bluuebunny/crossref_metadata_2025 huggingface dataset:
The Possibilities of Increasing the Flexibility of Intelligent Assembly Cell
Authors: Hruskova Erika , Holubek Radovan , Velisek Karol
Published: January 2011

In relation to how the complexity of modern assembly technology increases, requirements for precise, fast and relevant information specifically for the assemble process also increase. Automation allows the fast and precise measurement of various parameters, assessment of the values obtained and the implementation of the required measures in real time. Automation tools allow evaluation, parameter measurement, comparison and application via computer technology and various software resources. One of the aims of the VEGA 1/0206/09 Intelligent assembly cell project solution as per our institute is the creation of a means of forming assembly cells, their duly defined critical placements, verification of the assembly process as a dynamic system of consistency from a technological, handling and control sub-system point of view via means of 3D models in CATIA environment software. Authors of this paper are members and experts of project group (VEGA 1/0206/09) interested in robotics, manipulators and technological devices. Whereas mechanical production trends in the 21st century tend to focus more on resilience and flexibility, the authors of this article have taken into consideration the possibility of re-evaluating the above-mentioned data — which is an essential element in terms of raising flexibility, thus definitively contributing to increased competitiveness.
Effect of MOS2-Based Composite Coatings on Tribological Behavior and Efficiency of Gear
Authors: He Huibo , Lyu Sungki , Her Chursoo
Published: January 2011

MoS2-based Ti composite coatings were deposited on the AISI 4118 alloy and gears using an RF magnetron sputtering (RFMS) system. While MoS2 coating had been coated on the silicon substrate. The coatings structures were compared to each other to find the effect of Ti. The composite coatings have been performed by a ball-on-disk tribometer to investigate tribological behavior at various conditions. The structure of the coatings has been extensively studied by a variety of techniques, including X-ray diffraction (XRD) and scanning electron microscopy (SEM), etc, respectively. The composite coatings were also applied the gears of a reduction gearbox. The efficiencies of uncoated and coated gear with MoS2 based Ti coatings were measured and compared at various input rotating speed under absorption oil film condition. It was found that the efficiency of gear had significantly improved after MoS2-based Ti composite coatings deposition.
The Effect of Foot Mass on Bifurcation and Chaotic Behavior of a Simple Passive Walking Biped Model
Authors: Tayefi Siavash , Ohadi Abdolreza
Published: January 2011

In this study, a simple 2-D biped known as Garcia model [1] is used. This robot possessing two kneeless legs with point masses as its feet at the end of each leg and a third point mass at the “hip” joint. Three parameters, namely the ground slope angle, the normalized mass (ratio of foot mass to the hip mass) and leg length of the robot describe its gait. In previous works, the normalized mass was assumed zero, however, in this study, the effect of normalized mass on the bifurcation and chaotic behavior of biped is investigated. The numerical results show that, by increasing the foot masses, the system reaches the bifurcation point in smaller slopes with greater Poincare´ section fractal dimension. Thus, the biped with larger foot mass is more chaotic and the results show that in this case it has smaller gait length.
Molecular Dynamics Simulation of Iron Clusters Deposition on Copper Substrate
Authors: Hwang Shun-Fa , Hong Zheng-Han , Fang Te-Hua
Published: January 2011

A molecular dynamic method was used to simulate the film growth process of ionized cluster beam deposition for Fe clusters depositing on Cu substrate with low energy. The tight-binding many-body potential is used to simulate the interaction between atoms. It will focus on the diverse deposition process parameters including incident energy, and substrate temperature, and it will use atomic stress tensor to obtain the residual stress after the deposition process. During simulations, we will find out the critical value of the incident energy to create epitaxy growth or interfacial intermixing, observe the roughness of epitaxy growth surface to determine the quality of film, and compute the residual stress. From the simulation results, the effects of the deposition process parameters on the morphology of the deposited film could be evaluated.
Dimensioning and Simulation of a Pilot Plant for Solar Hydrogen Production
Authors: Ziari Kerboua Yasmina , Ziani Lofti , Mahmah Bouziane , Benzaoui Ahmed
Published: January 2011

Hydrogen is regarded as the potential bearer of energy of the future. Solar hydrogen is the hydrogen produced using renewable energy, particularly solar energy [15,8]. The availability of water and hours of sunshine make Algeria a place of choice for solar hydrogen production. In this work, solar hydrogen production by electrolysis of water is considered. The required energy for water dissociation is supplied by a photovoltaic system. A design and operation study of a photovoltaic system has been done for three different regions in Algeria. The production potential is highly significant particularly in the south parts of this country.
Various Criteria in Optimization of a Vapor Compression Refrigeration System
Authors: Nejatolahi Mostafa , Sayaadi Hoseyn
Published: January 2011

