International Journal of Mechanics

E-ISSN: 1998-4448
Volume 10, 2016

Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of NAUN Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.

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Volume 10, 2016

Title of the Paper: Feasibility Study for a Tonal Vibration Control System of a Mounting Bracket for Automotive Gearboxes


Authors: D. Magliacano, M. Viscardi, M. Ciminello, I. Dimino, A. Concilio

Pages: 403-410

Abstract: A conceptual design of an active device able to attenuate the tonal vibrations of a mounting bracket for automotive gearboxes is addressed in this paper. A preloaded piezo stack actuator is used to counteract the unbalanced vibrations of the component by monitoring its operational deformations. Firstly, a numerical modal analysis is carried out to characterize the normal modes in the frequency range of interest. The piezo stack is simulated by a rod element and its effect is numerically characterized. The upper and lower faces of the stack are mechanically coupled with the bracket structure, whereas the active control deals with the relative displacement of two points of the bracket. The primary disturbance was simulated by a shaker to control the vibrations in correspondence of the second bending mode (around 1.6 kHz). A 20 Hz narrow band was additionally selected as the control window. Then, this frequency range was enlarged around the resonance peak in order to optimize the control effect, till 80 Hz to investigate the resulting effects. Finally, focus is given to the structural damping by assessing its impact on the control forces and phases to cancel the deformation along the contact direction. The description of the experimental results concludes this work by generally confirming the numerical expectations.

Title of the Paper: Effect of the Support Domain Size in SPH Fracture Simulations


Authors: Martin Hušek, Jiří Kala, Petr Král, Filip Hokeš

Pages: 396-402

Abstract: The simulation of numerical methods is accompanied by problems caused by false dependencies arising from the mathematical basis of such methods. The use of the Smoothed Particle Hydrodynamics (SPH) method removes the problems caused by the presence of a physical mesh that occur, e.g. when the Finite Element Method (FEM) is used. Although meshfree methods are generally less likely to produce false numerical dependencies, in some cases certain measures must be taken in order to avoid obtaining unexpected results. In the case of the SPH this necessarily involved the regular distribution of particles in discretized domains. This contribution describes a fracture mechanics experiment in which L-shaped concrete specimens undergo dynamic fracture. The experiment is simulated via the SPH method, during which clusters of particles are artificially created so that the resulting distribution in the discretized domain (or a zone within it) is irregular. The consequences of this irregularity and its effect on the form of failure are studied along with possible ways in which false (dependent) behaviour can be prevented. The results from the SPH method are also compared to FEM results.

Title of the Paper: Design and Testing of a Prototype Foam for Lightweight Technological Applications


Authors: M. Viscardi, M. Arena, D. Siano

Pages: 383-395

Abstract: Over recent years, in the automotive field, numerous performance and aesthetic innovations have been produced thanks to the development process of the manufacturing technologies gained mainly in the aerospace industrial context. The automotive industry is currently experiencing relevant technology changes in the design of the engines, transmission and total drivetrain, induced by increasing customer demand for fuel efficiency and more stringent government requirements in emissions and safety. One of the problems relating to environmental impact concerns the noise emitted by the vehicle, for which various solutions have been experimented: new and more resistant materials have been worked out in order to minimize noise pollution and the environmental impact of the vehicle, even at the end of the operating life of its components. Several research programs are currently running or recently terminated worldwide to explore the feasibility of smart materials. The increasingly dominant role of lightweight materials in many technological sectors is motivated by the multitude of benefits that they could offer like the weight optimization and the reduction of the fuel burn and noise levels. This research illustrates a solution as a response to those requirements, as well as being a response to the targets of comfort: a viscoelastic material, appointed to increase the damping of structures involved in vibro-acoustic phenomena generated in a vehicle. The performance of these innovative materials have been analyzed both from a numerical standpoint that experimental. Static mechanical properties and modal parameters carried out in the laboratory, pertinent to each configuration were arranged into a rational database for further studies on the vibro-acoustic behaviour of the coupled cavity-structure system. The main goal of this research project has been reached in the design, manufacturing and testing of an innovative viscoelastic prototype got out by the best compromise of structural and acoustic characteristics of pre-existing trim materials.

Title of the Paper: Structural Performance Analysis of Smart Carbon Fiber Samples Supported by Experimental Investigation


Authors: M. Viscardi, M. Arena, G. Barra, L. Guadagno

Pages: 376-382

Abstract: The use of composite materials has grown significantly in recent years thanks to new manufacturing processes, which have allowed for competing of laminates with metal alloys in in a broad spectrum of technological applications. As known, a composite is a material made by joining two or more constituents, therefore key concept is to combine more performances in a single final product. For their peculiarities, such as the heterogeneity and anisotropy, composites are materials used as a solution to problems of different areas, taking advantage of lightweight, strength, stiffness, good behavior to fatigue and corrosion and reduced manufacturing costs. Precisely because of their complex nature, the execution into a potential industrialization stage pose to the designer new problems but also targets, dictated by the technical need to clearly characterize both the macroscopic that the microscopic properties. The main goal of this activity has been to assess the mechanical properties of two carbon fiber/epoxy samples by means of experimental tests and numerical simulations with a very good correlation level. The outcomes achieved and described in this paper have been performed within an ambitious research project focused on the development and application of self-healing materials: one of the specimens in fact was filled with microcapsules to trigger the self-repair process in case of damage. Among the significant advantages of these smart materials, the improved ability to dissipate vibration energy has been especially appreciated in this framework. The conducted tests have revealed a higher damping coefficient compared to that one of a standard CFRC. Relying upon the validated FEM, sensitivity nonlinear analyses were carried out to evaluate the stiffness trend with respect to first-ply failure.

Title of the Paper: Lift Capability Improvement for an Airfoil with Filled Cavity


Authors: Constantin Rotaru

Pages: 368-375

Abstract: This paper proposes an improved airfoil model for the helicopter rotor blade. This airfoil has a filled cavity on the upper surface where the filled body is a free rotating cylinder. The effect on the flow around the airfoil is the generation of vortices that reduce the flow separation downstream of the cavity. The CFD and vortex panel method results show an enhanced lift capability both for advancing and retreating helicopter rotor blade.

Title of the Paper: Numerical Simulation of Three Dimensional Turbulent Flow Structure and Heat Transfer in Ribbed-Straight, Divergent and Convergent Ducts


Authors: Amin Etminan, Zambri Harun, Ahmad Sharifian

Pages: 362-367

Abstract: Turbulent heat transfer and flow structure inside straight, divergent and convergent ducts with square ribs has been investigated for Reynolds number varying from 7000 to 100000 numerically. The simulations have been employed using the one and two turbulent models in particular Re-normalization group (RNG) as the most efficient model. The impact of divergence or convergence on thermal efficiency of ducts during cooling process is explored in two and three dimensional flow regimes. Results reveal that divergent channel transfers higher amount of heat in comparison to other kinds of channels. Furthermore, divergent channel records less pressure loss and higher thermal efficiency where fully developed flow can be seen just through the straight duct. Computational data show a good agreement with experimental results available in the literature.

