Scopus

Permanent URI for this collectionhttps://ada.atilim.edu.tr/handle/123456789/19

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Citation Count: 4
2D FE modelling of machining: A comparison of different approaches with experiments
(2005) Bil,H.; Tekkaya,A.E.; Kiliç,S.E.; Manufacturing Engineering
[No abstract available]
Citation Count: 4
Abstract conceptual database model approach
(2013) Çaĝiltay,N.E.; Topalli,D.; Aykaç,Y.E.; Tokdemir,G.; Information Systems Engineering; Computer Engineering
One of the main objectives of the software engineers is to provide software related solutions for social problems and to increase the availability of social welfare. In that sense, the quality of the software is directly related to address the users' needs and their level of satisfaction. To reflect user requirements to the software processes, the correct design of the database model provides a critical stage during software development. Database design is a fundamental tool for modeling all the requirements related to users' data. The possible faulty conditions in database design have adverse effects on all of the software development processes. The possible faulty conditions can also cause continuous changes in the software and the desired functionality of the targeted system which may result in user dissatisfaction. In this context, reflecting the user requirements accurately in the database model and understanding of the database model correctly by every person involved in the software development process is the factor that directly affects the success of software systems' development. In this study, a two-stage conceptual data modeling approach is proposed to reduce the level of complexity, to improve the understandability of database models and to improve the quality of the software. This study first describes the proposed two-stage conceptual data modeling. Than the proposed method's impact on software engineers' comprehension is also investigated and the results are compared with the degree of complexity of the related conceptual data models. Results of this study show that, the proposed two-stage conceptual modeling approach improves the understanding levels of software engineers and eliminated possible defects in this stage. © 2013 The Science and Information Organization.
Citation Count: 3
Achieving success in supply chain management software by agility
(Springer Verlag, 2007) Mishra,D.; Mishra,A.; Computer Engineering; Software Engineering
Supply chain management is comprehensive software. Due to its scope and unpredictable, complex and unstable requirements, it is not possible to develop it with predictable development process models. Agile methodologies are targeted towards such kind of problems that involves change and uncertainty, and are adaptive rather than predictive. The aim of this paper is to analyze the management and development methodologies used in development of supply chain management software. This paper shows how to overcome risks and handicaps in each development phase of a complex inventive project. It also provides a set of guidelines regarding how the agile methods may be adopted, combined and used in these kinds of projects. © Springer-Verlag Berlin Heidelberg 2007.
Citation Count: 0
Adapting test-driven development for innovative software development project
(Springer Verlag, 2007) Mishra,D.; Mishra,A.; Computer Engineering; Software Engineering
In Test-Driven development, first test is made according to the customer requirement and then code is prepared to execute this test successfully. In this approach, design is not done exclusively before preparing test cases and coding. Design emerges as software evolves but this may result in lack of design quality. We adapted TDD by incorporating exclusive architectural design phase in the successful implementation of an innovative, large scale, complex project. © Springer-Verlag Berlin Heidelberg 2007.
Citation Count: 0
Adapting test-driven development for innovative software development project
(Springer Verlag, 2007) Mishra,D.; Mishra,A.; Computer Engineering; Software Engineering
In Test-Driven development, first test is made according to the customer requirement and then code is prepared to execute this test successfully. In this approach, design is not done exclusively before preparing test cases and coding. Design emerges as software evolves but this may result in lack of design quality. We adapted TDD by incorporating exclusive architectural design phase in the successful implementation of an innovative, large scale, complex project. © Springer-Verlag Berlin Heidelberg 2007.
Citation Count: 3
Analysis of a dual frequency circular patch antenna
(2012) Can,S.; Kapusuz,K.Y.; Aydin,E.; Department of Electrical & Electronics Engineering
This study demonstrates resonant frequencies of several shorting pin loaded circular antennas, which are dual-frequency antennas. Dual-frequency operation is formed by using a shorting pin, which is connected between ground and the radiated part of the antenna. There are various studies, which are used to produce dual-frequency operation, and among those methods, a shorting pin is used to form dual frequency circular patch antennas since there are rare studies on this issue and size reduction is possible by inserting a pin to an antenna. This study is done to expand the studies in the literature about a shorting pin loaded circular patch antennas. The parameters that affect the resonant frequencies of the antenna are also evaluated. The thickness, permittivity and shorting pin positions are varied and the resonant frequencies are examined according to the change of these parameters. Frequency ratios are determined for each variation and the results are compared.
