ISSN: 1998-4448


Year 2011

All papers of the journal were peer reviewed by two independent reviewers. Acceptance was granted when both reviewers' recommendations were positive.

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    Paper Title, Authors, Abstract (Issue 1, Volume 5, 2011)


Evolution of Mechanical Properties of Gypsum in Time
P. Padevet, P. Tesarek, T. Plachy

Abstract: The paper presents time dependent changes of mechanical properties (Young’s Modulus, strength and creep ) of grey calcined gypsum. These material properties were measured in different time instants during hardening on the gypsum specimens of dimensions 40 x 40 x 160 mm using nondestructive and destructive methods. For the determination of Dynamic Young’s Modulus, the nondestructive impulse excitation method was used. The destructive methods were used for bending strength and compression strength. At the end of the paper, the time evaluation of grey calcined gypsum mechanical properties is presented and discussed.


Optimization of Withdrawing Cylinder at Vertical Continuous Casting of Steel Using CAD and CAE
M. Tufoi, I. Vela, C. Marta, D. Amariei, A. I. Tuta, C. Mituletu

Abstract: In this work is presented an optimization method of correcting cylinder-withdrawal to the withdrawal of the semi-finished steel to vertical continuous casting plant of steel. Optimizing cylinders was achieved by: use of statistical calculations applied to quantities, experimental measurements obtained directly from the withdrawal of blanks, using techniques CAD (Computer Aided Design) and CAE (Computer Aided Engineering) design, modeling and optimization of cylinders; using finite element method, FEM for static and dynamic simulations, the behavior of withdrawal-straightening rolls in continuous casting process for determining stress, strain and displacement that occur in this process. The studies is both experimental and theoretical, and aims to improve the process of withdrawal of the semi continuous casting with vertical curvilinear wire of steel, using modern methods of analysis, design and optimization of mechanical drives. The study has as a result in a pair of cylinders practical realization of withdrawal, multiple-ray machines, able to withdraw more dimensions of round profile. This is an advantage in that, to change the diameter of semi-products withdrawn, no is necessary to change withdrawal cylinders.


A Strain Gauge Based System for Measuring Dynamic Loading on a Rotating Shaft
M. Hilal Muftah, S. Mohamed Haris

Abstract: In a mechanical system, the acting mechanical power is the most important quantity of rotating shaft of machines. There are many methods to measure it such as measuring the torque directly on the rotating shaft and measuring the rotational speed. Also there are many widely used measuring methods and more or less standardized instruments for measuring the rotational speed. A digital hand tachometer was chosen for measuring speed. The torque measurement is more complicate than the speed measurement. It needs a special solution in every occasion. It must be built onto the machine’s shaft. This is because the high accuracy, a relatively simple application and the high dynamical behavior, the strain gauge sensor will be chosen for measuring the torque on the rotating shaft. During the design, the shaft was adapted for application of “V shape” strain gauge, to the shaft’s end a HBM made slip-ring assembly was connected the rotating shaft with the standing cable and the Spider8 measurement electronics. The HBM CATMAN-Express software was used during the calibration and the tests. The calibration was carried out with 0.5 m long lever and dead weights in 0.5 kg steps up to 4.5 kg.


Vibrations of Elastic Stretched Strips with Cracks
Jaan Lellep, Esta Kago

Abstract: Vibrations of elastic plate strips supported at two opposite edges and free at the other edges are studied. It is assumed that the thickness of the strip is piece wise constant whereas stable part-through cracks are located at the re-entrant corners of steps. Making use of the basic concepts of the fracture mechanics a method for determination of eigenfrequencies of stepped plates with cracks is developed. The influence of a crack on the behavior of the strip is modeled as a change of the local flexibility or as a distributed line spring. Numerical results are presented for strips with cracks and without any crack subjected to the tension applied at an edge of the strip.


Nonlinear Analysis of Transient Seepage by the Coupled Finite Element Method
Ahad Ouria, Ahmad Fahmi, Mohammad M. Toufigh

Abstract: In this paper, transient seepage beneath a dam is investigated considering the effect of the change of the permeability of the soil by the finite element method. Change of the permeability is considered as a function of the change of the void ratio. In order to calculate the change of the void ratio, the force equilibrium equations are taken in to account by coupling with the fluid continuity equation. Displacement method is used in the finite element formulation. Change of the soil permeability is calculated based on the soil deformation which is the primary unknown in the coupled models. Generalized Hook’s law is used for stress-strain behavior of the soil. Galerkin residuals method is used in the finite element formulations. Coupled analyses showed the effect of the change of the permeability on the transient seepage in the coupled models is les than its effect in the uncoupled models for elastic soils.