A cooling tower assisted vapor compression refrigeration machine has been considered for optimization with multiple criteria. Two objective functions including the total exergy destruction of the system (as a thermodynamic criterion) and the total product cost of the system (as an economic criterion), have been considered simultaneously. A thermodynamic model based on the energy and exergy analyses and an economic model according to the Total Revenue Requirement (TRR) method have been presented. Three optimized systems including a single-objective thermodynamic optimized, a single-objective economic optimized and a multi-objective optimized are obtained. In the case of multi-objective optimization, an example of decision-making process for selection of the final solution from the Pareto frontier has been presented. The exergetic and economic results obtained for three optimized systems have been compared and discussed. The results have shown that the multi-objective design more acceptably satisfies generalized engineering criteria than other two single-objective optimized designs.
A New Model for Integration of Process Planning and Production Planning for Cylindrical Parts
Authors: Farahnakian M. , Razfar M. R. , Korank Beheshti A. , Hadadzadeh M. , Khajehzadeh M.
Published: January 2011

In job shop and batch manufacturing, both process planning and production planning are responsible for the effective allocation and utilization of resources. Integration of process planning and production planning functions is necessary to achieve superior overall system performance. This paper proposes a model for the integration of process planning and production planning for cylindrical parts that can be implemented in the aggregated production planning (APP). The developed model considers simultaneously the technology-related constraints and shop floor constraint determined by the available time. In this approach, part machining time and cost are new variables for APP. In this model, the maximum depth of cut and feed for each feature are selected with regard to technology constrains, and the spindle speed is selected in aggregated production planning. The introduction of the overtime in the optimization process allows for the generation of improved planning according to several performance measures. The proposed optimization model is non-linear, unicriterion and multi-variable. A modern evolutionary algorithm, i.e., the particle swarm optimisation (PSO) algorithm, has been modified and applied to solve it effectively. A numerical example demonstrates the feasibility of applying the proposed model to APP problem.
Design and Implementation of an Electrically Control Circuit for Undulating Fins of Fish-Like Robot
Authors: Ghanbari Ahmad , Siahmansouri Mohsen , Fakhrabadi Mir Masoud Seyyed , Hashemi Nesaz Seyyed Reza
Published: January 2011

In this study, firstly, we compare various kinds of imitator robots and then by investigating of various fish robots properties, we design a mechanism and control circuit for a kind of these robots which its structure was inspired from knife fish. This robot has a segmental anal fin in its bottom which produces required force for advancement and maneuver. It consists of two servomotors and uses a kind of mechanical system to change direction and depth which is presented in this work. Another property of this robot is the existence of density control box for robot suspension which increases its capability for freight. The required signals are sent to this robot to produce the movement and maneuver by using a control handle and a wireless system which are installed on a control board. Therefore, it is possible to control the robot from out of the pool. In this paper, an electrical circuit is designed to control servomotors which enables us to control revolution, speed and phase differences of neighbor servomotors in fins. We also control two servomotors to regulate direction and depth.
Effect of Viscous Dissipation on Heat Transfer Between Two Concentric Cylinders for Carreau Fluids
Authors: Amoura Meriem , Zeraibi Noureddine
Published: January 2011

In this paper, we present a numerical study of the flow characteristics and heat transfer mechanism of a non-Newtonian fluid in an annular space between two coaxial rotating cylinders taking into account the effect of viscous dissipation. The Carreau stress-strain relation was adopted to model the rheological fluid behavior. The problem is studied when the heated inner cylinder rotates around the common axis with constant angular velocity and the cooled outer cylinder is at the rest. The horizontal endplates are assumed adiabatic. In-house code which is based on a Galerkin mixed finite element is developed to obtain numerical solutions of the complete governing equations and associated boundary conditions and is validated with the results reported in the literature. It is found that five parameters can describe the problem under consideration, the Reynolds number (Re), the Grashof number (Gr), the index of structure (n), Weissenberg number (We) and the Eckert number (Ec). The velocity, temperature and stream function distributions and the local Nusselt number variations are drawn for different dimensionless groups.
A Multi-Touch Planning Table to Support Participatory Factory Planning
Authors: Dombrowski Uwe , Riechel Christoph , Weckenborg Sebastian
Published: January 2011

The factory as a place of value-adding activities is forced to adapt continuously to turbulent conditions. New requirements regarding flexibility, speed, mobility and cost efficiency are some of factory planning. Hence the role of factory planning has developed from a one-time activity to a continuous management task. To achieve optimal results with regard to the new requirements it is necessary to analyze the existing processes and the functionality of the technical equipment at the workplace in detail. Therefore the existing methods of factory planning have to be improved. This paper focuses on the improvement of factory layout planning methods. One of the main areas of research of the Institute for Production Management and Enterprise Research (IFU) is the participatory layout planning. The goal of the research activities is to develop a method to integrate the employees from the shop-floor level into the planning process since they have special knowledge of the processes and technical equipment, which is necessary to achieve optimized planning results. To support the implementation of the participatory factory planning the IFU — in co-operation with the foresee GmbH — started the development of a participatory planning table called T3Pad (Tangible table top to enhance participation and development). The T3Pad is a conventional conference table with an integrated multi-touch display. The use of a gesture based software for layout planning offers the factory planning team the opportunity to design a layout by using the existing knowledge of the “classic” planning departments as well as the special manufacturing experience of the shop-floor employees. In order to realize the participation of the whole planning team the software has to comply with two major requirements: on the one hand the requirement in terms of the database and rules of factory planning; on the other hand the requirement of the usability of the software interfaces. Until now the users of factory planning methods have to adapt themselves to the function mode of computers instead of interacting and communicating in an intuitive way. This leads to limited interaction between user and hardware. The main goal of the T3Pad is an optimal support of the user by the software interface. To reach this goal the IFU started a field study to analyze the adoption of gesture based software interaction.
Finite Element Modeling of Spleen Tissue to Analyze Its Interaction With a Laparoscopic Surgery Instrument
Authors: Tirehdast Mojdeh , Mirbagheri Alireza , Farahmand Farzam , Asghari Mohsen
Published: January 2011

