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In this paper, solid particle erosion behaviors of AISI 1020 steel and Ti-6Al-4V titanium alloy materials were experimentally and numerically investigated. Experiments and numerical simulations were carried out for the conditions of different particle impact velocities (100, 127, 170, 210, 250 m/s) and angles (20, 30, 45, 60, 90‹). Moreover, erosion performances on the erosion shield of a helicopter rotor blade of aforementioned materials were numerically determined for the condition of angle of attack of 0. and impact velocity of 230 m/s. Numerical erosion analyzes were performed with ANSYS_Fluent 15.0 package program using discrete phase method with Eulerian- Lagrangian approach and an empirical erosion equation while experimental erosion tests were conducted by MIL-STD-3033 standard. As a result, numerical results were in good agreement with the experimental data, and it was obtained that erosion performance on the shield surface of AISI 1020 steel material is better than Ti-6Al-4V titanium alloy material. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Defense Sciences / Savunma Bilmleri Dergisi is the property of Turkish Military Academy Defense Sciences Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Defense Sciences / Savunma Bilmleri Dergisi is the property of Turkish Military Academy Defense Sciences Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Defense Sciences / Savunma Bilmleri Dergisi is the property of Turkish Military Academy Defense Sciences Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Defense Sciences / Savunma Bilmleri Dergisi is the property of Turkish Military Academy Defense Sciences Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Defense Sciences / Savunma Bilmleri Dergisi is the property of Turkish Military Academy Defense Sciences Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we propose a novel shockproof head gimbals assembly (HGA) structure incorporated with "a balanced-type head suspension" for 0.85-in hard disk drives (HDD5), and investigated its performance on external shock resistance during read/write operations. Experimental drop impact test results confirm that the 0.85-in drive equipped with the new suspension structure is durable over 2000 G (1.0 ms duration) of external shock, ensuring no head slider and/or disk surface damage. According to computer simulation and experimental results, potential shock resistance of more than 2000 G may also be possible with the head actuator itself, which points to its application in cellular phones. [ABSTRACT FROM AUTHOR]

In this paper a new RC - active polyphase filter section is presented. The section uses three conventional current conveyor (CCII). With a cascade of these sections, any higher order polyphase filter function can be realized. Frequency transfer functions, gain and phase errors of the proposed section are derived for ideal and nonideal CCIIs. In the case of using nonideal CCIIs filter characteristics are investigated by performing computer simulations. Also the paper deals with the leakage caused by the effects of a limited gains of a current conveyors. [ABSTRACT FROM AUTHOR]

Moisture-related building envelope problems such as condensation, damp, delamination of coatings, unsatisfied user's comfort requirements usually arise from the unexamined/unforeseen interactions of materials with ambient environment, and with other system components during design. Today, it is possible to estimate the in-use performance of building envelopes by computer simulations except for test methods. While use of building simulation software intended to determine indoor climate systems providing appropriate environmental conditions and to assess building energy performance is increasing, the use of simulation software to assess hygrothermal performance of building envelopes has only been recently started to spread. This paper primarily deals with computer simulation software analysing hygrothermal performance of building envelopes, and important issues associated with their structure and use are considered. A typical wall design case performed by WUFI 2D is explained for contributing to extend the efficient use of simulation software in practice. Finally, when using simulation software to assess hygrothermal performance, 'selection of appropriate software' and 'planning of simulation work' processes are found matters of utmost importance in achieving goals set by the use of simulation. [ABSTRACT FROM AUTHOR]

One of the main subjects that is studied in multi-robot applications is allocating tasks to robots and constructing objective-efficient tours for the robots using these allocated tasks. The main purpose of this paper is to allocate tasks via market-based task allocation architecture and to construct collision-free routes for multi-robot systems in a known indoor environment. For task allocation, a market-based architecture is constructed and applied to an example of a team of four heterogeneous mobile robots. In the study, tasks are allocated according to one of two constraints: minimizing the makespan of the robots and maximizing the robot task matching value of each robot in the group. These constraints are achieved by changing the value of a decision parameter. To show the effectiveness of the proposed method, comparisons are made within these constraints. To construct path, a combination of the Nearest Neighbor heuristic and Dijkstra's shortest path algorithms is used. To construct non-conflicting paths, a method that detects and solves collisions is developed. In the study, for agent communication Open Agent Architecture is used. Additionally, simulations on the MobileSim platform are conducted to verify the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, the goal is to primarily deal with the modeling of the railway traffic induced vibrations by using discrete computer models for analyzing related wave propagation problems with soil-structure interaction effects and mitigation of building responses by installation of wave barriers. Comprehensive parametric studies including the effects of localization and backfill material of trench barrier on the screening performance have been executed. [ABSTRACT FROM AUTHOR]