Reverse Engineering, CAD\CAM & Pattern Less Process Applications in Casting - A Case Study
T. Suresh Babu, Romy D. Thumbanga

Abstract: This paper details about pattern less casting process using CAD\CAM applications, scanning/digitizing, coordinate measuring arm machine, and 5-axis machine. One of the advantages is that the casting lead time is reduced drastically as compared to conventional methods of casting with patterns. An adjustable diffuser vane blade used in oil and gas industry was manufactured by reverse engineering and pattern less process starting from a worn out sample. First the blade was digitized by Cimcore-3000i 3D Coordinate Measuring Arm. The obtained point cloud data is imported to Pro/Engineer CAD\CAM software to develop the 3D model and design the moulds. Then direct sand blocks (cope and drag) milling on Poseidon CNC specific purpose 5-axis machine was adopted completely eliminating any use of patterns. The moulds were directly used for metal pouring at the casting stage.


Experimental Impact Force Location and Identification using Inverse Problems: Application for a Circular Plate
Z. Boukria, P. Perrotin, A. Bennani

Abstract: Estimating load by direct measurements for structures that are in use is in practice very difficult or impossible, either because the impact location is inaccessible or because the projectile is deformable and therefore cannot be instrumented. The problem of identifying impact force on mechanical structures is the inverse of the direct problem: the use of measured responses on a given structure to identify the causes, that is, the implicated impact forces. The approach needs to create experimentally or numerically, the transfer functions between the impact and the measurement points on the structure so as to measure the responses, and to find the load by deconvolution of the signal. It is known that this type of problem is poorly conditioned. To obtain a stable solution with a physical sense, it must be stabilized using conventional regulation methods, such as the Tikhonov method. The problem of characterizing the impact becomes more complex when the impact location is unknown; so it is necessary to create the transfer functions between several impacts and measuring points, and minimize the objective function, which can locate the impact and then identify the force impact history. This study develops an experimental method of identifying the impact force on two simple structures: a circular plate, using the transfer function obtained experimentally between the strain response and the force history applied to a point on the structure, and the Tikhonov method for the inverse problem. To locate the impact force, we used an experimental method based on the minimization of an objective function created from the transfer functions between several impact locations, forming a mesh structure with several measuring points.


    Paper Title, Authors, Abstract (Issue 2, Volume 5, 2011)


Stresses in an Anisotropic Elastic Plate due to Strip-Loading
Dinesh Kumar Madan, Shamta Chugh, Kuldip Singh

Abstract: The closed-form expressions for the stresses at any point of monoclinic elastic plate interfacing differently with the base due to strip-loading are obtained. The interface between the elastic plate and the base is assumed to be either „perfectly bonded? or „smooth-rigid? or „rough-rigid?. As particular cases the stresses in orthotropic elastic layered half-space, isotropic elastic layered halfspace and due to shear line-load in monoclinic elastic half space have been obtained. Numerically, in the monoclinic elastic half-space, the variation of shear stresses with the horizontal distance has been studied.


Determination of Flow Configurations and Fluid Forces Acting on Two Tandem Square Cylinders in Cross-Flow and its Wake Patterns
A. Etminan, M. Moosavi, N. Ghaedsharafi

Abstract: In this paper, the onset of vortex shedding and flow configurations over two equal square cylinders in tandem arrangement are carried out on a finite volume code based on the SIMPLEC algorithm and non-staggered mesh for both steady and unsteady incompressible laminar flow in the two dimensional regime. The calculations are performed for a Reynolds number range varying from 1 to 200 and spacing between the cylinders is five widths of the cylinders. The mesh is finer close to the cylinders walls in order to have a better description of boundary layer. In this research, the influence of Reynolds number and the onset of vortex shedding on the flow patterns around the cylinders are presented in detail. In addition, the quantities such as pressure and viscous drag coefficients, RMS lift and drag coefficients, recirculation length and phase lag are presented and explained. It is found that the onset of vortex shedding occurs for a Reynolds number varying 35 to 40.


