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Abstract - The classical truss bar element formulation is revisited by assuming that the bar elements can support elastic strain gradients along their length. The stress-strain relation for the bars is assumed to obey the gradient elasticity theory as proposed by the third author and used extensively in recent years to interpret size effects and eliminate singularities from dislocation lines and crack tips. Instead of an algebraic equation (1D classical elasticity stress-strain relation), a differential equation governs the response of the elastic bar element and extra boundary conditions are required at the nodes. Since the corresponding displacement field may present discontinuities when conventional shape functions are employed, we overcome this difficulty by deriving the associated stiffness matrix directly from the governing differential equation of the gradient elastic bar element. A numerical example is presented to illustrate the approach.

Keywords: Gradient Elastic Truss Bar, Gradient Elasticity Stiffness Matrix.

Non-Darcy Natural Convection Heat Transfer along a Vertical Cylinder Filled by o Porous Media with Variable Porosity
by M. Sammouda, K. Gueraoui, M. Driouich, A. El Hammoumi, A. Iben Brahim

Vol. 6 n. 4, pp. 698-704

Abstracts – Theoretical and numerical study of the phenomenon of natural convection in a cylindrical enclosure filled by a non-Darcy porous media and saturated by a Newtonian fluid.The porosity of the media considered is variable and approximated by an exponential function based on an empirical law and equal to the unity near the walls due to the effects of the walls. The hydrodynamic flow in the porous medium is governed by Forchheimer-Brinkman extension of Darcy model (EBFD) with non-uniform porosity.The dimensionless equations reveal some important dimensionless numbers controlling this phenomenon such as the thermal Rayleigh number, Ra, the number of Darcy, Da, the number of Prandtl, Pr, the aspect ratio, RA, and the porosity, ε. The results are discussed graphically. The heat exchange traduced by Nusselt number is also considered in the study. The results obtained under the limiting conditions were found to be in good agreement with the existing ones. The established numerical code can also be used in various other industrial applications.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Natural Convection, Porous Media, Variable Porosity, Cylindrical Cavity, Extension Darcy Law.

Solution to Natural Convection Heat Transfer by Two Different Approaches: Navier Stokes and Lattice Boltzmann
by Nor AzwadiC. Sidik, Godarzi Masoud

Vol. 6 n. 4, pp. 705-711

Abstract – In this paper, a natural convection heat transfer from a differentially heated walls in a square cavity was solved using two different scale of numerical approaches; Navier-Stokes and lattice Boltzmann formulations. The vorticity-stream function method was replaced in the continuum Navier-Stokes formulation to reduce the number of unknown variables while lattice Boltzmann method reconstructs the evolution of fluid particles to predict the heat transfer and fluid flow behavior in the system. Both numerical methods are of second order accuracy in space and time. The results of both methods were evaluated and compared. Good agreement between the Navier-Stokes and lattice Boltzmann formulation was found.

Keywords: Double Population, Lattice Boltzmann, BGK Collision, Vorticity - Stream Function, Navierstokes Equation, Natural Convection.

Application Ofthermal Wave Method to Determine the Effective Thermal Conductivity of Nanofluids
by Xiaohui. Zhang

Vol. 6 n. 4, pp. 712-718

Abstract - Nanofluids are evolving as potential enhanced heat transfer fluids due to their better thermal conductivity, in the present paper, a methodology is proposed for predicting the effective thermal conductivity of dilute suspensions of spherical nanoparticles (nanofluids) based on thermal wave method. The addition theorem for spherical Bessel functions is used to accomplish the translation between different coordinate system. The theory of Waterman and Truell is employed to obtain the effective propagating wave number and the non-steady effective thermal conductivity of composites. Comparing with other classical models, the proposed model takes into account some additional effects including not only volume fraction, thickness, thermal conductivity of the interfacial layer and particle size but also the thermal wave number and the interactions between the dilute particles.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Nanofluids, Non-steady Effective Thermal Conductivy, Thermal Wave.

A Study of the Mode Shape Effect in Automobile Braking System
by M.A.Salim, A.Noordin

Vol. 6 n. 4, pp. 719-723

Abstract - This paper presents experimental result of mode shape effect in automobile braking system. Experimental of modal testing and analysis is done by given an impact by hammer from point 1 to point 24 of the disk brake where the accelerometer is positioned. The average data is recorded and a three dimensional graph is plotted. From the recorded vibration, the modal parameters of this disk brake are determined from the mode shape developed using numerical and experimental approach. The result shows three natural frequencies are identified at 1100Hz, 2350Hz and 2600Hz. The first mode shape shows the direction of the bending is the same where it was a top bending. From initial condition, when the shape was moving at up and down, the contour color is slightly changed from blue to yellow and red. The second mode shape shows the bending moves up and down following the z-axis. When the point is far from the initial condition, the contour is changed from blue to yellow and frequently was red. The deformation of disk brake at second natural frequency is slightly increased when the point goes far from initial condition. For a third mode shape at positive and negative of z-axis, the color of shape is slightly changed when the area is bending condition. It means, the deformation of the disk brake is changed as well follow by the magnitude of bending.

