bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimisation of Springback Predicted by Experimental and Numerical Approach by Using Response Surface Methodology
Authors: Bahloul R. , dal Santo Phillippe , Mkaddem Ali , Potiron A.
Published: March 2009

Bending has significant importance in the sheet metal product industry. Moreover, the
springback of sheet metal should be taken into consideration in order to produce bent sheet metal parts within acceptable tolerance limits and to solve geometrical variation for the control of manufacturing process. Nowadays, the importance of this problem increases because of the use of sheet-metal parts with high mechanical characteristics (High Strength Low Alloy steel). This work describes robust methods of predicting springback of parts in 3D modelling subjected to bending
and unbending deformations. Also the effects of tool geometry in the final shape after springback are discussed. The first part of this paper presents the laboratory experiments in wiping die bending, in which the influence of process variables, such as die shoulder radius, punch-die clearance, punch nose radius and materials properties were discussed. The second part summarises the finite element analysis by using ABAQUS software and compares these results with some experimental data. It appeared that the final results of the FEM simulation are in good agreement with the experimental ones. An optimisation methodology based on the use of experimental design method and response surface technique is proposed in the third part of this paper. That makes it possible to obtain the optimum values of clearance between the punch and the die and the optimum die radius which can reduce the springback without cracking and damage of product.
Magnesium Sheet Metal Forming Considering its Specific Yield Behavior
Authors: Redecker M. , Roll Karl , Häussinger S.
Published: March 2009

In recent years very strong efforts have been undertaken to build light weight structures of car bodies in the automotive industry. Structural technologies like Space Frame, tailored blanks and relief-embossed panels are well-known and already in use. Beside that there is a large assortment of design materials with low density or high strength. Magnesium alloys are lighter by approximately 34 percent than aluminum alloys and are considered to be the lightest metallic design material. However forming processes of magnesium sheet metal are difficult due to its complex
plasticity behavior. Strain rate sensitivity, asymmetric and softening yield behavior of magnesium are leading to a complex description of the forming process. Asymmetric yield behavior means different yield stress depending on tensile or compressive loading. It is well-known that elevated temperatures around 200°C improve the local flow behavior of magnesium. Experiments show that in this way the forming limit curves can be considerably increased. So far the simulation of the forming process including temperature, strain rates and plastic asymmetry is not state-of-the-art.
Moreover, neither reliable material data nor standardized testing procedures are available. According to the great attractiveness of magnesium sheet metal parts there is a serious need for a reliable modeling of the virtual process chain including the specification of required mechanical properties. An existing series geometry which already can be made of magnesium at elevated temperatures is calculated using the finite element method. The results clarify the failings of standard calculation methods and show potentials of its improvement.
Basic Investigations on the Hot Stamping Steel 22MnB5
Authors: Geiger Manfred , Merklein Marion , Hoff Cornelia
Published: March 2009

Basic research concerning the material properties of the hot stamping steel 22MnB5 has been carried out. A survey is given about the as-delivered conditions with hardness tests, micrographs and flow curves. The process window of the austenitization time, before hot stamping can take place, is defined by austenitization tests. Also a new experimental set-up to detect the cooling rate in dependency on the contact pressure is presented. In addition to that the cooling experiments were simulated with ABAQUS and the heat transfer coefficient for each contact pressure is determined by inverse modeling.
Advanced Cutting Technology in Process Chains for High Strength Steels
Authors: Neugebauer Reimund , Kräusel V. , Bräunlich H.
Published: March 2009

The application of high-tensile sheet metal materials in car body construction requires the development of new production strategies for preparing sheet metal part edges where laser welding operations have to be performed. Using up this sheet materials in cutting processes for car bodies lead to higher stressing of active tool parts. To arrive the same tool life quantities as is presently the standard in the production process using conventional materials it is necessary to modify the tool
designs for cutting tools, to determine well adapted tool materials and coatings, to choose modified lubricants and to optimize the surface quality of tools for cutting operations.
An Automatic Cost Calculation System for 3-D Laser Cutting Based on Characteristic Numbers
Authors: Masur M. , Liébana F. , Stute U.
Published: March 2009

At present, small and medium-sized enterprises (SME) in the sheet metal industry
performing 3-d laser cutting have to invest a considerable amount of time in offer preparation, although there is a low probability of obtaining the order. The offer calculation is mostly done manually and rapidly, as estimation. For example, the length of the contours to be cut are extracted from drawings and summed up. The actual production time for problem areas of the workpiece geometry like sharp angles and narrow radii can only be calculated by a post-processor simulation, or by a comparison with a similar workpiece that was manufactured before. This complicates the cost calculation and adds an unknown factor to it. Therefore, only experienced employees can estimate the costs for the cutting of 3-d workpieces. The aim of the proposed automatic cost calculation algorithm is the quick machining time calculation for 3-d laser cutting. Less experienced persons should be able to use a pre-configured tool. Characteristic numbers are generated on the basis of the workpiece geometry. They describe all necessary machine work that is required to
manufacture the current workpiece. In a next step, the dynamic machine behaviour for these problem areas needs to be examined. It is projected to specific machine parameters. As example the acceleration and the maximum cutting velocity are basic parameters. By connecting the characteristic numbers with the machine parameters, the machining time for a specific machine is calculated. This machining time is an important factor for the cost calculation. The characteristic numbers can also be used to find similar workpieces within a database. This database contains existing and already evaluated offers. As a plausibility check the user can search for similar offers and compare them with the currently prepared one.
Preparation of Arsenic Trioxide-Loaded PLGA Nanoparticles and Investigation of its Inhibitory Effects on Proliferation of Rabbit Vascular Smooth Muscle Cells In Vitro
Authors: Zhao Su Su , Lu Qin , Zhang Dong Sheng
Published: March 2009