Title of the Paper: On the Effect of the Temperature Boundary Conditions on the Walls for the Processes of Heat and Mass Transfer


Authors: Aliya S. Askarova, Saltanat A. Bolegenova, Symbat A. Bolegenova, Valeriy Yu. Maximov, Meruyert T. Beketayeva, Zhanar K. Shortanbayeva

Pages: 349-355

Abstract: Combustion of fossil fuel accompanied with difficult physical processes and chemical interactions of flows. Inadequate study of determining the behavior of the heat flow and mass transfer processes in the combustion chamber during the burning of pulverized coal at different boundary conditions of temperature on the walls of the chamber focuses on realistic model of choice is almost arbitrary. In this paper by using of modern computational technologies investigated combustion behavior of pulverized coal in 3D designed combustion chamber in two boundary conditions for the temperature of the walls. By numerical calculation were obtained heat and mass transfer characteristics of coal combustion. Determined results can help to find special activities to improve ecological and economic situation of energy objects at all.

Title of the Paper: Overall Heat Transfer Coefficients, Pressure Drop and Power Demand in Plate Heat Exchangers During the Ammonia Liquor Cooling Process


Authors: Enrique T. Tamayo, Eduardo J. Díaz, María P. Cedeño, Carlos L. Vargas, Segundo G. Peralta, Manuel A. Falconi

Pages: 342-348

Abstract: In the Ammonia Recovery process of the nickel company the pressure drop of the Ammonia liquor cooling process, by means of the plate heat exchangers, is associated to the incorrect estimate of the overall heat transfer coefficients and fluid parameters: Water and ammonia liquor outlet temperature, Water and ammonia liquor mass flow. The above increases the consumption of water, the available energy in the system and the maintenance costs. The investigation was carried out in plate heat exchangers, with the objective of determining the overall heat transfer coefficients and the behavior of pressure drop and power required for the ammonia liquor cooling process. By means of an iterative procedure was determined the equation and behavior of the overall heat transfer coefficients and their dependence with the Reynolds and Prandtl, for it was used a multifactor experimental design and measurements of the installation work parameters in function of the time. The results predict the knowledge of the overall heat transfer coefficients for the calculation of the Nusselt number with the Reynolds and Prandtl values for both fluids (water and ammonia liquor). The comparison with other investigators shows correspondence with Thonon results. To the overall heat transfer coefficient values less than 2500 W/m2K, the outlet temperature of the ammonia liquor exceeds 40 OC so the maintenance of the installation is recommended in less than 27 days period. The behavior of pressure drop and power demand as a function of the Reynolds number was obtained. Values for cooling the liquor are diminished compared to the water, it is because more water is used.

Title of the Paper: Simplified Variational Principles for Stationary non-Barotropic Magnetohydrodynamics


Authors: Asher Yahalom

Pages: 336-341

Abstract: Variational principles for magnetohydrodynamics were introduced by previous authors both in Lagrangian and Eulerian form. In this paper we introduce simpler Eulerian variational principles from which all the relevant equations of non-barotropic stationary magnetohydrodynamics can be derived for certain field topologies. The variational principle is given in terms of eight independent functions for stationary barotropic flows. This is the same as the eight variables which appear in the standard equations of non-barotropic magnetohydrodynamics which are the magnetic field B the velocity field v, the entropy s and the density ρ.

Title of the Paper: Experimental and Numerical Assessment of Innovative Damping Foams


Authors: M. Viscardi, M. Arena, D. Siano

Pages: 329-335

Abstract: The automotive industry is currently experiencing relevant technology changes in the design of the engines, transmission and total drivetrain, induced by increasing customer demand for fuel efficiency and more stringent government requirements in emissions and safety. One of the problems relating to environmental impact concerns the noise emitted by the vehicle, for which various solutions have been experimented: new and more resistant materials have been worked out in order to minimize noise pollution and the environmental impact of the vehicle, even at the end of the operating life of its components. This research illustrates a solution as a response to those requirements, as well as being a response to the targets of comfort: a viscoelastic material, appointed to increase the damping of structures involved in vibroacoustic phenomena generated in a vehicle. The performance of these innovative materials have been analyzed both from a numerical standpoint that experimental. Starting from the empirical results of tests carried out in the laboratory, finite element models have been developed in order to have a suitable numerical database for further vibro-acoustic simulations.

Title of the Paper: Young’s Equation for Non-Planar Surfaces


Authors: Jeng-Rung Jiang, Falin Chen, Min-Hsing Chang

Pages: 326-328

Abstract: In 1805, Young described the so-called Young’s equation for a liquid drop resting on a planar surface, which since has been successfully applied for different designs and extended to cover various physical situations. In this paper, we used the method developed by Lubarda to derive a Young’s equation for a liquid drop resting on an axisymmetric concave surface, which is considered to account for an extended form of nonplanar surfaces. As a result, a new form of Young’s equation is derived, which can be reduced into the Young’s equation for either a planar boundary or a vertical tube and accordingly can be considered as an extended form of Young’s equation for surfaces of various forms.

Title of the Paper: Influence of Boundary Conditions to Heat and Mass Transfer Processes


Authors: Aliya S. Askarova, Saltanat A. Bolegenova, Symbat A. Bolegenova, Valeriy Yu. Maximov, Meruyert T. Beketayeva

Pages: 320-325

Abstract: Investigation of heat and mass transfer processes in the area of combustion chamber during fuel burning is the one of the most difficult task for solving. Combustion processes accompanied with difficult physical and chemical reactions of two-phase flow at high temperatures. In this regard it’s effective and preferable using of computational technologies. Computational modelling of pulverized coal combustion is an actual problem that needed to be solved. During combustion processes there occurring highly reactive flows that interact with each other, and release hazardous components to the environment. It is difficult to find any decisions to minimize their amount. Holding natural experiments nowadays are very problematic regarding of economic issues. So the best way to study these problems is computational experiments. It helps to determine results that can help to find and offer special activities to improve ecological and economic situation of energy objects. So in cooperating with engineers of combustion institute in this paper were carried out computational experiments on modelling of heat-mass transfer processes during combustion of pulverized coal.

Title of the Paper: Supersonic Boundary Layer of Binary Mixture and its Stability


Authors: Sergey A. Gaponov, Boris V. Smorodsky

Pages: 312-319

Abstract: Properties of binary-mixture compressible boundary layers are investigated theoretically. Self-similar equations are deduced which describe the boundary-layer of air with distributed injection of a foreign gas from the porous surface. Mach=2 boundarylayer velocity, density, temperature and concentration profiles have been computed for foreign gases with various molecular mass. It has been found that increase of foreign gas injection leads to the monotonous reduction of surface friction and heat transfer. Stability of Mach=2 binary-mixture boundary-layer has been investigated by means of the linear stability theory (LST). It was established that action of heavy gas injection on the boundary-layer is similar to the action of wall cooling and leads to an increase of boundary-layer stability and to the delay of the laminar-turbulent transition. Theoretical estimate of the position of laminar-turbulent transition by means of known N e -method has been performed. A principal possibility to enlarge the transition Reynolds numbers in approximately two times has been revealed.

