bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of Degradation of Polyolefins Used in Solar Domestic Hot Water Components
Authors: Camisa William , Mantell Susan C. , Davidson Jane H. , Singh Gyanender
Published: January 2011

Solar Domestic Hot Water systems may include polymer components such as heat exchangers and absorbers. These components must be designed to consider heat transfer performance, mechanical (strength) performance and lifetime. Polymer degradation in potable hot water can be delayed through the use of antioxidant additives. In the present study, data are presented which show that antioxidant depletion in polyethylene (with a phenolic additive) is accelerated in potable hot water. Characteristic time scales are derived for this polymer/antioxidant combination at 80°C. These time scales indicate that the rate of antioxidant depletion is controlled by chlorine diffusion into the polymer (and subsequent reaction between the chlorine and antioxidant).
The Dynamical Behavior of Y-Shaped Tubes Conveying Fluid
Authors: Al-Rajihy Ahmed A. , Alwan Hazim U.
Published: January 2011

The present work deals with the vibrational characteristics of a Y-shaped tube conveying flowing fluid. The tube is considered to be composed of 3-stright tube segments mathed at the intermediate junction. The governing equation of straight tube conveying fluid is used with each of the three segments. This work introduce the clamped-pinned and clamped free boundary conditions. The coupled effects of the type of boundary conditions, angle between the two Y-segments, fluid velocity and length ratio of segments on the dynamics of the tube are studied. It seen that the Y-tube loses its stability at flow velocity higher than that for straight tube of the same characteristics.
Analytical Response for the Prototypic Nonlinear Mass-Spring-Damper System
Authors: Omran Ashraf , Newman Brett
Published: January 2011

In this paper, a procedure to analytically develop an approximate nonlinear solution for the prototypic nonlinear mass-spring-damper system based on multi-dimensional convolution expansion theory is offered. An analytical nonlinear step response is also conducted to characterize the overall system response. The developed analytical step response provides an illumination for the source of differences between nonlinear and linear responses such as initial departure time, differences in settling times and steady value, and non-symmetric response. Feasibility of the proposed implementation is assessed by a numerical example. The developed kernel-based model shows the ability to predict, understand, and analyze the system behavior beyond that attainable by linear-based model.
Process Simulation and Exergy Analysis of a Reverse Osmosis Desalination Plant Powered by Photovoltaic Panels in Basra (Iraq)
Authors: Esposto Stefano , Sciubba Enrico , Toro Claudia
Published: January 2011

The paper presents the simulation and the exergy analysis of a solar-powered reverse osmosis plant (PV-RO) located in Basra (Iraq) characterized by an average production of 5 m3 of fresh water per hour. The system layout includes the PV system powering the reverse osmosis unit. Since the purpose of the plant is to supply freshwater to a rural village, the installation of a battery pack as an energy storage is not foreseen. The influence of some relevant process parameters like ambient temperature, global radiation and salinity of the raw water are studied by means of numerical process simulations of the plant. A suitable thermodynamic model of the PV-RO has been developed and implemented into the library of a modular object-oriented Process Simulator, CAMEL-Pro™ and the code has been then used to study the exergetic performance of the plant, to help identify and quantify irreversibilities and losses in energy quality. In CAMEL, the exergy flow associated with each energy and material stream in the plant is calculated on the basis of mass- and energy balances and of a proper set of libraries of material properties, so that the values of the exergy destruction, ExD and of the exergy efficiency, ExEff, of each component can be evaluated.
On Some Particularities of the Axisymmetric Wave Propagation in the Initially Twisted Circular Compound Cylinders
Authors: Akbarov Surkay , Guliev Mugan , Kepceler Tamer
Published: January 2011

This paper investigates some particularities related with the influence of the magnitude of the initial twisting of the axisymmetric wave propagation in the initially twisted circular bi-material compounded cylinder. The investigation is carried out within the scope of the piecewise homogeneous body model with the use of the three-dimensional linearized theory of elastic wave propagation in an initially stressed body. The mathematical formulation of the problem is presented and the corresponding solution method is proposed and developed. The numerical results are further presented and discussed. In particular, the mechanism of the arising of the new type modes caused by the initial twisting of the circular compounded cylinders is established.
The Effect of Triangular Vortex Generators on Turbulent Flow and Heat Transfer in a Channel
Authors: Soltanipour Hosseinali , Mirzaei Iraj , Choupani Parisa
Published: January 2011

In the present work heat transfer characteristics and flow structure in turbulent flow through a rectangular channel containing built-in triangular winglet-type vortex generators have been analyzed by means of solutions of the Navier-Stokes and energy equations using finite volume method. The geometrical configuration is representative of single element of plain-plate heat exchangers. Each winglet-pair induces longitudinal vortices behind it. Shear stress transport (SST) model is used in this study. The underlying physical phenomena have been described and the effects of Reynolds number and angle of attack, on the heat transfer, pressure drop and thermal performance have been presented.
Modes of Wave Propagation and Dispersion Relations in Inclusion Reinforced Composite Plates
Authors: Liu Yu Cheng , Huang Jin Huang
Published: January 2011