Laparoscopic surgery is a Minimally Invasive Surgery (MIS) procedure which is performed in the abdominal cavity. In this paper, the spleen tissue and a laparoscopic surgical grasper were modeled using ABAQUS software to investigate the tool-tissue interaction, considering large deformations for the spleen tissue. The spleen tissue was modeled as a hyper-elastic material. The laparoscopic grasper includes three gripping jaws that always remain parallel. The sliding can occur between the gripping jaws and the spleen tissue. It was found that the relationship between the pinch forces and push forces keeps its linearity in different values of friction coefficient (0–0.3). The pushing force varies from 0 (N) in pinch force of 1 (N) and the frictionless situation to 6.125 (N) in pinch force of 6 (N) and the friction coefficient equal to 0.3. Changing the shape of jaws can increase the pushing force up to 100%. The results could help surgeons to predict the correlation between grasping conditions and applied forces for a safe grasping procedure in the laparoscopic operations.
Tribological and Viscoelastic Behaviour of Carbon Black Filled Rubber
Authors: Marvalova Bohdana , Petri´kova´ Iva , Cirkl David
Published: January 2011

The paper describes a complex experimental research of tribological and mechanical properties of styrene-butadiene-rubber (SBR) filled with carbon black. Tribological properties of SBR rubber material are investigated experimentally using a home made device of ball-on-disc type. The response of SBR in sliding friction depends on sliding speed and on the loading force. The rate-dependent behaviour of carbon-black filled rubber is investigated in tensile tests with different loading rates and in relaxation tests. The viscosity-induced rate-dependent effects are described. The storage and loss moduli and phase angle δ dependency on different amplitudes and frequencies are determined by strain controlled dynamical mechanical analysis. The temperature dependence of dynamic and tribological behaviour of SBR is also investigated.
A Numerical Approach to Investigate Mixed Friction Systems in the Micro Scale
Authors: Albers Albert , Lorentz Benoit
Published: January 2011

This article deals with an approach on the numerical analysis of mixed friction systems. By means of the Finite Element Method, the influence of a set of selected parameters on the behavior of frictional contact systems is determined. A two dimensional model is built in a Finite Elements (FE) software and composed of one fluid lubricating two sliding rough surfaces. To model the interactions between the fluid and the solid structure, the Coupled-Eulerian-Lagrangian meshing process is utilized for its ability to simulate large contact domain topology changes occurring when two rough lubricated surfaces are sliding. Based on an axial floating bearing, the model calculates the contact pressure, the stress and also the friction coefficient between the two lubricated solids. The main friction coefficient is separated into solid-solid and fluid-solid friction part. This approach gives the opportunity to identify the influence parameters on the tribological behavior of mixed friction systems.
Stiffness Analysis of a Spatial Parallel Mechanism With Flexible Moving Platform
Authors: Rezaei Amir , Akbarzadeh Alireza , Enferadi Javad
Published: January 2011

In this paper, stiffness analysis of a 3-DOF spatial, 3-PSP type, parallel manipulator is investigated. Most previous stiffness analysis studies of parallel manipulators are performed using lumped model as well as assuming a rigid moving platform. In this paper, unlike traditional stiffness analysis, the moving platform is assumed to be flexible. Additionally, a continuous method is used for obtaining mathematical model of the manipulator stiffness matrix. This method is based on strain energy and Castigliano’s theorem [1]. For this purpose, first we solve inverse kinematics problem then We must find relationship between the applied external torques on the moving platform and the resultant joints forces. Next, strain energy moving platform is calculated. Strain energy of this element is calculated using force analysis and inverse kinematics problem. Finally, a FEM model is generated and used to simulate the physical structure. Simulation results are compared with the analytical model.
Performance and Exhaust Emission Studies of a Compression Ignition Engine Fueled With Waste Chicken Oil Methyl Ester (WCOME)-Diesel Fuel Blends
Authors: Ozcanli Mustafa , Aydin Kadir , Keskin Ali
Published: January 2011

