Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
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Article Citation - WoS: 2Citation - Scopus: 3Design and Manufacturing of a Hip Joint Motion Simulator With a Novel Modular Design Approach(Springer, 2024) Torabnia, S.; Mihçin, D.Ş.; Lazoglu, I.The study is aimed to develop a hip joint wear simulator using a modular design approach to help experimentally monitor and control critical wear parameters to validate in-silico wear models. The proper control and application of wear parameters such as the range of motion, and the applied force values while estimating the lost material due to wear are essential for thorough analysis of wear phenomena for artificial joints. The simulator's dynamics were first modeled, then dynamic loading data was used to calculate the forces, which were further used for topology optimization to reduce the forces acting on each joint. The reduction of the link weights, connected to the actuators, intends to improve the quality of motion transferred to the femoral head. The modular design approach enables topology-optimized geometry, associated gravitational and dynamic forces, resulting in a cost-effective, energy-efficient product. Moreover, this design allows integration of the subject specific data by allowing different boundary conditions following the requirements of industry 5.0. Overall, the in-vitro motion stimulations of the hip-joint prosthesis and the modular design approach used in the study might help improve the accuracy and the effectiveness of wear simulations, which could lead into the development of better and longer-lasting joint prostheses for all. The subject-specific and society-based daily life data implemented as boundary conditions enable inclusion of the personalized effects. Next, with the results of the simulator, CEN Workshop Agreement (CWA) application is intended to cover the personalized effects for previously excluded populations, providing solution to inclusive design for all. © 2023, The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.Data Paper Database Covering the Previously Excluded Daily Life Activities(2023) Mihçin, Şenay; Şahin, Ahmet Mert; Yılmaz, Mehmet; Alpkaya, Alican Tuncay; Tuna, Merve; Can, Nuray Korkmaz; Şahin, Serap; Akdeniz, Sevinç; Tosun, AliyeIn biomedical engineering, implants are designed according to the boundary conditions of gait data and tested against. However, due to diversity in cultural backgrounds, religious rituals might cause different ranges of motion and different loading patterns. Especially in the Eastern part of the world, diverse Activities of Daily Living (ADL) consist of salat, yoga rituals, and different style sitting postures. Although databases cover ADL for the Western population, a database covering these diverse activities of the Eastern world, specific to these populations is non-existent. To include previously excluded ADL is a key step in understanding the kinematics and kinetics of these activities. By means of developments in motion capture technologies, excluded ADL data are captured to obtain the coordinate values to calculate the range of motion and the joint reaction forces. This study focuses on data collection protocol and the creation of an online database of previously excluded ADL activities, targeting 200 healthy subjects via Qualisys and IMU motion capture systems, and force plates, from West and Middle East Asian populations. Anthropometrics are known to affect kinematics and kinetics which are also included in the collected data. The current version of the database covers 50 volunteers for 12 different activities, the database aims for 100- male and 100- female healthy volunteers as the final target including C3D and BVH file types. The tasks are defined and listed in a table to create a database to make a query based on age, gender, BMI, type of activity and motion capture system. The data is collected only from a healthy population to understand healthy motion patterns during these previously excluded ADLs. The collected data is to be used for designing implants to allow these sorts of activities to be performed without compromising the quality of life of patients performing these activities in the future.Conference Object A Parametric Numerical Analysis of Laminar Hydrogen Diffusion Flames(International Association for Hydrogen Energy, IAHE, 2022) Korucu, Ayşe; Benim, Ali CemalAtmospheric, laminar, diffusion flames of hydrogen and air are numerically investigated. A detailed hydrogen combustion reaction scheme, in combination with the extended Zeldovich mechanism for the thermal nitrogen oxide formation are used. For comparison purposes, a global mechanism is also applied. The numerical procedure is first validated by comparisons with results of other authors. Subsequently, parametric studies are performed to find optimal solutions with respect to the related to the operation parameters of such flames to achieve minimum low nitrogen oxide emission levels. The question that are addressed include the Reynolds number effect on nitrogen emissions, and the interaction of neighbouring flames, when they are applied in an array. For ensuring an adequately fine resolution of the flame fronts, local adaptive grid refinement techniques are applied to track the flame front. For preliminary results the radiative heat loses has assumed to be insignificant however it should be taken into the account for the further analyses. The maximum temperature is predicted to be ~2040 K which is higher than the reported adiabatic stoichiometric flame temperature, 2023K for the exit velocity