This paper mainly analyzes the wave dispersion relations and associated modal pattens in the inclusion-reinforced composite plates including the effect of inclusion shapes, inclusion contents, inclusion elastic constants, and plate thickness. The shape of inclusion is modeled as spheroid that enables the composite reinforcement geometrical configurations ranging from sphere to short and continuous fiber. Using the Mori-Tanaka mean-field theory, the effective elastic moduli which are able to elucidate the effect of inclusion’s shape, stiffness, and volume fraction on the composite’s anisotropic elastic behavior can be predicted explicitly. Then, the dispersion relations and the modal patterns of Lamb waves determined from the effective elastic moduli can be obtained by using the dynamic stiffness matrix method. Numerical simulations have been given for the various inclusion types and the resulting dispersions in various wave types on the composite plate. The types (symmetric or antisymmetric) of Lamb waves in an isotropic plate can be classified according to the wave motions about the midplane of the plate. For an orthotropic composite plate, it can also be classified as either symmetric or antisymmetric waves by analyzing the dispersion curves and inspecting the calculated modal patterns. It is also found that the inclusion contents, aspect ratios and plate thickness affect propagation velocities, higher-order mode cutoff frequencies, and modal patterns.
Effect of Dual Fuel Engine Parameters and Fuel Type on Engine Noise Emissions
Authors: Elnajjar Emad , Selim Mohamed Y. E. , Omar Farag
Published: January 2011

Investigating experimentally the effects of different fuel types and engine parameters on the overall generated engine noise levels. Engine parameters such as: Engine speed, Injection timing angle, engine loading, different pilot fuel to gases fuel ratio and engine compression ratio. Engine noises due to combustion, turbulent flow and motoring were reported in this study by direct sound pressure level SPL (dB) measurements and compared to the maximum cylinder pressure rise rate with respect to the engine crank angle (dP/dθ)max. Experimental procedures conducted using a Ricardo diesel version variable compression research engine. The study was conducted for three different fuels: single diesel fuel, and dual fuel engine that uses LPG or natural gas. The study for each fuel type covered the following operating parameters range, engine speed from 20–28 rev/sec, injection timing form 20 to 45° BTDC, compression ratio from 16 to 22, load range 2 to 14 N.m, and ratio of pilot to gaseous fuel from 0 to 10%. The study reported the location (crank angle) corresponding to maximum cylinder pressure and max pressure rise rate. Results from testing dual fuel engine with varying design and operating parameters are presented and discussed. The present work reported higher SPL (dB) generated from burning a dual fuel compared to burning diesel fuel only.
Application of the Perturbation Method With Parameter Weighting Matrix Assignments for Estimating Variability in a Set of Nominally Identical Welded Structures
Authors: Abu Husain Nurulakmar , Haddad Khodaparast Hamed , Mottershead John E. , Ouyang Huajiang
Published: January 2011

A perturbation method is employed in this paper and the problem of model updating in the presence of uncertainty due to manufacturing variability is addressed. Statistical properties of experimental data are considered and updating parameters are treated as random variables. The perturbation equations are used for estimation of means and covariances of updating parameters. The perturbation formulation is included and two approaches of parameter weighting matrix assignments are explained. Results from one of the approaches demonstrate good correlation between the predicted mean natural frequencies and their measured data, but poor correlation is obtained between the predicted and measured covariances of the outputs. In another approach, different parameter weighting matrices are assigned to the means and covariances updating equations. Results from the latter approach are in very good agreement with the experimental data and excellent correlation between the predicted and measured covariances of the outputs is achieved.
Effect of Macro Geometry on the Performance Characteristics of Reciprocating Seals
Authors: Gu¨l Cihat , Temiz Vedat
Published: January 2011

Since reciprocating motion is commonly encountered in many industrial applications like hydraulic cylinders, performance characteristics of reciprocating seals is important for design of such systems. In this paper, some reciprocating seals having different macro geometry have been investigated experimentally. An experimental setup has been developed to perform as a hydraulic cylinder. Experiments have been carried out with different types of hydraulic seals which are made of NBR. Through the experiments, variation of the friction force applied to the hard chrome coated piston rod by seals, have been measured under various oil pressures in the main cylinder. In the second step of experiments, the amount of leakage from the seal in one out-stroke of the piston rod has been determined for various oil pressures. The effect of oil viscosity to the performance characteristic of reciprocating seals has also been studied. As a result of systematical experiments, the variations of friction force and leakage amount with oil pressure for various types of reciprocating seals have been obtained.
Analysis of Flow Over a Circular Cylinder by CFD and Reduced Order Modeling
Authors: Paksoy Akin , Apacoglu Buryan , Aradag Selin , Kasnakoglu Cosku
Published: January 2011