Title of the Paper: Stability Assessment of an Historical Masonry Bridge through the LA Kinematic Theorem for NT Structures


Authors: I. Corbi, O. Corbi, F. Tropeano

Pages: 305-311

Abstract: The paper focuses on a study case concerning an historical masonry bridge in the Campania region. The Devil’s bridge on the Sele river is characterized by a single vaulted span. The arcade presents an elliptical shape with five focal points “anse de panier”. It burdens on the foundation directly. The bridge is made of masonry both in its tympanum and in the fill; the fill is made of masonry bricks with mechanical properties similar to those ones of the main structure; so it is expected to cooperate to the structural function by contributing to the absorption of deformational and tensional effects. This paper is focused on the analysis of the behaviour of the bridge trough the setup of a preliminary study regarding the vault stability under its own weight; thereafter possible collapse mechanisms based on the kinematic theorem of Limit Analysis for masonry constructions under the No Tension assumption are selected, allowing to identify the most dangerous position of the variable load component for the bridge.

Title of the Paper: Utilizing Grillage of One-Dimensional Elements for Stability Problems of Rectangular Plates Resting on Elastic Foundations


Authors: Abdulhalim Karasin, Rehber Akdogan, Murat Arda Ugurlu

Pages: 299-304

Abstract: In many cases solution for stability of plate resting on elastic foundation problems have been available for limited regular geometries, but where irregular boundaries or partial contact are encountered difficulties arise because it will be necessary to describe the governing equation of motion in a general mathematical form. The intention of this study is to extend analytical solutions of the discrete one-dimensional beam elements resting on elastic foundation for solution of plate buckling problems. The solution can be stated as an extension of the so-called discrete parameter approach where the physical domain is broken down into discrete sub-domains. The derivations of the governing differential equations and geometric stiffness terms obtained to observe the influences of foundation parameters. Analytical solution of the discrete one-dimensional elements extended for solution of complex plate problems.

Title of the Paper: Static Equilibrium States of Von Mises Trusses


Authors: Zdeněk Kala, Martin Kalina

Pages: 294-298

Abstract: The paper deals with the stability problems of steep von Mises trusses with or without influence of initial geometrical imperfections. The complicated nonlinear problem is concerned which was solved by the method form finding. This method seeks an ideal shape of the von Mises truss at displacement of top joint. The paper presents a detailed description of calculation by this method. Applying the method form finding, areas of static equilibrium states of three steep von Mises trusses at displacement of top joint both in vertical and horizontal directions were obtained. The calculation process of these areas, and their drawing are described. These areas are illustrated for the von Mises trusses with influence or without influence of initial curvature of one bar.

Title of the Paper: Dynamic Modeling, Simulation and Control of a Hybrid Driven Press Mechanism


Authors: Mehmet Erkan Kütük, Lale Canan Dülger

Pages: 288-293

Abstract: Hybrid driven mechanism combines the motion of a large constant velocity motor with a small servo motor, and a mechanism. The constant velocity motor provides the main torque and motion requirements, while the servomotor contributes to modulations on this motion. Hybrid driven mechanism has higher flexibility in producing motion. Dynamic modeling and simulation of the hybrid system is presented in this study. A motion scenario is designed to be used on metal forming process. The equation of motion is derived by Lagrangian technique. Actuator dynamics for both axes are included with a PID control algorithm. The system simulation is performed with an explicit method; the fourth order Runge-Kutta method as an integration technique to get an approximate solution. The simulation results are presented.

Title of the Paper: Crack Identification in Beams Using Haar Wavelets and Machine Learning Methods


Authors: Ljubov Jaanuska, Helle Hein

Pages: 281-287

Abstract: This article addresses a numerical identification of some characteristic parameters of cracks in a vibrating beam. The beam rests on Pasternak elastic foundation. The depth or location of crack(s) is predicted using the feedforward artificial neural networks or the random forest method. The machine learning methods are trained twice using two independent datasets based on the natural frequencies or the Haar wavelet transform of the first or third mode shapes. The approaches are compared to each other. The significance of the Haar wavelet transform and the random forest lies in their ability to make relatively fast parameter predictions; however, the complex approach of Haar wavelets and neural networks provides more precise results.

Title of the Paper: Wave Responses and System Identification of Long Structures with Continuous Modeling


Authors: Ruichong Zhang, Zhanguo Ma, Guozhen Zhao

Pages: 274-280

Abstract: This paper introduces a wave-based approach for system identification of high-rise building structures with a pair of seismic recordings, which can be used to evaluate structural integrity and detect damage in post-earthquake structural condition assessment. The fundamental of the approach is based on wave features of generalized impulse and frequency response functions (GIRF and GFRF), i.e., wave responses at one structural location to an impulsive motion at another reference location in time and frequency domains respectively. With a pair of seismic recordings at the two locations, GFRF is obtainable as Fourier spectral ratio of the two recordings, and GIRF is then found with the inverse Fourier transformation of GFRF. With an appropriate continuous model for the structure, a closed-form solution of GFRF, and subsequent GIRF, can also be found in terms of wave transmission and reflection coefficients, which are related to structural physical properties above the impulse location. Matching the two sets of GFRF and/or GIRF from recordings and the model helps identify structural parameters such as wave velocity or shear modulus. For illustration, this study examines ten-story Millikan Library in Pasadena, California with recordings of Yorba Linda earthquake of September 3, 2002. The building is modeled as piecewise continuous layers, with which GFRF is derived as function of such building parameters as impedance, cross-sectional area, and damping. GIRF can then be found in closed form for some special cases and numerically in general. Not only does this study reveal the influential factors of building parameters in wave features of GIRF and GRFR. It also shows some system-identification results, which are consistent with other vibration- and wave-based results. Finally, this paper discusses the effectiveness of the proposed model in system identification.

Title of the Paper: Adapted Numerical Methods for Oscillatory Evolutionary Problems


Authors: Angelamaria Cardone, Dajana Conte, Raffaele D’Ambrosio, Beatrice Paternoster

Pages: 266-273

Abstract: It is the purpose of this paper to consider a selection of adapted numerical methods for the solution of evolutionary problems showing a periodic behaviour in their dynamics. The treatise will cover both evolutionary problems in time and space (i.e. reactiondiffusion problems generating a periodic wavefront in time and space) and problems with memory (i.e. Volterra integral equations with periodic solutions), also underlining the necessity to introduce suitable quadrature rules adapted to the problems under investigation. The approach is mainly problem-oriented, in order to match qualitative properties of the problem with the numerical methods, in order to get better accuracy, efficiency and stability properties with respect to existing numerical schemes.

Title of the Paper: A Computational Mechanics Using Nonlinear Analysis Method in Tensioned Fabric Structure


Authors: Yee Hooi Min, Choong Kok Keong

Pages: 261-265

Abstract: Nonlinear analysis method is one of the earliest methods proposed for form-finding analysis of tensioned fabric structures. However due to some inherent weaknesses, the method has not been fully developed. In this paper, computational strategies for form-finding analysis of tensioned fabric structure using the nonlinear analysis method has been proposed. For the purpose of verification, form-finding analysis using the proposed computational strategies have also been applied on cable reinforced two saddle-shaped tensioned fabric structure model, cable reinforced double Chinese hat tensioned fabric structure model and cable reinforced tent H?fingen tensioned fabric structure model which have been studied by other researchers. The proposed computational strategies can be presented as a general tool capable of form-finding analysis of tensioned fabric structures for structural engineer.