Numerical Model for Vaporization Simulation of a Single Droplet
S. Torfi, S. M. Hosseini Nejad

Abstract: A numerical model is developed in this study to simulate single droplet heat and mass transfer in saturated solvent vapor environment by finite volume method and transient SIMPLEC algorithm in spherical coordinates system. In this model, for simulation of the mass transfer, dimensionless equations of motion, heat transfer and mass transfer are solved simultaneously. The numerical analysis results are presented for mass transfer of lithium bromide solution droplet in 300K and initial concentration of 50%. Verification of method is done by compare these numerical results with analytical and numerical analysis of other studies. Droplet Growth Chart, average temperature and concentration, variation of drag coefficient diagrams, Nusselt number and flow line, temperature and concentration and temperature distribution contours, penetration rate of mass and the level of tangential velocity at droplet surface as the modeling results are presented.


Analysis of Surge in Pipelines Systems by Characteristis Method
M. Salmanzadeh, S. Torfi

Abstract: Transient flows in pipelines mostly occur by closing the valves , turning off or starting up of pump and other any factor which cause flow acceleration or deceleration . Newton was the first one who started researching about the analysis of the transient flow . Then characteristis method for solving equations with partial differential was invented and this method completed more by Streeter at 1950 .The results of characteristis in a simple pipeline are completely correct , since the pipeline can be divided in parts that the characteristis can pass through them . But in a system made of two or more pipelines for computing all the pipelines , definite time interval Δt in order to establishing the boundary conditions in the joint of the pipelines , is considerd . Δt also should satisfy the courant stability condition(C) . If the considered time of Δt was in a state which the pipelines cannot be divided in equal parts through CΔt , then in some intervals , characteristis don’t pass through the divided points of these flow in pipes and they pass another points.


3D Model Retrieval from Mechanical Drawings Analysis
R. Furferi, L. Governi, M. Palai, Y. Volpe

Abstract: Computer Aided Engineering (CAE) techniques provide effective solutions for automating the whole product development chain process. Designers, engineers, manufacturing professionals and researchers can now leverage solid modeling data and multi-physics analysis in ways that were inconceivable just few years ago. Among CAE techniques, Computer Aided Design (CAD) has been the most effective in providing methodologies capable of compressing product design and manufacturing cycles, assuring faster turnaround time between design and simulation and improving product quality. Designers and manufacture companies reap the rewards of 3D CAD modelling; as a consequence, research is unceasingly stimulated to look forward. On one hand, research aims to improve capabilities of existing CAD methods and tools; on the other hand novel approaches are extensively investigated with the ambition of carrying out innovative CAD techniques capable of lighting sparking design innovation and creativity. This is particularly true for mechanical design: fast and robust 3D retrieval from 2D drawings that was considered future trend few years ago, is now a key target for commercial software houses like Dassault Systems® and Autodesk® as well as a vigorous focus from an academic outlook. Unfortunately, even if a number of works have been carried out during the last decades, these are mainly described by a conceptual point of view. To derive an orderly procedure covering the necessary steps for retrieving 3D models from mechanical drawings could provide a dramatic boost to researchers and practitioners that introduce this issue on their research. Therefore, the main aim of the present work is to carry out a systematic clear and concise step-by-step procedure for 3D retrieval starting from wireframe models. Since the intent is to afford an as clear as possible, guided, procedure for 3D reconstruction, mathematical description is limited to the simplest case of polyhedral objects. The proposed procedures, inspired by state of the art works, can be effectively contribute to speed-up the possible implementation of methodologies confronting the 3D reconstruction problem.


Establishing a Correlative Model for Improving NC Machining Process
Chang-Tzuoh Wu

Abstract: Based on the machining conditions of the uses of flat end cutter (FC), ball-end cutter (BC) and disc cutter with a concave end (DCC) in the numerically controlled machining (NC) process, current studies aimed to establish related geometry model for efficiency evaluation and demonstrate qualitative and quantitative analysis by utilizing computer modeling. The compound surfaces are divided into three kinds of regions by the theory of differential geometry. The correlative mathematical models for defining the cutter parameters, the step-forward length, and the path intervals in the NC machining of the surfaces are described based on the feature of the regions. The analyzed parameters such as efficiency, accuracy and economical utility for different machined surfaces will be discussed to provide reliable selection principles of FC and DCC in order to improve NC machining.


    Paper Title, Authors, Abstract (Issue 3, Volume 5, 2011)


Flexure of Thick Beams using New Hyperbolic Shear Deformation Theory
Atteshamuddin S. Sayyad, Yuwaraj M. Ghugal

Abstract: In this paper a new hyperbolic shear deformation theory is developed for the static flexure of thick isotropic beam, considering hyperbolic functions in terms of thickness co-ordinate associated with transverse shear deformation effect. Rotation of normal is taken as combined effect of shear slope and bending slope at the neutral axis. The most important feature of the theory is that the transverse shear stress can be obtained directly from the constitutive relations satisfying the shear stress free surface conditions on the top and bottom of the beam. Hence the theory obviates the need of shear correction factor. Governing equations and boundary conditions of the theory are obtained using the principle of virtual work. Results obtained for static flexure of simply supported isotropic beam subjected to single sine load are compared with those of other refined theories and exact solution.