Performance and exhaust emission studies of Waste Chicken Oil Methyl Ester (WCOME)-diesel fuel blends has been presented in this paper. The production of biodiesel from waste chicken oil was carried out via transesterification method. Blending ratios were preferred as 5% (B5), 10% (B10), 25% (B25) and 50% (B50) respectively. Performance and emission studies were carried out in a commercial diesel engine. The performance results reveal that blends of WCOME with diesel fuel provide increase on the brake specific fuel consumption (bsfc) and decrease on the brake power output proportional to the reduction in the heating value of blends. As a result, while the carbon monoxide (CO) and the carbon dioxide (CO2) emissions were reduced, nitrogen oxides (NOx) emissions were stated higher compared with the diesel fuel emission characteristics.
Derivaton of Kinematic Relations and Finite Element Stress Analysis of Flexspline in a Harmonic Drive Gear Box
Authors: Shishesaz Mohammad
Published: January 2011

This article investigates the kinematic relationships in a harmonic drive gearbox with a fixed circular spline. According to derived equations, as well as finite element results on flexspline, the ratio of vertical to horizontal deflection is constant for all values of the applied load. This ratio barely depends on geometric dimensions of the flexspline. According to kinematic relations, the difference in gear teeth of the flexspline and that of circular spline can only take values of 2 or 3. Finite element results, enforces value of 2 to be used. According to the results, flexspline deflection reveals similar behavior to that of a cylindrical shell. This similarity manifests itself in terms of a correlation factor Cf, through which one can find the flexspline deflections ratio using cylindrical shell results. A complete knowledge on this factor can eliminate any cumbersome work on finite element modeling of the flexspline. Moreover, using the proposed design curves (based on finite element results), one can calculate the required force for a full engagement of gear teeth without exceeding the bearing stress values of a flexspline, in a typical harmonic drive gearbox.
Thermally Developing 3D Cross Flow Between Cross Corrugated Parallel Plates in Evaporative Coolers
Authors: Tavakoli Ehsan , Hosseini Reza
Published: January 2011

The 3D cross flow between parallel corrugated plates with perpendicular directions of corrugation is numerically modeled as a laminar, incompressible, steady flow. The present work tries to investigate the thermally developing characteristics of the flow in this type of geometry, in the case of constant temperature on walls. The main emphasis is on introducing correlations for saturation efficiency and simply modeling the evaporation process within evaporative coolers with such geometries. The applied numerical method is the Chorin’s artificial incompressibility method and finite difference discretization is used to model the Navier-Stokes and energy equations in a structured mesh. The results show that saturation efficiency decreases with increase in Reynolds number. This also depends on the depth of evaporative media along the flow direction. Increasing the number of waves along the flow direction, results higher saturation efficiencies and also more pressure drop. For a specific saturation efficiency, the overall pressure drop decreases at higher amplitude to wavelength ratios. Also the overall pressure drop grows as the depth of the domain increases. The same trend is observed for experimental data of commercial evaporative pads.
Magnetic Pulse Driven Semi Compliant Four Bar Mechanism
Authors: S¸entu¨rk Mutlu , Turan Murat Can , Tekin Aslı , So¨nmez U¨mit , Kahraman Kerim , Bozkurt Eray
Published: January 2011

A partially compliant four-bar mechanism consists of a rigid crank, a rigid coupler and a flexible link (a rocker) is considered and its actuation by a magnetic force drive is investigated. The magnetic force applied to the coupler or the flexible rocker is converted to a rotational motion of the crank arm. This magnetic actuation force is applied in one direction until the rocker tip reaches its limit position, then with the energy stored in the elastic rocker link, the mechanism returns to its original position resulting of a complete revolution of the crank arm. The magnetic actuation is achieved by an external electromagnet driven by a voltage source and a neodymium permanent magnet attached on the mechanism. A prototype mechanism in macro scale is manufactured and it proved the conceptual contribution of the mechanism. The magnetically actuated compliant mechanism may also find applications in micro scales, actuating the rocker with a conventional rotational comb drive.
Production Method for Solid Oxide Fuel Cell Substrate Using Powder Injection Molding Process
Authors: Mirahmadi Amin , Rezaee Saraji Mostafa
Published: January 2011

Solid oxide fuel cells (SOFC) are a promising high-efficient power generating system that can directly convert chemical fuel to electrical power. Cost reduction of materials and processing is one of the key issues for commercialization of SOFCs. Powder injection molding is a good solution for producing low cost and defect free components and is adapted with mass production. In this study, effect of five powder loading and sintering temperature and holding time on porosity and thermal shock characteristics of SOFC substrate is investigated. Finally, the results show powder loading is not key factor in porosity and thermal shock characteristics and it is better to use high powder loadings. High sintering temperature for long time leads to high density sintered parts and are not suitable for SOFC substrate. All parts show high thermal shock characteristics.
Effect of Reduced Frequency on the Boundary Layer of a Plunging Airfoil
Authors: Rasi Marzabadi F. , Soltani M. R. , Masdari M.
Published: January 2011