Proliferation and migration of vascular smooth muscle cells(VSMCs) into the sub-intimal space play an important role in intimal thickening in atherosclerosis and in-stent restenosis. Arsenic compounds are natural substances that have been used in the treatment of patients with acute promyelocytic leukemia (APL).And Arsenic trioxide (As2O3) is known to be a potent inhibitor of cell proliferation.The aim of this study was to prepare arsenic trioxide (As2O3) -loaded PLGA nanoparticles(As2O3-PLGA-NP) and investigate its general properties, preservation of As2O3 bioactivity and their inhibitory effects on Rabbit Vascular Smooth Muscle Cells(RVSMCs) in vitro. With PLGA as carrier,As2O3 drug delivery nanoparticles were prepared by w /o /w double-emulsion evaporation technique，and their inhibitory effects on Rabbit Vascular Smooth Muscle Cells(VSMCs) in vitro was investigated.The results of the experiment show the self-prepared As2O3-PLGA-NP were approximately spherical,with the mean diameter of 90±25.03 nm, and the average drug loading was 1.72% .The As2O3-PLGA-NP has drug sustained-release character and can prolong the phase of the inhibitory effect of As2O3 against RVSMCs.The As2O3-PLGA-NP do not reduce the biological activity of As2O3.
Precision Calculation for Stiffness of the Complex Microstructure
Authors: Liu Yu , Wen Zhi Yu , Yang Hong Yun
Published: March 2009

The stiffness of microstructure is an important parameter of the microsensor. It is usually obtained by FEM approach, which is difficult to give an analytical expression. This paper reports on a 2-D microaccelerometer with the complex microstructure. Its main axial stiffness is carried out by using force method as well as principle of work and strain energy. During the deduction, deformation of all beams is taken into account, so the theoretical results are in accordance with that of FEM approach very well and the error is less than one in thousand. Furthermore, we neither introduce the other assumptions nor design the special dimension. So this methodology is strict in theory, and can be extended to analysis for the displacement and stiffness of the symmetric and statically indeterminate microstructure.
Deep Hole Fabrication Based on ICP Process
Authors: Zhuo Min , Chen An Ding , Zhu Jian , Zhang Long
Published: March 2009

This paper presents deep-hole etching process by inductively coupled plasma (ICP),the hole is higher than 400um ,and its diameter is 200um wide. Etching process successfully used in anchor fabrication below 150 um deep in micro-inertial devices, is first used in deep-hole etching .The result is badly, the sidewall surface is coarse, and the sidewall perpendicularity is poor,the dimension difference between upper and down diameter is as large as 35um.Because with the depth increasing , deep-hole etching brings new problem, such as fluorine(F) radical and ions distributing very differently between in down and upper area, also extracting reactant and temperature distribution . To solve above problems, process parameters such as gas flow mass and time in one reaction cycle, source and substrate power, reaction pressure and temperature should be adjusted. Through several experiments, optimal process is applied and the result is satisfied .From SEM figure, The the sidewall surface is smoother, the sidewall perpendicularity is good, the dimension difference between upper and down diameter is controlled in 1.6um,the sidewall angle is 89.78°. The process has been used in deep-hole fabrication of micromachined filter, and the rate of device enhances largely at present.
Highly Sensitive Determination of Dopamine Using Osmium/Nafion Modified Disposable Integrated Biosensor
Authors: Liu Chun Xiu , Liu Hong Min , Yang Qing De , Lin Nan Sen , Song Yi Lin , Wang Li , Cai Xin Xia
Published: March 2009

A biosensor based on gold electrode modified by Pt nanaoparticles/Osmium redox polymer/Nafion trilayer film was fabricated and used for selective and sensitive determination of dopamine. The biosensor is explored for DA sensing using the cyclic voltammetry (CV), amperometric and differential pulse voltammetric (DPV) methods. The CV anodic peak currents showed a linear range with a correlation coefficient of 0.996, localized in the concentration range 0~192 μM. The differential pulse voltammetric (DPV) peak currents were linear with DA concentration during 2~425 μM with correlation coefficient of 0.99. The biosensor showed high sensitivity of 0.5 nA /nM cm2 and excellent reproducibility with the detection limit of ~10 nM (S/N=3) for the determination of DA. The easy fabrication, low detection limit and high sensitivity of the integrated biosensor making it particularly suitable for the analytical purposes.
Size-Dependent Elasticity of Silicon Nanowires
Authors: Zhang W.W. , Huang Qing An , Yu H. , Lu L.B.
Published: March 2009