An Accurate Numerical Prediction of Solid Particle Fluid Flow in a Lid-Driven Cavity
Nor Azwadi C. Sidik, Seyed Mohamad R. Attarzadeh

Abstract: Research on solid particle flows has been quite intensive in the past decade. The difficulties associated with accurate predictions of the interactions between the solid and surroundingfluid. Hence, in the present paper, we focus on the simulation of liddriven cavity flow containing a solid particle immersed in an incompressible fluid. In the present analysis, we adopt an Eulerian- Lagrangian approach where the solid particle is treated as a point in the cavity. To achieve the accuracy, the numerical scheme for the fluid is properly chosen so that the resultant force on the solid particle can be accurately determined. Our aim is to seek further improvement on the fundamental knowledge of the trajectories of a solid particle in a lid-driven cavity. To broaden our understanding of the particle dynamics in the cavity, we also study the vortex structure in the cavity which directly influence the trajectories of solid particle.


Wind Turbine Noise: Theoretical and Experimental Study
Claudio Guarnaccia, Nikos E. Mastorakis, Joseph Quartieri

Abstract: Wind turbine acoustical noise is a relevant element to be considered and studied because of the growing interest in renewable energies. The environmental impact of these structures in the surrounding areas is deeply investigated, especially on the acoustical and the landscape point of view. This paper is mainly devoted to the integration between analytical, experimental and software analysis on noise production and propagation, in the framework of a single turbine or a wind farm. The results of a measurement campaign in an operating wind farm are reported and used to tune the model and software parameters, in order to validate the theoretical assumptions. In particular, the pointlike source and other assumptions are verified by means of comparison between experimental and simulated data. The noise mapping is also pursued in the framework of a commercial predictive software, exploiting the possibility to monitor the behaviour of noise in a complex area, in terms of number of sources, propagation, absorption, terrain orography, etc., such as a wind farm.


Study on Powdered Samples and Particle Size Determinations by Scanning Eletronic Microscopy (SEM), Diffraction of X-rays
Cristiana-Zizi Rizescu, Elena Valentina Stoian, Dan Nicolae Ungureanu, Zorica Bacinschi, Cristi Petre Fluieraru

Abstract: Study has been analyzed qualitatively and particle size determinations powders from blast furnace by scanning eletronic microscopy (sem), diffraction of x-rays. X-ray spectrum shows that the sample contains the following elements: Fe, Ca, Mn, Ti, K, S, Al, Si and Mg. It is mentioned that using EDX spectrometer cannot detect light elements (e.g. oxygen). Sample morphology is revealed by scanning electron microscopy images, secondary electron images (SEI). To investigate the scanning electron microscope, small amounts of samples were spread on a foil tape, conductive, carbon. For a qualitative analysis by X-ray diffraction, a monochromatized CuKα X-ray beam with a Ni filter have been used. The particle size determinations were made by means of ANALYSETTE FRITSCH particle size analyzer.


Avoiding Collisions Maneuvers Using a Stochastic Approach
Vivian Martins Gomes, Antonio F. B. A. Prado

Abstract: The research considered here is related to the problem of orbital maneuvers. A satellite has to perform such maneuver to escape from a possible collision with a cloud of particles. To perform this task, a low thrust control is available. The question of minimizing the fuel consumption is considered and this is the most important goal in the maneuver. For this problem, the hybrid optimal control approach is used, where it is possible to take into account the accuracy in the satisfaction of the constraints. The spacecraft is considered to be traveling in Keplerian orbits perturbed only by the thrusts. These thrusts have a fixed magnitude and operating in an on-off mode. Several results are shown to exemplify the maneuvers simulated.


Synergistic Issues of Motor Learning Sequences as an Outcome of its Internal Refactoring
Nicolae Neagu, Dana Badau, Cristina Branea

Abstract: The current study is mostly addressed to athletics coaches who deal with the selection and training of athletes for hurdle events. The research aims to develop few certain aspects of beginner and advanced athletes, training for professional athletics, within the orientation stage to short hurdle races. Our brief presentation intends to develop several particular aspects, less approached in the literature of motor learning and on selection field for children and juniors. In motor learning process, approached as a synergetic and inferential procedure, certain internal reconfigurations of learning units can be defined as effective refactoring steps, aimed on forming high level and very stable motor skills. Some of them may describe aspects of a narrow field of investigation, consisting in supportive arguments based on good practice experiences.


