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Fractional Order Systems in Industrial Automation-A Survey
(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2011) Efe, Mehmet Onder; Turkish Aeronautical Association; Turk Hava Kurumu University
This paper describes an emerging tool for industry: fractional order systems. Conventional understanding of the notion of derivative and integral uses integer orders and our sense is mature in their physical interpretations. Derivatives or integrals of fractional orders are generalizations of the concept containing the classical cases and solutions based on fractional order operators utilize the full flexibility offered by the mathematical definitions. The interest of the industry to fractional order systems lie in the fact that complicated modules can be simplified significantly and practical applications can be diverse. This paper describes linear and nonlinear cases with necessary stability and performance considerations for the benefit of a practicing engineer exploiting informatics in industry.
Evaluation of corporate energy management practices of energy intensive industries in Turkey
(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Ates, Seyithan Ahmet; Durakbasa, Numan M.; Technische Universitat Wien; Turkish Aeronautical Association; Turk Hava Kurumu University
Turkey is one of a number of countries who still lack a national management standard for energy. Industrial energy consumption accounts for 42% of Turkey's total energy consumption. With the help of a questionnaire and analytical framework, this paper investigates Industrial Energy Management Practice in Turkey and highlights significant bottlenecks and shortcomings of energy intensive industries in terms of energy management application. The survey was carried out as a multiple case study of the Turkish iron, steel, cement, paper, ceramics and textile industries. Outcomes of the questionnaire are evaluated according to the analytical framework which covers company characteristics, regulations, external relations of the companies and internal organizational conditions. After analyzing these elements on the basis of a minimum requirement list, it was found that only 22% of the surveyed companies actually practice corporate energy management in Turkey. The main barriers to proper energy management implementation were identified as lack of synergy between the stakeholders, the extent and scope of energy manager courses, and inadequate awareness of and lack of financial support for energy management activities. As a guideline to overcome present obstacles, a set of policy options are offered: strengthening and restructuring of legal and institutional frameworks, promotion of energy efficiency, education, training and capacity building and facilitating implementation of the international energy management standard ISO 50001. (C) 2012 Elsevier Ltd. All rights reserved.
Amyloid Inspired Self-Assembled Peptide Nanofibers
(AMER CHEMICAL SOC, 2012) Cinar, Goksu; Ceylan, Hakan; Urel, Mustafa; Erkal, Turan S.; Tekin, E. Deniz; Tekinay, Ayse B.; Dana, Aykutlu; Guler, Mustafa O.; Tekin, Emine Deniz; Turk Hava Kurumu University; Turkish Aeronautical Association; Ihsan Dogramaci Bilkent University
Amyloid peptides are important components in many degenerative diseases as well as in maintaining cellular metabolism. Their unique stable structure provides new insights in developing new materials. Designing bioinspired self-assembling peptides is essential to generate new forms of hierarchical nanostructures. Here we present oppositely charged amyloid inspired peptides (AIPs), which rapidly self-assemble into nanofibers at pH 7 upon mixing in water caused by noncovalent interactions. Mechanical properties of the gels formed by self-assembled AIP nanofibers were analyzed with oscillatory rheology. AIP gels exhibited strong mechanical characteristics superior to gels formed by self-assembly of previously reported synthetic short peptides. Rheological studies of gels composed of oppositely charged mixed AIP molecules (AIP-1 + 2) revealed superior mechanical stability compared to individual peptide networks (AIP-1 and AIP-2) formed by neutralization of net charges through pH change. Adhesion and elasticity properties of AIP mixed nanofibers and charge neutralized AIP-1, AIP-2 nanofibers were analyzed by high resolution force distance mapping using atomic force microscopy (AFM). Nanomechanical characterization of self-assembled AIP-1 + 2, AIP-1, and AIP-2 nanofibers also confirmed macroscopic rheology results, and mechanical stability of AIP mixed nanofibers was higher compared to individual AIP-1 and AIP-2 nanofibers self-assembled at acidic and basic pH, respectively. Experimental results were supported with molecular dynamics simulations by considering potential noncovalent interactions between the amino acid residues and possible aggregate forms. In addition, HUVEC cells were cultured on AIP mixed nanofibers at pH 7 and biocompatibility and collagen mimetic scaffold properties of the nanofibrous system were observed. Encapsulation of a zwitterionic dye (rhodamine B) within AIP nanofiber network was accomplished at physiological conditions to demonstrate that this network can be utilized for inclusion of soluble factors as a scaffold for cell culture studies.