Molecular dynamics simulations are carried out to characterize the mechanical properties of [001] and [110] oriented silicon nanowires, with the thickness ranging from 1.05nm to 3.24 nm. The nanowires are taken to have ideal surfaces and (2×1) reconstructed surfaces, respectively. A series of simulations for square cross-section Si nanowires have been performed and Young’s modulus is calculated from energy–strain relationship. The results show that the elasticity of Si nanowires is strongly depended on size and surface reconstruction. Furthermore, the physical origin of above results is analyzed, consistent with the bond loss and saturation concept. The results obtained from the molecular dynamics simulations are in good agreement with the values of first-principles. The molecular dynamics simulations combine the accuracy and efficiency.
Thermal Conductivity Measurement for Carbon-Nanotube Suspensions with 3ω Method
Authors: Wu Gen Sheng , Yang Jue Kuan , Ge Shu Lin , Wang Yu Juan , Chen Min Hua , Chen Yun Fei
Published: March 2009

The stable and homogeneneous aqueous suspension of carbon nanotubes was prepared in this study. The stability of the nanofluids was improved greatly due to the use of a new dispersant, humic acid. The thermal conductivity of the aqueous suspension was measured with the 3ω method. The experimental results showed that the thermal conductivity of the suspensions increases with the temperature and also is nearly proportional to the loading of the nanoparticles. The thermal conductivity enhancement of single-walled carbon nanotubes (SWNTs) suspensions is better than that of the multi-walled carbon nanotubes (MWNTs) suspensions. Especially for a volume fraction of 0.3846% SWNTs, the thermal conductivity is enhanced by 40.5%. Furthermore, the results at 30°C match well with Jang and Choi’s model.
The Dispersivity of Multi-Walled Carbon Nanotubes (NMWTs) and Pressure-Sensitive Property of NMWTs Reinforced Cement Composite
Authors: Luo Jian Lin , Duan Zhong Dong
Published: March 2009

The individual and/or combinatory impacts of two surfactants (polyoxyethylene nonyl phenyl ether 10 (Tx-100), Arabic gum powder (AG)) on the dispersivity of multi-wall carbon nanotubes (NMWTs) were firstly investigated and evaluated through naked and microstructures observation; hereafter, NMWTs with 1.0% loading were firstly dispersed in aqueous solution with surfactant ultrasonic dispersion process, and cast-mixed into cement matrix to fabricate 2 groups NMWTs reinforced cement composites (NMTRCs), associated with the plain reference. Wheatstone bridge configurations were simultaneously employed to obtain the resistances and the monoaxial stresses, to investigate the pressure-sensitive properties of these nanocomposites. Results with naked observation reveal that either Tx-100 or AG at some concentration has good dispersion effect on NMWTs, the blackness homogeneity and stability of NMWTs suspended solution could retain more than 15 d; yet microstructures results show that NMTRC with AG has more homogeneous dispersion impact and more compatible with cement hydration than that with Tx-100. Results related on the pressure-sensitive properties of NMTRCs demonstrate that, the fractional change in resistivity of NMTRC with AG linearly falls down by increment of applied pressure within elastic range, this good pressure-sensitive traits mainly contribute to the increasing chance of physical contacts, the denser of current chargers between NMWTs, and the shortened trend of the potential barrier widths between NMWTs and matrix by increment of pressure, after efficient dispersion with AG. Yet that of NMTRC with Tx-100 has not good linearity descending trend, but some exaggerate fluctuations, and that of the reference has also no any regular descending trend.
The Characterization and Photocatalytic Properties of Mesoporous WO3•0.33H2O•NiO Nanocrystalline Synthesized through Using the Microwave Radiation Method
Authors: Zou Li Xia , Liu Qing Cheng , Zhong Qing , Bai Xiu Ming , Dong Li Jun
Published: March 2009

Mesoporous WO3•0.33H2O was synthesized by the microwave radiation method using surfactant as the template-directing agent, and the template was removed by Soxhlet extraction. The degree of framework substitution had been monitored by means of powder X-ray diffraction (XRD), nitrogen adsorption, and UV-vis diffuse reflectance (DRUV) spectroscopy techniques. Nitrogen adsorption data and XRD patterns confirmed that, the structure, high surface area, and uniform pore size distribution were maintained in the crystallized samples. The photocatalytic activity for the photo-oxidation of gaseous formaldehyde on the mesoporous WO3•0.33H2O synthesized was improved by NiO loading, the photocatalytic activity was higher than both that of the materials synthesized using calcination in high temperature and commercial Degussa P25 TiO2 under visible light and UV irradiation.
An Excellent Platinum Piezoresistive Pressure Sensor Using Adhesive Bonding with SU-8
Authors: Pang Cheng , Zhao Zhan , Shi Li , Du Li Dong , Fang Zhen
Published: March 2009

An excellent pressure sensor based a simple fabrication technology is presented. Differently from the present prevailing fabrication process of silicon piezoresistive pressure sensor: platinum is used as the sensing material, with a smaller but acceptable sensitivity and much simpler processes; adhesive bonding with SU-8 is used as an alternative choice to anodic bonding, and we choose a vacuum hot plate to avoid using a bonding machine. To achieve a successful bonding, it is found that pre-bake time and pumping time are the most important factors. Bonding quality is evaluated by inspection through the glass with 95% of the area successfully bonded and the failed area in the edge of the wafers. The measured bonding strength is 17.34 MPa. The Pressure-Voltage characteristic test results display a good linearity within 0.2% and especially a good precision within 0.035% in square fitting. The temperature drifting is also tested and the TCO is 1250 ppm/(°C FSO). The long-term stability of the sensor at a constant pressure is a fluctuation within 40 Pa (0.098% FSO) in 7 days. Both the simple fabrication process and the excellent performance of the sensor suggest that this sensor is a much good choice in measuring atmospheric pressure.
Design and Parameter Estimation of a Three Phase Induction Motor Using a User-Interactive Computer Programme
Authors: Ubeku E.U. , Ogujor E.A.
Published: March 2009