Dynamic Response of Spherical Shells Impacted by Falling Objects
Yury A. Rossikhin, Marina V. Shitikova, Vyacheslav Shamarin

Abstract: The problem on normal low-velocity impact of an elastic falling body upon an elastic spherical shell is studied. At the moment of impact, shock waves (surfaces of strong discontinuity) are generated in the target, which then propagate along the body during the process of impact. Behind the wave fronts upto the boundary of the contact domain, the solution is constructed with the help of the theory of discontinuities and one-term or multiple-term ray expansions. Nonlinear Hertz’s theory and linearized elastic contact laws are employed within the contact region. For the analysis of the processes of shock interactions of the elastic sphere or elastic spherically-headed rod with the spherical shell, nonlinear integro-differential equation has been obtained with respect to the value characterizing the local indentation of the impactor into the target, which has been solved analytically in terms of time series with integer and fractional powers. In the case of the linear elastic shock interactions, the governing differential equations for the target and the impactor are solved analytically by the ray method.


An Explanation of Possible Damascus Steel Manufacturing Based on Duration of Transient Nucleate Boiling Process and Prediction of the Future of Controlled Continuous Casting
Nikolai Kobasko

Abstract: In the paper the new explanation in manufacturing of Damascus steel, based on discovered the specific characteristics of transient nucleate boiling processes, is provided. Also, the future of continuous casting in the paper is discussed. According to discovered characteristics, duration of transient nucleate boiling process is directly proportional to squared size of a steel part and inversely proportional to thermal diffusivity of material, depends on configuration and initial temperature of component, thermal properties of liquid. The surface temperature of steel part during transient nucleate boiling process maintains at the level of boiling point of liquid and cannot be below it. Based on these characteristics, the new hypothesis regarding manufacturing of Damascus steel is proposed according to which the melted high carbon steel (containing 1 – 2% carbon) was casted into copper forms cooled by cold water and then the steel was many times forged and quenched in special water salt solutions until finishing transient nucleate boiling process. Such simple technology provided extremely small spherical carbides distributed in steel which acted as a saw and made steel very strong. It is stated that high strength materials with fine microstructure can be achieved by applying intensive cooling to continuous casting.


The Influence of the Valve Lift Strategies on the Combustion Characteristics of a Homogeneous Charge Compression Ignition Engine Model
Radu Cosgarea, Mihai Aleonte,Corneliu Cofaru

Abstract: This paper presents the results of the simulations made to investigate the influence of the burned gases trapped in the cylinder at the end of the exhaust stroke on the start of the auto ignition process and on the combustion characteristics of a homogeneous charge compression ignition (HCCI) engine. Different quantities of trapped burned gasses, used to control the auto ignition timing, were obtained by displacing the valve lifts. The cylinder pressure, cylinder temperature, heat release rate and mass fraction burned are calculated and compared.


Heat Transfer in Cemented Hip Replacement Process
Kamonchat Kaorapapong, Somkid Amornsamankul, I-Ming Tang, Benchawan Wiwatanapataphee

Abstract: This paper proposes a mathematical model of heat transfer in the cemented hip replacement using the metal-metal implant with no cup. Computational domain consists of three subregions including a femur region, an implant region and a femoral canal region. The femoral region is divided into two parts which are the top and the bottom parts occupied by the cement and the ambient air. The governing equation is a unsteady heat equation. Heat transfer by conduction is considered in this study. Finite element formula for the solution of heat transfer problem is derived. Effect of the initial temperature of the cement and the implant material on heat transfer process are investigated. Numerical results show that the initial temperature has significant effect whereas the implant materials has less effect.


The Influence of Ionizing Radiation on Chemical Resistance of Polymers
Zdenek Holik, Michal Danek, Miroslav Manas, Jakub Cerny,Martina Malachova

Abstract: The topic of this research paper is a comparison of influence of chemical and petrochemical products on the mechanical properties of the selected types of polymers modified by irradiation cross-linking. After irradiation by beta radiation the materials were load into the chemicals. For the evaluation of the mechanical properties of irradiated and non-irradiated test specimens the tensile test and impact hammer test were used.