In this paper numerical technique through Computational Fluid Dynamics (CFD) codes was used in order to investigate thermo-fluid-dynamics field (velocity, pressure, temperature) in the combustion chamber of a Diesel engine. Another important objective was the possibility of modelling and prediction of pollutant formation during the combustion process in these engines. Mathematical model was based on the conservation equations of mass, momentum and energy (Favre-averaged Navier-Stokes equations). To close these equations system was add also: state relations equations, Renormalized Group Theory (RNG) k-epsilon turbulence model and spray mechanism model. Since processes in Diesel engine have not only thermo-fluid nature but also chemistry, a special attention was for chemistry models for both chemical reaction simulation and for the chemistry models of pollutants. Formation of NOx is predicted by Zeldovich mechanism. Soot formation relies on the nucleation, surface growth, coagulation and oxidation process. Result of simulation shown that thermal NOx is seen at stoichiometric mixture fraction at high temperatures, while soot formation is seen fuel-rich and relatively low- temperature regions. [ABSTRACT FROM AUTHOR]

This paper studies the computerized tooth profile generation of spur gears cut with generating-type cutters. Based on the theory of gearing the mathematical models of pinion-type shaper cutters and generated gears with involute teeth are given. The corrections on geometry such as addendum modification (profile shift) and asymmetric tooth profile are also considered. Computer simulation programs are developed to obtain graphs of generating tools and generated external and internal teeth surfaces. The effects of geometric varieties of the rounded corner of the tool, addendum modification and the degree of asymmetry on generated surfaces can be investigated. [ABSTRACT FROM AUTHOR]

In this paper, a systematic design process model is proposed to model Flexible Manufacturing Systems (FMS). Generally, FMS systems design is complicated and cost very high as installation phase. Therefore, technical analysis of system design should be exact and accurate even for the installation phase. At this stage, the proposed model is Integration Definition for Function Modeling (IDEF) diagram which is a structured design technique. Proposed model is exemplified with a practical example in TAI which is operating in the aerospace industry. The performance of the proposed model is analyzed using simulation and queueing network technique. In the performance analysis, test parameters are determined as service rates, number of servers, routing information and number of transporters and also performance parameters are determined cycle time and machine utilization. [ABSTRACT FROM AUTHOR]

This paper describes the optimal tuning for the parameters of the power system stabilizer (PSS), which can improve the system damping performance within a wide region of operation conditions to enhance power system stability using artificial bee colony algorithm (ABC) based PSS instead of a conventional PSS and particle swarm optimization (PSO) based PSS. The parameters of the optimized PSS are obtained by minimizing a performance index based on integral of the absolute error (IAE) that shows steady state stability of power system. Single machine infinite bus (SMIB) system and two types of excitation system were used for the present work. The simulation results demonstrate that the proposed ABC based PSS performs well in damping and quicker response when compared with the other two PSSs. [ABSTRACT FROM AUTHOR]

This paper studies the computerized tooth profile generation of spur gears cut with generating-type cutters. Based on the theory of gearing the mathematical models of generating cutters and generated gears with asymmetric involute teeth are given. Trochoidal envelope traced by cutter during the generating process is investigated. Computer simulation programs are developed to generate the tooth profile of asymmetric involute gears and to illustrate the effect of tool geometry on generated surfaces. The geometric varieties of the rounded corner of the rack and pinion-type cutters determine the position of trochoidal paths relative to the center line of the tooth space of the generated gear. [ABSTRACT FROM AUTHOR]

Nowadays the popularity of the Electric Vehicles (EV) has increased more than ever. The "green" trend and the oil-dependent automotive industry's strong will to find alternative energy resources are taking a big part in bringing the EV projects to life. Most of the carmakers devote significant budgets for developing this technology which had been partially industrialized at the end of 19th century. However, there are still some difficulties to industrialize the EVs due to the unsatisfactory level of battery technology. Therefore, most of the studies concerning EVs are focused on the battery. In this paper, the Renault Fluence ZE's li-ion battery computer-based modelling and specifically the cell balancing development study has been presented. [ABSTRACT FROM AUTHOR]