This investigation addresses the boundary layer study of a plunging airfoil. It specifically concerns the effect of reduced frequency on transition and separation/reattachment of the unsteady boundary layer. The wind tunnel measurements were conducted using multiple hot-film sensors, pressure transducers and a boundary-layer rake, at Reynolds numbers of 0.42 to 0.84 million, and over reduced frequencies from 0.05 to 0.11. It was observed the boundary layer transition occurs by a laminar separation bubble. The unsteady laminar separation is promoted (delayed) by the increase of the reduced frequency in upstroke (downstroke) portion of the equivalent angle of attack.
Numerical Simulation of Elastic and Thermoelastic Wave Propagation in Two-Dimensional Classical and Generalized Coupled Thermoelasticity
Authors: Hosseini zad S. K. , Komeili A. , Akbarzadeh A. H. , Eslami M. R.
Published: January 2011

This study concentrates on the simulation of elastic and thermoelastic wave propagation in two-dimensional thermoelastic regions based on the classical and generalized coupled thermoelasticity. A finite element scheme is employed to obtain the field variables directly in the space and time domains. The FE method is based on the virtual displacement and the Galerkin technique, which is directly applied to the governing equations. The Newmark algorithm is used to solve the FE problem in time domain. Solving 2D coupled thermoelasticity equations leads to obtain the distribution of temperature, displacement and stresses through the domain. The problem is solved for two different type of boundary conditions (BCs), and the behavior of temperature, displacement and stress waves according to these BCs and based on the classical and generalized coupled thermoelasticity theories are shown and compared with each other. Several characteristics of the thermoelastic waves in two-dimensional domains are discussed according to this analysis.
Wear Resistance of Hard Coatings in Powder Injection Molding (PIM)
Authors: Keshavarz Panahi Ali , Khoshkish Hossein , Rezaee Saraji Mostafa
Published: January 2011

The degree of machine wear decisively determines the economic feasibility of powder injection molding. According to higher hardness of alumina powders (ca. 2000HV), manufacturing of ceramic components via PIM requires hard wear resistance equipments to overcome the wear phenomena. The wear test is based on the ASTM rubber wheel but the rubber wheel is replaced by a steel wheel of the same grade used in the barrel of an injection molding machine. The potential of hard coatings for wear protection in feedstock processing units is investigated in the present study. Model wear tests were carried out to demonstrate the tribological situation inside the screw/barrel system of extruders and injection molding machines. The substrate material was AISI 4140 steel which is used for PIM machine components. Hard coatings prepared by physical vapor deposition (PVD) and chemical vapour deposition (CVD) offer a good opportunity for wear protection. Due to higher temperature of feedstock and compression, the amount of wear in the metering zone is higher in comparison with other zones. The wear behavior also was strongly influenced by the characteristics of the feedstock (e.g. amount, size, shape and hardness of ceramic particles).
Large Amplitude Free Vibration Analysis of Thin Annular Sector Plates Using Differential Quadrature Method
Authors: Mirtalaie S. H. , Hajabasi M. A.
Published: January 2011

In this paper, the Differential Quadrature Method (DQM) is used to study the large amplitude free vibration of thin annular sector plates. The geometrical nonlinear governing equations of motion are derived based on the classical plate theory and using the von Karman nonlinear strain-displacement relationships. Following the DQ-procedure and employing the concept of new degrees of freedom a nonlinear eigenvalue problem is obtained which is solved iteratively and nonlinear natural frequencies of the plate are obtained. The results show a very good convergence and they are compared with the available literature for the clamped boundary conditions to demonstrate the validity of the work. The effects of boundary conditions, inner to outer radius ratio and sector angle on the large amplitude free vibration of thin plate are studied.
Numerical Study on Mass Transfer Effects on Spherical Cavitation Bubble Collapse in an Acoustic Field
Authors: Samiei Ehsan , Shams Mehrzad , Ebrahimi Reza
Published: January 2011

A numerical code to simulate mass transfer effects on spherical cavitation bubble collapse in an acoustic pressure domain in quiescent water has been developed. Gilmore equation is used to simulate bubble dynamics, with considering mass diffusion and heat transfer. Bubbles with different initial radii were considered in quiescent infinite water in interaction with sinusoidal shock waves with different magnitudes of amplitude and frequency. Simulations were done in two cases; with and without considering mass transfer. Good agreement with reference data was achieved. For bubbles with small radii in high frequency pressure field with low amplitude, mass transfer causes larger maximum radii and growth time, and more violent resultant collapse. Decreasing pressure frequency or increasing its amplitude causes larger maximum radii, longer collapse time, and more violent collapse. But, in cases with mass transfer because at the last moments of collapse stage a large amount of water vapor is trapped inside the bubble, the collapse will become less violent. For larger bubbles collapse becomes more violent for the cases without mass transfer in all pressure amplitudes and higher frequencies. But decreasing pressure frequency makes the collapse of the bubbles with mass transfer more violent. However, mass transfer effects decreases with increasing initial bubble radius.
Hardware in the Loop Simulation and Analysis of a Model of Fish Robotic System
Authors: Zeinoddini Meymand S. , Vosoughi G. R. , Farshchi M. , Nemati A.
Published: January 2011