of 0.5 m/s. The radial mole fractions of N2 and H2 at the centerline are observed to be 0.66 and 0.41 respectively at the axial distance of 10 mm. Furthermore, the width of the high temperature region of the flame is observed to be ~6.5 mm. © 2022 Proceedings of WHEC 2022 - 23rd World Hydrogen Energy Conference: Bridging Continents by H2. All rights reserved.Research Project Otomobil endüstrisi için mukavemeti yüksek seramik katkılı kapalı hücre alüminyum köpük metallerin geliştirilmesi(2009) Güden, Mustafa; Taşdemirci, Alper; Yüksel, Sinan; Toksoy, Ahmet Kaan; Gültürk, Elif; Karsu, Nurettin DenizFarklı seramik ve metal toz katkılarının Al toz tabletlerinde köpükleşme ve mekanik davranışlara etkileri incelenmiştir. Katkı malzemesi olarak sıvı Al ile ıslatılan Ti6Al4V ve diyatomdan elde edilen silika parçacıkları ve Al tarafından yarı ıslatılan SiC parçacıkları, SiC nano toz ve SiC viskır kullanılmıştır. Ti6Al4V parçacıklarının sıvı Al içerisinde küçük boyutlu TiAl3 intermetalik fazı oluşturması ile artan sıvı tablet viskozitesi köpüğün kararlılığını artırmakta; fakat, köpükleşmeyi azalmaktadır. Köpük kararlılığı ve köpükleşme uzaması kullanılan Ti6Al4V toz boyutu ve yüzdesi ile değişmektedir. Sıvı Al tarafında ıslatılan bir diğer toz olan diyatom SiO2 katkısında ise düşük yüzdelerde köpükleşme maksimum uzamaya kadar artmaktadır. Artan katkı yüzdelerinde ise viskozite artışı ile tabletlerin köpükleşmesi azalmaktadır. SiC katkılı tabletlerde köpükleşme, kullanılan tozların toplam yüzey alanı ile değişmektedir. Optimum parçacık toplam yüzey alanında (~100000 mm2), SiC içeren tabletlerin uzamaları katkısız tabletlere göre daha yüksektir. Küçük boyutlu tozlarda artan yüzey alanı düşük parçacık yüzdelerinin, büyük parçacık boyutlarında ise daha yüksek parçacık yüzdelerinin kullanılmasının gerekliliği gösterilmiştir. Mikroskobik çalışmalar SiC parçacıklarının çoğunlukla hücre duvar yüzeylerinde asılı, Ti6Al4V ve SiO2 parçacıklarının ise tamamen hücre duvar içlerinde yer aldığını göstermiştir. Çalışılan parçacık boyu ve yüzdelerinde SiC katkısı plato gerilmesi ve enerji emme miktarlarını sırası ile %35 ve %20 artırmaktadır. Simülasyon sonuçları kritik köpük yoğunluğunun altında ticari olarak kullanılan boş 6063 T6 Al ve çelik tüplerin köpük dolu tüplerden maliyet ve ağırlık açısından daha avantajlı olduğunu göstermiştir.Article Citation - WoS: 2The Effect of the Temperature of Heat Treatment Process and the Concentration and Duration of Acid Leaching on the Size and Crystallinity of Nano-Silica Powders Formed by the Dissociation of Natural Diatom Frustule(American Scientific Publishers, 2022) Ülker, Sevkan; Güden, MustafaThe present study focused on the processing of nano-silica powders in varying sizes and crystallinities through IP: 846247.10 On: Wed, 14 Dec 2022 07:29:25 heat treatment (900-1200 degrees C), hydrofluoric acid leaching (1-7 N), and ball milling (1 h, 500 rpm) of natural Copyright American Scentfic P blishers diatom frustules. The starting natural frustules were determined to be composed of amorphous silica (88%) Delivered by Ingenta and quartz. The partially ordered crystalline low-quartz and or precursor to low-cristobalite started to form at-900 degrees C. As the heat treatment temperature increased, the crystallinity of the frustules increased from 9.3% at 25 degrees C to 46% at 1200 degrees C. Applying a ball milling reduced the mean particle sizes of the as-received and heat-treated frustules from 15.6-13.7 mu m to 7.2-6.7 mu m, respectively. Acid leaching of the as-received and heat-treated frustules resulted in a further increase in the crystallinity. Furthermore, a ball milling applied after an acid leaching was very effective in reducing the particle size of the as-received and heat-treated frustules. The mean particle size of the acid-leached frustules decreased to 774-547 nm with a crystallinity varying between 12 and 48% after ball milling. A partially dissolved amorphous phase was observed in between crystalline silica grains after acid leaching, which resulted in a rapid fracture/separation of the frustules in ball milling.Conference Object Mechanisms, Transmissions and Applications(Springer, 2018) Dede, Mehmet İsmet Can; İtik, Mehmet; Lovasz, Erwin-Christian; Kiper, GökhanThis volume contains the proceedings of MeTrApp 2017, the 4th Conference on Mechanisms, Transmissions and Applications, that was held in Trabzon, Turkey, July 3-5, 2017. The topics treated in this volume are Mechanism Design, Parallel Manipulators, Control Applications, Mechanical Transmissions, Cam Mechanisms, and Dynamics of Machinery. The conference was organised by the IFToMM Technical Committees for “Linkages and Mechanical Controls” and “Gearing and Transmissions” under the patronage of the IFToMM and sponsorship of Karadeniz Technical University, Izmir Institute of Technology and IFToMM Turkey (MAKTED). The aim of the conference was to bring together researchers, scientists, industry experts and students to provide, in a friendly and stimulating environment, the opportunity to exchange know-how and promote collaboration in the field of Mechanism and Machine Science.Conference Object Cash Flow Forecasting by Using Time Series Methods in Geothermal District Heating Systems: Balcova - Narlidere Case(National Technical University of Athens, 2006) Erdoğmuş, Abdullah Berkan; Özerdem, BarışCash flow forecasting is one of the difficult and important tasks in an economic evaluation of a geothermal investment. Geothermal district heating systems are characterized by a high capital cost. In addition, relatively low operation and maintenance costs occur