In Norm Fasteners Co. die failure analysis and fatigue life estimations have been done since 2003. By using Finite Element Analysis; material flow, die filling, lap formation, forging forces, ductile fracture and tool failures can be predicted before production. Necessary changes in design are made to produce defect-free product in shortest time and to lower cost. A few case studies experienced in Norm Fasteners Co. about estimation and improvement of die service life by modifications in process as well as in die design and estimation of hardness distribution of final part are presented in this paper. [ABSTRACT FROM AUTHOR]

This paper studies the computerized tooth profile generation of involute helical gears cut by rack cutters with asymmetric teeth. The asymmetry means that different pressure angles are applied for driving and coast sides, respectively. Based on the theory of gearing and the geometry of straight-sided rack cutter, a complete mathematical model of asymmetric helical gears including working region, root fillet and bottomland is given. Undercutting analysis is also investigated by considering the relative velocity and equation of meshing. A computer program is developed to generate the tooth profile of helical gears with asymmetric involute teeth. [ABSTRACT FROM AUTHOR]

In this study, the numerical simulation of turbulence hydrogen-methane blending flame was performed by using the CFD code Fluent in a conical entry combustion chamber. The main aim of the presented study is to determine the best combustion model constant to be agree with experimental measurements in numerical simulation of the hydrogen-methane blending fuels. In the numerical simulation, the fuel including 30% hydrogen and 70% methane by volumetrically, 40 kW thermal power, and 20% of excess air was used. In addition, the fuel mixture of 30% hydrogen and 70% methane by volumetrically was also used to determine the effect of hydrogen amount on the emissions including NOx, CO ve CO2 in the numerical simulation. Numerical simulations of the blended fuel, two different values (A=4 and A=1) of the combustion model constant A were used. In order to determine the most suitable combustion model constant, temperature, NOx, CO, and CO2 measurement values were compared with numerical results. The velocity, temperature and gas composition distributions obtained from numerical simulation were also given and discussed in this paper. In numerical simulations of the hydrogen-methane blended fuel combustion, it is determined that the predictions for combustion model constant of 1 are closer to experimental values compared with the predictions for combustion model constant of 4. [ABSTRACT FROM AUTHOR]

This paper studies the equations of rack cutters for generating conical gears with asymmetric involute teeth. By applying the equations of designed profile of rack cutter, the principle of coordinate transformation, the theory of differential geometry, and the theory of gearing, the mathematical model of involute conical gear with asymmetric teeth is given. Based on the given mathematical model, a computer program is developed for simulating the generation process. Numerical illustrated examples are given for straight and helical beveloid gears. [ABSTRACT FROM AUTHOR]

This paper examines how to automatically reconstruct 3D models from their orthographic two views and explains a new approach developed fort hat purpose. The approach is based on the identification of geometric features with the interpretation of 2B views, their volumetric intersections and reconstruction of solid models. A number of rules have been defined for this goal and they implemented on a prottype software with the approach of expert systems. The developed software allows determination of some features efficiently such as slot, holes, blind holes, closed prismatic holes, etc. Another contribution of this research is to reconstruct solid models from their sectional and half section views that is almost noneexistend in the related literature. [ABSTRACT FROM AUTHOR]

Copyright of Teknoloji is the property of Engineering Science & Technology, an International Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Teknoloji is the property of Engineering Science & Technology, an International Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Faculty of Educational Sciences is the property of Ankara University, Faculty of Educational Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Turkish Journal of Education is the property of Mehmet Tekerek and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the results of an extensive study of numerical simulation of steady, incompressible and axisymmetric developing turbulent flow in circular-sectioned pipes at several Reynolds numbers. Employing the conventional finite-volume method, a computer program based on the SIMPLE algorithm has been developed. Numerical simulations for radical profiles of axial velocity, turbulence model, are obtained using an iterative numerical solution technique. Near the solid boundary, wall-functions are employed. Numerical simulations for radial profiles of axial velocity, turbulence kinetic energy, turbulence kinetic energy dissipation rate, effective viscosity, axial variation of centre-line velocity, wall-shear stress distribution and variation of coefficient of friction along axisymmetric pipe flow geometry are presented and compared with experimental measurements. The results of numerical simulations are generally in good agreement with various experimental measurements. [ABSTRACT FROM AUTHOR]

Copyright of ITU Journal Series D: Engineering is the property of Istanbul Technical University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)