Keywords: Mode Shape, Disk Brake, Braking System, Vibration.

Processing of Stir Cast AL-7075 Hybrid Metal Matrix Composites and their Characterization
by V. C. Uvaraja, N. Natarajan

Vol. 6 n. 4, pp. 724-729

Abstract - In the present study, aluminum 7075 alloy-base matrix reinforced with mixtures of silicon carbide (SiC) and boron carbide (B4C) particles, know as hybrid composites have been produced by stir casting method. Dry friction and wear performance of the hybrid composite and unreinforced Al-7075 alloy at room temperature were investigated by using pin-on-disk wear testing machine. The hybrid composite wear resistance and co-efficient of friction has been investigated as a function of load, sliding velocity and volume fraction of the particles. The investigation results show that the wear rate of the test specimens increases with the increasing load and sliding velocity. The hardness of the specimens at room temperature was measured before the wear test by Rockwell hardness test machine. The magnitude of hardness increases obviously as the function of the volume fraction of the particle. The coefficient of friction of specimen decreases with increasing volume content of reinforcements. The specimens were examined by Optical Microscope and Scanning Electron Microscope (SEM). These investigation overviews that Al-7075 based hybrid composites which are having the better combination of hardness can replace the conventional material for better performance and longer life.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Wear, SEM, Hybrid Composite, Stir-cast, Pin-on-Disk.

Design of Heater for City Gate Station Assisted by Solar Energy
by Arash Mohammadzadeh, N. Etemadee

Vol. 6 n. 4, pp. 730-735

Abstract - The present paper relates to a method of heating natural gas in preparation for reduction in its pressure. In a natural gas distribution system, the gas generally travels from the field at relatively high pressure and velocity. In Iran’s City Gate Station, water bath heater equipped with burner is used for heating gas flow. These equipments have additional cost for energy consumption. Also may lead to Environmental pollution. This paper is dedicated to using solar energy in the form of solar heater to provide energy needed for heating gas stream before entering the pressure-reducing valves. According to required temperature (38^oC), we can use simple solar heating system to have least cost and simple operating conditions. Hot water from solar collector is pumped to hot water bath heater. In water bath, cold natural gas receives heat from hot water and warms to set point temperature. When the solar collectors aren’t able to provide the necessary heat for system the auxiliary heating system provides that.

Keywords: Solar Heater, City Gate Station, Hot Water Bath, Natural Gas, System.

Optimization of Gas Turbines Performances by Air Combustion Cooling
by Bendjaima Belkacem, Benhamou Amina, Smail Rachid

Vol. 6 n. 4, pp. 736-744

Abstract - The optimization of a process and the increase in its performances remain permanent challenges with any industry. In the field of the electrical energy production, often the increase in the turbomachinery performances is very required. One of the ways which make it possible to achieve this goal is the design of new machines starting from existing machines. This present work integrates this step by using the concepts of evaporative cooler and scale factor. The analysis of the results of the reception essays of the initial machine allowed validating the theoretical calculation started, and the results are used to determine the expression of the scale factors for the new machines design. A study of performance of the designed machine is carried out by using this concept as well as the use of a system of cooling of the combustion air (the evaporative cooler). The machines designed by using this processes involve a considerable gain in performances what induces a better environmental protection by the reduction of the emissions. An approximate calculation of the scale factor, and performances was also carried out numerically.

Keywords: Meridian Flow, Gas Turbine, Flow Rate, Scale Factor, Performances, Evaporative Cooler.

Optimization of Surface Damping Treatments for Vibration Control of Marine Structures
by Ranganath B. A., Kamalakar K., Ramji Koona

Vol. 6 n. 4, pp. 745-751

Abstract - Uncontrolled vibration develops into a serious of problems in machinery and structures and damping is the simplest method of limiting the amplitudes. Active damping involves complicated electronic ‘gadgets and is yet to gain popularity. Structural damping is usually very small in metals but can be greatly enhanced by either adding a layer of viscoelastic (VE) material to form what is called as Free Layer Damping (FLD) or sandwiching the viscoelastic layer in between two or more metal layers, an arrangement known as Constrained Layer Damping (CLD). Different beam samples were made comprising of Mild Steel (MS) beams as well as CLD and FLD beams of varying material thickness. Their response to sinusoidal excitation was measured at different frequencies and the results plotted. These samples were also modeled using ANSYS and analyzed as per Ross, Kerwin and Ungar (RKU) method as suggested by Macioce [2]. The loss factor was calculated for CLD as a function of layer thickness by the Oberst and Schommer [3] approach with the help of RKU equations. From these equations optimum loss factor was determined. It was found that the results as projected by the Finite Element Analysis validate the experimental results. A CLD thickness of 1.5mm increases the loss factor from 0.107 for the base MS beam to a value of 0.123, an increment by 16% for a CLD beam. A marine structure comprising two VE layers of 1mm thickness each sandwiched between two MS layers of thickness 1.5mm and a base plate of 12mm was also taken up as a case study and the results are plotted. In conclusion both CLD and FLD improve damping characteristics significantly and between these two, CLD performs better. Hence these techniques open up an economical and simple method of controlling undesirable vibrations.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Constrained Layer Damping, Optimization, Vibrations.