This paper presents the use of a user-interactive MATLAB programme for the design and the parameter estimation of a three-phase induction motor (TPIM) using a per phase equivalent circuit model. Optimum design parameters such as the bore diameter, the rotor diameter, the slot dimensions, the air-gap length and the performance curves are obtained by iterative procedure of a design algorithm. The performance curves of the TPIM i.e., torque and efficiency are drawn from the model’s per phase parameters and then analyzed for different number of poles, number of slots ,varying air-gap, rated slip etc and their effect on the performance of the TPIM are analyzed and the results discussed. The results obtained were validated with similar studies carried out using finite element software FEMM. The comparison shows that the TPIM model is satisfactory.
An Impact Assessment of the Nigerian Power Sector Reforms
Authors: Wara S.T. , Abayomi-Alli A. , Umo N.D. , Oghogho I. , Odikayor C.D.
Published: March 2009

This paper examines the various reforms carried out in the Nigerian power sector between the year 1999 and 2007 and its impact on the life of the average citizens. Efforts were made to review relevant literatures, questionnaires were administered and forty-nine responses were received and the result was analyzed through the use of simple percentages and correlation coefficient. The correlation coefficient method, r (the product moment of the correlation was negative and of magnitude -1, implying a perfect correlation in the negative direction (deregulations and reforms are not improving the power sector of Nigeria yet). The research hypothesis, HR, stated that the deregulation and reforms did not evidently improve the power sector. It was recommended that the government should continue the rehabilitation of the various power systems in a guided manner to allow a core Nigerian investor, consider alternative sources of energy like solar, tide, biomass, wind.
Investigation of the Characteristics of Radio Signal Propagation in Indoor Environment
Authors: Emagbetere J.O. , Edeko F.O.
Published: March 2009

The success of wireless local area networks (WLANs) has led to an intense interest among wireless engineers in understanding and predicting radio propagation characteristics within buildings. This paper present radio signal propagation measurement and modeling at 2.4GHz, within a building in the Faculty of Engineering, University of Benin. A base station built around SENAO access point, and a PA24 flat panel directional antenna of 19dBi gain and 17.50 beam-widths was setup for the experimentation. Signals were monitored from the fixed BS using LINKSYS, and NET STUMBLER version 4.0 software run on a Laptop. In this report, the effect of multi-path and delay spread was not considered. The result of the investigation revealed a significant attenuation of the radio signal within the small distance. A path loss exponent of 7.8 to 8.9 on the ground floor, and 2.9 to 5.2 for the 2nd floor were obtained for the period of investigation.
Automatic Transfer and Controller System for Standby Power Generator
Authors: Adoghe A.U. , Odigwe I.A.
Published: March 2009

An automatic transfer system (ATS) was developed to monitor the a.c. voltage coming from Power Holding Company of Nigeria (PHCN) line for power failure conditions. Upon detection of an outage for a predetermined period of time, the standby generator is started, once is up to speed, the load is transferred from the PHCN line to the local Generator.
This ATS is capable of electrically monitoring fuel level, oil level, Battery strength, next maintenance schedule and then start or stop the unmanned Generator from the computer system located in the comfort of homes or offices outside the Generator site.
In this paper therefore, an Automatic Transfer System (ATS) for Power Generator is designed to improve the operation and maintenance of power generators. The ATS which includes both hardware and software module, provides a functionality that allows a power generator to be controlled and monitored from a remote location
Determination of Cutting Resistance of Sugar Cane (Saccarum officinarum) Using a New-Type Test Machine
Authors: Maude F.A. , Itodo I.N. , Sule S.
Published: March 2009

The cutting resistance of sugar cane was determined by use of a new-type manually operated agricultural test machine using two sugar cane varieties Noble (A) and Indigenous canes (B). The moisture content of the sugar cane used in the study was determined by the oven dry method. The cutting force and power required were determined using the test machine. The results showed that the average liquid content for variety A and B were 80% and 75% respectively. The cutting resistant for variety A and B were 3.93 kN/m and 5.5 kN/m respectively. The average applied cutting force of 147.3 N for variety B was higher than 130.7 N for variety A. The average power requirement for cutting variety A and B were 8.28W and 9.89W respectively. An analysis of the results using ANOVA at p ≤ 0.05 showed that there was no significant difference in the measured parameters for the two varieties of sugar cane used in this study. The results obtained will be useful in the design and manufacturing process of cutting tools for sugar cane.
Development and Performance Evaluation of a Manually Operated Cowpea Thresher
Authors: Umogbai V.I. , Shehu A.
Published: March 2009