Macroscopic Assembly of Indefinitely Long and Parallel Nanowires into Large Area Photodetection Circuitry
(AMER CHEMICAL SOC, 2012) Ozgur, Erol; Aktas, Ozan; Kanik, Mehmet; Yaman, Mecit; Bayindir, Mehmet; Yaman, Mecit; Ihsan Dogramaci Bilkent University; Ihsan Dogramaci Bilkent University; Ihsan Dogramaci Bilkent University; Ministry of Science, Industry & Technology - Turkey; Turk Hava Kurumu University; Turkish Aeronautical Association
Integration of nanowires into functional devices with high yields and good reliability turned out to be a lot more challenging and proved to be a critical issue obstructing the wide application of nanowire-based devices and exploitation of their technical promises. Here we demonstrate a relatively easy macrofabrication of a nanowire-based imaging circuitry using a recently developed nanofabrication technique. Extremely long and polymer encapsulated semiconducting nanowire arrays, mass-produced using the iterative thermal drawing, facilitate the integration process; we manually aligned the fibers containing selenium nanowires over a lithographically defined circuitry. Controlled etching of the encapsulating polymer revealed a monolayer of nanowires aligned over an area of 1 cm(2) containing a 10 x 10 pixel array. Each light-sensitive pixel is formed by the contacting hundreds of parallel photoconductive nanowires between two electrodes. Using the pixel array, alphabetic characters were identified by the circuitry to demonstrate its imaging capacity. This new approach makes it possible to devise extremely large nanowire devices on planar, flexible, or curved substrates with diverse functionalities such as thermal sensors, phase change memory, and artificial skin.
Plasmon-polaritons on graphene-metal surface and their use in biosensors
(AMER INST PHYSICS, 2012) Salihoglu, Omer; Balci, Sinan; Kocabas, Coskun; Ihsan Dogramaci Bilkent University; Turk Hava Kurumu University; Turkish Aeronautical Association
We studied excitation of surface plasmon-polaritons on graphene-metal surface. The metal surface is functionalized by transfer printing of graphene grown by chemical vapor deposition on copper foils. Surface plasmon resonance characteristics of monolayer and multilayer graphene on the metal surface are presented. We were able to obtain the dispersion relation of graphene-metal surface which reveals the essential feature of the plasmon-polaritons. As an application, we fabricated a surface plasmon resonance sensor integrated with a microfluidic device to study nonspecific physical interaction between graphene layer and proteins. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4721453]
Implementation of Monte Carlo Method to an Electromagnetic Launcher Simulator
(IEEE, 2012) Sengil, Nevsan; Turkish Aeronautical Association; Turk Hava Kurumu University
In future, electromagnetic launchers are considered for transporting payloads to the space. Although many developments are achieved, still some technological barriers exist. Further studies are required to overcome these challenges. To develop electromagnetic launchers require experimental and theoretical studies in addition to the simulations. In this study an electromagnetic launcher is simulated. During simulation, magnetic flux density and self-induction are calculated using Monte Carlo methods. Following, these values are used to solve coupled equations of motion and electric circuit. Finally, this study ends with the presentation of the current and velocity profiles in the time domain.
Tuning surface plasmon-exciton coupling via thickness dependent plasmon damping
(AMER PHYSICAL SOC, 2012) Balci, Sinan; Kocabas, Coskun; Ates, Simge; Karademir, Ertugrul; Salihoglu, Omer; Aydinli, Atilla; Turkish Aeronautical Association; Turk Hava Kurumu University; Ihsan Dogramaci Bilkent University
In this paper, we report experimental and theoretical investigations on tuning of the surface plasmon-exciton coupling by controlling the plasmonic mode damping, which is defined by the plasmonic layer thickness. The results reveal the formation of plasmon-exciton hybrid state characterized by a tunable Rabi splitting with energies ranging from 0 to 150 meV. Polarization-dependent spectroscopic reflection measurements were employed to probe the dispersion of the coupled system. The transfer matrix method and analytical calculations were used to model the self-assembled J-aggregate/metal multilayer structures in excellent agreement with experimental observations.
