percent of data used in the upstream sector of the Nigeria Oil and Gas Industry.
Enhancing the Output Characteristics of a Photovoltaic Position Sensor Using a Feed-Forward Neural Network
Authors: Agee John T. , Masupe S. , Jeffrey M. , Jimoh Adisa A.
Published: March 2009

Tracking solar-power devices often employ photovoltaic position sensors to detect the angle of misalignment between the axis of mounted solar panels and that of sunlight. The nonlinear input-output characteristics of this type of sensors tend to complicate controller design in such systems. This paper presents a nonlinear mathematical model of the photovoltaic position sensor. A three-layer feedforward neural network was trained to linearise the characteristics of the sensor. The MATLAB neural network tool (nntool) was used for neural network training. A final error of was obtained after training. Simulation of the neural network showed that linear sensor characteristics could be reproduced throughout the domain of sensor operation.
Application of Wind and Small Hydro Energy Sources for Rural Electric Power Supply in Nigeria
Authors: Jimoh Boyi , Jibril Yusuf , Mu’azu Muhammed Bashir
Published: March 2009

The paper looks into the possibilities of using available renewable resources in rural areas for electric power generation for remote consumers. Based on meteorological data (the hourly wind speed) collected and analyzed for Dapchi, a north eastern rural settlement of Nigeria, coupled with hydrological data of River Kamadougu Gena, the hourly power produced from a hybrid power system comprising of wind and small hydro power systems is evaluated and considered as a supply source to electrical loads of the settlement.
Development of an Energy Efficient Solid Fuel for Maximum Emission-Reduction and Regular Heating Rate in Fired Heaters
Authors: Umosekhaimhe G.O.
Published: March 2009

In consideration to the numerous impacts of coal burning especially in domestic indoor fires, a coal-based composite solid fuel has been developed to immensely reduce gaseous emissions, while at the same time maintaining good heat generation rate. The fuel-type which was produced from a mixture of coal and clay solution yielded its optimum heating properties and minimum emission for a formulation of 2:1 of coal: clay solution (1:2.5 of clay: water) by mass fraction. The calorific value of the pure coal was higher than that of composite coal by a factor 1.2 for the same mass of sample used. The formulated composite solid fuel which was found to compete favourably with pure coal, was also efficient toward gaseous emission reduction when combusted at 400oC than at 800oC.
Optimum Seeking Position Control of Solar Collectors
Authors: Kadalla A.S. , Samaila I.L. , Oriolowo N.Z.
Published: March 2009

The main hindrance to the widespread of solar systems is the cost of the solar collectors. Researchers all over the world have been exploring different means of overcoming this limitation in order to make solar conversion more cost effective. This paper describes an experimental work on optimum seeking position of solar collectors using feedback control theory. Single axis tracking mode is employed together with sun seek sensor for automatic reset. The performance of the tracking collector compares favorably against a fixed collector.
System Potential-Based Productivity Evaluation Model
Authors: Anyaeche C.O. , Oluleye Ayodeji Emmanuel
Published: March 2009

Productivity evaluation if based on historical record, and not the system’s potential, does not fully account for the maximum exploitation of the system. This work uses an optimization technique, the Linear Program, to establish the system’s potential; and then developed the Potential-based Productivity Evaluation model. Applying this model in an example problem gave productivity as 0.98, price recovery 1.07 and profitability 1.06; while the historical approach gave 2.81, 0.34 and 0.97 respectively. A comparison show 187% over-reporting, 65% under-reporting and 8% lag respectively. These would affect the firm’s decisions differently. The model can be used for strategic planning.
Computer Aided Raw Material Requirement Planning (CARMRP) for Job Shop: A Case Study
Authors: Adejuyigbe Samuel B. , Ayeni J.A.
Published: March 2009

The use of Material Requirement Planning (MRP) and the evaluation of raw materials using Computer to aid the planning of a job shop have been undertaken. Raw Material Planning (MRP) models and computer programme (Visual Basic) to automatically generate the result was developed. A typical job shop industry was used to test the validity of the model and computer programme developed. It is found readily useful in a developed and developing countries where the situation prevails. The result shows an improvement upon the vigorous manual method used in the time part, and minimizes the service level to the firm’s customer and investment in inventory.
Application of Particle Swarm Optimization Approach to Optimal Tuning of Load Frequency Controller
Authors: Bakare G.A. , Inyanda A.K. , Kunduli M.
Published: March 2009