Citation Count: 1
Analysis of damage in metal forming
(Hanrimwon Publishing Co., 2008) Soyarslan,C.; Erman Tekkaya,A.; Department of Mechatronics Engineering
Investigation of central burst formation in direct extrusion is presented with experimental and numerical studies. On the experimental side, selecting certain unfavorable die angles and reduction ratios from the Chrysler processing standard for chevron-free extrusions curve [1], a set of extrusion tests are performed. Accordingly, chevrons are produced in the first and second pass for 100Cr6 and Cf53, respectively. On the numerical side, a multiplicative finite plasticity framework is coupled with a Lemaitre variant Continuum Damage Mechanics (CDM) model giving account for the crack closure effect and implemented as ABAQUS/VUMAT subroutine. Materializing an explicit finite element scheme, the effects of main process parameters, such as friction, semi-cone angle and reduction ratio on damage accumulation zones and intensities are studied. It is shown that, for the identical geometries, with an appropriately selected crack closure parameter and an element deletion procedure, the discrete periodic cracks can be captured, which are in correlation with the conducted experimental outputs.
Citation Count: 0
Analysis of force-indentation measurements on anisotropic metals
(Edizioni libreria progetto, 2005) Koray,E.; Topcu,N.; Tekkaya,A.E.; Manufacturing Engineering
Indentation tests are widely used with simultaneous measurements of indentation depth and force especially for determining material properties. In this study, findings on parameters affecting the force-displacement curves obtained from indentations on anisotropic metals using special not self-similar indenters will be presented. Parameters such as specimen dimensions, friction, surface roughness, specimen clamping and indentation spacing have been investigated by finite element analysis and by experiments. Optimum values of these parameters to achieve higher repeatability and accuracy are determined.
Citation Count: 0
An approach for Improving Performance of Sensorless Field Control
(Institute of Electrical and Electronics Engineers Inc., 2018) Bulent Ertan,H.; Filci,T.; Electrical-Electronics Engineering
Sensorless vector control is preferred in some applications, because there is no need for speed or position sensor. However, by their very nature, they are susceptible to making position error in rotor position estimation. As a consequence the performance of motor drives employing this technology is lower than those which employ sensors. This paper presents a new approach which identifies and uses rotor slot harmonic current component in the stator current to identify rotor position. The time taken by the algorithm used is short enough to be embedded within the vector control algorithm. The essence of the algorithm is treating the current component due to rotor slot harmonics as an amplitude modulated signal on the fundamental current component. The magnitude of this current component is identified via demodulation. Using this information rotor position and speed can be determined. This approach is tested on a commercial induction motor and some results are presented which illustrate that rotor position can be successfully determined. © 2018 IEEE.
Citation Count: 0
An approach for Improving Performance of Sensorless Field Control
(Institute of Electrical and Electronics Engineers Inc., 2018) Bulent Ertan,H.; Filci,T.; Electrical-Electronics Engineering
Sensorless vector control is preferred in some applications, because there is no need for speed or position sensor. However, by their very nature, they are susceptible to making position error in rotor position estimation. As a consequence the performance of motor drives employing this technology is lower than those which employ sensors. This paper presents a new approach which identifies and uses rotor slot harmonic current component in the stator current to identify rotor position. The time taken by the algorithm used is short enough to be embedded within the vector control algorithm. The essence of the algorithm is treating the current component due to rotor slot harmonics as an amplitude modulated signal on the fundamental current component. The magnitude of this current component is identified via demodulation. Using this information rotor position and speed can be determined. This approach is tested on a commercial induction motor and some results are presented which illustrate that rotor position can be successfully determined. © 2018 IEEE.