A Sufficient Condition for Checking the Attractiveness of a Sliding Manifold in Fractional Order Sliding Mode Control
(WILEY, 2012) Efe, Mehmet Onder; Turk Hava Kurumu University; Turkish Aeronautical Association
Stability issues of fractional order sliding mode control laws are analyzed in this paper. For differentiation orders less than unity, it is shown that a stable reaching law in the fractional order case corresponds to a stable reaching law in the integer order case. The contribution of the current study is to explain the stability of the closed loop by the use of the Caputo and Riemann-Liouville definitions of fractional order differentiation. Copyright (c) 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Implementation of a Monte Carlo method to a two-dimensional particle-in-cell solver using algebraic meshes
(INST NUCLEAR CHEMISTRY TECHNOLOGY, 2012) Sengil, Nevsan; Tumuklu, Ozgur; Celenligil, Mehmed Cevdet; Turkish Aeronautical Association; Turk Hava Kurumu University; Middle East Technical University
Particle-in-cell (PIC) technique is a widely used computational method in the simulation of low density collisionless plasma flows. In this study, a new two-dimensional (2-D) electrostatic particle-in-cell solver is developed that can be applied to non-rectangular configurations.
Autonomous quadrotor flight with vision-based obstacle avoidance in virtual environment
(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Eresen, Aydin; Imamoglu, Nevrez; Efe, Mehmet Onder; Turk Hava Kurumu University; Turkish Aeronautical Association; Middle East Technical University; Nanyang Technological University
In this paper, vision-based autonomous flight with a quadrotor type unmanned aerial vehicle (UAV) is presented. Automatic detection of obstacles and junctions are achieved by the use of optical flow velocities. Variation in the optical flow is used to determine the reference yaw angle. Path to be followed is generated autonomously and the path following process is achieved via a PID controller operating as the low level control scheme. Proposed method is tested in the Google Earth (R) virtual environment for four different destination points. In each case. autonomous UAV flight is successfully simulated without observing collisions. The results show that the proposed method is a powerful candidate for vision based navigation in an urban environment. Claims are justified with a set of experiments and it is concluded that proper thresholding of the variance of the gradient of optical flow difference have a critical effect on the detectability of roads having different widths. (C) 2011 Elsevier Ltd. All rights reserved.
Performance increase in turbomolecular pumps with curved type blades
(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Sengil, Nevsan; Turkish Aeronautical Association; Turk Hava Kurumu University
Mostly, flat-type blades are used in the turbomolecular pumps in both rotor and stator sections. In this study, performance characteristics of the turbomolecular pumps consist of one rotor or rotor-stator pair with flat-type blades is calculated in different flow regimes. Next, the same calculations are realized for the curved-type blades in dissimilar geometries. Following, these performance characteristics are compared to find out which combination is the most efficient in terms of maximum pumping speed and maximum compression ratio. In case of turbomolecular pump consists of only one rotor, flat blades give the best performance. However in rotor-stator pairs, the performance of the flat-type only blades is surpassed by a combination of rotor with flat-type blades and stator with curved-type blades. Consequently, it is concluded that curved-type blades should also be considered in stator sections in addition to the flat-type blades in order to increase the performance of the multi-stage turbomolecular pumps. (c) 2011 Elsevier Ltd. All rights reserved.
Probing molecular interactions on carbon nanotube surfaces using surface plasmon resonance sensors
(AIP Publishing, 2012-11-26) Nurbek Kakenov; Osman Balci; Sinan Balci; Coskun Kocabas
In this work, we present a method to probe molecular interactions on single-walled carbon nanotube (SWNT) surfaces using a surface plasmon sensor. SWNT networks were synthesized by chemical vapor deposition and transfer-printed on gold surfaces. We studied the excitation of surface plasmon-polaritons on nanotube coated gold surfaces with sub-monolayer, monolayer, and multilayer surface coverage. Integrating the fabricated sensor with a microfluidic device, we were able to obtain binding dynamics of a bovine serum albumin (BSA) protein on SWNT networks with various tube densities. The results reveal the kinetic parameters for nonspecific binding of BSA on SWNT coated surfaces having various tube densities.
Implementation of Monte Carlo Method on Electromagnetic Launcher Simulator
(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2013) Sengil, Nevsan; Turk Hava Kurumu University; Turkish Aeronautical Association
Electromagnetic launcher (EML) is a prominent candidate for transporting payloads to the earth orbits or deep into space. Major space powers have been developing EMLs for a long time either nationally or internationally. Although a lot of progress has been made, some technological barriers still exist. Further studies are required to overcome these challenges. These research and manufacturing activities include, not only experimental and theoretical studies, but also simulations. In this paper, a small-scale EML is simulated. During simulation, magnetic flux density and self-induction are calculated using the Monte Carlo methods. These findings are validated with the analytical solutions taken from the literature and found to be identical. These values are used to solve coupled equations of motion and electric circuits. Finally, this paper ends with the presentation of current and velocity profiles in the time domain.