In the present study, an adaptive sliding mode control method was employed to control a fish robotic system using hardware in the loop methodology. Up to now, few researches have focused on autonomous control of fish robot in dynamic environments which may be the result of difficulties in modeling of hydrodynamic effects on fish robot. Therefore, following the introduction of the nonlinear model for the robot, elongated body theory, suggested by Lighthill, was used to analyze fish movements. Then, kinematics control to track desired trajectories was designed for under-actuated model of robot. Adaptive sliding mode controller, capable of adapting according to changes and uncertainties, was designed and implemented. Using a fabricated stand, experimental tests were performed using hardware in the loop simulation. Computer simulations accompanied by experimental results verify that the presented adaptive controller has two main advantages: first, they make a robot versatile and capable of moving in unknown environments because of system robustness under changes and uncertainties of parameters. Second, they leave out the need for expensive and time consuming experiments to recognize system model and reduce operations for final tuning of controller.
Power Train NVH Analysis With Excite in a Four Cylinder Inline Engine by Including Crankshaft Dynamics and Flywheel Swirl
Authors: Duran E. Tolga , Braumueller Dirk
Published: January 2011

Engine mount vibration level, which is mainly driven by gas and unbalanced inertial forces, is one of the key metrics for the NVH (Noise Vibration Harshness) performance of a vehicle. In addition to gas and unbalanced inertial forces, crankshaft dynamics has also effect on engine mount vibrations. This project is concentrating in including the effect of crankshaft dynamics on engine mount vibrations with the aid of Finite Element Methods and Multi Body Dynamics. Flywheel swirl mode, its effect on engine mount vibration levels and engine mount acceleration for different flywheel configurations will be simulated.
Free Vibration Control of MRE Embedded Viscoelastic Cored Sandwich Beam With Time Varying Magnetic Field
Authors: Nayak Biswajit , Dwivedy Santosha K. , Krishna Murthy K. S. R.
Published: January 2011

The present work deals with the free vibration control of a simply supported and cantilevered sandwich beam with magnetorheological elastomer (MRE) embedded viscoelastic core and conductive skins subjected to time varying magnetic field. The skins of the sandwich beam are conductive such that magnetic loads are applied to the skins. Considering the core to be stiff in transverse direction, classical sandwich beam theory has been used along with extended Hamilton’s principle and Galarkin’s method to derive the governing equation of motion. The resulting equation reduces to that of a parametrically excited system. Method of multiple scales has been used to study the response and stability of the system. Critical parameters of amplitude and frequency of magnetic field have been determined to actively control the free vibration response of the system. Effects of percentage of iron particles and carbon black in attenuation of vibration of the sandwich beam have been studied. Here the experimentally obtained properties of recently developed magnetorheological elastomers based on natural rubber containing iron particles and carbon blacks have been considered in the numerical simulation.
Optimization of a High Pressure Swirl Injector by Using Volume-of-Fluid (VOF) Method
Authors: Rezaeimoghaddam Mohammad , Moin Hossein , Modarres Razavi M. R. , Pasandideh-Fard Mohammad , Elahi Rasool
Published: January 2011

In this paper, the effects of various geometric parameters of a high pressure swirl Gasoline Direct Injector (GDI) on the injection flow quality are investigated. The two-dimensional axisymmetric Navier-Stokes equations coupled with the Volume-of-Fluid (VOF) method were employed for simulation of the formation mechanism of the liquid film inside the swirl chamber and the orifice hole of the pressure swirl atomizer. To validate the model, results for base injector were compared in the steady state operation with those of available experiments in the literature. Good agreements were obtained for discharge coefficient (Cd) and cone angle (θ) with experimental data. The effects of five characteristic geometric parameters of swirl injectors such as orifice ratio (orifice length to orifice diameter), angle of swirl chamber, orifice diameter, needle lift and needle head angle (assumed to be cone) were investigated. The results show that increasing the swirl chamber angle leads to an increase in mass flow rate and a decrease of the cone angle of liquid sheet. Through extensive simulations, geometric parameters of an optimum injector were obtained.
A Computational Investigation on Seat Belt Use for Pregnant Drivers in Airbag Equipped Automobiles
Authors: Acar B. Serpil , Esat Volkan
Published: January 2011

Pregnant women are a vulnerable and sensitive group in road traffic accidents, prone to sustaining varying levels of injury following an automobile crash accident. The objective of this research is to investigate various frontal impacts that pregnant women may undergo through simulations with a computational model of the pregnant driver, ‘Expecting’. Injuries when the seat belt is properly used in an airbag equipped automobile are compared with the cases where the seat belt is not worn by the pregnant driver. Displacements and strains occurring in the uterus are presented as well as injury criteria such as HIC, 3ms maximum and maximum VC in order to demonstrate the injury levels. The responses of the pregnant driver model in varying accident conditions particularly to demonstrate the injuries that they may be exposed to when the seat belt is not worn in airbag equipped automobiles emphasise that the air bags are supplementary restraint systems, and not meant to replace seat belts.
Design and Analysis of Rotary Positive Displacement Mechanism for Oil-Less Compression
Authors: Roser Holger
Published: January 2011