Citation Count: 3
Approximate seismic evaluation methods for large building inventories with high variability in their seismic resistance
(2006) Gunes,B.; Yakut,A.; Gunes,O.; Department of Civil Engineering
Seismic hazard mitigation for urban infrastructures located in seismic regions is a challenge faced by many countries around the world, especially those with infrastructures known for their variability in quality of construction and compliance with the seismic codes. Two recent major earthquakes that hit the densely populated urban areas in Northwest Turkey resulted in a large-scale destruction and loss of life. Scientific studies indicate that the probability of occurrence of another severe earthquake along the North Anatolian Fault near Istanbul is quite high in the next few decades. This situation presents a serious threat to the large building stock and their occupants in Istanbul and adjacent areas. Structures in these areas are known to have high variability in their seismic resistance, which makes it difficult to estimate the potential losses in case of a major earthquake. Thus, there is an urgent need for a systematic strategy that will allow for rapid and reliable assessment of the seismic risk associated with existing buildings through an effective methodology that properly considers the local infrastructure characteristics. In this paper, approximate methods for seismic assessment of buildings are reviewed and are evaluated through their application to a group of 131 reinforced concrete frame buildings located in various seismic regions of Turkey. The results show that the recently developed preliminary methods that are customized for the local building characteristics provide improved prediction of seismic hazard, and may serve as an efficient and reliable risk assessment tool upon further improvement and calibration. The first stage procedures show large variability and result in considerable cases of misclassifications.
Citation Count: 0
ARTIFICIAL INTELLIGENCE TECHNIQUES FOR PERFORMANCE SIMULATION: SOLID OXIDE FUEL CELLS V-J CURVE PREDICTION VIA ARTIFICIAL NEURAL NETWORKS
(ENEA, 2017) Baldinelli,A.; Barelli,L.; Bidini,G.; Bonucci,F.; Iskenderoğlu,F.C.
For their high flexibility of operation, Solid oxide fuel cells (SOFCs) are promising candidates to coach the transition towards cleaner and efficient energy generation. Yet, SOFC performance might be markedly affected by fuel composition variability and operative parameters. For that, a reliable simulation tool is necessary for SOFC performance, to optimize its working point and to provide a suitable control. Given the high variability ascribed to the fuel and the electrochemical system high nonlinearity, the implementation of artificial intelligence techniques, like Artificial Neural Networks (ANNs), is worth considering. In ANNs, the correlation between system inputs and outputs is handled by virtual neurons, establishing in-out correlations without entering in knotty kinetics and material properties issues. For what above, a suitably sized experimental campaign is to be designed to provide a large data-set. This to guarantee high ANN performance in the voltage estimation and, at the same time, a wide application domain of the neural simulator. © EFC 2017 - Proceedings of the 7th European Fuel Cell Piero Lunghi Conference.
Citation Count: 0
Assessment of online exam system perception in COVID-19 pandemic era
(IADIS Press, 2021) Eryılmaz,M.; Genis-Gruber,A.; Computer Engineering
The swift conversion of courses to online exams has labelled the recent Covid-19 pandemic era. In educational agenda, all educators in the globe have faced the obstacles of abrupt adoption of distance education learning methods. Although distance education methods have been exercised in the past decade, the usage was not common. The pandemic has brought not only the sudden transformation of education format, but also online security issues. The online exam solution in e-learning techniques, tools and adoption has been a popular topic to research. Recent literature review shows various analyzes in the field, however the outcome of the research proves that the challenges are similiar in the globe. The aim of this research is to determine the essential problems and develop solutions based on the students perception of online exams which became compulsorily transitioned during the pandemic process. The custom-made survey was conducted on 165 students to have an insight on their approach to e-learning and online exam. Descriptive statistics method is used to describe the features of the data in the study. © 2021
Citation Count: 0
ATA50 telescope: Hardware
(Universidad Nacional Autonoma de Mexico, 2014) Yesilyaprak,C.; Yerli,S.K.; Aksaker,N.; Yildiran,Y.; Güney,Y.; Güçsav,B.B.; Yaşar,E.
ATA50 Telescope is a new telescope with RC optics and 50 cm diameter. It was supported by Atatürk University Scientific Research Project (2010) and established at about 2000 meters altitude in city of Erzurum in Turkey last year. The observations were started a few months ago under the direction and control of Atatürk University Astrophysics Research and Application Center (ATASAM). The technical properties and infrastructures of ATA50 Telescope are presented and we have been working on the robotic automation of the telescope as hardware and software in order to be a ready-on-demand candidate for both national and international telescope networks.
Citation Count: 17
Automatic continuity of surjective n-homomorphisms on banach algebras
(Iranian Mathematical Society, 2015) Eshaghi Gordji,M.; Jabbari,A.; Karapinar,E.; Mathematics
In this paper, we show that every surjective n-homomorphism (n-anti-homomorphism) from a Banach algebra A into a semisimple Banach algebra B is continuous. © 2015 Iranian Mathematical Society.