Designing a Retrofit Kit for Reducing Fuel Consumption in I.C. Engines
by Saeb Moosavi, Amir Hossein Davaie Markazi, Seyed Saeid Moosavi

Vol. 6 n. 4, pp. 752-762

Abstract - In this paper a new retrofit kit for reducing fuel consumption and exhaust pollutions in I.C. engines is designed and constructed. The retrofit kit is designed in Catia-V5 to be used in a Zenith-Stromberg variable venturi carburetor and then it is constructed in laboratory. At first, by generating all the sufficient equations governing the dynamics of the components in the fuel feeding system and the designed kit, the carburetor and the kit are modeled and simulated in MATLAB software. Afterward, the kit is mounted on a test vehicle to see how much it can reduce the fuel consumption in real situations. The simulation results are validated by comparing to the results obtained from experimental investigations under similar working conditions. Experiments show that this new kit has considerable effects on reducing the fuel consumption and exhaust pollutions. Since the fundamental concepts of variable venturi carburetors are very similar, similar procedure can be carried out for any other variable venturi carburetor as well, only by replacing the characteristics of the carburetor in the related equations.

Keywords: Exhaust Pollutions, Fuel Consumption, I.C. Engines, Retrofit Kit, Zenith-Stromberg Variable Venturi Carburetor.

Total Dynamic Response in Time Domain of Soil-Structure Interaction Systems Using Elastodynamic Infinite Elements with Scaled Bessel Shape Functions
by Konstantin S. Kazakov

Vol. 6 n. 4, pp. 763-769

Abstract - This paper is devoted to a new approach the total dynamic response of Soil-Structure Systems (SSS), the far field of which is discretized by decay or mapped elastodynamic infinite elements, based on scaled Bessel shape functions to be calculated. These elements are appropriate for Soil-Structure Interaction problems, solved in time or frequency domain and can be treated as new forms of the recently proposed elastodynamic infinite elements with united shape functions infinite elements (EIEUSF). In the research the time domain form of the equations of motion is demonstrated and used in the numerical example. Only the formulation of 2D horizontal type infinite elements (HIE) is used, but by similar techniques 2D vertical (VIE) and 2D corner (CIE) infinite elements can also be formulated. Continuity along the artificial boundary (the line between finite and infinite elements) is discussed as well and the application of the proposed elastodynamical infinite elements in the Finite element method is demonstrated in brief. The numerical example shows the computational efficiency and accuracy of the proposed infinite elements, based on scaled Bessel shape functions.

Keywords: Soil-Structure Interaction, Wave Propagation, Infinite Elements, Finite Element Method, Bessel Functions, Duhamel Integral.

Response Behaviors for a Liquid Ship Strongly Excited Due To Heave Motion
by Mohamed A. EL-Sayad

Vol. 6 n. 4, pp. 770-778

Abstract - The considered system is a harmonically excited, non-linear spring pendulum which simulates the ship heave motion. The strong nonlinear impact loads are modeled based on the form of a power function with a higher exponent. The method of multiple time scale is applied to solve the non-linear differential equations describing the system up to the fifth order approximation. The resultant secular terms explain the relationships between the external excitation frequency Ω_y and the two natural frequencies of the system w_ and w₂. For the weak nonlinearity case, the vector field equations include cubic non-linearity due to geometric inertia terms. In the neighborhood of excitation resonance, the first mode achieves a steady state response that is locally stable. For the strong non-linearity, the amplitude response switches from soft to hard nonlinear characteristics. Another solution for the first mode is found to be in the form of chaotic behaviors by the change for initial conditions. On the other hand, when the second mode is excited, it is found that amplitude is behaving as linear oscillator in the defined region of the steady state solutions. The system response follows another form of chaotic behaviors due to change for the initial conditions.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Liquid Sloshing Impact, Ship Motion, Spring Pendulum.