The main idea of flow control is the improvement of aerodynamic characteristics of flow, such as, reducing drag and unsteadiness of loads compelled by the flow field onto structures exposed to the flow. The ultimate aim of this research is to build a flow control system with the help of artificial neural networks (ANN) in order to be able to control the vortex shedding behind a two dimensional (2D) cylinder. In this study, flow over a 2D circular cylinder at laminar Reynolds numbers is analyzed by Computational Fluid Dynamics (CFD), where obtained results are compared with the experimental values stated in literature, and flow structures are separated according to their frequency content by application of the Proper Orthogonal Decomposition (POD) method to the resulting data.
Multi-Objective Optimal Design of Hybrid Laminates Using Continuous Ant Colony Method
Authors: Abachizadeh Mahdi , Shariatpanahi Masoud , Yousefi-Koma Aghil , Dizaji Ahmad Feiz
Published: January 2011

Hybrid laminated composites are gaining increasing popularity in applications where improved mechanical properties as well as reduced weight and cost are desired. However, the highly nonlinear nature of the governing equations and the combination of continuous and discrete design variables has rendered the problem a challenging one. This paper implements the nature-inspired method of continuous ant colony optimization (ACOR) for hybrid laminates comprising high-stiffness graphite/epoxy and low-stiffness glass/epoxy. The number of surface and core layers and their layouts (discrete) as well as the fiber angles in each layer (continuous) form the design variable set; whereas the composite’s fundamental frequency and cost (to be maximized and minimized, respectively) are taken as the objective functions. Comparison of the results with those reported in the literature having used standard discrete fiber angles and implemented methods such as the ant colony system (ACS) and GA, indicates a clear improvement in the values of the objective functions for the majority of the studied cases. It is nonetheless recommended that, for practical purposes, the closest standard fiber angles to the optimal values be adopted (a procedure generally being used but not proven to be optimal), as the corresponding deviations would be negligible.
Establishment and Safety Evaluation of a Removable Experiment Platform for VAWT
Authors: Lin Sheam-Chyun , Yanto Harki Apri , Chen Chao-Chang , Chen Yen-Wen , Wang Shih-Yu
Published: January 2011

This investigation intends to establish an experimental test platform for a small vertical-axis wind turbine (VAWT), which is installed on the rooftop of a building. The experiment platform designed here is flexible and suitable for executing the systematic performance evaluation on different types of VAWT. By utilizing the data acquisition system (DAQ), all environmental information and power data from sensors and generator on the platform are recorded and transferred to the computer automatically. Later, these analogy signals are transformed to digital format for transmitting into computer. Also, with the aids of a visual software programming within the framework of Labview, the real-time monitoring on the input/output parameters of generator and the wind condition on the rooftop can be accomplished simultaneously. Afterwards, the data processing and in-depth analysis on the experimental outcomes are carried out via the established computer program. Consequently, the on-site performance of the wind turbine generator system is attained in an automatic and systematic manner. Moreover, to ensure for providing sufficient data and its accuracy, statistic concept is enforced to judge whether the test data are qualified or not in the data-processing procedure. Regarding the safety evaluation on this test platform, the numerical models of the wind turbine and platform are analyzed numerically via ANSYS Workbench to obtain the force exerting on the main shaft and blades. This force distribution can be analyzed for checking if they can stand and meet the safety criterion under various wind speeds. In summary, together with the data-acquisition software programmed under the framework of Labview, this experimental system can provide the capability for monitoring, recording, and filtering these test data in an rigor manner, and is appropriate for executing the R&D and performance evaluation on different VAWTs.
Optimal Stabling of Attitude Maneuver for a Special Satellite With Reaction Wheel Actuators
Authors: Miri Roknabadi Seyed Hasan , Fakhari Mehrjardi Mohamad , Mirshams Mehran
Published: January 2011

This paper presents an optimal attitude maneuver by Reaction Wheels to achieve desired attitude for a Satellite. At first, Dynamic Equations of motion for a satellite with just three Reaction Wheels of its active actuators are educed, and then State Equations of this system are obtained. An optimal attitude control with the LQR method has exerted for a distinct satellite by its Reaction Wheels. As a result simulation has presented an optimal effort by calculated Gain matrix to achieve desired attitude for chosen Satellite. It shows that satellite becomes stable in desired attitude with a low energy and time consumption. Furthermore equations derivation, coupling of electrical Reaction Wheel equations with dynamic equations of satellite motion, linearizes them and Reaction wheel saturation avoidance approaches are innovative. Simulation results, accuracy of achieving desired attitude and satellite stability support this statement.
Estimation of the Heat Generation in a Cutting Tool Using a Sequential Inverse Method
Authors: Samadi Forooza , Kowsary Farshad , Hamedi Mohsen , Sarchami Araz
Published: January 2011

