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Yayın Optimum torque distribution during regenerative braking in a fully electrical vehicle via dynamic programming(IEEE, 2023-10-28) Ergün, Ömer; Çaycı, N. Okan; Dinçmen, Erkin; İstif, İlyasIn electric vehicles, it is important to maximize their regenerative braking performances for obtaining longer driving distances. In this study, for an electric vehicle having motors on the front and rear axles, an optimum torque distribution algorithm based on dynamic programming method is proposed for maximizing the regenerative braking energy. Electric motor limits, efficiency maps, battery model and braking force constraints given in the European regulations are considered in the proposed algorithm. The dynamic programming algorithm code and simulation studies for different braking scenarios are carried out via MATLAB. Simulation studies show that via the proposed torque distribution algorithm, significant improvements in the regenerated braking energy are obtained with respect to the fixed-rate torque distribution algorithm.Yayın Tribo-corrosion behavior of electroplating, nitrocarburizing, and QPQ processes on barrel finishing(Walter de Gruyter GmbH, 2023-11-27) Yücel, Aysu Hande; Yılmaz, Alpay; Bakkal, Mustafa; Kuzu, Ali TanerIn this study, the effects of nitrocarburizing, QPQ, and Cr coating on the surface properties of 32CrMoV12-10 gun barrels are discussed. Hardness measurements, pin-on-disc tests, and anodic polarization tests were performed to examine the hardness values, wear resistance, friction coefficient, and corrosion resistance. The hardness of the specimen treated with QPQ was found to be the highest. Comparing the hardness profiles, it was observed that the casing depth of the nitrocarburized sample was shallower than that of the QPQ-treated sample. The pin-on-disc test revealed that the nitrocarburized sample exhibited a high coefficient of friction, while the Cr-coated sample showed the lowest coefficient of friction. Analyzing the Tafel polarization curve, it was determined that the nitrocarburized and QPQ-treated specimens demonstrated similar levels of corrosion resistance. However, it can be noted that the QPQ-treated specimen had a slightly lower corrosion rate.Yayın Eksenel çıkışlı radyal fan sistemi tasarımı(TMMOB Makina Mühendisleri Odası, 2021-11) Develi, Salih Deniz; Sönmez, Olgun; Ayder, ErkanRadyal fanlar hava veya gaz nakline gerek duyulan klima santralleri, havalandırma tesisatları vb. gibi pek çok yapıda kullanılmaktadır. Son zamanlarda radyal fanların performans artırımlarına yönelik pek çok çalışma yapılmakta ve fan kanatları üzerinde yapılan değişiklikler ile yüksek performanslı fanlar elde edilebileceği vurgulanmaktadır. Bilindiği üzere radyal fanlarda, akış fanın içerisine eksenel olarak girip 90° dönerek ve radyal olarak çıkmaktadır. Klima santrallerinde çoğunlukla çift emişli salyangozlu radyal vantilatörler ve salyangozsuz plug fanlar kullanılmaktadır. Plug fanlar, salyangozlu vantilatörlere göre daha düşük verimli olsa da sağladığı montaj kolaylığı ve yer tasarrufu üstünlüğü nedeniyle daha yaygın olarak kullanılmaktadırlar. Plug fanlarda, rotorda basınçlandırılmış hava, çıkışta enerjisinin önemli bir kısmını yitirmekte ve hava hızındaki büyük değişim sistemin gürültü seviyesinin artması ile sonuçlanmaktadır. Birden fazla fanın dizilmesi ile oluşturulan fan demeti uygulamalarında, fanların birbirleriyle etkileşimini ortadan kaldırma amacıyla fanların aralarına belirli uzaklıklarda ayırıcı duvarlar yerleştirilmekte ve bu nedenle sistem boyutları büyümektedir. Rotor çıkışına bir eksenel yönlendirici yerleştirilmesiyle plug fanların bu dezavantajlarının ortadan kaldırılabileceği öngörülmektedir. Plug fan çıkışındaki akışın eksenel hale getirilmesi, klima santrallerindeki diğer ekipmanların (filtre, eşanjör, nemlendirme ünitesi vb.) performanslarını da arttıracaktır. Bu nedenle bu çalışma kapsamında radyal fanın hemen çıkışına konumlandırılan, akışı 90° döndürerek eksenel hale getiren bir yönlendirici bileşen tasarlanmış ve performansı hesaplamalı akışkanlar dinamiği (HAD) analizleri ile incelenmiştir. Ayrıca tasarlanan bu yönlendiricinin fan performansı üzerindeki etkisi de çalışılmıştır. Varılan sonuç yönlendiricinin sistemin debisini ve verimini arttırdığı yönündedir.Yayın Design of the near infrared camera DIRAC for East Anatolia Observatory(SPIE, 2022) Zhelem, Ross; Content, Robert; Churilov, Vladimir; Kripak, Yevgen; Waller, Lew; Case, Scott; Mali, Slavko; Muller, Rolf; Gonzalez, Mario; Adams, Dave; Binos, Nick; Chin, Timothy; Farrell, Tony; Klauser, Urs; Kondrat, Yuriy; Kunwar, Nirmala; Lawrence, Jon; Lorente, Nuria; Luo, Summer; McDonald, Erica; McGregor, Helen; Nichani, Vijay; Pai, Naveen; Vuong, Minh; Zahoor, Jahanzeb; Zheng, Jessica; Norris, Barnaby; Bryant, Julia; Vaccarella, Annino; Herrald, Nick; Gilbert, James; Yeşilyaprak, Cahit; Güçsav, Bülent; Coker, Deniz; Keskin, Onur; Jolissaint, LaurentThe 