Threshing is one of the major problems associated with cowpea production in Nigeria. In spite of the food and nutritional importance of the crop to human diet, its threshing has been and remains a serious problem to the farmers. The techniques for threshing cowpea in most rural areas are still the traditional methods of seed separation which are uneconomical, labourous and time consuming. A manually operated cowpea thresher to stimulate manual threshing has been designed, fabricated and tested. The thresher was fabricated using locally available materials at the engineering workshop of the University of Agriculture, Makurdi. Two varieties of cowpea (B301 and C70) were tested on the thresher for performance evaluation in terms of thresher efficiency and mechanical (visible) damage. The test results revealed that for optimum performance, the thresher should operate at a cylinder speed of between 60-75rpm at a feed rate of 24kg/hr.94%-97% threshing efficiency was achieved for the two varieties of cowpea. The cost of production is N15,686:00
Effects of Linear Alkyl Benzene Sulfonate Detergent on the Activity of Cassava Fermenting Enzyme
Authors: Aisien E.T. , Elaho E.R. , Aisien F.A.
Published: March 2009

The effect of linear alkyl benzene sulfonate (LAS) detergent on the activity of cassava fermenting enzymes was investigated for 72 hrs. Enzymatic assay methods were used to determine the activity of cassava fermenting enzymes: cellulase, α-amylase, pectin methyl esterase and phosphorylase. The cassava fermenting media were made up of LAS detergent concentration of between 1g/L to 5g/L. The results show that the LAS detergent of 2g/L and 3g/L gave optimum enzyme activity. The order of enzyme activity was pectin methyl esterase > α-amylase > phosphorylase > cellulase.
Responsive Production Systems and Roles that Robots can Play
Authors: Weston R.H.
Published: March 2009

With increased product dynamics world-wide, the average economic lifetime of production systems is falling. Industrial robots are widely assumed to be inherently flexible and therefore that they can function as a programmable building block of response production systems. This paper reviews common capabilities of contemporary industrial robotic systems and investigates their capability to extend the useful lifetime of production system by coping with different types of product dynamic. Also considered are relative capabilities of conventional programmable robots and an emerging generation of programmable and configurable component-based machines.
Design of Compatibilizing Interfacial Polymer Layers Using a Macroinitiator
Authors: Oduola M.K.
Published: March 2009

. Immobilization of an amine-containing peroxide macroinitiator APM onto solid mineral surfaces has been achieved via physical/chemical adsorption of its macromolecules from solution. A systematic variation of reaction parameters upon graft polymerization initiated by surface-attached APM including nature of monomer and solvent has been conducted. The effect of solvent and nature of monomer on the overall constant of polymerization, effective activation energy, initiation efficiency as well as other parameters of elementary stages of the process has been established. It has been revealed that the involvement of TiO2 particles with the surface-attached radicals in the heterogeneous polymerization process profoundly influenced all the elementary stages, particularly chain transfer and termination.
Determination of Optimum Welding Flux Composition Using the Bend Strength Test Technique
Authors: Achebo Joseph I. , Ibhadode Akii Okonigbon Akaehomen
Published: March 2009

This work developed several welding flux compositions and came up with an optimum composition using the bending strength test technique. The technological performance of the optimum flux compositions with respect to the bend test was 230kN/m2. Preliminary weld tests showed that the flux performed well.
Influence of Gamma Radiation on the Radiofrequency Dielectric Properties of Nigerian Crude Oil
Authors: Osahon O.D. , Nworgu O.D.
Published: March 2009

This paper examines the relative permittivity of irradiated and non-irradiated crude oil samples in the frequency range 0.1 – 100.0MHz and room temperature regulated at 25 ± 1oC. Samples of crude oil of mean specific gravity 0.780 ± 0.015 were irradiated for periods of two, four, six, eight and ten months respectively using a gamma radiation source (Cobalt 60) at a dose rate of 0.65mSv per hour. Dielectric measurements were made by using a Boonton RX meter type 250A admittance bridge manufactured by central research Laboratories, Inc, Red, Wing, Minnesota. Analysis of the resulting dielectric data revealed that both the irradiated and non-irradiated samples exhibited dielectric dispersion over the frequency range investigated. However, the relative permittivity values of the irradiated samples were found to be higher than those of the non-irradiated sample. This difference is understandable as it can be attributed to the ionization of atoms and weakening of molecular bonds in the irradiated samples. The increase in relative permittivity for the irradiated samples was observed to be time dependent as the longer the time of irradiation of sample the higher the value of its relative permittivity. Also, in this study, it was observed that the non-irradiated crude oil sample has longer relaxation time than the irradiated ones. The relaxation time decreases gradually with increasing irradiation time. This has physical significance on the basis of the molecular theory of matter and the fact that relaxation time is inversely proportional to relaxation frequency. These results are comparable with the work of other researchers for which similar trends have been observed.
A New Correlation for the Viscosity of Natural Gas
Authors: Ohirhian P.U. , Abu I.N.
Published: March 2009