In this paper the Sequential Function Specification Method is used to estimate the transient heat flux imposed on the rake face of the cutting tool during the cutting operation. The cutting tool is modeled as a three dimensional object. The capabilities of the geometric modeling, mesh generation as well as solver of the commercial software ANSYS is utilized in order to reduce the time expended for modeling and direct heat conduction solution. This way the inverse heat conduction algorithm employs ANSYS as a subprogram through the ANSYS Parametric Design Language (APDL). The stability as well as accuracy of the heat flux estimation is investigated using familiar triangular as well as step heat flux test cases. The effect of noise level, the number of temperature sensors as well as their locations are investigated in order to arrive at an optimal experimental procedure. Finally, a typical temperature data during the working condition are used to recover the heat flux at the cutting tool surface.
Investigation of Exergy Destruction Based on Avoidable and Unavoidable Concepts for Helical Coils
Authors: Bahiraee Farid , Salehzadeh Aidin , Khoshbakhti Saray Rahim
Published: January 2011

An inevitable problem challenges heat exchanger designers is that the heat transfer augmentation in a thermal system is always achieved at the expense of an increase in pressure loss. Thus, the optimal trade-off by choosing the most proper configuration and best flow condition has become the critical problem for design work. The brief survey on literature shows that optimal Reynolds number (i.e. the Reynolds number which corresponds to minimum entropy generation) of laminar forced convection in a helical tube, was specified based on minimum entropy generation. Therefore, the present study analyzes the thermodynamic potential of improvement for steady, laminar, fully developed, forced convection in a helical coiled tube subjected to uniform wall temperature based on the concept of avoidable and unavoidable exergy destruction. The influence of coil curvature ratio, dimensionless inlet temperature difference, dimensionless passage length of the coil, and fluid properties on avoidable exergy destruction have been investigated for water as working fluid. Results show considerable potential of thermodynamic optimization of helical coil tubes. Also, in the range of present study a relation for determining the amount of optimum Dean number is proposed.
Experimental and Numerical Analysis of Carbon Black Formation in Hydrocarbon/Air Diffusion Flames
Authors: Heravi D. F. , Heravi H. M. , Bashirnezhad K. , Sanaei Hassan , Samiee Amirhomayun
Published: January 2011

Carbon black has been widely used in industry, especially in rubber and plastic production. The present study is concerned with measuring and simulating the carbon black formation process in Propane-air and Acetylene-Air diffusion flames. The carbon black concentrations in the furnace have been measured by means of a soot pump and gravimetric method. The flue gas analysis is also done by means of Testo XL-350 Gas Analyzer. The numerical predictions are carried out with the CFD code, Fluent. The chemical reaction formulation relates the production of the carbon black to the incomplete combustion and pyrolysis of propane and Acetylene as both the main gas and the feedstock. The effects of feedstock mass flow rate, the position of feedstock injection, the feedstock material and the shape of the furnace on carbon black are studied. The results show the effect of temperature on soot and carbon black formation in which as the temperature increases the soot and carbon black mass fraction is also increased. The results also show that as the feedstock mass flow rate increases the formation of the carbon black is increased up to point where the mass flow rate of feed stock is three times greater than the mass flow rate of the main gas and after that the carbon black production rate starts decreasing because of the decreasing of temperature due to cold fuel injection to the furnace. The position of feedstock injection affects the mixing process of air and fuel, and complete mixing causes the temperature to be increased. The injection of feedstock in the pre-combustion zone influences the maximum of the flame temperature. As the hydrocarbon initially pyrolyzes to acetylene and afterwards acetylene breaks into soot and carbon black in the present study acetylene is used as feedstock, the results show huge increasing of soot and carbon black mass fraction in the products. The results also show that predictions and the experimental measurements are in good agreement.
Fast AFM Scanning With Parameter Space Based Robust Repetitive Control Designed Using the COMES Toolbox
Authors: Necipog˘lu Serkan , Demirel Burak , Gu¨venc¸ Levent
Published: January 2011

Atomic Force Microscope (AFM) is a very strong and beneficial instrument for acquiring images at nanometer scale. Hence, obtaining better image quality and scan speed is a research area of great interest. Improving the dynamic responses of the scanning probe and the vertical motion of the scanner mechanisms are the two major areas of concentration in this sense. Improving the vertical dynamics is achieved either by designing more complex scanner mechanisms with higher bandwidth or designing more sophisticated controllers rather than the PI, PID or PIID types of controllers that are mostly used in practice. In this paper, the authors focus on designing a repetitive control scheme for fast and accurate scanning. It is possible to implement repetitive control to achieve this goal when it is considered that the successive lines of the scan are quite similar due to the very small steps taken to advance on the sample. Repetitive control can reject higher frequency disturbances due to the surface topography in AFM much better than a conventional controller can, as it can drive the error caused by any periodic input signal to zero. Besides increasing the scan speed, it is also important that the phase lag can be compensated perfectly using repetitive control, with the knowledge of the surface topography from the previous period by introducing appropriate phase advance.
Synchronization of Unified Chaotic System by Robust H∞/Sliding Mode Control
Authors: Yazdanbakhsh Omolbanin , Hoseinia Saeid
Published: January 2011