In this paper, a simple positive displacement mechanism is investigated, which comprises two counter-rotating meshing rotors within a casing. Although considered for various applications more than a century ago, the basic geometry of this mechanism has not been further explored or adapted to modern gas compressor technology. As a fully balanced rotational mechanism operating at uniform angular velocity, potential applications range from pumps to expanders, from slow large displacement to high-speed devices; nonetheless, this research focuses on high-performance oil-less gas compressors as an ideal application. During one complete cycle, the main rotor compresses and discharges the fluid, whilst the secondary rotor seals the compression chamber. Important features of this mechanism are the circular profiles of the rotors, the potential to accommodate large ports for reduced flow losses, and ease of cooling. The simple geometry facilitates a cost-effective means of achieving tight operating clearances between rotors and casing for enhanced sealing without the need for liquid lubricants such as oil. This study and preliminary tests indicate that pressure ratios suitable for standard industrial applications can be obtained over a broad speed range, whilst minimizing friction and flow losses, a major drawback of current technologies. Moreover, two-phase compression and injection of liquids prior to compression have been studied and identified as a means to further improve efficiency and cooling.
Design and Fuzzy Control of a Moving Magnetic Levitation Device for 3D Manipulation of Small Objects
Authors: Jazi Mehdi Molavian , Vossoughi Gholamreza , Tajaddodianfar Farid
Published: January 2011

Magnetic levitation is an appropriate solution for noncontact 3D manipulation. Workspace of the previously proposed maglev systems are confined to a relatively small cube, and this severely limits application of this technology. In addition, most of the previously given mechanisms require design and application of a subsystem for unifying their magnetic field. In this paper, a moving magnet is implemented which results in horizontally extendable work space; moreover, the field unifying section is not needed since one electromagnet only is used. Further, details of the mechanism and finite element based design procedure of the magnet are presented. Dynamic equations of the system derived by finite element analysis of the magnetic field are highly nonlinear and non-affine with respect to the control input. Two decoupled Fuzzy logic based controllers are used to deal with the 3D manipulation of the ball. The designed controllers provide the system with the precise trajectory tracking capability and robust stability. Simulation results confirm the findings.
Flexural Sensitivity of a V-Shaped AFM Cantilever Made of Functionally Graded Materials
Authors: Rahaeifard M. , Kahrobaiyan M. H. , Moeini S. A. , Ahmadian M. T. , Hoviattalab M.
Published: January 2011

In this paper, two lowest resonant frequencies and sensitivities of an AFM V-Shaped microcantilever made of functionally graded materials are studied. The beam is modeled by Euler-Bernoulli beam theory in which rotary inertia and shear deformation is neglected. It is assumed that the beam is made of a mixture of metal and ceramic with properties varying through the thickness of the beam. This variation is function of volume fraction of beam material constituents. The interaction between AFM tip and surface is modeled by two linear springs which expresses the normal and lateral contact stiffness. A relationship is developed to evaluate the sensitivity of FGM micro cantilever beam. Effect of volume fraction of materials and geometric parameters on resonant frequencies and sensitivities is studied. Results show that natural frequencies and sensitivities are significantly affected by volume fraction of material constituents and geometric parameters. Using these results, optimum geometric parameters and mass distributions of material constituents can be chosen so that high resolution images could be obtained.
Fatigue Reliability Assessment of Marine Risers in Deep Offshore Fields in Indian Ocean
Authors: Khan Rizwan A. , Ahmad Suhail
Published: January 2011

Depleting oil reserves in shallow water are opening the avenues of new ventures in deep sea conditions. India is no exception; deep sea explorations are highly recommended and exercised. As part of the design process, there are requirements of structural strength based on criteria referring to failure modes, such as rupture by over loading, fatigue failures, buckling or an unstable fracture. 3D Nonlinear dynamic analysis of riser is obtained in the time domain using finite element solver ABAQUS/Aqua. The response histories so obtained are employed for the study of fatigue reliability analysis of riser. It is based on a bi-linear relationship to model fatigue crack growth and incorporates a failure criterion to describe the interaction between fracture and plastic collapse. Uncertainty modeling, especially on fatigue crack growth parameters, is undertaken with the aid of recently published data in support of the bi-linear crack growth relationship. Results pertaining to fatigue reliability and fatigue crack size evolution are presented using Monte Carlo Simulation. The bi-linear S-N curve and crack growth models are found to lead to higher fatigue life estimation. Sensitivity behavior pertinent to limit state adopted has been thoroughly investigated. These findings implicate inspection schemes for components of the marine structures to ensure minimization of the surprises due to wide scatter of the fatigue phenomenon in marine environment.
The Atomic-Scale Hysteresis in Non Contact Atomic Force Microscopy
Authors: Pishkenari Hossein Nejat , Meghdari Ali
Published: January 2011