Citation Count: 3
Bifurcation in a 3D Hybrid system
(2010) Akhmet,M.U.; Turan,M.; Mathematics
In this paper, we study a 3 dimensional Hybrid system which involves a switching mechanism such that at the moment of switching the differential equation that governs the mode] is changing. We first show that there is a center manifold and based on the results in [2] we show that the system under investigation has a Hopf bifurcation. An appropriate example is constructed to illustrate the theory. © Dynamic Publishers, Inc.
Citation Count: 4
Bioinspired conceptual design (BICD): Conceptual design of a grasshopper-like jumping mechanism as a case study
(2011) Eroglu,A.K.; Erden,Z.; Erden,A.; Department of Mechatronics Engineering; Mechatronics Engineering
The evolution process of nature creates highly effective, power efficient, and perfectly structured biological systems. These excellent systems provide an inexhaustible source for engineers and scientists who desire to inspire ideas, processes, structures, functions, and behaviors from biological domain and implement them into engineering domain. This approach is called "Bioinspired" and challenging for engineers. However, some problems of the practical approaches are observed. One of the problems is "ad hoc" nature of the process. Each bioinspired design product has resulted in a differing design process and a generalization was not possible. Another problem rises due to the terminology difference between engineers and biologists. To overcome these problems, a need for a systematic bioinspired design (BID) process was realized in early 2000s and since then, considerable research on the BID methodology has been progressed. Within the context of BID, this paper introduces a new approach on bioinspired conceptual design (BICD) procedure for hybrid bioinspired robots which can be inspired from multiple biological systems. An illustrative case study is given in the paper.
Citation Count: 9
Biomechanical Design and Control of Lower Limb Exoskeleton for Sit-to-Stand and Stand-to-Sit Movements
(Institute of Electrical and Electronics Engineers Inc., 2018) Qureshi,M.H.; Masood,Z.; Rehman,L.; Owais,M.; Khan,M.U.; Mechatronics Engineering
In this paper, we present design and development phase of lower limb robotic exoskeleton that can assist paralyzed individuals. Motion of the human wearing exoskeleton is introduced by actuators. Both exoskeleton legs are attached to the supporting frame by passive universal joints. The exoskeleton provides 3 DOFs per limb of which two joints are active and one passive. The control actions i.e., sit-to-stand and stand-to-sit movements are triggered using Double Pole Double Throw (DPDT) toggle switch. The control scheme is implement using Switch control method and the feedback is provided by means of current measurement. This assistive device can be utilized for the disabled persons. The simulation results are provided that evaluates the performance of the control actions on exoskeleton. © 2018 IEEE.
Citation Count: 9
Biomechanical Design and Control of Lower Limb Exoskeleton for Sit-to-Stand and Stand-to-Sit Movements
(Institute of Electrical and Electronics Engineers Inc., 2018) Qureshi,M.H.; Masood,Z.; Rehman,L.; Owais,M.; Khan,M.U.; Mechatronics Engineering
In this paper, we present design and development phase of lower limb robotic exoskeleton that can assist paralyzed individuals. Motion of the human wearing exoskeleton is introduced by actuators. Both exoskeleton legs are attached to the supporting frame by passive universal joints. The exoskeleton provides 3 DOFs per limb of which two joints are active and one passive. The control actions i.e., sit-to-stand and stand-to-sit movements are triggered using Double Pole Double Throw (DPDT) toggle switch. The control scheme is implement using Switch control method and the feedback is provided by means of current measurement. This assistive device can be utilized for the disabled persons. The simulation results are provided that evaluates the performance of the control actions on exoskeleton. © 2018 IEEE.
Citation Count: 25
Blockage/shadowing and polarization measurements at 2.45GHz for interference evaluation between Bluetooth and IEEE 802.11 WLAN
(2001) Kara,A.; Bertoni,H.L.; Department of Electrical & Electronics Engineering
We present measurement results at 2.45 GHz to evaluate blockage shadowing and fading effects due to furniture and people next to terminals for short range indoor communication systems. The followings are the results: people crossing the link near to a terminal can cause fading up to 20dB which is more than furniture blockage measured of about 5-13dB depending on objects over the links, polarization coupling was also measured by using dual polarized antenna at receiving end, and coupling is higher for obstructed links, which suggests polarization diversity.

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