This paper investigates the chaos synchronization problem for a class of uncertain unified chaotic systems with external disturbances. Based on the proportional-integral (PI) switching surface, a sliding mode controller (SMC) is derived to not only guarantee the occurrence of a sliding motion of error states, but also reduce the effect of external disturbances to an H∞-norm performance. Also, a new reaching law is introduced to reduce the chattering problem that is produced by traditional sliding mode control. The parameters necessary for constructing both PI switching surface and the SMC can be found by the linear matrix inequality (LMI) optimization technique. Finally, a numerical simulation is presented to show the effectiveness of the proposed method.
Buckling Analysis of Thin Functionally Graded Rectangular Plates Resting on Elastic Foundation
Authors: Mohammadi Meisam , Saidi A. R. , Mohammadi Mehdi
Published: January 2011

In the present article, the buckling analysis of thin functionally graded rectangular plates resting on elastic foundation is presented. According to the classical plate theory, (Kirchhoff plate theory) and using the principle of minimum total potential energy, the equilibrium equations are obtained for a functionally graded rectangular plate. It is assumed that the plate is rested on elastic foundation, Winkler and Pasternak elastic foundations, and is subjected to in-plane loads. Since the plate is made of functionally graded materials (FGMs), there is a coupling between the equations. In order to remove the existing coupling, a new analytical method is introduced where the coupled equations are converted to decoupled equations. Therefore, it is possible to solve the stability equations analytically for special cases of boundary conditions. It is assumed that the plate is simply supported along two opposite edges in x direction and has arbitrary boundary conditions along the other edges (Levy boundary conditions). Finally, the critical buckling loads for a functionally graded plate with different boundary conditions, some aspect ratios and thickness to side ratios, various power of FGM and foundation parameter are presented in tables and figures. It is concluded that increasing the power of FGM decreases the critical buckling load and the load carrying capacity of plate increases where the plate is rested on Pasternak in comparison with the Winkler type.
Development of an R-Cube-Based General Purpose Haptic Device System
Authors: Bilgincan Tunc¸ , Dede Mehmet I˙smet Can
Published: January 2011

A novel 6-Degree-of-Freedom (DoF) hybrid haptic device is presented in this paper. Hybrid mechanism consists of parallel kinematic structure, R-CUBE and a 3-DoF orientation mechanism. In our previous study, the original configuration of the R-CUBE mechanism was investigated. In this work, the original design of R-CUBE is reconfigured as a haptic mechanism and the final mechanism is reoriented in order to equally distribute the gravitational effects to all grounded actuators. Rotational motions of the end-effector are monitored through the 3-DoF orientation mechanism placed on the moving platform of the parallel platform. The design of this haptic device is suitable to reflect forces in translational motions, thus point-type of contact is available for this system. The designed device is manufactured utilizing various types of manufacturing processes, such as wire erosion, laser cutting, milling and turning. Finally manufactured mechanism is integrated with electromechanical components and tested for manipulability.
Control of Mechatronics Systems: COMES Toolbox
Authors: Demirel Burak , Gu¨venc¸ Levent
Published: January 2011

An interactive software tool based on MATLAB to analyze and design controllers for mechatronic systems is presented in this paper. This toolbox called COMES is a graphical user interface (GUI) to routines for four different control approaches: classical control (lead, lag, PID etc.), preview control, model regulator control and repetitive control. These control approaches have all found widespread use in the practical implementation of controllers for mechatronic systems. The aim is to design a user-friendly toolbox with a well designed graphical user interface (GUI), which hides all calculations from the user as much as possible. Thus, the user can focus on the design and analysis phases through the graphical displays rather than being burdened by the complicated calculations that are involved. The effectiveness of the use of this MATLAB-based toolbox was demonstrated by carrying out some design and simulation studies for several position control applications available in the literature.
Second Law Based Analysis of Supplementary Firing Effects on the Heat Recovery Steam Generator in a Combined Cycle Power Plant
Authors: Karrabi H. , Rasoulipour S.
Published: January 2011

The supplementary firing is one of the techniques which are used to increase the output power of the combined cycle power plants (CCPP). The low construction cost per generated power encourages designers to consider it in the new CCPP. In this paper the thermal and exergy analyses of HRSG for various operating conditions in variation of loads and variation of ambient temperature carried out. They are based on the performance test data at different operating conditions. The objective of these analyses is to present the effects of supplementary firing on gross power output, combined cycle efficiency and the exergy loss in Heat Recovery Steam Generator (HRSG) devices at different ambient temperatures and different gas turbine loads. This study is based on 420 MW Neka combined cycle power plant operation and performance data sheet. The results show that the most effective components for the exergy losses are stack, HP Evaporator and HP Superheater at the rated load. The results reveal that although the supplementary firing increases the gross output power of the combined cycle power plant, however it increases the total exergy loss of HRSG and consequently decreases the total exergy efficiency. Moreover, it shows that the most effective components for the exergy losses in this case are HP Evaporator and HP Economizer at partial loads. Also, LP Evaporator and LP Superheater have the same effect at the different ambient temperature.
Effects of Droplet Size and Air Preheating on Soot Formation in Turbulent Combustion of Liquid Fuel
Authors: Ghasemi Amirmahdi , Moghiman Mohammad , Javadi Seyed Mohammad , Hosseini Naseh
Published: January 2011