Numerical flow analysis of coronary arteries through concentric and eccentric stenosed geometries
(ELSEVIER SCI LTD, 2013) Guleren, K. Melih; Turk Hava Kurumu University; Turkish Aeronautical Association
In this study, the flow characteristics through specific concentric and eccentric plaque formations are investigated via Large Eddy Simulation (LES) turbulence technique considering pulsatile flow conditions adjusted for a single frequency-sinusoidal motion (SIN) and for the coronary arteries namely the Left Anterior Descending (LAD) and Right Coronary Artery (RCA). This specific plaque formation is a combination of a highly eccentric shape with triangular-like cross-section for which the flow behaviour has not been studied before. The pulsatile flow behaviour in conjunction with non-Newtonian blood model for SIN, RCA and LAD is found to have considerable effect on formation of separation bubbles and jets, coherent structures associated with vortex rings and horseshoe vortices, wall shear and pressure drop. It should be stated that the quantitative outcome from this study has been the extra pressure load estimated on the heart which was approximately 17% of eccentric model and 9% of concentric model both in RCA or LAD case for a 75% occlusion scenario. (C) 2013 Elsevier Ltd. All rights reserved.
Multi-objective optimization of stochastic disassembly line balancing with station paralleling
(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Aydemir-Karadag, Ayyuce; Turkbey, Orhan; Turk Hava Kurumu University; Turkish Aeronautical Association; Gazi University
One of the major activities performed in product recovery is disassembly. Disassembly line is the most suitable setting to disassemble a product. Therefore, designing and balancing efficient disassembly systems are important to optimize the product recovery process. In this study, we deal with multi-objective optimization of a stochastic disassembly line balancing problem (DLBP) with station paralleling and propose a new genetic algorithm (GA) for solving this multi-objective optimization problem. The line balance and design costs objectives are simultaneously optimized by using an AND/OR Graph (AOG) of the product. The proposed GA is designed to generate Pareto-optimal solutions considering two different fitness evaluation approaches, repair algorithms and a diversification strategy. It is tested on 96 test problems that were generated using the benchmark problem generation scheme for problems defined on AOG as developed in literature. In addition, to validate the performance of the algorithm, a goal programming approach and a heuristic approach are presented and their results are compared with those obtained by using GA. Computational results show that GA can be considered as an effective and efficient solution algorithm for solving stochastic DLBP with station paralleling in terms of the solution quality and CPU time. (C) 2013 Elsevier Ltd. All rights reserved.
Shape memory behavior of high strength NiTiHfPd polycrystalline alloys
(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Karaca, H. E.; Acar, E.; Ded, G. S.; Basaran, B.; Tobe, H.; Noebe, R. D.; Bigelow, G.; Chumlyakov, Y. I.; University of Kentucky; National Aeronautics & Space Administration (NASA); NASA Glenn Research Center; Tomsk State University; Turk Hava Kurumu University; Turkish Aeronautical Association
Systematic characterization of the shape memory properties of a quaternary Ni-45.3-Ti-29.7 Hf-20-Pd-5 (at.%) polycrystalline alloy was performed in compression after selected aging treatments. Precipitation characteristics were revealed by transmission electron microscopy. The effects of aging temperature and time on transformation temperatures, recoverable and residual strains, and temperature and stress hystereses were determined by differential scanning calorimetry, constant-load thermal cycling experiments and isothermal strain cycling (superelasticity) tests. The crystal structure and lattice parameters of the transforming phases were determined from X-ray diffraction analysis. It was revealed that precipitation hardening significantly improved the shape memory properties of the NiTiHfPd alloy. Under optimum aging conditions, shape memory strains of up to 4% under 1 GPa were possible, and superelasticity experiments resulted in full strain recovery without any plastic deformation, even at stress levels as high as 2 GPa. The NiTiHfPd polycrystalline alloy exhibited very high damping capacity/absorbed energy (30-34 J cm(-3)) and work output (30-35 J cm(-3)), which were attributed to the ability to operate at high stress levels without significant plastic deformation and to a high mechanical hysteresis (>900 MPa) at temperatures ranging from 20 degrees C to 80 degrees C. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
EFFECTS OF TiN COATING ON WEAR BEHAVIOUR OF MOLD PUNCHES
(SCIBULCOM LTD, 2013) Aytac, A.; Ozturk, U.; Sert, H.; Milli Savunma University; Gazi University; Turkish Aeronautical Association; Turk Hava Kurumu University
In this study, a research was conducted on the effects of TiN coating using the physical vapour deposition method on wear behaviour of AISI 3343 steel which is extensively used in the molding sector. Wear tests were done with an instrument of pin-on-disk, under the loads of 5 and 10 N, at a sliding speed of 0.4 m/s over sliding distances of 500, 750, and 1000 m. Besides, mechanical characteristics and metallographical analyses were accomplished. Test results revealed that the TiN-coated sample has a smaller coefficient of friction and a smaller rate of wear than that of the uncoated samples.