The task of load frequency controller (LFC) is to maintain the area generation–demand balance by adjusting the outputs on regulating units in response to deviations of frequency and tie-line power exchange. In this paper, the gain of an integral controller for a two area interconnected power system is designed based on the particle swarm optimization (PSO) technique. PSO is a population based stochastic optimization technique derived from simulation of simplified social model. Simulation results on a two area network revealed that the proposed approach optimizes the parameter of integral controller by selecting the optimal gain, which dampens the frequency oscillations and change in tie-line power to zero following a step disturbance.
Surface Roughness Optimization of some Machining Parameters in Turning Operations Using Taguchi Method
Authors: Dagwa Ishaya Musa
Published: March 2009

In this study, an attempt has been made to optimize cutting parameters (cutting speed, depth of cut, and feed rate) in conventional turning operations. A Taguchi orthogonal array (L933) was used in surface roughness optimization of a solid round bar of mild steel material. The experimental runs were randomized; two skilled machinists were involved in the turning operation using the same machining parameters. ANOVA analysis was performed to identify the percentage contribution of the factors affecting surface roughness during machining. The optimal cutting combination was determined by using the signal-to-noise ratio and the following results were obtained; speed (level 2) = 55.m/min, depth of cut (level 3) = 0.08mm, and feed rate (levels 3) = at 0.08mm/rev. A prediction of surface roughness was carried out using the optimal setting followed by a confirmatory test on the lathe. The result shows that the confirmatory runs compared favourably (96.44%) with the predicted surface roughness.
Risering of a Four-Cavity Die Production Mould by Convectional Method
Authors: Zhengwuvi L.B. , Ibhadode Akii Okonigbon Akaehomen
Published: March 2009

This paper demonstrates the possibility of developing skill in producing sound metal casting from a four-cavity die production mould by assessing the riser design criteria and the castings. The assessment takes into account the location of the casting’s hot spots, casting modulus, liquid metal mass in the risers and the principle of directional solidification. The mould flask is oriented in such a way that a riser is placed directly on top of the casting’s hot spots for proper feeding during solidification. The assessment result of casting modulus shows that the feeder modulus Mf = 5.85 x 10-3 M and the casting hot spot modulus Mh = 1.88 x 10-3 M .The assessment result of castings solidification time shows that the castings solidify within 12 seconds while the feeders solidify within 30 seconds. From the assessment results it is observed that the risers hold liquid metal, feed the castings to full solidification and solidify later than the castings which they feed. Examinations at the cross sections of the finished castings revealed the absence of void formation which is a clear indication of effective and functional risers. Thus, the risers have achieved the desired requirement.
An Electronic Patient Record Management System Using Smart Cards
Authors: Eyinagho M.O. , Solomon E. , Adeyemi T. , Ebhohimen D. , Adeniyi D. , Adams D.
Published: March 2009

In this paper, a prototype of an electronic patient record management system using smart cards is described. An application using visual basic was developed, a database using Microsoft access was built, the visual-basic-based application was then interfaced to the database. An interface module that allows any person with no programming knowledge to store easily, required information on a smart card was also developed. The application was then interfaced to a smartcard reader. With this system, relevant patient information including, but not limited to allergies, blood-group, and past operations can be retrieved from the smart card.
Design and Manufacture of Palm Nut/Fibre Separator
Authors: Igboanugo A.C. , Ovuworie Godwin C.
Published: March 2009

Sorting of palm nuts from palm fruit cake, a byproduct obtained after palm oil has been extracted from the batch of digested palm fruit, is burdensome especially to small-scale entrepreneurs involved in palm oil processing business in Africa. This paper has triumphed over the perceived difficulties by using the knowledge of processing engineering to design pilot nut/fibre separator that can efficiently and speedily sort out nuts from nut/fibre mesh. Basic design considerations necessary to achieve reliability of the machine are discussed. Performance evaluation data from the machine obtained were related to its industrial correlate and, in particular, the van der Waerden Normal Scores test carried out inclined us to accept, at a p-value of 0.941, the null hypothesis of no significant difference in processing time between the pilot nut/fibre separator and its industrial counterpart.
Computerised Design Approach to a Sub-Press Mould for Composite Materials Manufacture
Authors: Dagwa Ishaya Musa , Ibhadode Akii Okonigbon Akaehomen
Published: March 2009