Fuzzy Switching of Hybrid Piezoelectric Damping System
by Sohair F. Rezeka, Bassyouny M. El-Souhily, Hassan El-Gamal, Moataz M. Shawkey

Vol. 6 n. 4, pp. 779-789

Abstract - The goal of this paper is to achieve maximum possible damping of structural vibration while minimizing the active control effort used. A new variable hybrid piezoelectric damping using the fuzzy logic is proposed for the switching actuation between two types of hybrid damping systems. One is a series (Integrated) type, where the piezoelectric actuators are actively driven by external voltage source with the passive tuned RL circuit in series. The other type is a separated type in collocated condition, where the external voltage source and the passive tuned RL shunting circuit are separated from each other. The feasibility of the proposed fuzzy hybrid piezoelectric damping system is analytically demonstrated by simulating the response of a simple cantilever beam model with surface bonded piezo-elements. From the view point of vibration suppression; the variable hybrid fuzzy absorbers results in better performance than both the integrated and separated Hybrid absorbers. However the integrated type still gives the best performance with respect to active control power. The Mamdani FIS absorber gives better performance than the Sugeno FIS absorber and it is also superior to the separated type (26% reduction from the separated). It was demonstrated that the fuzzy switched type of the absorber is more efficient than the simple linear switching between the integrated/separated types developed earlier in the literature.

Keywords: Fuzzy Logic, Piezoelectric Elements, Variable Hybrid Structural Damping.

Influence of Fly ash / Gr Reinforcements on Corrosion Behaviour of Aluminium Matrix Composites
by P.Shanmughasundaram, R.Subramanian, A.R.Ravikumar

Vol. 6 n. 4, pp. 790-795

Abstract - Particulate metal matrix composites have been developed for potential use in tribological applications due to good resistance to wear and seizure for automotive and aerospace industries. One of the main difficulties is the influence of reinforcement on corrosion resistance. This paper presents the susceptibility of pure Al, Al – fly ash and Al – fly ash / Graphite composites which are fabricated by modified stir casting process to corrosion in a corrosive environment (3.5% NaCl solution) using the potentiodynamic polarization method. Results showed that the pitting susceptibility was more for the composites than Al. The corrosion resistance of the composites decreased as the weight fraction of fly ash increased. The high corrosion rate of Al –fly ash / Gr is due to the graphite particles being cathodic relative to the Al thus leading to galvanic corrosion in the presence of an electrolyte. SEM and EDS analysis revealed that the presence of interfacial products increases the corrosion rate of the composites due to the occurrence of galvanic corrosion.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Al- fly ash / Graphite Composite, Corrosion Rate, Galvanic Corrosion, Potentio Dynamic Polarization Method, Stir Casting Process .

Variability Reduction in Collapsible Tubes Production, Using Eddy Current Measurement Technique
by Vrassidas I. N. Leopoulos

Vol. 6 n. 4, pp. 796-802

Abstract - This paper presents the experience of a project aiming to reduce variability through improvement actions in a production line of light metal industry (collapsible tubes), supported by a non destructive quality control method. A specialised instrument for the non-destructive measurement (NDT) of the thickness of the internal layer of the varnishing color has been installed in the quality control laboratory. The installation of the NDT method gave the company the possibility to acquire the necessary data at low cost and to understand variability of a critical manufacturing process. Improvement actions reduced material consumption and the relevant important cost in the collapsible tubes production unit. The project was co-financed by the Greek General Secretariat of Research and Technology.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Variability Reduction, Non-Destructive Measurement.

Study of Indentation Fracture Toughness of WC-6.5%Co Cermet
by D. Bouteghmes, M. Hamidouche, N. Bouaouadja

Vol. 6 n. 4, pp. 803-809

Abstract - WC-Co cermets are widely used in applications that require good wear resistance (cutting tools, mining equipments, drilling…). This good quality is the result of the combination of high hardness and moderate fracture toughness. The damage of WC-Co cutting tools begins from the surface, and indentation technique is an adequate mean for studying the fracture toughness mechanisms of these materials. The crack systems generated by Vickers indentation depends mainly on the materials fracture toughness. On materials with a high toughness values, we generally have a "Palmqvist" cracking profile, whereas on low toughness materials, a "Median/Radial" cracking system is more common. In practice, several IFT equations were proposed and applied for ceramic materials to evaluate the fracture toughness using Vickers indentation. According to literature, only few of these equations give reliable estimation of the fracture toughness if the values are compared to those obtained by conventional methods. In this work, we studied the fracture toughness of a WC-6.5%Co cermet using Vickers indentation technique. For that, indentation tests were carried out using different loads (100-500 N). The cracking system obtained is of Palmqvist type. Five Palmqvist formula and three formula obtained empirically by fitting curves were selected from literature and applied for obtaining the indentation fracture toughness. The results show that there is a large KC values scattering (3 to19 MPa.m1/2). Some formulas (Schetty et al., Lankford and partially equation of Evans) give acceptable values in comparison to the reference values given in the literature and based on conventional fracture toughness methods. The other equations give Kc values, different enough from the reference. Finally from this work, we concluded that Schetty’s model seems to be the most appropriate for the applied loads domain studied, because the corresponding fracture toughness values are load independent and are comparable to those obtained by conventional methods. This also confirms the Palmqvist cracking profile. The other formulas are load dependant. Weibull analysis is introduced to show how the 2c parameter scatter affects the Kc dispersion .
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: WC-6.5% Co, Vickers Indentation, Fracture Toughness, Weibull Analysis.