A new equation for the viscosity of Natural Gas under Reservoir conditions has been developed. The equation was obtained by the analysis of experimental Pressure, Volume and Temperature (PVT) Data of Gas associated with Nigerian Crude Oil. The PVT Data were those of renowned companies that operate in Nigeria. The pressure ranged from 144 psia to 4100 psia, and a temperature variation between 130oF and 220oF. Comparison of the equation formulated in this work with experimental PVT viscosity gave an average absolute error of 1.55%, a maximum absolute error of 4.878% and a standard deviation of 1.29. A comparison of viscosity obtained from the charts of Carr et al and the equation of Lee et al with Nigerian PVT Viscosity showed that the new equation gave more accurate result. Since some Correlations perform better when applied to data from which they were derived, a further comparison test was performed. In this test, the new equation was used to solve two problems for which solutions by the method of Carr et al were available. The first problem from the Handbook of Natural Gas Engineering by Katz et al gave a viscosity of 1.158cp while the new equation gave 1.157cp. The second problem from Ikoku’s book (Natural Gas Production Engineering) gave a viscosity of 1.178cp and the new equation also gave 1.178cp. This closeness of the viscosity of the new equation to the values from the Carr et al method proved the applicability of the new equation to any type of Natural Gas.
Designing Architect’s Brief for a Faculty of Engineering
Authors: Oladiran M.T. , Foster J.
Published: March 2009

A team of academics produced a Design Brief (DB) to assist architects design a scholarly physical environment for modern engineering education and research. The information gathered from external and internal sources was used to define important themes that the buildings should reflect and hence to arrive at a list of the required spaces. Critical internal and external reviews and budget constraints led to a series of successive refinements of the DB. A design competition was organised for all interested architects in the country to select the architect for the project and consolation prizes were awarded to second and third finalists. The planned development will provide 17900 m2 and 25200 m2 net usable space and estimated gross building area respectively.
Evaluating Solution Methods to Bicriteria Scheduling Problems
Authors: Oyetunji Elkanah , Oluleye Ayodeji Emmanuel
Published: March 2009

This paper considers the scheduling problem of minimizing two criteria (bi criteria) at a time. The challenge of how to evaluate solution methods for bicriteria problems was first addressed. Then, two important issues of skewness (arising when the values of one criterion is a multiple of the other) and dimensional conflict (arising when the two criteria are not of the same unit) were tackled through a proposed normalization procedure. The methodology for determining the minimum and maximum possible values of the two criteria was also demonstrated.
Evaluation and Improvement of Dvorak Keyboard Layout Using CADWORK
Authors: Udosen U.J.
Published: March 2009

The keyboard layout proposed by Dvorak has been evaluated and improved by CADWORK. Data prepared with characters of the Dvorak layout were fed into CADWORK to search for improvement. The criterion employed by CADWORK for evaluation is the cycle time simulated using methods analysis of operations data. An improved layout was generated yielding a cycle time of 616.09 TMU while the Dvorak layout yielded a time of 622.69 TMU. A test to determine acceptability of the CADWORK improved layout using experienced keyboard users indicated that some participants typed faster with the CADWORK layout than others using the Dvorak layout.
A Study of Urban Traffic Management- A Case Study of Lagos State Traffic Management Authority
Authors: Bello E.I. , Usifo C.I.
Published: March 2009

Lagos state is the commercial and financial capital of Nigeria. It is a coastal city with a population of 12 million and covers 2000 square kilometers. The road network extends over 2700 km with a vehicle density of 740 vehicles per kilometer. It consumes over 85% of petroleum products imported into the country. It has no rail or sea mass transit system and all movements of people and goods are by road. This has created a major traffic Management challenge and government intervention is the establishment of the Lagos State Traffic Management Authority( LASTMA). To understand the structure, strength, and weaknesses of the authority, the enabling law and accident statistics, were obtained from the Authority, the Nigerian Police, and the Federal Road Safety Commission. Questionnaires were administered to drivers unions and the general public. The results were analyzed and it was discovered that conflicts across agencies, corruption and high handedness exist. It was also established that the authority has to a great extent succeeded in improving orderliness on Lagos roads. LASTMA needs to pursue an aggressive public enlightenment to change driver’s behaviors.
Development of a Model for Analysing Forging Process
Authors: Akpobi John A. , Edobor C.O.
Published: March 2009

This paper reports an examination of the stresses and pressure fields set up at various cross-sections of a material during forging operation by the weighted residual finite element method. We present the numerical solution to the one-dimensional differential equation which describes the pressures and stresses exerted on a forging. In conducting the analysis, we split the blank into a finite number of elements and apply the Bubnov-Galerkin weighted residual scheme to obtain the weighted integral form; the finite element model is then developed from this weighted integral form which is solved to yield a three-parameter polynomial solution. Using series of examples, we show that the weighted residual finite element method is capable of accurately predicting the pressures and stresses in an open die forging operation.
Mathematical Modeling of a New Improved Design of a Rail Carriage Suspension System for the Wagons Used in Zimbabwe
Authors: Mbohwa C. , Agwa-Ejon J. , Murasiki C.
Published: March 2009

This paper discusses the mathematical modeling of a new improved design of the carriage bogie suspension system with emphasis on design for human comfort. The research mainly covered the shock absorbers with the aim of improving ride comfort at higher speeds. The paper focuses on how to reduce vibration transmission to the carriage while designing a railway bogie suspension damping system that is easier to maintain but does not compromise on quality with particular interest in dynamic attributes of the shock absorber. The principal research issues are introduced and looked at in the modeling and the results so obtained are used to calculate the relative transmissibility in the motion of the carriage.
Additives Effects of Cement and Silica Clay on the Thermophysical Properties of Sawdust
Authors: Ogunleye I.O.
Published: March 2009