Title of the Paper: Spatial Energy Distribution in a Harmonic Oscillator and the Golden Section


Authors: B. Müller, E. Koyutürk, D. Göncü

Pages: 253-260

Abstract: The high school physics curriculum mostly targets the time dependent physical quantities of the harmonic oscillator e.g. velocity, acceleration and energies, because harmonic oscillations are defined as “periodic time dependent changes of physical quantities”. The focus of our interest in this paper is indeed the spatial dependence of the physical quantities, especially the spatial distribution of the three energies, which continuously change their amount in a harmonic oscillator system: kinetic energy ( ), potential energy ( ) and elastic potential energy ( ). The idea for this has been given by some students of the 11’th grade from the German high school of Istanbul (Özel İstanbul Alman Lisesi) in May 2015. We found out that the golden section plays an important role in the spatial energy distribution, especially between potential energy and elastic potential energy. Until today the role of the golden section has not been mentioned in such a simple system like the harmonic oscillator, but in more complicated systems. We cited the role of the golden section in the KAM- theorem and in Burgers-turbulence and found parallelisms to our results.

Title of the Paper: A Case Study on Seismic Behavior of Rectangular Tanks Considering Fluid - Structure Interaction


Authors: K. Kotrasova, E. Kormanikova

Pages: 242-252

Abstract: Liquid-storage tanks are used to store a variety of liquids. The fluid develops impulsive and convective action on liquid storage rectangular container during earthquake. This paper provides the theoretical background for specification of hydrodynamic effect of fluid on solid of tank fixed to rigid foundation and numerical solution for Finite Element Method (FEM), Arbitrary Lagrangian Eulerian (ALE), Fluid Structure Interactions (FSI) formulation. FEM ALE FSI formulation was used for numerical model of seismic response of tank - the endlessly long shipping concrete channel. The accelerogram Loma Prieta was considered as horizontal ground motion.

Title of the Paper: FE Nonlinear Analysis of Lateral-Torsional Buckling Resistance


Authors: J. Valeš, Z. Kala, J. Martinásek, A. Omishore

Pages: 235-241

Abstract: The article focuses on the analysis of the effects of stability phenomena on the ultimate limit state of a steel beam subjected to uniform bending moment along its length. The key parameters that influence the load carrying capacity include imperfections and slenderness. The elastic and inelastic resistance obtained using the nonlinear finite element method were compared with analytical and standardised approaches in the article. The effects of warping of the end sections on the resistance and reliability of steel beams is studied. For this purpose, bending of the beam was introduced, firstly with forces on the end sections, and secondly by rotating the end sections.

Title of the Paper: Using of the Design Assisted by Testing Method in case of the Experimental Verification of the Load-Carrying Capacity of Expansion Anchors


Authors: Michal Štrba, Marcela Karmazínová

Pages: 227-234

Abstract: In this paper they are described the information about an evaluation of the test results in case of an experimental research which was focused on a selected type of the steel mechanical fasteners to concrete under a tension loading. Generally, problems of an anchoring it is one of the most important parts of a design and realization in civil engineering from the basic building constructions to the bridges or high-rise buildings. In this event they are used especially two systems of steel fasteners. At first they are so called cast-in-place members (mostly the usual anchor bolts) and secondly, they are used post-installed anchors, which can be the expansion or the bonded ones, where both of them have their own advantages, disadvantages, their specific characteristics as well as the actual behaviour under different loading. However, this paper is oriented only to the verification of mean and design values of load-carrying capacity of the steel post-installed mechanical expansion anchors to concrete subjected to a monotonic and repeated tension loading.

Title of the Paper: Electromechanical Actuators Affected by Multiple Failures: a Simulated-Annealing-Based Fault Identification Algorithm


Authors: M. D. L. Dalla Vedova, D. Lauria, P. Maggiore, L. Pace

Pages: 219-226

Abstract: The identification of early evidences on monitored parameters allows preventing incoming faults. Early alerts can avoid rate of the failures and trigger proper out-of-schedule maintenance activities. For this purpose, there are many prognostic approaches. This paper takes into account a primary flight command electromechanical actuator (EMA) with multiple failures originating from progressive wear and proposes a fault detection approach that identifies symptoms of EMA degradation through a simulated annealing (SA) optimization algorithm; in particular, the present work analyses the functioning of this prognostic tool in three different fault configurations and it focuses on the consequences of multiple failures. For this purpose, we developed a test bench and obtained experimental data necessary to validate the results originated from the model. Such comparison demonstrates that this method is affordable and able to detect failures before they occur, thus reducing the occurrence of false alarms or unexpected failures.

Title of the Paper: Probabilistic Buckling Analysis of Thin-Walled Steel Columns Using Shell Finite Elements


Authors: Zdeněk Kala, Jiří Kala, Abayomi Omishore

Pages: 213-218

Abstract: The article deals with the probabilistic analysis of the reliability of a compressed steel column with hollow thin-walled rectangular cross-section. The stochastic computational model is based on the non-linear finite element method and numerical simulation Latin Hypercube Sampling method. Initial geometric imperfections were introduced according to the local and global buckling modes. Statistical analysis of the load carrying capacity was performed for four variants of wall thicknesses. The influence of the nominal thickness of the wall of the hollow rectangular cross-section on the ultimate limit state was studied.

Title of the Paper: The Ultrasonic C-Scan Technique for Damage Evaluation of GFRP Composite Materials


Authors: Anna Castellano, Pilade Foti, Aguinaldo Fraddosio, Salvatore Marzano, Mario Daniele Piccioni

Pages: 206-212

Abstract: We show experimental results obtained by an innovative non-destructive approach for the characterization of the damage of composite materials. The analysis regard an aeronautical rotor made of glass fiber–reinforced composite material, and is developed by applying an ultrasonic immersion C-Scan technique. The experimental data are employed in a damage model developed in the context of the Continuum Damage Mechanics theory. In this model, the evaluation of the damage level depends on a synthetic scalar damage parameter, connected to the quantities directly measured in an ultrasonic test, and related to the specific variation of the acoustical impedance. In particular, from the measurement of the ultrasonic velocity in the undamaged and damaged composite, respectively, we evaluated the damage parameter for an artificially damaged GFRP component.

Title of the Paper: Verification and Actual Behavior of Shear Connection of Composite Steel and Concrete Structures Using Pcb-W Technology


Authors: V. Přivřelová

Pages: 200-205

Abstract: The paper deals with the problems of the theoretical and experimental investigation of load carrying capacity of steel and concrete composite members using pcb-W (precast composite beam - coupled in Web) technology. Pcb-W technology is new and economic solution of continuous shear connection of composite steel and concrete beams and walls. This construction method is based on a rolled steel beam cut longitudinally, with a special unique cut, in two T-sections and a concrete top chord is concreted. The shape of the cut hereby allows the shear transmission in the shear joint. The longitudinal shear forces between steel and concrete parts of a composite member are transmitted by composite dowels, generated by the special cut of steel surrounded by concrete, instead of headed studs as it is common in traditional composite structures. The paper deals with the actual behavior and corresponding relevant failure mechanism of these composite dowels in particular with the failure modes and bearing capacity of the composite dowels and with the stress distribution in the steel dowels. Within the framework of this research, three types of shear connection have been (or will be, respectively) investigated, all of them composed of three specimens.