4m DAG telescope is under construction at East Anatolia Observatory in Turkey. DIRAC, the " DAG InfraRed Adaptive optics Camera", is one of the facility instruments. This paper describes the design of the camera to meet the performance specifications. Adaptive and auxiliary optics relay the telescope F/14 input 1:1 into DIRAC. The camera has an all refractive design for the wavelength range 0.9 - 2.4 micron. Lenses reimage the telescope focal plane 33 x 33 as (9 x 9 mm) on a 1k x 1k focal plane array. With magnification of 2x, the plate scale on the detector is 33 mas/pixel. There are 4 standard filters (Y, J, H, K) and 4 narrowband continuum filters. A 12 position filter wheel allows installation of 2 extra customer filters for specific needs; the filter wheel also deploys a pupil viewer lens. Optical tolerancing is carried out to deliver the required image quality at polychromatic Strehl ratio of 90% with focus compensator. This reveals some challenges in the precision assembly of optics for cryogenic environments. We require cells capable of maintaining precision alignment and keeping lenses stress free. The goal is achieved by a combination of flexures with special bonding epoxy matching closely the CTE of the lens cells and crystalline materials. The camera design is very compact with object to image distance <220 mm and lens diameters <25 mm. A standalone cryostat is LN2 cooled for vibration free operation with the bench mounted adaptive optics module (TROIA) and coronagraph (PLACID) at the Nasmyth focus of the DAG telescope.Yayın Analysis of mechanical behavior of termoplastic composites(Necip Fazıl YILMAZ, 2022-03-04) Kuzu, Ali Taner; Kosemen, Elifnur; Yücel, Aysu Hande; Bakkal, MustafaThis paper presents the effect of fiber orientation on the tensile, compression, impact, and flexuralproperties of glass fiber reinforced acrylic-based thermoplastic composites. The mechanical behaviorof three different composite plates, produced by the resin transfer molding (RTM) method, with0°/90°/45°, 0°/90° and ±45° glass fiber orientations were investigated by carrying out tensile,compression, three-point bending and Charpy impact tests. A Weibull distribution model wasimplemented to explain the variation in mechanical properties of the acrylic-based composite.According to Weibull analysis results with 63.2% probability, the highest tensile strength (561 MPa),compressive strength (293 MPa) and impact values (19.44 J) were obtained when the plate with0°/90° glass fiber orientation was tested, whereas the highest flexural strength was obtained when theplate with 0°/90°/45° was tested.Yayın Neural network steering control algorithm for autonomous ground vehicles having signal time delay(SAGE Publications Ltd, 2024-03) Dinçmen, ErkinAn adaptive neural network–based steering control algorithm is proposed for yaw rate tracking of autonomous ground vehicles with in-vehicle signal time delay. The control system consists of two neural networks: the observer neural network and the controller neural network. The observer neural network adapts itself to the system dynamics during the training phase. Once trained, the observer neural network cooperates with the controller neural network, which constantly adapts itself during the control task. In this way, an adaptive and intelligent control structure is proposed. Through simulation studies, it has been shown that while a proportional-integral-derivative type steering controller fails to perform its control task in case of steering signal delay, the proposed control algorithm manages to adapt itself according to the control problem and achieves reference yaw rate tracking. The robustness of the control algorithm according to the signal delay magnitude has been demonstrated by simulation studies. A rigorous Lyapunov stability analysis of the control algorithm is also presented.Yayın The development of a hybrid cutting model for workpiece temperature distribution via advection heat partition approach(Springer Science and Business Media Deutschland GmbH, 2023-04-15) Kara, Mehmet Emre; Kuzu, Ali Taner; Bakkal, MustafaThis paper presents a novel hybrid cutting model for the prediction of workpiece temperature distribution during the dry milling process of compacted graphite iron (CGI). The hybrid model consists of an analytical force model based on a mechanistic approach and finite element analysis (FEA) based on the thermal model. The heat