throughout their life. The aim of this research is to estimate the potential cash flows for Balcova - Narlidere Geothermal District Heating System by using historical data accumulated over a period of time and several forecasting methods: moving average, exponential smoothing, adjusted exponential smoothing and curve fitting functions. Mean absolute percentage deviation (MAPD) which is the most common approach to select the appropriate method to a particular time series is used in the selection of the most suitable model. Alternative methods are compared with each other regarding to their MAPD values. It is found that the models represented by exponential curve fitting functions have smaller MAPD values and give better results in cash flow forecasting of investment investigated.Conference Object Underground Gasification in Western Black Sea Area and Thermodynamic Analysis(2006) Atagündüz, GürbüzAs known, western Black Sea carboniferous coal fields consist of two main fields: Zonguldak and Amasra. Previous research works have shown that Zonguldak area is not suitable for underground coal gasification. The joint studies done since 1994 by the Department of Geology and the Solar Energy Institute of Aegean University and, the Mineral Research and Exploration Institute of Ministry of Energy and Natural Sources have shown that the Amasra coal field is suitable with certain restrictions for the underground coal gasification. In the present work, the suitability of the Amasra - coal field for underground coal gasification will be discussed and the "Controlled Retraction of the Injection Point; CRIP"- Method which was successfully used and tested in the American field experiments will be described briefly. A brief thermodynamic analysis of the gasification process will be given which should help, as a tool, to the theoretical prediction of the underground coal gasification.Conference Object Circular and Semi-Circular Constructal Vascular Channels for Cooling and Reduced Stresses(Publishing Romanian Academy-Editura Academiei Romane, 2017) Çetkin, ErdalIn this paper, we show how the vascular channel configuration and its shape affect the mechanical strength which is simultaneously subjected to heating and mechanical load. The effect of channel cross-section on the coolant mass flow rate, peak temperature and peak stresses are documented. The material properties were defined as functions of temperature in simulations. The results show that the flow of stresses and fluid is minimum with the circular channels and the resistance to the heat flow is the smallest with semi-circular channels. In addition, morphing the vascular design provides almost the smallest resistance to the heat flow with circular channels (0.3% difference in the peak temperature). This shows that even the convective resistances are the smallest with circular-cross section, overall thermal resistance is smaller in semi-circular design for the fixed fluid volume. The peak stress is smaller with semi-circular channels than the circular ones if the pressure drop is less than 500 Pa for the radial design. However, the peak stress is smaller with hybrid design than the semi-circular radial designs for the entire pressure drop range. In addition, the effects of mechanical load, heating rate and reference temperature on the stress distribution are also documented. Furthermore, the thermal and mechanical stresses are also documented separately, and then compared with the coupled solution cases. The chief result of this paper is that for a coupled system minimizing only one of the resistance terms is not sufficient, all the resistances considered simultaneously in order to uncover the best performing design. In addition, the results show that the designs should be free to vary, the unexpected designs can be the best performing designs for the given parameters and constraints. Therefore, the design parameters based on the experience does not always yield the best performing designs as the objectives and constraints vary. This result is in accord with the constructal law.Conference Object Molecular Modeling of Force Driven Gas Flows in Nano-Channels(International Conference on Computational Fluid Dynamics (ICCFD), 2016) Barışık, MuratNano-scale gas transport plays an important role in many micro/nanotechnology applications where the rarefied gas dynamics based solutions are frequently used by maintaining a “dynamic similarity” between low pressure (rarefied) and nano gas flows. However, such a consideration is incomplete since the surface force field effects dominant in nano-levels induce significant variations. In order to specify the surface force effects on gas transport, we define a new parameter (B) as the ratio of force penetration length to the channel height, and studied the length scales and conditions for applicability of current rarefied gas dynamics on nano-scale gas flows. Using Molecular Dynamics, force driven gas flows were characterized as a function of B parameter and Knudsen number. Results showed that for a negligible value of B parameter (B?0) transport can be described by rarefied gas dynamics in the whole Knudsen range while the velocity profiles are parabolic and the variation of mass flow rate shows the well-known Knudsen minimum around Kn=1. As the flow dimension decreases, B becomes a finite value indicating the dominancy of surface force effects over rarefaction, and gas velocities and mass transport significantly deviates from the kinetic theory predictions. © 2016 9th International Conference on Computational Fluid Dynamics, ICCFD 2016 - Proceedings. All rights reserved.