Title of the Paper: Design of Multi-Charge Gun


Authors: Michal Kovarik

Pages: 192-199

Abstract: The multi-charge gun is barrel weapon system comprising more combustion chambers connected to the barrel bore for the purpose of ballistic pressure course improvement and ballistic output increase. The internal ballistics of the gun were described mathematically and examined experimentally with positive results as the basis of formulation of recommendations in explicit form suggested for the utilization in the phase of initial design of the complex multi-variable weapon system.

Title of the Paper: Modeling and Numerical Calculation of Waterflooding Using the Weierstrass Elliptic Functions


Authors: Vladimir I. Astafev, Andrey E. Kasatkin

Pages: 182-191

Abstract: Waterflooding is the most commonly used secondary oil recovery method for both conventional and heavy oil reservoirs because of its relative simplicity, availability of water and cost-effectiveness. The recovery factor for waterflooding is determined by much number of external factors, including number and placement of water injection and oil production wells. The choice of these parameters to maximize the reservoir sweep is the first step of waterflooding optimization and an essential part of the oil field development modeling. The water injection and oil production wells are usually placed as some periodic array of wells. A five-spot pattern is often the most effective type of waterflooding. Some other patterns are four-spot, seven-spot, nine-spot, direct-line drive, staggered-line drive and so one. All these patterns may be considered as elements of an unbounded double periodic array of wells. Prediction of the motion of the oil-water contact boundary has great importance in the problems of design of oilfield development by waterflooding: knowledge of the nature of coupled motion of oil and water, displacing oil in the reservoir allows us to optimize the system of oil field development. The simplest model of coupled filtering of oil and water is the model of "multicolored" liquids, which assumes that oil and water have the same or similar physical properties (density and viscosity). A more complex "piston-like" model of oil-water displacement takes into account differences in viscosity and density of the two fluids. Oil reservoir assumed to be homogeneous and infinite, fixed thickness, with constant values of porosity and permeability coefficients. It is assumed that the reservoir is developed by a group of a finite number of production and injection wells recurrent in two directions (doubly-periodic cluster). Filtration of liquids is described by Darcy's law. It is assumed, that both fluids are weakly compressible and the pressure in the reservoir satisfies the quasi-stationary diffusion equation. Piston-like displacement model leads to the discontinuity of the tangential component of the velocity vector at the boundary of oil-water contact. Use of the theory of elliptic functions in conjunction with the generalized Cauchy integrals reduces the problem of finding the current boundaries of oil-water contact to the system of singular integral equations for the tangential and normal components of the velocity vector and the Cauchy problem for the integration of the differential equations of motion of the boundary of oil-water contact.

Title of the Paper: Verification of the Elasto-Plastic Behavior of Nonlinear Concrete Material Models


Authors: Petr Kral, Jiri Kala, Petr Hradil

Pages: 175-181

Abstract: The aim of this paper is the verification of the behavior of nonlinear concrete material models subjected to dynamic loading. The behavior of five selected nonlinear concrete models is tested within numerical simulations of the testing of the mechanico-physical properties of concrete in uniaxial and triaxial compression, using cylinders. These numerical simulations are performed using the explicit finite element approach and their results take the form of load-displacement and load-time diagrams created for a concrete cylinder under dynamic compressive loading whose behavior was calculated by individual nonlinear models of concrete. The results gained from the numerical simulations are compared with experimental results obtained from laboratory tests performed for the purpose of verifying the nonlinear concrete models. This comparison shows the differences in the behavior of the individual nonlinear models of concrete and the approximations of the experimental data. The comparison allows conclusions to be drawn as to which nonlinear models provide the best approximation of the test data, and therefore which models best describe the behavior of the tested concrete in compression.

Title of the Paper: Response of Stepped Conical Shells to the Blast Loading


Authors: Jaan Lellep, Ella Puman

Pages: 167-174

Abstract: Problems of the blast loading of inelastic plates and shells have theoretical and practical importance. The plastic response of a conical shell to the blast loading is studied. Material of the shell is assumed to be a perfect plastic material. Piece wise linear approximations of the exact yield surface are used. Making use of the velocity field corresponding to the associated flow law the statically admissible field of stress resultants is constructed. For determination of residual deflections the method of mode form motions is applied. Numerical results are obtained for the exponentially decaying load intensity.

Title of the Paper: Nonlinear Numerical Simulation of a Fracture Test with Use of Optimization for Identification of Material Parameters


Authors: Filip Hokes, Jiri Kala, Ondrej Krnavek

Pages: 159-166

Abstract: The application of a nonlinear description of construction material behaviour in numerical simulations represents a step forward in enabling mathematical modeling methods to ever more closely describe the real actions of structures. This statement is also valid in the case of the numerical modeling of fracture experiments, but in both cases this modeling is complicated by the existence of unknown material parameters for the nonlinear material model. However, fracture experiments provide the opportunity to identify unknown parameters from data that are measured during the performance of such experiments. The submitted article deals with the numerical simulation of a three-point bending test carried out on a concrete specimen. It describes the process by which the inverse identification of material parameters takes place via optimization. The inverse analysis was based on the utilization of a load-displacement curve measured during the experiment. The main aim of the article is to present a method describing the inverse identification of parameters from the simulation of a fracture experiment which can then be used in the performance of comprehensive nonlinear simulations of the behaviour of structural details and whole structures manufactured from concrete.

Title of the Paper: New Sufficient Conditions for the Hadamard Stability of a Mooney-Rivlin Elastic Solid in Uniaxial Deformation


Authors: Pilade Foti, Aguinaldo Fraddosio, Salvatore Marzano, Mario Daniele Piccioni

Pages: 151-158

Abstract: A procedure for obtaining a lower bound estimate of the critical load for a homogeneously deformed Mooney-Rivlin incompressible cylinder is presented. By considering a lower bound estimate for the second variation of the total energy functional based on the Korn inequality, we establish sufficient conditions for the infinitesimal Hadamard stability of a distorted configuration. We then sketch the procedure for determining an optimal lower bound estimate of the critical load in a uniaxial compressive loading process and discuss its effectiveness for applications by comparing our results to other estimates proposed in the literature.

Title of the Paper: High Speed Loading of Concrete Constructions with Transformation of Eroded Mass into the SPH


Authors: Jiří Kala, Martin Hušek

Pages: 145-150

Abstract: The paper describes some negative aspects of high speed loading simulations by using the finite elements method. A simple terminal ballistics experiment illustrates the issue. It consists in a collision of a high speed flying fragment with a concrete target. Penetration and spalling of the concrete target surface are considered as main characteristics of the failure. A large elements deformation in the simulations causes numerical problems such as elements locking, negative volumes formation and increased computational time. These negative simulations aspects can be removed by using some numerical tools such as elements erosion and eroded mass transformation into smoothed particle hydrodynamics. The both numerical tools are explained and their connection with a material model physical nature as well as their application in the simulation are described afterwards. The results show the functionality of these tools in the end of the paper.