The thermo-physical properties of some varieties of sawdust and some additives are presented. They are thermal conductivity, heat capacity and specific gravity. The methods of investigation used are Lee’s Disc Apparatus, heat balance and gravimetric method respectively. The sawdust specimens were obtained from six varieties of wood. The additives employed on two typical sawdust samples are cement and silica clay. The values of thermal conductivity range between 0.440 and 0.204 W/m K, and heat capacity between 58,644.08 and 29,584 J/kg K. The highest specific gravity is 0.256 and the least value is 0.107. It was observed that as the clay content increases, specific gravity and the thermal conductivity also increases while the specific heat capacity decreases.
Modelling of Sediment Transport Capacities of Ogbese and Owena Rivers in S.W. Nigeria
Authors: Okoli C.S. , Ojo S.I.A. , Oguntuase A.M.
Published: March 2009

The movement of sediment such as sand, silt or gravel by flowing water is of interest to a wide range of engineering disciplines. This study is aimed at developing models, which can be used to predict the magnitude and levels of sediment concentration in Ogbese and Owena Rivers in Ondo State S.W. Nigeria for engineering design purposes. Data were collected from field investigations conducted at the respective sampling stations on the two rivers. The live bed concept used was derived from Liu – Hwang (1954) resistance equations and that of Einstein-Brown (1981) sediment transport concept. The problem was reduced to that of a power law relationship. These data ere fitted into the power relationship to obtain the predicted model of the form: F1Q = k2k1, where the parameters F1Q is the dimensionless sediment discharge,  is the dimensionless bed shear stress, k1 and k2 are sediments transport coefficients. Calibrating the models yielded the values of k1 and k2 for Ogbese river as 0.592 and 0.865 and for Owena river as 0.335 and 1.197 respectively. When tested the predicted models for Ogbese and Owena rivers performed well in comparison with the established models such as Ackers and White (1973), Engleund and Hansen (1967), Yang (1973) a\and Karim (1998). It is concluded that the models developed would be useful for engineering design purposes for Ogbese and Owena rivers.
Bio-Treatment of Crude Oil Polluted Water Using Mixed Microbial Populations of P. Aureginosa, Penicillium Notatum, E. Coli and Aspergillus Niger
Authors: Obahiagbon K.O. , Owabor C.N.
Published: March 2009

Bioremediation as a strategy of clean- up of crude oil spills in water using a mixed microbial population of E. Coli, Aspergillus niger, Penicillum notatum and Pseudomonas aeruginosa was investigated in this study. The sample of crude oil polluted water containing the mixed microbes and the control was monitored for parameters such as BOD, pH, Total Hydrocarbon Content (THC) and Turbidity over a period of nine weeks. At the end of the bioremediation period, the results obtained showed that the sample remediated with the mixed microbes gave a THC drop from 14975mg/l -1.960mg/l (99.9% drop) compared to the control with a drop from 14975 – 18.72mg/l (99.8% drop). A BOD drop from 1447.4mg/l – 17.1mg/l (98.8% drop) for the sample mixed microbes and 1447.4 – 90.8mg/l (93.7% drop) for the control. Turbidity values increased from 5.0 NTU – 25.2NTU for sample with mixed microbes and 5.0 NTU – 23.1 NTU for the control. The values of THC (1.96 mg/l) and BOD (17.1 mg/l) at the end of the experimentation period fell within the FEPA and DPR limits of 10mg/l and 30mg/l for THC and BOD respectively.The results above thus indicates that the use of mixed microbial population of Pseudomonas aureginosa, Penicillium notatum, E. Coli and
Residual Stress and Surface Molding Conditions in Thin Wall Injection Molding
Authors: Lee H.K. , Yang G.E. , Kim Hong Gun
Published: March 2009

Residual stress distribution and surface molding state of polymeric materials are presented for thin-walled injection molding. The residual stress is computed by computational numerical analysis, observed with a stress viewer and birefringence. The residual stress on the surface of the polymeric part can indicate the surface quality as well as flow paths. The residual stress distribution of the polymeric part is related with the part’s thickness, the gate layout, and the polymer type. Molecular orientation, affected by flow paths, is simulated and validated by observing the birefringence of the polymeric specimens. The residual stress and molecular orientation are closely related to the surface molding states.
Residual Stress and Stress-Strain Relationship of Electrodeposited Nickel Coatings
Authors: Zhou Yi Chun , Jiang Y.P. , Pan Y.
Published: March 2009

The uniform nickel coatings on substrate of low carbon steel were prepared by an electrodeposition method. The residual stress in the electrodeposited nickel coating was measured by X-ray diffraction (XRD). It was tensile when the coating was not treated. Laser beam thermal shock was used to modify the mechanical properties of the nickel coating. Laser beam thermal shock could redistribute the residual stress in the nickel coating. The residual stress could be converted from tensile to compressive. A tensile method to determine the stress-strain curve of the coating is proposed where the stress-strain relationship of the substrate without coating was determined for the specimen loaded by an applied tensile force.
Failure of Thermal Barrier Ceramic Coating Induced by Buckling Due to Temperature Gradient and Creep
Authors: Mao W.G. , Zhou Yi Chun
Published: March 2009