Ultrastrong plasmon-exciton coupling in metal nanoprisms with J-aggregates
(OPTICAL SOC AMER, 2013) Balci, Sinan; Turkish Aeronautical Association; Turk Hava Kurumu University; Turk Hava Kurumu University; Turkish Aeronautical Association
In this Letter, ultrastrong plasmon-exciton coupling in an Ag nanoprism-J-aggregate hybrid nanostructure is reported. A localized surface plasmon wavelength of Ag nanoprisms is tunable starting from 400 to 1100 nm. Because of the large electric field localization at the corners of the nanoprisms, the observed Rabi splitting energy is higher than the previously reported Rabi splitting energies using metal nanoparticles. A giant Rabi splitting energy of more than 400 meV corresponding to similar to 19% of the j-band energy has been observed, thus indicating the ultrastrong coupling regime. The hybrid nanostructure of nanoprism-J-aggregate is easy to prepare in large quantities and it can be uniformly assembled on solid substrates. (C) 2013 Optical Society of America
Effects of nanoprecipitation on the shape memory and material properties of an Ni-rich NiTiHf high temperature shape memory alloy
(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Karaca, H. E.; Saghaian, S. M.; Ded, G.; Tobe, H.; Basaran, B.; Maier, H. J.; Noebe, R. D.; Chumlyakov, Y. I.; University of Kentucky; Turk Hava Kurumu University; Turkish Aeronautical Association; Leibniz University Hannover; National Aeronautics & Space Administration (NASA); NASA Glenn Research Center; Tomsk State University
Shape memory properties of a Ni50.3Ti29.7Hf20 (at.%) polycrystalline alloy were characterized after selected heat treatments. The effects of heat treatment temperature and time on the transformation temperatures (TTs) and temperature hysteresis were determined by differential scanning calorimetry. Thermal cycling under constant compressive stress was carried out to reveal the changes in transformation strain, temperature hysteresis, and TT as a function of stress. Isothermal stress cycling experiments were conducted to reveal the critical stresses, transformation strain, and stress hysteresis as a function of temperature. The crystal structure and lattice parameters of the transforming phases were determined by X-ray diffraction at selected temperatures. Precipitate characteristics and martensite morphology were revealed by transmission electron microscopy. Precipitation was found to alter the martensite morphology and significantly improve the shape memory properties of the Ni-rich NiTiHf alloy. For the peak aged condition shape memory strains of up to 3.6%, the lowest hysteresis, and a fully reversible superelastic response were observed at temperatures up to 240 C. In general, the nickel-rich NiTiHf polycrystalline alloy exhibited a higher work output (approximate to 16.5 J cm(-3)) than other NiTi-based high temperature alloys. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Forecasting electricity infeed for distribution system networks: An analysis of the Dutch case
(PERGAMON-ELSEVIER SCIENCE LTD, 2013) Tanrisever, Fehmi; Derinkuyu, Kursad; Heeren, Michael; Eindhoven University of Technology; Turkish Aeronautical Association; Turk Hava Kurumu University; Capgemini
Estimating and managing electricity distribution losses are the core business competencies of DSOs (distribution system operators). Since electricity demand is a major driver of network losses, it is essential for DSOs to have an accurate estimate of the electricity infeed in their network. In this paper, motivated by the operations of a Dutch electricity distribution system operator, we examine how to estimate the electricity infeed in distribution networks one year in advance with hourly forecasting intervals, so that the DSOs may effectively hedge for their physical losses in the wholesale markets. We identify the relevant factors for DSOs to forecast the electricity infeed in their networks, and to quantify their effects. We show that most of the calendar variables, such as national holidays, bridge days as well as days near holidays have a significant effect on electricity infeed. Our analysis reveals that the impact of calendar variables significantly depends on the hour of the day. On the other hand, economic and demographic factors do not seem to influence the electricity infeed for the planning horizon of DSOs. We also explore the influence of meteorological factors on the electricity infeed in the Netherlands. Finally, we develop and compare methods for electricity infeed forecasting, based on multiple regression and time series analysis. Our analysis reveals that the regression-based method outperforms the time series-based method on the average measures whereas the time series-based method is better in the worst case analysis. Hence, we point out that the forecasting methods used by DSOs may have significant implications on their financial hedging policies. (C) 2013 Elsevier Ltd. All rights reserved.

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