generated during the milling process transferred to the workpiece is computed via the advection heat partition model. The workpiece temperature distribution obtained through the heat loads, using as boundary conditions in the FEA, was calculated by means of cutting forces. The developed force and thermal models have been experimentally validated, and good agreement between the measured and calculated results has been observed. The energy and active work calculations show that by doubling the feed during CGI milling, an energy saving of about 10% is achieved despite almost doubling the cutting forces.Yayın Development of acoustic and thermal insulation materials from pantyhose waste(Trans Tech Publications Ltd, 2023-03-31) Küçükali Öztürk, Merve; Sezgin, Hande; Yalçın Enis, İpek; Dolu, CemPopulation growth, urbanization, industrialization, developing technology, increasing welfare level and changing consumption habits cause solid wastes to increase day by day. There are also sub-waste groups that have not yet been fully recognized among the solid waste groups in which textile wastes have a large share. One of them is pantyhose, which has been indispensable for modern life since the day it was presented to the consumer. These socks, which are made of polyamide and elastane fibers that are easily punctured, run and become unusable when worn once or several times, are generally thrown away after use. These pantyhose wastes, which are not biodegradable due to their raw materials, also pose an environmental risk. Within the scope of the study, thermal and sound insulation properties of carded and needle-punched pantyhose wastes are investigated. The results show that the thermal and acoustic properties of the developed material are at a sufficient level, and it has ensured that polyamide wastes, which have superior properties among thermoplastic polymers and have high economic value, are brought back into the economy.Yayın Eastern Anatolia Observatory (DAG): the status in 2022, towards the first light(SPIE, 2022) Yeşilyaprak, Cahit; Keskin, Onur; Jolissaint, LaurentEast Anatolian Observatory's DAG telescope, with its 4m diameter primary mirror and VIS/IR observation capability, Eastern Anatolian Observatory's 4m diameter class DAG telescope, with VIS/IR observation capability, will be located on the Konakll-Karaya summit at an altitude of 3170 m, near the city of Erzurum, Turkey. DAG contains both active optics (aO) and adaptive optics (AO) systems. With the enclosure assembly nearly done, and the dummy mirror integration including the M1 cell integration performed at the end of 2021; DAG telescope's AIV is planned to take place by the end of May/2022 and the Provisional Acceptance by November/2022. DAG is equipped with an in-flange derotator-KORAY (K-mirror Optical RelAY) that will direct the light to the seeing limited Nasmyth platform containing TROIA (TuRkish adaptive Optics system for Infrared Astronomy). The scientific instruments that DAG will receive in 2022, are but not limited to, a stellar coronagraph and a 30"NIR diffraction limited camera. In his paper, a global status update and expected optical performance characteristics will be presented.Yayın Investigation of residual stresses induced by milling of compacted graphite iron by x-ray diffraction technique(Springer, 2024-04) Kara, Mehmet Emre; Kuzu, Ali Taner; Bakkal, MustafaThis study investigates the relationship between residual stresses, cutting parameters, and machining performance in the milling process of compacted graphite iron (CGI). X-ray diffraction (XRD) analysis is employed to measure residual stresses on the cast and milled surfaces, while cutting force modeling is utilized to calculate the tangential force, power, and active work. The results demonstrate that tensile residual stresses are predominant on the milled surfaces, attributed to the both mechanical and thermal loads generated during milling. By analyzing various cutting conditions, it is observed that lower feeds contribute to reduced plastic deformation, resulting in lower residual stress levels. Additionally, higher cutting speeds lead to higher temperatures, but due to the shorter machining time, heat accumulation is limited, resulting in higher residual stresses, especially at low feeds. At high feeds, residual stresses decreased as the cutting speed increased. The interplay between cutting parameters and residual stresses highlights the need for optimizing cutting conditions to enhance fatigue strength in CGI components. These findings provide valuable insights for process optimization and quality control in the milling of CGI materials.
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