Influence of the Amount of Cross-linking Agent on Properties of Irradiated Polyamide 6
Zdenek Holik, Michal Danek, Miroslav Manas, Jakub Cerny

Abstract: The main objective of the study is investigation of mechanical properties of polyamide 6. These properties were examined in dependence on the dosage of the ionizing electron beam (beta) radiation and in dependence on the amount of cross-linking agent. Non-irradiated samples and those irradiated by dosage 66, 99 and 132 kGy were compared.


Transient of Thermal Stresses in Printed Circuit Boards
Oldrich Suba, Libuse Sykorova

Abstract: Results of FEM modelling of thermal stress analysis in printed circuit boards are given in the article. It is shown that thermal stress alone is not solely caused by differences in coefficients of thermal expansion of individual layers. The emergence of thermal stress is subject to both the layered structure of the wall and given boundary conditions, as well as the existence of a temperature gradient in the direction normal to the surface of the wall. A practical application focuses on the issue of recycling of PCB with the effort to achieve separation of layers due to thermal stress. Role modelling of thermal stress in this area lies in predicting the possibility of separation, depending on the type of thermal stress and material parameters.


The Transient Temperature Field Simulation of Polymeric Materials During Laser Machining
Libuse Sykorova, Oldrich Suba

Abstract: The paper deals with possibilities of using the laser in technologies. The parametric temperature field analysis was realized by the finite element method. The analysis was run in COSMOS/M software solver. A thermal module HSTAR makes it possible to realize cases of the temperature dependences on the material properties. Material data can be entered as a function of a temperature. The thermal and physical characteristics of the polymeric materials change significantly. The output of the analysis was described by colourful spectrograms with temperature field distribution of various materials.


Modular Measurement System for Strain Gauge Sensor Evaluation
Petr Dostalek, Jan Dolinay,Vladimir Vasek

Abstract: Process measurement is one of the most important tasks in the many areas of technical branches. Quality of the final products in a production sector can be reasonably improved when whole process is carefully analyzed by measurement of main technology parameters before batch production. Measurement of the cutting forces enables to find optimal ratio between work piece uality and processing time in dependency on used cutting tool. Work presents design of modular multichannel measurement system for strain gauge sensor evaluation in laboratory of mechanical engineering mainly intended for practical exercises of our students. Measurement device is based on 8-bit Freescale microcontroller unit which is the main control part of the device. Device implements modular hardware design enabling easy functionality expansion in future demands. Hardware of the device is split into the two parts: main board and measurement modules. Communication with supervision system is provided by USB interface. Software works under real-time operating system RTMON for HCS08.


Prediction of Grinding Parameters for Plastics by Artificial Neural Networks
David Samek, Ondrej Bilek, Jakub Cerny

Abstract: The grinding technology is widely used in the manufacturing of various materials. This technology process is driven by many input parameters that influence resulting product. This work is focused on an application of artificial neural network with radial basis function in modeling of polymer materials grinding. In this paper the two key parameters were selected – feed rate and depth of cut. The task of the artificial neural network based predictor is to provide resulting arithmetical mean roughness and maximum height of the profile parameter. Furthermore, the article presents extensive experimental measurements aimed to grinding of polypropylene, polyamide 6 filled with 30% of glass fibers, polytetrafluoro-ethylene and polycarbonate. All measurements results are statistically evaluated and presented in the figures.


    Paper Title, Authors, Abstract (Issue 4, Volume 5, 2011)


A Study of the Mechanics of an Oscillating Mechanism
Christopher G. Provatidis

Abstract: This paper discusses aspects of the mechanics involved in the Dean-like Space Drives, which are mechanisms with two eccentric lumped masses that rotate in opposite direction about parallel linear axes which are rigidly connected and driven by electric motors. The typical mechanism is based on the induced centrifugal forces and it achieves to convert rotary motion to unidirectional motion. In case of a constant angular velocity, we derived closed form analytical expressions for all mechanical quantities related to the motion of an object to which the inertial mechanism is attached. Based on these formulas, we found that although this device is not capable of achieving long-term propulsion, it can operate like a catapult thus reaching a maximum altitude. We also discuss the effect of predefined time varying angular velocity imposed by the motors, the oblique motion, the possible absence of power supply, the conservation of the linear momentum and the efficiency in the conversion process from rotary to unidirectional motion.


Experiences of Pilot Operation of the Photovoltaic System
F. Hruska

Abstract: The system LABI is extended a experiment DE10 – photovoltaic system. The experiment DE10 offers remote access for students and a professional community studying and testing the photovoltaic specifics without time, financial and other regression. At the moment the system consists a photovoltaic panel of monocrystal semiconductor, a system of measurement and control and a system of remote date transfer via the Internet. During a pilot operation there are confirmed functions and practicing of the system. There were achieved positive experiences.