The present study is concerned with the effect of fuel droplet size, air inlet preheating and air swirl number on complex soot process in a turbulent liquid-fuelled combustor. A hybrid Eulerian-Lagrangian method is employed to model the reactive flow-field inside the combustor. Equations governing the gas phase are solved by a control volume based semi-implicit iterative procedure while the time-dependent differential equations for each sizes of the fuel droplets are integrated by a semi-analytic method. The processes leading to soot consist of both formation and combustion. Soot formation is simulated using a two-step model while a finite rate combustion model with eddy dissipation concept is implemented for soot combustion. Also, mathematical models for turbulence, combustion, and radiation are used to take account the effects of these processes. Results reveal the significant influence of liquid fuel droplet size, air inlet temperatures and swirl numbers on soot emission from turbulent spray flames. The predictions show that reduction of spray droplet size and increases of air inlet temperature and swirl numbers considerably, increases soot emission from spray flames.
Comparison of Gasketed Plate Heat Exchangers With Double Pipe Heat Exchangers
Authors: Cetinbas Cankur Firat , Tuna Burak Ahmet , Akin Cevat , Aradag Selin , Sezer Uzol Nilay
Published: January 2011

In this study, a computer program is developed to design and compare gasketed plate heat exchangers with double pipe heat exchangers. The computer program is coded in MATLAB. The user interface of the program is prepared in MATLAB Guide. The program uses hot and cold fluid properties as input data and calculates the characteristics of gasketed plate heat exchangers and double pipe heat exchangers designed for the given conditions. The outputs for gasketed plate heat exchanger design include number of plates, effective area, total heat transfer coefficient, pressure losses, pumping power and cost, whereas, the outputs for double pipe heat exchanger selection are: pump power, total number of hairpins, effective area, pressure drop, total heat transfer coefficient and cost. Correlations selected from literature are used in the program for the analysis. Water is selected as the working fluid to be able to make the comparison. The program compares the heat exchangers based on cost, effective area, and pumping power. The computer program is also used to understand and compare operational behaviors of these two heat exchangers under different operating conditions.
Design and Analysis of a Novel Sensory System for a Humanoid Robot Foot
Authors: Soorgee Mohammad Hossein , Yousefi-Koma Aghil , Aghbali Behnam , Kordbache Maryam , Ghasemi Amir Masoud
Published: January 2011

This paper describes a novel design of force sensors arrangement for measuring ground reaction force on a humanoid foot to find the zero momentum point (ZMP) which is usually used as a stability criterion for a walking biped robot. Precise locating of ZMP highly depends on accurate measurement of reaction force distribution on the foot. Design and fabrication of a sole for a full scale humanoid robot, “Surena” is of interest. A rubber layer is placed on robot sole parallel to force sensors to reduce the effect of impact while robot is walking. Consequently, the force measured by sensors is not total force exerted by the ground. Several foot interaction condition with ground have been modeled using finite element method and force distribution in sole rubber and sensors have been obtained. The resultant is a model which predicts the total force distribution based on four point force measurement. Several experimental situations have been tested and forces have been measured. Experimental results have shown that numerical model could predict force distribution in a good way and location of ZMP has been found successfully.
Investigating the Relationships Between Full Spinal Curvatures and Falls in the Ageing Population
Authors: Acar B. Serpil , Kentel Behzat B. , Acar Memis
Published: January 2011

Falls cause substantial morbidity and mortality in the ageing population. Many different causes and risk factors of falls have already been identified for fall prevention. The aim of this study is to investigate the role of the degenerated spinal curvature on the falls in the ageing population. 48 community-dwelling adults over 65 years old participated in this study. Spinal curvatures of the participants are measured in erect posture with a non-invasive device. In addition, questionnaire surveys and in-depth interviews are conducted with the participants during data collection sessions. After normalising and fitting a Fourier series curve up to 3rd harmonics to the actual data, the spinal curvatures are classified into groups according to the fall histories, general health and age of the participants. Significant differences (p<0.05) are found between the spinal curvatures of faller and non-faller participants in the 65–80 years age group. In addition, the effect of arthritis on spinal curvatures is also studied. The preliminary results indicate that the changes in the spinal curvature may be identified as a risk factor for falls in the ageing population.
Surface Roughness Analysis in High Speed-Dry Turning of a Tool Steel
Authors: Vaxevanidis N. M. , Galanis N. I. , Petropoulos G. P. , Karalis N. , Vasilakakos P. , Sideris J.
Published: January 2011