Title of the Paper: Analysis of Heat and Mass Transfer on Free Moving Urea/Water-Droplets in SCR-Systems by Numerical Methods


Authors: Lukas Möltner, Aldo Giovannini, Verena Schallhart

Pages: 138-144

Abstract: The selective catalytic reduction (SCR) of nitrogen oxides (NOx) is the most promising technique to meet prospective emission regulations. Due to its toxic potential the reducing agent ammonia cannot be stored in a car, but it can be carried in the form of an urea-water-solution (UWS), which is injected into the hot exhaust gas and reacts to ammonia. This generation of ammonia upstream the catalytic converter is responsible for the efficiency of the complete SCR-process-chain. This study deals with the analysis and description of interactions between droplets of urea-water-solution and the exhaust gas. For the description of the droplets? trajectories a numeric model was developed, which considers contrary to previous surveys the loss of the droplets? mass due to evaporation of water and thermal decomposition of urea. The model for the droplets? motion includes an evaporation model for binary fluids and it was extended by a kinetic approach to describe the thermal decomposition. This model is able to determine the exact position of the flying droplet, velocity, composition, current temperature and thermo- and fluid-dynamic parameters. These parameters are substantial for the discussion of the heat and mass transfer between droplets and exhaust gas.

Title of the Paper: Stabilization of Telescopic Inverse Pendulum Verification by Physical Models


Authors: Zdeněk Úředníček

Pages: 132-137

Abstract: Article deals with physical models of mathematical and simple and double physical pendulum for its stabilization possibilities verification in instable inverse position. Whereas classical stabilization by proximal joint horizontal movement of inverse mathematical pendulum is well known and in article is just why and when is possible, the case of stabilization by proximal joint vertical oscillation comings-out from chaos theory and is referred in article by multiport physical models and their behavior.

Title of the Paper: Membrane Surface Porosity and Pore Area Distribution Incorporating Digital Image Processing


Authors: Mohammad Abbasgholipourghadim, Musa Bin Mailah, Intan Zaurah, A. F. Ismail, M. Rezaei Dashtarzhandi, Mehdi Abbasgholipourghadim

Pages: 124-131

Abstract: Hollow Fiber Membrane surface properties are crucial factors of evaluating the membrane performance in a special application. Hence, this study aims to develop an attractive and convenient digital image processing program package (IPP) for calculating membrane surface pore area, pore distribution and surface porosity. The results also can suggest how to control the spinning conditions towards fabricating a suitable membrane based on the requirements of a process. Different HFMs under various compositions and spinning conditions were fabricated and investigated in this study, including polyvinylidene fluoride (PVDF) with 12 – 22 wt.% and changes of dope extrusion flow rate and bore fluid flow rate. Fabricated HFMs were visualized and detected using Field Emission Scanning Electron Microscope (FESEM). The IPP changed the qualitative surface information from the outer surface FESEM images to quantitative results. The IPP determines the pore area, pore area distribution and surface porosity of membrane. The calculated surface porosity of the membranes was compared with the achieved value obtained from gas permeation test. There was no significant difference between the results of both methods confirming the applicability of IPP for the study of membrane surface properties. This work presents a novel approach in order to evaluate pore size, pore area and surface porosity of HFM material in different range.

Title of the Paper: Innovative Mechanical Characterization of Materials by Combining ESPI and Numerical Modelling


Authors: C. Barile, C. Casavola, G. Pappalettera, C. Pappalettere

Pages: 115-123

Abstract: Mechanical characterization of materials allows measuring elastic constants (i.e. Young’s modulus, Poisson’s ratio, etc.). A complete experimental plan consists of several mechanical tests which may results expensive both in terms of time and costs. Particularly when manufacturing process itself is expensive or when controlling all parameters involved in the manufacturing process is complicated, only a limited number of specimens will be tested and so results risk to be unreliable. The procedure proposed in this work aims to simplify the traditional mechanical characterization of all materials and to obtain the elastic properties by carrying out a reduced number of non-destructive tests. This new methodology combines two techniques: Electronic Speckle Pattern Interferometry (ESPI) with Finite Element Model (FEM). It works iteratively and proposes to minimize the difference between the displacement fields, experimentally evaluated by ESPI in three-point-bending tests, and their counterpart computed by FEM analysis, applying the same loads and boundary conditions. In this way the approach could be defined as a hybrid procedure based on a combination of an optical interferometric technique, commonly used in experimental mechanics, having sub-micrometric sensitivity with a numerical procedure, which uses an optimization algorithm. Once the procedure has been validated on materials whose properties are known, the purpose of the paper is to accurately evaluate mechanical properties of new materials, today widely applied in numerous fields ranging from aerospace to biomedicine, allowing to deeply reduce experimentation time and costs.

Title of the Paper: Bypass Flow Influence on Energy Performance of Data Center Cooling


Authors: J. Novotný, J. Nožička, J. Matěcha

Pages: 105-114

Abstract: The study aims to describe the influence of bypass on cooling of the data center. In this study, both numerical and experimental methods were combined in order to describe an undesirable effect of the bypass flow; a simplified analytical procedure was also used. The paper first describes basic metrics used when defining main parameters of data center cooling. The following part describes experimental data center where individual experiments were performed. For the needs of CFD simulations, suitable boundary conditions were defined in order to get as close as possible to the real flow inside the data center, based on measurements taken. Finally, a simplified analytical solution was used. On the basis of the analytical solution, detailed information on various components of the simulated data center are applied, the information being obtained during measurement. All three approaches are compared at the end and the influence of missing blanking plugs on the overall energy performance of data center cooling is described with the help of the performed analysis

Title of the Paper: An Empirical Model for Gas-Dynamic Characteristics Microturbines Rotor Wheels


Authors: Andrey Yu. Fershalov, Mikhail Yu. Fershalov, Lyudmila P. Tsigankova

Pages: 99-104

Abstract: This study aims to present empirical models of gas-dynamic characteristics of microturbines rotor wheels, namely the ratio of the rotor wheels speed and the angle of exit gas stream from the rotor wheel. The paper was studied rotor wheels with a large angle of rotation flow Δβ=180°–(β1?+β2?)=151°…164°. Empirical models of gas-dynamic characteristics of rotor wheels microturbines need to model and analyze the characteristics of the rotor wheels. Empirical models were subjected to regression analysis. Impact of the studied factors on gas dynamic characteristics driving wheels was estimated.

Title of the Paper: Comparison of Analysis of Linear Inhomogeneous and Nonlinear Half-Space in Foundation-Subsoil Interaction


Authors: J. Labudkova, R. Cajka

Pages: 90-98

Abstract: The solution of tasks of interaction of foundation and subsoil is more difficult the less accurate the input data. Lower accuracy of input data is related to the description of the properties and behavior of foundation soil. Foundation soil consists of heterogeneous particles. The modulus of deformability in the subsoil model varies smoothly with increasing depth. It was resolved by use of an inhomogeneous half-space. The other alternative, besides linear inhomogeneous half-space, is nonlinear analysis. The results of both alternatives of solutions are compared in this paper. Values calculated by interaction models bases on FEM with 3D elements of subsoil were also compared with values measured during the loading test.