Heat and Mass Transfer in a Solar Tunnel Dryer: Modelling and Simulation
by Chaouki Ali, Slimen Attyaoui, Faouzi Nasri, Habib Ben Bacha

Vol. 6 n. 4, pp. 810-817

Abstract - This paper presents a solar tunnel dryer which consists of three compounds, solar collector, fun and a thin layer tunnel dryer. The advantages of this system is environmental protection, energy saving and low operation cost. Outlet solar collector air is reheated upon a demand before to be forced in the tunnel dryer to take moisture by evaporation from a wet basis. The Henderson and Pabis mathematical model has been used to describe the drying kinetics of mint leaves, air temperature and velocity effect on the drying model constants was determined using experiments result and regression analysis techniques. The drying experiments were performed at a forced air inlet tunnel temperature and velocity ranging from 40 ˚C to 60 ˚C and from 0.1 m/s to 0.5 m/s respectively. A dynamic model based on heat and mass transfer in a solar tunnel dryer is developed and numerically resolved using the finite volume method.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Tunnel Dryer, Mint Leaves, Solar Energy, Dynamic Model, Numerical Simulation.

Optimization of Gmaw Process Parameters Using Genetic Algorithm
by P, Sreeraj, T, Kannan, Subhasis Maji

Vol. 6 n. 4, pp. 818-827

Abstract - For improving the corrosion resistant properties of carbon steel usually cladding process is used. It is a process of depositing a thick layer of corrosion resistant material over carbon steel plate. Most of the engineering applications require high strength and corrosion resistant materials for long term reliability and performance. By cladding these properties can be achieved with minimum cost. The main problem faced on cladding is the selection of optimum combinations of process parameters for achieving quality clad and hence good clad bead geometry. In this study an experimental work is conducted to optimize various input process parameters (welding current, welding speed, gun angle, contact tip to work distance and pinch) to get optimum dilution in stainless steel cladding of low carbon structural steel plates using Gas Metal Arc Welding (GMAW). Experiments were conducted based on central composite rotatable design with full replication technique and mathematical models were developed using multiple regression method. The developed models have been checked for adequacy and significance. Using Genetic Algorithm (GA) the process parameters were optimized to get optimum dilution.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Carbon Steel, Clad Bead Geometry, Cladding, Corrosion, GMAW, GA, Mathematical Model, Multiple Regression.

Thermal Performance of Ammonia-Cooled Microchannel Heat Sink
by Ahmed Mohammed Adham, Normah Mohd-Ghazali, Robiah Ahmad

Vol. 6 n. 4, pp. 828-836

Abstract - The minimization of integrated circuits in powerful electronic devices generates a large amount of heat that has to be removed effectively and efficiently. One of the methods applied is to use a microchannel heat sink. Past optimization attempts have looked at the microchannel geometry, material, and coolant types using various models to represent the heat sink. This paper reports the analytical study on the optimization of the thermal resistance and pressure drop of a rectangular microchannel heat sink using a new coolant, ammonia gas which has never been reported before. The applicability of ammonia gas as a new coolant was investigated and showed excellent performance. The effect of different channel aspect ratio, fin spacing ratio, different structural materials and Reynolds number was investigated. Significant reduction in thermal resistance was obtained with 0.213 ^oK/W for ammonia gas compared to that of 0.266 ^oK/W for air under the same operating conditions. The total pressure drop achieved was 4.82 mbar and 9.52 mbar for ammonia and air respectively. The results indicate promising potential for ammonia gas as a coolant for rectangular microchannel heat sink.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Microchannel, Ammonia, Heat Transfer.

Machinability Investigations of Flank Wear in Carbide Cutting Tool
by R. Thirumalai, P. Selvarani, J. S. Senthilkumaar

Vol. 6 n. 4, pp. 837-845

Abstract - This paper describes the development of response model of flank wear for machining Inconel 718. The machining experiments are conducted based on the design of experiments by varying the cutting speed, feed, and depth of cut as machining parameters against the response flank wear. The performance of uncoated carbide cutting tool was investigated at various cutting conditions under dry machining and refrigerated coolant machining. This paper made an attempt to Taguchi optimization technique to study the machinability performances of Inconel 718. An orthogonal array of L 27 was used and anova analysis was carried out to identify the significant factors. The objective of this study is to predict the optimum cutting conditions to minimize the flank wear. Taguchi’s optimization analysis indicates that the factors level, its significance to influence the flank wear for the machining processes. Confirmation tests were conducted at an optimal condition to make a comparison between the experimental results foreseen from the mentioned correlations and found satisfactory.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: High Speed Machining, Dry Cutting, Refrigerated Coolant Cutting, Carbide Cutting Tool, MINITAB.