In this research, the hysteresis in the tip-sample interaction force in noncontact force microscopy (NC-AFM) is measured with the aid of atomistic dynamics simulations. The observed hystersis in the interaction force and displacement of the system atoms leads to the loss of energy during imaging of the sample surface. Using molecular dynamics simulations it is shown that the mechanism of the energy dissipation occurs due to bistabilities caused by atomic jumps of the surface and tip atoms in the contact region. The conducted simulations demonstrate that when a gold coated nano probe is brought close to the Au (001) surface, the tip apex atom jumps to the surface; and instantaneously, four surface atoms jump away from the surface toward the tip apex atom. Along this line, particular attention is dedicated to the dependency of the energy loss to different parameters such as the environment temperature, the tip orientation, the surface plane direction, the system size, the distance of the closest approach and the tip oscillation frequency.
A Study on the Buckling Characteristics of Conical Shell Using Differential Quadrature Method
Authors: Jomehzadeh E. , Mirtalaie S. H. , Noori H.
Published: January 2011

In this paper, the buckling analysis of conical shell under transverse pressure or axial compression is studied using the Differential Quadrature Method (DQM) for various boundary conditions. Based on the Donnell theory of shell, the equilibrium equations are obtained using Hamilton’s principle. The adjacent equilibrium criterion is employed to defining the stability equations of conical shell subjected to lateral pressure and axial compression. Then the stability equations are solved numerically using DQM and employing the concept of extra degrees of freedom. The acquired results in special cases are compared with the results in literature for the accuracy evaluation of the method and a good agreement can be seen. The non-dimensional critical buckling loads are tabulated for different vertex angles, some thickness-radius ratios and various combinations of boundary conditions. Also, the effects of the vertex angle, boundary conditions, length-radius ratio and thickness-length ratio on the buckling behavior of the conical shell are investigated in details.
Application of Modified Discrete Ordinate Method to Combined Conductive and Radiative Heat Transfer Problems in Irregular Geometry
Authors: Amiri H. , Mansouri S. H. , Safavinejad A.
Published: January 2011

A blocked-off region concept is implemented with the modified discrete ordinates method (MDOM) to solve combined conductive and radiative heat transport problems in irregular geometries. The media analyzed are absorbing, emitting and isotropically or anisotropically scattering. The walls have temperature or flux boundary conditions. The finite-volume method is used to solve the energy equation and the modified discrete ordinates method is employed to solve the radiative transfer equation. The SDOM and MDOM are compared in all cases, and the accuracy of the results is assessed by comparing the results with those obtained by other researchers. The results confirm the capability of the MDOM to minimize the anomalies due to ray effects in combined mode heat transfer problems.
Thermodynamic Effects on Cavitation in Water and Cryogenic Fluids
Authors: De Giorgi Maria Grazia , Rodio Maria Giovanna , Ficarella Antonio
Published: January 2011

The present study focuses on the formation of cavitation in cold and hot water and in cryogenic fluid, characterized by strong variations in fluid properties caused by a change in temperature. Cavitation phenomenon is investigated in water and nitrogen flows in a convergent-divergent nozzle through pressure measurements and the optical visualization method. High-speed photographic recordings have been made, the cavitation phenomena evolution and the related frequency content are investigated by means of pixel intensity time series data. The results obtained concur with those obtained with the spectral analysis of the pressure signals. In the case of cryogenic fluid frequency peaks are shifted towards lower frequencies, with respect to cold water and the magnitude of the signal rises, in particular at low frequencies, for nitrogen and hot water. This can be due to thermal effects that contribute also to the low frequencies in the case of cryogenic fluid. To verify the validity of this assumption, a simple model based on the resolution of Rayleigh equation is used.
Optimal Gear Ratio and Gear Shift Strategy Design for a Parallel Hybrid Electric Vehicle Equipped With AMT
Authors: Montazeri-Gh Morteza , Pourbafarani Zeinab , Nehzati Hassan
Published: January 2011

This paper presents an optimal approach for the design of gear ratios and gear shifting strategy for parallel hybrid electric vehicle (HEV) equipped with automated manual transmission (AMT). For this purpose, an AMT model is firstly provided and integrated with a pre-transmission parallel HEV model to develop a comprehensive simulation tool for vehicle powertrain performance evaluation. Using genetic algorithm (GA), an optimization problem is then formulated for the optimal design of the AMT variables including its gear ratios as well as the variables defined for the gear shifting strategy. A weighted aggregation of the HEV fuel consumption and emissions is also employed as the fitness function. In addition, the vehicle driving performance characteristics are considered as the optimization constraints. To optimize the gearshift strategy and gear ratios, GA optimization process is performed for several traffic conditions. The results show that the approach is quite effective. A considerable improvement is achieved at congested condition due to its sensitivity to the stop-start operation of the vehicle.