The intent of this article was to study the failure mechanism of thermal barrier coatings (TBCs) induced by buckling. The main content included the following two parts. The first part investigated the thermal residual stresses fields in TBCs with thermal cycles, which induced by the non-linear coupled effect of temperature gradient, thermal fatigue and creep strain of TBCs. One found that the residual stresses in ceramic coating were compressive and accumulated with thermal cycles, which may be high enough to induce the buckling failure of ceramic coating. The second part studied the critical buckling failure loading of the ceramic coating in TBCs under the condition of the compressive loading by use a theoretical model. Finally, a buckling plane, i.e. s T n − plane, was obtained by combined the above sections and applied to predict the buckling failure of the TBCs system. In this plane, it was divided into the two parts, i.e., non-buckling region and buckling region.
Influence of Surface Properties on Microscratch Durability of Aluminum Nitride Semiconductor Processing Component
Authors: Chouanine L. , Takano M. , Ashihara F. , Kamiya Osamu , Nishida M.
Published: March 2009

The effect of the surface properties on the microtribological characteristics of AlN-based electrostatic chuck (EC) for silicon plasma etching was investigated using automatic microscratch testing technique in combination with SEM examination of the scratch track. The scratch testing was performed by applying a progressive indenter load. The scratch failure model varied systematically with the surface properties of AlN. The data of the onset of brittle fracture were used as characteristic features of the AlN failure. It was found that the critical load, Lc, the smallest applied normal load leading to unacceptable damage such as chipping and cracking, increases with decreasing the average grain size, density and fracture toughness of AlN and decreases with increasing the surface roughness and area density of pre-existing polishing damages. The resistance to cohesion and adhesion failure of AlN with 0.1 µm Al2O3 oxide layer on top was stronger than that of the AlN bulk material. The fracture initiation and ductile to brittle transition in AlNAl2O3( 0.1µm) was in form of discontinuous chipping. The results infer the potential of the combination of the scratch data with the material properties for the understanding of the effect of the surface topography on the mechanical properties and chucking performance of AlN-based EC.
Nanocomposite TiC-TiB2 Powders by SHS through Metastability Approach
Authors: Vallauri Dario , López Y. , DeBenedetti Bruno , Amato Ignazio
Published: March 2009

The aim of this work is the achievement of nanostructured TiC–TiB2 powders through a
metastability approach based on the Self–propagating High–temperature Synthesis (SHS) process
followed by quench to obtain highly metastable powder agglomerates. An optimisation of the
reaction stoichiometry was carried out in order to obtain products with approximately eutectic
composition (i.e. 67%mol TiC – 33%mol TiB2). An optimized amount of sodium borate was used
as gasifying additive to produce dispersed nanostructured powder agglomerates.
The metastability of the nanocomposite powders obtained through the (SHS+quench) route was
evaluated by annealing. The morphological evolution of the powders after thermal treatment
yielded a recrystallisation with limited grain growth of the nanostructured TiC–TiB2 phases and
demonstrated the metastability of the products obtained by the (SHS+quench) route.
Fabrication of SPS Compacts from Ta, Hf-Containing ZrB2-ZrC Powder Mixtures Synthesized by the MA-SHS in Air Process
Authors: Tsuchida T. , Mochizuki K.
Published: March 2009

Mechanical Activation assisted Self-propagating High-temperature Synthesis in air
(MA-SHS in air process) was successfully applied to the synthesis of the powder mixtures of ZrB2 and
ZrC containing Ta and Hf as a precursor of Ultra High Temperature Ceramic (UHTC) matrix
composites. When the powder mixtures of (Ta or Hf+Zr)/B/C=2/2/1 (Ta or Hf/Zr=0/2, 0.1/1.9, 0.2/1.8,
0.4/1.6) in molar ratio were mechanically activated (MA) by ball milling for 45-60 min and then
exposed to air, they self-ignited spontaneously and the self-propagating high-temperature synthesis
(SHS) was occurred to form ZrB2 and ZrC. From these MA-SHS powders, the Ta, Hf-containing
ZrB2-ZrC composite compacts having a fine and homogeneous microstructure composed of < 5
μm-sized grains were fabricated by spark plasma sintering (SPS) at 1800°C. The mechanical
properties of the composites evaluated by Vickers indentation method was improved by the addition
of Ta and showed the values of Vickers hardness (HV) of 16.9 GPa and fracture toughness of 4.3
MPa·m1/2.
Dense γ-Alon Materials Derived from SHS Synthesized Powders
Authors: Zientara Dariusz , Bućko Mirosław M. , Lis Jerzy
Published: March 2009

Dense polycrystalline aluminium oxynitride with spinel structure, γ-alon, is noted for its
excellent thermal properties, high-temperature mechanical properties, low dielectric constant,
thermal expansion coefficients and intrinsic transparency extending from ultraviolet to mid-infrared
wavelengths. The conventional way for synthesis of γ-alon powder is high-temperature reaction of
aluminium nitride and corundum in pure nitrogen or a vacuum. The dense materials are made by
reactive pressureless sintering or hot-pressing of a powder compact. This work is focused on
preparation of γ-alon materials derived from SHS synthesized powders. The powders for sintering
were synthesized from mixtures of aluminium and corundum powders of different proportions. The
products of the SHS synthesis were composed mostly of γ-alon and aluminium nitride with small
amount of non-reacted substrates. Ground powders were hot-pressed at 1750, 1850 and 1950°C for
1 h under 25 MPa in nitrogen flow. Such procedure allowed dense material composed of pure γ-alon
with good mechanical properties to obtain.