High-speed machining is widely applied for the processing of lightweight materials and also structural and tool steels. These materials are intensively used in the aerospace and the automotive industries. The advantages of high-speed machining lie not only in the speed of machining (lower costs and higher productivity) but also in attaining higher surface quality (prescribed surface roughness without surface defects). Based on this concept, in the present paper the high speed-dry turning of AISI O, (manganese-chromium-tungsten / W.-Nr. 1.2510) tool-steel specimens is reported. The influence of the main machining parameters i.e., cutting speed, feed rate and depth of cut on the resulted center-line average surface roughness (Ra) is examined. Types of wear phenomena occurred during the course of the present experimental study as well as tool wear patterns were also monitored.
Molecular Modeling for Calculation of Mechanical Properties of Polyaniline-Carbon-Nanotubes
Authors: Ionita Mariana
Published: January 2011

Atomistic models of polyaniline (PANI)-single walled carbon nanotubes (CNTs) were built in order to assess the effect of quantity and quality of CNTs and temperature on the calculated mechanical properties of PANI. Three different types of CNTs were considered: single walled carbon nanotubes m-polyaminobenzene sulfonic acid functionalized (CNTs-PABS), single walled carbon nanotubes octadecylamine functionalized (CNTs-ODA) and single walled carbon nanotubes carboxylic acid functionalized (CNTs-CX). Atomistic models were built for PANI-functionalized CNTs with a range of CNTs content, contained within periodic boundary conditions and were subject of multistage equilibration procedure. In order to test the mechanical behaviour of the models virtual uniaxial traction tests along the three perpendicular edges of the models were performed. The Young’s moduli generally increased with increasing of CNTs content and values range from 0.48 GPa in the case of pure PANI to 1.35–1.83 GPa in the case of PANI-CNTs-PABS composite system.
On the Use of Statistical Process Control Approaches for Automated and Real-Time Monitoring of Machining Processes
Authors: Colosimo Bianca Maria , Moroni Giovanni , Grasso Marco
Published: January 2011

The paper proposes an SPC approach for automatic forecasting and monitoring of sensor signals in presence of cycle-based data (i.e. signal data which periodically repeat themselves) which can be observed in different machining processes, such as milling, forming or water-jet cutting. The monitoring system exploits an univariate time series analysis and monitoring technique based on an Exponentially Weighted Moving Average (EWMA) Control Chart for auto-correlated data coupled with the Holt-Winters exponential smoothing method, that is used to forecast future signal behaviour given its past history. The approach allows one to exploit only data coming from the on-going process and avoids the need for a-priori knowledge about signal pattern. Furthermore the control limits are automatically defined on-line by using only statistical moments of the currently monitored time-series. A case study is proposed to demonstrates the feasibility of monitoring the condition of the tool in milling processes by on-line analysis of cutting force signals.
Influence of Chemical Structure on the Boundary Lubrication Properties of Vegetable Oils
Authors: Mannekote Jagadeesh K. , Kailas Satish V.
Published: January 2011

Vegetable oils are increasingly used as lubricant base oils, because of sustainability issues and regulations. In present study coconut, palm, sunflower and castor oils were used to represent different levels of unsaturation, where as castor oil was selected to represent influence of hydroxyl group. The effect of oxidation on the boundary lubrication properties was evaluated by subjecting the oils to accelerated ageing at 333,353 and 373 k according to AOCS method. The experiments were carried out by using of four ball tester increase in observed wear scar diameter with temperature was more with oil having higher percentage of unsaturated fatty acids. At the same time it was also observed that increase in wear scar diameter with temperature was more with castor oil compared to other oil samples. The poor boundary lubrication properties observed with aged oil samples was possibly due to the deterioration of the triglyceride structure.
Identification of the Mechanical Properties of Composite Materials by Inverse Analysis
Authors: Filippini Mauro
Published: January 2011

A procedure based on the principles of inverse analysis has been employed to identify the elastic material parameters and the strength characteristics of epoxy carbon fiber reinforced composite laminates. By adopting a classical optimization algorithm, elasticity parameters are chosen by minimizing the mean squared error between the values predicted by the classical theory of elastic laminates and the experimentally observed ones. The average modulus of the laminate has been calculated from elastic parameters of laminas by implementing the classical equations of anisotropic elasticity in a subroutine, in order to speed up the optimization process. In a similar fashion, even though under strongly simplifying hypothesis, the strength characteristic parameters of laminas have been identified by inverse analysis, with the aim of assessing the strength of the composite laminates in the case of complex stress state.
Artificial Intelligence in Analysis of Fast Dynamic Actions
Authors: Stasˇ Ondrej , Tolnay Maria´n , Magdolen Lubosˇ
Published: January 2011