Project of Thermal Comfort System
F. Hruska

Abstract: Parameters of interiors are very important for comfort, for energy consumption and cost of utilizing of buildings. There are using some different principles and exists big conservatism. New access in the project of system of thermal comfort is solving it newly. It uses new standards and new view using the knowledge of this category. The project solves measurement system, control system and describes the differences between new and conservative accesses. The measurement system deals about new measurement of meadium radiation temperature and standard measurement of temperature and moisture of air, flow of air in interiors. The control system is projected by new technique a give the opportunity the optimal comfort with minimum of cost for energy.


Universal Serial Bus Musical Instrument Digital Interface Hardware
Dalibor Slovak

Abstract: This article explores possibilities of coordination between computer made music and other stage devices. Purpose of develop was to create simple universal hardware for using in music software communicating via MIDI protocol and USB. This hardware is meaning for professional music live performance. At the input this device communicates via MIDI and USB protocols. At the output is tension. Its value is managing by pulse-width modulation. This modulation value is given to value of the third byte in MIDI message. This value is sound power of control note. There is device is connected as one of USB interfaces at the input. There is device is connected to power transformation device on output. There are artificial smokes, lights and fountains are connected to power transformation device as ending equipment.


Ultraviolet Radiation Device for Prototype Production Printed Circuit Boards
Michal Brazda, Martin Pospisilik, Milan Adamek

Abstract: For the production of high quality PCB in small quantities is the photo etching method the most favorable. For the needs of our university and its students, when creating their diploma theses, device for generating ultraviolet radiation was created.


Mathematical Model of Control Valves of Three-Tank System
Petr Chalupa, Jakub Novak, Vladimir Bobal

Abstract: The paper is focused on development of a mathematical model of valves of a hydraulic system. Laboratory three tank model (Amira DTS200) was investigated and characteristics of its valves were measured. Consequently, the process of creating a mathematical model of the valves is described in detail. The three tank system is a classical modeling task but this paper focuses on nonlinearities which are present in real system and other differences between ideal mathematical model and real-time system. Especially hysteresis represents a big difference between ideal mathematical model and real-time system. Even thought all valves the system is equipped with are of the same type, big differences were observed between their characteristics. The approach to modeling of the system is not restricted to the particular system but can be used for many real-time hydraulic systems.


A Shock Filter for Bearing Slipping Detection and Multiple Damage Diagnosis
Bechir Badri, Marc Thomas, Sadok Sassi

Abstract: This paper describes a filter that is designed to track shocks in the time domain, and to isolate them from any other random or harmonics components. This innovative tool can be used in the time domain as a denoising filter to estimate the proportion of the total signal energy caused by the shocks and to quantify the severity of damage. It can also be applied in the frequency domain and will allow through envelope or time-frequency analysis to clearly identify the sources of the shocks even if they are from various origins. This method makes also possible for differentiating the synchronous shocks from the pseudo-synchronous ones often caused by the slip of mechanisms and help to diagnose the severity of damage even with multiple defects.


Instability on Condensate Propagation in Porous Media
Eko Siswanto, Hiroshi Katsurayama, Yasuo Katoh

Abstract: Instability on condensate propagation in porous bed of glass-beads and alumina-balls media is observed experimentally. This study is done by streaming the varied temperature of saturated humid-air over the media. Towards the humid air temperatures, the ambient temperatures are restrained on constant 308 K and on constant-ratio, respectively. By calculated evaluation, it is clear that the condensate propagation is in Darcian regime. In this theoretically stable regime, however, based on visualization and on modified Lyapunov-exponent for the longest finger, the propagation lies respectively on stable-dominant, unstable-dominant, and temporal-chaos behavior. It is known that the instability propagation is not only depended on porosity and permeability, but also controlled by wettability of the porous media and concentration gradient of the condensate in the porous layer. From this study, it is also evident that the ambient temperature plays a key role on generating the concentration gradient.