Reduction of Amount of Cutting Fluid in Flood Turning by Finite Element Analysis
by M. N. Islam, Motoi Noguchi, S. A. Chowdhury, Brian Boswell

Vol. 6 n. 4, pp. 846-854

Abstract - In recent years, applying cutting fluids during machining operations has attracted immense scrutiny due to the adverse effects on human health and the environment. As a result, a large quantity of research has been undertaken worldwide to reduce the application of cutting fluids. This paper presents a new approach to reducing the amount of cutting fluid in flood machining by determining the amount of cutting fluid necessary for the job. The heat generation mechanism and its contributions to the workpiece, tool, and chips are examined, and the temperature rise of the tool is calculated with Finite Element Analysis (FAE) using the ANSYS CFX software package. The maximum permissible temperature was set as the tempering temperature of the cutting tool because at this temperature the cutting tool starts to lose its strength. The amount of cutting fluid adequate for a machining operation is determined by finding the intersection point between the temperature rise curve and the tempering temperature of the cutting tool. Finally, a graph illustrating the relationship between the flow rate of the cutting fluid and the heat that enters the cutting tool is presented which provides an estimate of the flow rate of the cutting fluid necessary for an arbitrary cutting condition.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Cutting Tool, Finite Element Analysis (FAE), Flood Turning, Tempering Temperature.

Gas Radiation Effect on Thermal Characteristics of Porous Radiant Burner
by M. M. Keshtkar, S. A. Gandjalikhan Nassab

Vol. 6 n. 4, pp. 855-864

Abstract - Thermal characteristics of a porous radiant burner (PRB) including gas radiation effects are identified in the present study. This system operates on the basis of effective energy conversion method between flowing gas enthalpy and thermal radiation. At the PRB, the gas and solid phases are considered in non-local thermal equilibrium and combustion in the PRB is modeled by considering a non-uniform heat generation zone. The porous media as a gray body, in addition to its convective heat exchange with the gas, can absorb, emit and scatter thermal radiation. In order to determine the thermal characteristic of PRB accurately, the gas radiation is also considered into account and a theoretical analysis is conducted for a two dimensional model where convection, conduction and radiation take place simultaneously in porous medium and gas flow. Discrete ordinates method is used to obtain the distribution of radiative heat flux in the porous media and the coupled energy equations for the gas and porous medium in steady condition are solved numerically. The crucial influence of gas radiation effect on the system's performance is thoroughly explored. In order to validate of the applied numerical method, the present results are compared with some reported theoretical and experimental results by other investigators and good agreement is found.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Porous Radiant Burner, 2-D Radiative Field, Gas Radiation.

Optimization on Parameter Settings in Determining Warpage Factors of a Side-Gated Thin Shallow Part Injection Molding for PP, ABS & PC+ABS Materials
by N.A. Shuaib, S.M. Nasir, M.Fathullah, Z. Shayfull, M.S. Bahari

Vol. 6 n. 4, pp. 865-870

Abstract - The injection molding process of thin shallow part requires several concerns in order to produce a quality output. In part of determining the best parameter settings, among other considerations that need to be taken are the types of plastic materials selected and the mold design. This research is performed to optimize the parameter settings for the injection molding process of thin shallow part using three different types of plastic materials; Polypropylene(PP), Acrylonitrile Butadiene Styrene+Polycarbonate(PC+ABS) and Acrylonitrile Butadiene Styrene (ABS). The parameters setting and warpage results are analyzed using Taguchi Method and optimized using Analysis of Variance (ANOVA) to identify the contribution of each parameter. The processes are simulated in three experiments corresponds to the three selected materials using Moldflow Plastic Insight (MPI) software. The result shows that the process of thin shallow part using ABS and PC+ABS materials are influenced by the packing time parameter by more than 85%. For PP material, the most affecting parameter is the packing pressure by 58%. For all three materials analyzed, it can be concluded that the warpage of the thin shallow part are most affected by both packing parameters; the packing time and packing pressure.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Thin Shallow, Injection Molding, Warpage, Taguchi Method, ANOVA.

Experimental Investigation on Thermosyphon Heat Sink Integration Technology for CPU Cooling
by Shanmuga Sundaram Anandan, Anirudh Bhaskaran, A. B. K. Rajan

Vol. 6 n. 4, pp. 871-885

Abstract - A rapid increase in high performance devices built in Personal Computer (PC) to enhance the processing speed of the Central Processing Unit (CPU) makes its thermal design power to increase sharply. Hence, this paper discusses the concept of “Indirect heat removal” technology which involves the use of a two phase working fluid to transfer heat from the heat source to an ambient heat sink. Therefore, a cooling module in the form of Thermosyphon Heat Sink Integration Technology (THSIT) is developed as a replacement for the conventional cooling method (Direct heat removal). An experimental investigation was conducted to predict the performance of a specific TPCT in which R-134a is employed as a working fluid. The experimental work is conducted in both natural and forced convection situations. The forced convection heat transfer is carried for various volumetric flow rates of air in order to have a better assessment of the performance of the THSIT for various heat inputs. The analytical formulation is employed to investigate the effect of variables on the performance evaluation of THSIT. This includes the determination of the effectiveness using the thermal resistance model developed and comparing it with the conventional cooling method (fan heat sink). It is found that there is an appreciable improvement in the present model compared to the conventional one.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Direct Heat Removal, Effectiveness, Fan Heat Sink, Thermosyphon Heat Sink Integration Technology.