This paper focuses on the design of a sub-press mould mounted on a 100-Tonne hydraulic press during compression moulding of composite materials manufacturing process. The sub-press consisting of platens, punch and mould, and guide columns were designed using Microsoft Visual Basic software to minimize time wastages in trail-and-error procedures and mould modifications resulting after the mould is manufactured. Graphical representations of variables which were used in the design such as: platen thickness, guide pin dimensions, clamping force, heat supply, heat losses, and heating element were obtained. The program developed was tested on a solved example in a standard textbook and the result obtained compared well with the result in the book.
Quality Characteristics of Basic Hand Tools Sold in Nigeria
Authors: Oyawale F.A. , Ogunmolati M.A.
Published: March 2009

Hand tools sold in Nigeria have become increasingly unreliable due to critical failures during use. The objective of this study is to test samples of these tools vis-à-vis manufacturer’s claims. A total of fifteen (15) hand tools from six (6) different countries available on the Nigerian market were tested for their quality characteristics. The tested tools included spanners, hammers, screwdrivers, pliers and chisels. Three samples of each of the groups of hand tools were ranked in accordance to their impact energy which is a major property of percussion tools. The results showed that built-in mechanical properties of these hand tools were largely controlled by their alloying elements, manufacturing processes and heat-treatment. Five (5) of the fifteen (15) selected hand tools conformed to BS 876, 1981 and were adjudged safe and reliable.
Design, Development and Performance of Palm Waste Briquette Stove for Domestic and Industrial Usage
Authors: Ilechie C.O. , Aibangbee G.F. , Ogblechi S.R. , Amiolemhen P.E.
Published: March 2009

A low cost heat-conserving stove that uses palm waste briquette (substitute for fuel wood) has been developed. It has a furnace size of 400mm diameter and a height of 400mm with a 90mm inner cylindrical burner. The heating surface of the stove generated about 966 kilojoules of heat. A natural draught of 6m/s (efflux velocity) was used to determine the chimney size. The stove which was designed and fabricated mostly from 3mm low carbon steel (mild steel) material can accommodate different sizes of briquette for both domestic and industrial cooking. The air inlet has a regulating duct that controls the burning of the briquette. The burning rate of the palm waste briquette using the briquette stove was estimated to be approximately 3.0kg/hr. This value was found to be lower than values obtained when the same quantity of briquette was burnt in the open air. The technology is recommended for adoption by women preparing snacks (such as roasted yam. plantain and corn) in market places and along commercial roads.
Batch Treatment of Palm Oil Mill Effluent
Authors: Aisien F.A. , Ojarikre A.A. , Aisien E.T.
Published: March 2009

Batch treatment of palm oil mill effluent (POME) was investigated using physical, chemical and biological methods. Physiochemical parameters such as pH, sulphate (SO42-), total dissolved solids (TDS), total suspended solid (TSS), chloride ion (Cl-), biological oxygen demand (BOD), chemical oxygen (COD) and metals (Fe2+, Zn2+, Ca2+ and Mg2+) concentrations were determined using American Public Health Association (APHA) methods. The results revealed that significant treatment was achieved at each stage. However, the biological method proved to be the best with percentage reductions of 45.6%, 97.6%, 71,0%, 50.1%, 80.4%, 93.8%, 72.0%, 85.4%, 93.2%, 77.7%, 86.2% and 85.7% for pH, SO42-, TS, TDS, TSS, Cl-, BOD, COD, Fe2+, Zn2+, Ca2+ and Mg2+ respectively. The concentrations after treatment were in conformity with the minimum acceptable standard of FEPA and WHO.
Solid Waste Crisis in Nigeria – A Case Study of the Constraint to Effective Private Sector Participation (PSP) on Solid Waste Management in Lagos Metropolis
Authors: Igbinomwanhia D.I. , Olanikpekun J.
Published: March 2009

Among the multitude of problems existing in the fast urbanizing towns and cities in Nigeria, Solid waste appears to be the most prominent in recent years. Solid waste is seen in huge heaps on any piece of unused land, around buildings and in the open market places. Living with solid waste littered around appears to be an acceptable way of life among the people in most cities in Nigeria in recent years. The work reported in this paper involves a preliminary study of residential solid waste management in the Lagos metropolis in Nigeria. A site-specific study was carried out to estimate the quantity of residential solid waste generation, disposal and management in the metropolis. Structured questionnaires were applied to collect primary information such as size of households, income, Educational level etc. from households. The results obtained indicated that the problem of insufficient available data, insufficient funding, poor understanding of solid waste management by the PSP operators and poor publics attitude are the causes of solid waste crisis in Nigeria. Proposal on strategies for the improvement of the effectiveness of the PSP operators in Lagos metropolis has been presented.