A Data Mining Approach to Automate Fault Detection Model Development in the Semiconductor Manufacturing Process
Kittisak Kerdprasop, Nittaya Kerdprasop

Abstract: In the semiconductor manufacturing process, fault detection is a major step of process control aiming at constructing a decision tool to help detecting as quickly as possible any equipment or process faults in order to maintain high process yields in manufacturing. Traditional statistical based techniques such as univariate and multivariate analyses have long been employed as a tool for creating model to detect faults. Unfortunately, modern semiconductor industries have the ability to produce measurement data collected directly from sensors during the production process and such highly voluminous data are beyond the capability of traditional process control method to detect fault in a timely manner. We thus propose the techniques based on the data mining technology to automatically generate an accurate model to predict faults during the wafer fabrication process of the semiconductor industries. In such process control context, the measurement data contain over 500 signals or features. The feature selection technique is therefore a necessary tool to extract the most potential features. Besides the feature selection method, we also propose an over-sampling technique to handle the highly imbalance situation of fail versus pass test cases. Such imbalance cases refer to rare class prediction in the data mining context. The experimental results support our assumption that choosing the right features and over-sampling rare cases can considerably improve detection accuracy of fault products and processes.


Service Robots Assisting Human: Designing, Prototyping and Experimental Validation
Y. Maddahi, S. M. Hosseini Monsef, A. Maddahi, R. Kalvandi

Abstract: This paper addresses the design, prototyping and experimental validation of two different types of wheeled mobile machine, employed as service robots to assist the human. The focus is on the explanation of modeling and design procedure as well as the optimization of robot positioning during the motion along some given and unseen trajectories. Using the coordination defined for mobile robots, the equations of motion are firstly derived and then the simulation study is carried out. Using the simulation results, the robots are prototyped. Next, to overcome the positioning errors, the mobile robots are tested and moved along some given paths. The position error consists of systematic and non-systematic errors. As pointed out, the systematic errors are modified and reduced using benchmark method where the absolute measurements of errors are compared with the desired posture of robots. Specifically, the results derived from experimental analyses concede that in the mean error improvement was at least 83% in both CW and CCW directions. The procedure explained in this paper should therefore be considered seriously as a new tool to design the wheeled mobile robots.


T-72 Tank Barrel Bore Wear
Robert Jankovych, Stanislav Beer

Abstract: The paper provides results of an analysis of character of smooth barrel bore wear of the T-72 tank, a combat vehicle that remains in service with a number of armed forces throughout the world. The BG20 MkII Gun Barrel Bore Gauge system purchased from Aeronautical & General Instruments Ltd in the UK was used to take measurement in the barrels of T-72 tank. Three types of the wear of leading part of the barrel bore were documented. There are also, in original way, mathematically formulated conditions of formation of a specific type of wear caused by firing the armour-piercing finstabilized discarding sabot 3BM-15 in the paper.


Analysis of Feeding Device with Two Degrees of Freedom
Jiri Balla, Van Yen Duong

Abstract: The paper deals with kinematic and dynamic analysis of the feeding device mounted on the Czech 152 mm Self-propelled Howitzer mod. 77 (152 mm SPH M77). Kinematic analysis of the feeding device has been worked out using MATLAB software. The dynamic problem has been solved using Lagrange multiplier method applied for closed chain multi-body system. After that both kinematic and dynamic tasks has been simulated using of Rigid Dynamic component of software ANSYS with Finite Element Method (FEM).


A Comparative Analysis between the Vehicles’ Passive and Active Suspensions
Catalin Alexandru, Petre Alexandru

Abstract: This paper presents a comparative analysis between the passive and active suspension systems of the motor vehicles. The study is performed for a half-car model, which corresponds to the guiding - suspension system of a rear axle. The active suspension system is obtained by placing a force actuator in parallel to passive suspension, the goal being to minimize the effect of the road disturbances. The passive and active suspensions are analyzed in the passing over bumps dynamic regime. The response of the active suspension is compared with the passive suspension, important improvements in the dynamic behavior (in terms of stability and comfort) being observed for the active suspension.


A Comparison between Traffic Noise Experimental Data and Predictive Models Results
Claudio Guarnaccia, Tony L. L. Lenza, Nikos E. Mastorakis, Joseph Quartieri

Abstract: Traffic Noise predictive Models (TNMs) are often used in order to predict and/or monitor road traffic noise impact on environment. Usually a statistical approach is followed in the most used model building and compiling. A large set of experimental data is collected on one or more sites under investigation and on these data a best fit is performed with a functional relation. A logarithmic function is generally postulated and the fit parameters are evaluated and used to predict noise level for any traffic flow. This procedure produce of course a kind of "site bias" in the prediction, since the parameters are evaluated on data collected in that specific area and conditions. In this paper, after having summarized some of the most known models, a comparison between simulated and experimental data is performed, in order to highlight the behaviour of models in two different sites. The strong dependence on the site, and consequently on the vehicle flow volume and typology, will be sketched, together with the influence of climatic parameters.


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