Indicator-Based Multiobjective Evolutionary Algorithms and An Application in Filament Winding Process
by Iryna Yevseyeva, Francisco Queirós de Melo, José Grácio, Vitor Basto-Fernandes

Vol. 6 n. 4, pp. 886-895

Abstract - This work presents recent developments on multiobjective evolutionary algorithms, so-called set-based evolutionary algorithms. These techniques are shown to approximate a Pareto front of efficient solutions taking into account both quality of the approximation and its diversity, both important in the design of these methods. Set-based evolutionary algorithms outperform their predecessors on a variety of benchmark problems and are suggested as tools to be used for solving complex mechanical engineering problems, such as filament winding process discussed in this work.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Optimization, Evolutionary Algorithms, Filament Winding Process.

A Study on Conversion of Higher Sulfur Pig Iron to Ductile Iron Using in-Mold Treatment Technique
by Mohd Rashidi. M, Mohd Hasbullah. I

Vol. 6 n. 4, pp. 896-900

Abstract - Processing of iron will never stop. The demand of selected iron properties is depend on market requirement. Conventional ductile iron is one of the main components for industrial used. It is developed to have different microstructure compare to ordinary iron. It has nodule graphite compare to flake graphite. The conversion is succeeded using magnesium treatment. But, the processing of ductile iron required low sulfur content in iron composition due to magnesium treatment respond. Sulfur reacts with magnesium during melting. Thus, the conversion of flake to nodule shape is disturbed. To minimize the reaction, magnesium treatment using an In-Mold treatment is utilize. In-Mold technique is known as late magnesium treatment. It minimizes magnesium from fade away during melting. Therefore this study is performed purposely to investigate the conversion of higher sulfur iron using In-Mold technique. A group of heats were melted and test conducted to explore its microstructure and mechanical properties. It was discovered that the graphite shape was nodule. Hardness and tensile strength was related with percentage of magnesium treatment used.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Ductile Iron, In-Mold Technique, Mechanical Properties.

Solar Energy Availability on Horizontal and Tilted Surfaces: a Case Study
by Ali M. Jawarneh, Mohammad Al-Tarawneh, Amer Ababneh, Hitham Tlilan

Vol. 6 n. 4, pp. 901-917

Abstract - Beam and diffuse radiation data are extracted analytically from measured data on a horizontal surface in Zarqa governorate, Jordan. Radiation data on a tilted surfaces with various slopes have also been deduced and analyzed. Radiation data consists of of beam, diffuse, and ground-reflected contribution. Hourly, daily, and monthly radiation data are estimated for various slopes (β=0⁰,20⁰, 32⁰, 45⁰, and 90⁰). Based on the monthly average day of month, horizontal surface possesses the highest values of hourly radiation data that occurred on June 11 and July 17 then it decays as the slope increases with the greatest decrease happened for vertical surface. The hourly radiation data in winter have the highest values for a surface with a slope of 45⁰ and the lowest values for a horizontal surface. The hourly values in summer have the highest values for a slope of 200, while it’s the lowest for a vertical surface. Concerning the daily radiation for various slopes, the greatest value of daily radiation of 31.1 MJ/m² was recorded on June 15 for a horizontal surface. This value is the highest value in the year for all slopes. The maximum beam contribution effects occurred in June and July for a horizontal surface, while it decays as the slope increases. In winter, beam possesses high values for a slope of 45⁰, while in summer it possesses high values for a slope of 20⁰. The bulk beam effects along the year occurred for slopes of 20⁰, and 32⁰. The diffuse radiation grows with decreasing the slope and the best diffuse happened for a horizontal surface, while it’s minimum for a vertical surface. The best values of diffuse occurred in summer time. In contrary, the ground-reflected contribution decays with decreasing the slope.
The best harvesting of solar annual energy of 7771 (2158.6 kWh/m²) and 7754 MJ/m² (2154 kWh/m²) occurred for surfaces with slopes of 20⁰ and 32⁰, respectively. Deviations in slopes of 20⁰ and 32⁰ have small effect on total energy availability. Per day, the best average annual solar radiation is 21.3 MJ/m² (5.9 kWh/m²) for slopes of 20⁰ and 32⁰. Maximum winter energy availability of 2091 MJ/m² (581 kWh/m²) occurred for a surface with slope of 45⁰ with an average of 17.4 MJ/m² (4.84 kWh/m²) per day. The maximum summer energy availability of 5864 MJ/m² (1629 kWh/m²) occurred for a surface with slope of 20⁰ with an average of 24.4 MJ/m² (6.8 kWh/m²) per day.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Energy Availability, Horizontal and Tilted Surface, Beam and Diffuse Radiation.