Title of the Paper: Modal Parameters Identification on Environmental Tests of an Ancient Tower and Validation of its FE Model


Authors: M. Diaferio, D. Foti, N. I. Giannoccaro

Pages: 80-89

Abstract: An accurate knowledge of the dynamical parameters of structures is definitely useful for seismic assessment and for the design of risk mitigation interventions. In this paper, the opportunities provided by dynamic identification techniques for the non-destructive evaluation of heritage structures are discussed with focus on the bell tower of Announziata (Corf?, Greece), a masonry tower, which shows a high damaged scenario and, consequently, a high vulnerability to dynamic and seismic forces. The paper presents the experimental investigations and the operational modal analysis results, useful for defining the finite element (FE) model of the tower. The monitoring system consists of several elements properly connected. The positioning of the instrumentation has been conditioned by many operative problems due to the limited accessibility of the structure, not only to the main access but also to reach the top. This difficulty and the presence of a higher level connected only with very slender columns in correspondence of the arched-windows have affected the finite element model that cannot act as a non-linear structure for the local modes at this level. However, it has been possible to identify with a certain confidence the first six frequencies of the tower and their corresponding mode shapes.

Title of the Paper: Utilization of Temperature Dependency of Asphalt Belts to Reduce Shear Stress into Foundation Structures


Authors: Martina Janulikova

Pages: 75-79

Abstract: Asphalt belts are commonly used to the hydro insulation of flat roofs and to the hydro insulation of foundations. These belts are also used to auxiliary function as part of roof layer or as under layer in many construction. But asphalt belts can be also used to reduce shear stress into foundation structures. The basic principle of this reduction is in application asphalt belts between foundation and concrete base layer. This creates a sliding layer which eliminates friction forces in foundation bottom. This paper explains reasons for using of sliding joint in to foundation structures and its basic function in the building. The experimental tests of modern sliding joint and their results are presented too. At the long term tests it was verified that the ambient temperature has a heavy effect of asphalt belt behavior. For this reason the new laboratory tests deal with electronic temperature control directly in the sliding joint. Such sliding joint can be also very helpful for all types of foundation which are loaded with horizontal deformations (undermining, pre-stressing, creep and shrinkage etc.).

Title of the Paper: Numerical and Experimental Modeling for Thermal Developing Pipe Flow with Microwave Heating


Authors: G. Cuccurullo, L. Giordano, G. Viccione

Pages: 68-74

Abstract: The work here presented is concerned with the analysis of forced convection of Newtonian liquids flowing in a circular duct under microwave heating. Spatial temperature field in the illuminated cavity was numerically obtained by solving coupled energy and Maxwell’s equations since it was assumed to be dependent on the dielectric properties of the fluid flowing in the duct. Attained temperature levels justified no phase changes and no gas phases. Temperature contour is detected by an outer infrared camera looking inside the microwave chamber in correspondence of the applicator-pipe. The proposed procedure is intended to realize relatively high spatial resolution temperature readings while microwave heating takes place. In facts, temperatures are usually measured in few points which can’t enable a proper temperature profile reconstruction, the latter being strongly uneven along the pipe due to electromagnetic field distribution. Numerical results are compared with the corresponding experimental ones for different temperature levels, showing a good agreement.

Title of the Paper: Peculiarities of Reactions Control for Rotor Positioning in an Active Journal Hybrid Bearing


Authors: Roman Polyakov, Denis Shutin, Leonid Savin, Alexander Babin

Pages: 62-67

Abstract: The most important part of rotor motion control using the active bearings is the regulation of the forces that act on the rotor from the bearing. In an active hybrid bearing it is implemented by means of changing the supply pressure in the area of friction. The mathematical model of such bearing based on the hydrodynamic lubrication theory allows studying the dependencies of the forces, which act on the rotor from the lubricant film, on the pressure distribution in the feeding chambers. The research results show the principal opportunity to control the rotor motion in a fluid-film bearing through a separate controlled supply of a lubricant to the friction area. An active journal hybrid bearing with four feeding chambers allows implementing a simple rotor position control scheme inside its radial displacement without a necessary consideration of the crosslinks between the regulated parameters in the control system. Moreover, the use of the control system allows increasing the load capacity of the fluid-film bearing, which is used to provide stability under the conditions of complex load schemes.

Title of the Paper: Wind Generator Innovative Blade Design: Variable Twist and Start-Up Control


Authors: Giuseppe Sirigu, Mario Cassaro, Manuela Battipede, Piero Gili, Giacomo Frulla

Pages: 53-61

Abstract: This paper presents the preliminary results obtained in the VENTURAS (VENTo: Una Risorsa Altamente Sfruttabile or 'wind: a highly exploitable resource') project, funded by the Italian Environmental, Land and Sea Protection Ministry, within a call for the funding of research projects aimed at improving the energy efficiency measures and the use of renewable energy sources in urban areas. This project addresses to improve the efficiency and to widen the range of the wind speed at which the micro wind turbines operate effectively and safely. This goal is achieved by developing variable pitch blades, which have morphing capabilities that enables the control system to select the optimum twist law along the blade, to optimize the efficiency also in non-nominal conditions. The proposed control strategy aims at maximizing the rotor efficiency, by maintaining the rotor in the nominal working condition. The control algorithm is based on a finite state machine, which commands the twist law to the blades, according to different strategies, predesigned for each working condition. At low wind speed, the control system changes the blade twist law, in order to maintain the angular speed and maximize the electrical efficiency. In this paper, the performance of different start-up strategies are compared.

Title of the Paper: The Possibilities of Numerical Modeling of Reinforced Masonry and its Comparison with Real Measurements on a Test Sample of Masonry


Authors: Marie Kozielova, Martina Janulikova, Pavlina Mateckova, Lucie Mynarzova

Pages: 46-52

Abstract: The paper deals with various ways of modeling pre-stressed masonry and examination of the influence input data on the modeling results. The process modeling of properties of masonry is carried out for many years. The expression of optimal solution of the modeling is very large and is dealt with in a number of works, therefore should be limited for some procedures. The aim is to create the simplest models with outputs that are most correspond with the actual measurement. The basic model is designed as micro-model. Process of modeling is divided into three phases. In the first stage it is used the material linearity of all input data considering on the initial strain in the pre-loaders element. Subsequently is performed consideration of the effective area in the anchorage zone. In the last phase enters into modeling material nonlinearity of selected materials. All phases are implemented in software ANSYS. At the end all phase are compared. Then the models are compared with real measurements on a test sample of masonry. All input values are obtained from laboratory tests of the experimental measurements including statistical evaluation of the input data. The comparison is serving as verification of the functionality of individual phases of models.