This paper introduces the application of artificial intelligence based on the artificial neural networks, the parallel computational algorithm for analyzing the nonlinear actions. Two similar applications are studied: the artificial neural network (ANN) trained and simulated for position estimation (position tracking) and ANN network for velocity estimation. This methodology can be used for various appliances and for generalization process. The comparison in time of processing for classical analyses and AI analyses differs, depending on the type of computational hardware used for analyze. Generally it could be said that AI solution is time less time-consuming than the standard algorithmic and propose results in quasi real time without need of signal preprocessing. As an experimental solution, this proposes future trends in vision signal processing where the classical methods are replaced by the artificial intelligence, which is not always the correct direction, but as we can see in this method possible.
On the Stochastic Stability and Observability of Controlled Serial Kinematic Chains
Authors: Bonsignorio Fabio
Published: January 2011

In this paper the stability and observability of a controlled serial kinematic chain are analyzed with reference to a characterization of observability and stability for a stochastic system grounded in the application of Shannon theory to controlled systems. This approach was proposed in 2004 by H. Touchette and S. Lloyd. In particular it is analyzed in depth the case in which errors on the joints follow (concentrated) Gaussian distributions. In this case the property of Lie Groups (and related tangent space Lie algebra), studied from G. Chirikjian et al., allow to carry out the study of stochastic serial kinematic chains in a simplified way and to properly identify stability and observability conditions from a Shannon information standpoint.
Measurement Simulation Model and Qualitative Analysis of Tapping Mode Atomic Force Microscopy Under Vibration Environment
Authors: Lin Zone-Ching , Chou Ming-Ho
Published: January 2011

This study constructs a novel Tapping Mode Atomic Force Microscopy (TM-AFM) model under vibration environment and analyzes the effect of probe size. The TM-AFM measurements are affected by external vibration and the size of the probe. In this study, a sinusoidal external vibration is applied, and TM-AM fixed-amplitude vibration simulated measurements made. The effect of external vibration on the surface profile acquired the simulated measurement of a nano-scale ladder standard sample. The simulated measurements under sinusoidal vibration are compared with actual experimental measurements without vibration isolation facilities, and the corrugations in the two cases were similar, indicating that the simulated measuring model under sinusoidal wave vibration proposed in this study is effective in qualitative analysis. An external vibration during the TM-AFM measurements causes an error between the measured surface profile of the sample and the actual appearance. Additionally simulated measurements are made on the edge of the nano-scale ladder standard sample, and the wave shape is affected by external vibration. The effects of the bevel angle and radius of the sharp end of the TM-AFM probe on the bevel edge effect of the probe and the measured appearance are studied. Qualitative analysis reveals that the bevel angle. Additionally, a smaller probe radius is associated with a simulated result that is closer to the perpendicular side of the ladder standard sample. The results in this study serve as a reference in the selection of probe size and in the qualitative analysis of the effect of external vibration on TM-AFM measurement.
A Study on the Development of a Practical Postprocessor for 5-Axis Machining
Authors: Hwang J. D. , Jung H. C. , Park K. B. , Jung Y. G.
Published: January 2011

This paper deals with the development of a practical postprocessor for 5-axis machine tools. Recently, special 5-axis machine tools with non-orthogonal rotary axes as well as typical 5-axis machine tools with orthogonal rotary axes have been introduced. In the present work, the general equations of NC data for 5-axis configurations with non-orthogonal rotary axes are exactly expressed by the inverse kinematics, and a Windows-based postprocessor written in Visual Basic was developed according to the proposed algorithm. The developed postprocessor is a general system suitable for all kinds of 5-axis machine tools not only with orthogonal rotary axes but also with non-orthogonal rotary axes, thereby expanding the range of application of the developed postprocessor. In addition, through implementation of the developed postprocessor and verification by a cutting simulation and machining experiment, the effectiveness of the proposed algorithm was confirmed. Compatibility was improved by allowing exchange of data formats such as RTCP controlled NC data, Vector post NC data, and POF CL data, and convenience was increased by adding the function of work-piece origin offset. Consequently, a practical post-processor for 5-axis machining has been developed.
Modeling and Experimental Validation of the Effect of Sand Filling on Avoiding Wrinkling Phenomenon in Thin-Walled Tube Bending Process
Authors: Taheri Kahnamouei Jalal , Behjat Bashir
Published: January 2011

This paper investigates a method to avoid the wrinkling in thin-walled tubes in bending process. In the tube bending process there are several effective parameters such as wall thickness, outer diameter-to-wall thickness ratio, centerline bending radius-to-outer diameter ratio. Any mismatch in the selection of the process parameters would cause defects like wrinkling, serve changes in wall thickness, and cross section distortion. For example, the depth of wrinkling increases with reduction in wall thickness and outer diameter-to-wall thickness ratio for a certain bending angle and radius. In this research, to avoid wrinkle initiation, tube is filled by sand and then bended. This sandy core is supported the tube from inner, and tube is prepared to bending. After bending process, sand is removed. In this work, to study the process numerically, a 3D finite element model of the horizontal bending process is built using ANSYS software. Then, experimental tests have been carried out to verify the simulation results and are developed to provide additional insight. A comparison between numerical and experimental results shows a reasonable agreement. It shows that wrinkle initiation can be avoided with filler material like sand.