The Temporal Neuro-Fuzzy Systems Learning Using Artificial Immune Algorithm
by Mahdaoui Rafik, Mouss Leila Hayet, Mouss Med Djamel, Chouhal Ouahiba

Vol. 6 n. 4, pp. 918-922

Abstract - In this work we propose an immune approach for learning neurofuzzy systems, namely NEFDIAG (NEuro Fuzzy DIAGnosis). NEFDIAG is a software devoted primarily to creation, training and test of a classification Neuro-Fuzzy system of industrial process failures. But in case of great number of input variables NEFDIAG structure grows essentially and the dimensionality of learning task becomes a problem. Existing methods of NEFDIAG learning allow only to identify parameters of NEFDIAG without modifying its structure. We propose an immune Artificial learning approach for NEFDIAG learning based on clonal selection and immune network theories. It allows not only to identify NEFDIAG parameters but also to reduce number of neurons in hidden layers(rules layer) of NEFDIAG.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: NEFDIAG,Neuro-Fuzzy Systems, CLONCLASS, Fault Diagnosis.

Thermal Properties of Natural Graphite Flake Composites
by Desai S., Njuguna J.

Vol. 6 n. 4, pp. 923-926

Abstract - Graphite flake composites are important thermal management materials with strong potential in applications such as electronic cooling devices and aerospace materials. Here we present thermal properties of some model composites with various graphite flake sizes following carbonization and graphitization. The thermal diffusivity is measured by standard laser flash and an in-build line heat-source method and a ratio of graphitic peak to disorder peak from Raman spectrum is used to calculate a-direction coherent length using empirical equation. Thermal conductivities significantly higher than that of copper have been calculated for certain compositions.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Natural Graphite, Thermal Conductivity, Graphite Composites.

Hybrid of Probabilistic and Finite Element Analysis in Biological Structure Failure: A Review
by A. Zulkifli, A. K. Ariffin

Vol. 6 n. 4, pp. 927-933

Abstract - The purpose of this paper is to review the literature in the area probabilistic approach of the bone fracture associated finite-element method. It describes research findings on compressive loading of the vertebra with crack existence in the context of probability of failure. The lumbar vertebra region is the generally common problem occurred to the people and refers to the low back pain (LBP). The elderly is the most frequent group affected by LBP due to decreasing bone mass density, and this disease called osteoporosis. However, the bone fracture related the younger patient normally caused by stress fracture, trauma, collision and fall. The fracture of bones are considered by stress intensity factor (SIF) approach namely linear elastic fracture mechanics (LEFM) due to bone is brittle material. This review paper also discusses the effect of uncertainty influence the material properties, geometry and loading condition of the bone failure, particularly on crack entity. Eventually, sensitivity parameter makes the result more significant to this study.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Probabilistic, Finite Element, Review, Low Back Pain.

Bayesian Modeling of Reliability and Maintainability of Systems
by S. Beleulmi, A. Bellaouar, M.Lachi

Vol. 6 n. 4, pp. 934-939

Abstract - The lack of reliability testing in a project, finds its basis in financial considerations and deadlines. In this context, Bayesian techniques have applications to the extent that they contribute to a significant reduction in the amount of reliability testing established on the basis of the classical approach, with the knowledge of the reliability data on a priori components involved. This article is devoted to a Bayesian approach of the optimization of reliability cost of tests conducted on the electronic components installed in a lift. The Bayesian estimation provides a failure rate of 1.795.10 -6. hr -1 to 60% instead of 2.771.10-6 .hr- 1 after testing. A gain of 64.77% in terms of time and therefore the cost of testing will be reduced considerably. When the number of panes increases (K0 = 2, 3 and 5), the real tests do not add to virtual ones, and we recorded a decrease in time to win. This explains why the decrease in reliability. A second test of confidence was performed at 70% to check if the expert opinion may be still valid.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Bayesian Approach, Optimization, Reliability, Failure Rate, Maintainability.

A Theoretical Approach to Swarm Computations by Nano Intelligent Agents
by Ali Alifard, Afshin Ghanbarzadeh, Naghmeh Sohrabian

Vol. 6 n. 4, pp. 940-946

Abstract - There are several types of attempts to research deeply on social behaviors. These research areas have been inspired from behavior of animals such as birds, fishes, ants, bees and so forth in biological sciences. Recently it has been expanded to other scientific fields such as robotics. One of the main purposes in these researches is finding out how a society of animals/robots/agents which work together can have access to efficient complicated behaviors while each of individuals does a very simple work (or has a very simple role) in the population. This article tries to extract the notion of social mental interaction and specifically social/swarm computations behaviors between autonomous intelligent agents and explain general theoretical foundations. Although there is a huge potential of computations and a population of agents, just a small spatial mass is needed and occupied.
Copyright © 2012 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Bayesian Approach, Optimization, Intelligent Agents, Swarm Intelligence, Social Computations, Distributed Processing, Distributed Computations, Computational Performance, Nano Robots, Nano Calculator Machines.