Title of the Paper: Quality Analysis of 3D Reconstruction in Underwater Photogrammetry by Bootstrapping Design of Experiments


Authors: M. Martorelli, A. Lepore, A. Lanzotti

Pages: 39-45

Abstract: Nowadays photogrammetric techniques have known important developments and are widely employed for 3D acquisitions in different fields of application. The paper analyzes the effects of different parameters (texturization, ambient light and water turbidity) on the quality of the 3D reconstruction in underwater photogrammetry. Several experimental tests were performed on a wind turbine blade using a common action camera, the GoPro 4 black edition and a commercial software, Photoscan by ©Agisoft. By means of a DoE (Design of Experiments) approach, 3D models were reconstructed varying the chosen parameters. Each of them was compared with a CAD model, used as reference, obtained by more accurate laser scans VI-9i by Konica Minolta. The results showed that blade texturization, ambient light and water turbidity significantly impact on the quality of the 3D reconstruction. Optimal results were obtained with textured blade, morning ambient light (exposure 1/60, f/2.8 and ISO sensitivity 100) and clear water. Moreover, in order to calculate confidence intervals for regression coefficients, even with few acquisitions, a computer-intensive bootstrap procedure was applied to the regression model. Finally, further confirmation experiments carried out in a deeper swimming pool and with poor conditions (e.g., very low ambient light and no blade texturization) in order to reproduce the real submarine environment. In such situations, an additional source of light and one or more grids, which allow a pattern to be created on the edges of the wind turbine blade, may help reconstructions.

Title of the Paper: Experimental Testing of Post-Tensioned Concrete Industrial Floor Model – Subsidence Analysis


Authors: Petr Mynarcik, Radim Cajka

Pages: 33-38

Abstract: The behavior of slab-on-ground constructions - subsidence of constructions and interaction between concrete structure and subsoil is one of the main research directions at the Faculty of Civil Engineering, VSB – Technical university of Ostrava Actually, scope of research is focused on concrete post-tensioned slab-on-ground. The article presents the process of a static load test on a post-tensioned concrete industrial floor model. The experimental model was designed as a cutout of a post-tensioned concrete industrial floor, and the static load test was conceived as a simulation of loading by base plate of a heavy rack. During the static load test, measurements focused on observation of subsidence and results of subscribed experiment were used for comparison with basic FEM model.

Title of the Paper: Friction and Wear Characterization of a New Ecological Composite: Glass Waste Beads Reinforced Epoxy


Authors: Alessandro Ruggiero, Vincenzo D’Agostino, Massimiliano Merola, Petr Valasek, Karolina Dedicova

Pages: 27-32

Abstract: Sandblasting is a process that allows smoothing and cleaning rough surfaces, by means of a hard abrasive material streamed at high pressure against the interested surface. The abrasive material could be glass beads, which are wasted after the process. This paper investigated the opportunity to recycle the glass beads as reinforcement inside a polymeric matrix. This new composite material could be an economic and green alternative to the more common polymer matrix composite (PMC). Therefore, the tribological properties of this composite were studied through reciprocating sliding tribotest. The influence on friction and wear of different glass dimensions and concentrations within epoxy resin were analyzed.

Title of the Paper: An Experimental Investigation on the Impact of Brine Composition on Silica Solubility at High Temperature


Authors: Ahmed F. A., Elraies A. K., Ayoub A. M., Gaafar R. G.

Pages: 23-26

Abstract: The theory of silica-water system or silica solubility is quite complex as it involves dissolution, polymerization and precipitation processes to form the silicate scale. The type and amount of silicate scale observed is dependent on several factors including pH, salinity, magnesium concentration, and the ratio of calcium to magnesium. This paper describes the impact of some factors including brine salinity and composition on silica solubility using crash quartz sandstone core samples. Synthetic brine with different salinities ranged between 20,000ppm to 60,000ppm were utilized to determine the change in soluble silica at 80°C. The amount of silica dissolved from the sandstone sample was measured using Silicomolybdate method and validated using Energy Dispersive X-RAY and X-RAY Diffraction techniques. The results clearly showed that the composition of the brine has a significant effect on the silica solubility. The amount of silica dissolution increased from 41.0mg/L to 67.8mg/L when the brine salinity increased from 20,000ppm to 60,000ppm, due to the increasing in salt contents of the brine. It was also observed that the addition of magnesium and calcium with ratio 1:1 to the brine would greatly affect the silica solubility. This has been confirmed by analyzing the samples before and after saturation by the use of Energy Dispersive X-RAY.

Title of the Paper: Environmental Noise Level Threshold Surpassing Analysis by Non-Homogeneous Poisson Model with Informative and Non-Informative Prior Distributions


Authors: Claudio Guarnaccia, Joseph Quartieri, Nikos E. Mastorakis, Carmine Tepedino

Pages: 14-22

Abstract: The dangerous effect of acoustical noise on health, both auditory and non-auditory, is largely documented in literature. The study of noise problem and the development of several predictive models are very important issues in cities and areas in which relevant noise sources are present. A model based on threshold exceedances is suitable since a great number of national regulations define limits to acoustical levels, according to the area and to the kind of buildings and activities occurring in them. In this paper, a non-homogeneous Poisson model will be presented and applied to a large dataset of noise measurements. The aim of this model is to predict, from a probabilistic point of view, the number of threshold exceedances in a given future period. This can be achieved estimating the parameters of the mean function, that represents the number of surpassings of the threshold as a function of the time, and of the rate function of the Poisson process. Different models of the rate function form can be chosen, according to their functional dependence from time. The choice adopted in this work will be the Goel Okumoto (GO) model. The estimation of the parameters probability distributions will be performed using a Bayesian approach, based on Monte Carlo Markov Chains and Gibbs algorithm. Once the parameters will be tuned, the mean function can be compared with the observed exceedances plot. The two GO parameters will be estimated using non-informative uniform prior distributions and also informative gamma distributions. Different starting points sets will be implemented for the Markov chains to evaluate possible effects on the posterior distributions.

Title of the Paper: Main Engine Fuel Oil Consumption by Using Flow Meter on Tug Boat


Authors: A. Danny Faturachman, B. Shahrin Febrian, C. Theresiana D. Novita, D. Achmad Djaeni, E. Tyas Alva Oktavia

Pages: 7-13

Abstract: Fuel oil is one of natural resources owned by land where the stock is very limited so caused many companies was trying to efficiency the use. Vessel requires fuel oil enough to move a main engine properly. Today with stores of fuel oil prices depleting and the fuel price increases make a company used a flow meter to control the fuel consumption so can be checked the real fuel oil used on ships while operating. Expected after using flow meter discharging fuel controllable and can be reduced to be more efficient in use. Issues discussed is the number of fuel consumption in real used when a vessel is in operation, the way which the control of fuel better used manually or used by flow meters , and finally we got the outcome of the comparison of fuel consumption manually and when using used a flow meter. .Methodology research conducted is the descriptive method and quantitative analysis of data processing literature and from the vessel operation data. The result is after using the flow meter there is efficiency of fuel oil consumption Titan 03 is 9.833 % and Titan 05 is 21.220%.

Title of the Paper: Improvement of Broached Involute Gearing on Engine Components


Authors: Andre Gleser, Oldřich Ondráček

Pages: 1-6

Abstract: This paper deals with the improvement of broaching processes with respect to cost-effective solutions – e.g. less process steps. In the considered case an involute spline has to be manufactured with the flank fit “7H” according to DIN 5480 considering an orientation of one teeth pair to an outer contour. The size between pins and the run-out is considered as critical dimensions. The measurements are taken in three different levels of the spline, which brings exact results that can be used for a conclusion. When the goal is to avoid an additional process after broaching with an orientation of the spline to an outer contour there is there is a need for sophisticated fixtures.