Teknik Bilimler MYO, Elektrik ve Enerji Bölümü, Makale Koleksiyonu
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Öğe Power generation prediction of a geothermal-thermoelectric hybrid system using intelligent models(Elsevier Ltd., 2024) Çetin, Meriç; Urkan, Osman Doğukan; Hekim, Mahmut; Çetin, EnginThis study focuses on the most effective use of energy resources, which is the main goal of sustainable energy systems. The first contribution of the research is to ensure that the waste and geothermal fluids generated during the geothermal energy production process are evaluated in the most efficient way and reused for energy production. For this purpose, a geothermal-thermoelectric hybrid experimental system has been designed to produce electrical energy through heat exchange and how waste thermal energy could be reused in this process has been examined. Experimental tests have been performed under electrical load and in the presence of real-time uncertainties such as temperature changes, thermal conductivity, electrical noise, heat losses and random variations in thermal interaction. The second main contribution of the study is to predict and evaluate different power generation performances in the Thermoelectric Generator (TEG) system, which is affected by the mentioned experimental limitations based on artificial intelligence models. In addition, the optimal prediction performance of artificial intelligence models using hyper-parameter optimization has also been compared. Experimental results have shown that intelligent models are a successful tool for energy prediction in geothermal power generation. As a result of the hyper-parameter optimization, each model is improved by ?5 % to ?30 % in various error metrics. However, it was observed that the decision tree-based learning techniques resulted in ?46 % to ?96 % less inaccurate predictions on various error metrics compared to other methods. Power production predictions obtained using intelligent models have been obtained with 98.7 % accuracy with LightGBM learning algorithms. Most of the models used to classify different hot and cold water levels exhibit very high classification performance. The results show the successful integration of artificial intelligence models in effectively utilizing waste thermal energy and adopting a sustainable approach to energy production. © 2023 Elsevier LtdÖğe Detector design for surgical guidance(CRC Press-Taylor & Francis Group, 2022) Bedir, Muhammed Emin; Thomadsen, Bruce R.Occult, non-palpable tumor localization has always been a challenge for surgeons due to the difficulty of identifying the margins of the tumor, is indistinguishable from normal tissue, leading to situations requiring a re-excision. The conventional localization techniques rely heavily on preoperative imaging. The large size and long acquisition time associated with preoperative-imaging devices make them infeasible for intraoperative use. Registering preoperative imaging information with the anatomy of the patient real time in the operating room often is difficult and inaccurate. To provide a real-time guidance and let the surgeon track tumor and anatomy of the patient simultaneously requires a radiotracer taken up by the tumor and a hand-held or robotic-arm supported detection device. The radiotracer could be a material such as 123I-labeled CLR1404 that deposits in most tumors but not in normal tissues, and 99mTc-labeled nanoparticles injected to locate Sentinel Lymph Nodes (SLNs). This detector needs characteristics such as: a high energy resolution to distinguish the gamma emissions from the tumor-seeking agent (159 keV) from that from the SLNs (140 keV); a fine spatial resolution to resolve deeply seated nodes from each other and identify the margins of the tumor; a sufficient sensitivity to image the structures live-time in the OR; and a light weight to be handled easily. Hence, the detector selection, in terms of both its components (detector type, collimation type, and front-end electronics) and its characteristics (detector thickness, width, energy resolution, detection efficiency, sensitivity, and decay time), is very important. If the selected crystal is a scintillator, selection of the photon multiplication device is another important component as part of a compact and efficient photomultiplier device. The collimation of the detector affects most aspects of the detector and requires careful optimization. This chapter discusses design characteristics and development of an inorganic scintillator-based lanthanum bromide (LaBr3) detector unit based on the performance characteristics needed to accomplish the goal of radio-guided surgery.Öğe Design of an android wear smartwatch application as a wearable ınterface to the diabetes diary application(2021) Pektaş, Ömer; Köseoğlu, Murat; Muzny, Miroslav; Hartvigsen, Gunnar; Rsand, EirikIn this study, an application was developed for Android-based smartwatches which has the capacity of monitoring the state of diabetes mellitus and indicating the data concerning the physical activities and cardiac rhythm. Android Studio was used to develop and design the application. The application consists of five pages (glucose, insulin, carbohydrate, physical activity, and heart rate) and a watch face. The Dexcom G4 Platinum sensor was used to provide the user’s continuous glucose data. The application not only provides monitoring but also allows the users to enter data entry from the pages. Thus, it is possible to use it as a diary by people with diabetes. The development process of the application was done in collaboration with the Norwegian Centre for e-Health Research in Tromsø, Norway. Also, the application operates simultaneously with an Android phone application called Diabetes Diary, which is developed by this research center.Öğe Energy analysis of a geothermal power plant with thermoelectric energy harvester using waste heat(John Wiley and Sons Ltd., 2021) Hekim, Mahmut; Çetin, EnginThis study investigates the integration of thermoelectric generators (TEGs) into geothermal power plants to harvest energy from the waste heat and possibly, as a result, to increase the electrical energy generation of geothermal power plants. For this purpose, a model of a geothermal power plant-TEG hybrid system has been designed and implemented as an experimental setup. In addition, the optimized layout configuration of TEGs is obtained by using Matlab & Simulink for 48 pieces of the TEGs. A parametric energy analysis is conducted by varying the temperature of the reinjected geothermal brine and the inlet temperature of the cooling water, since TEGs are planned, so they can be employed between the pipelines of the cooling water and the reinjected geothermal brine. The effects that this has on the performance of the organic Rankine cycle (ORC) and the TEGs are then determined. It was found that the power output of the TEGs increases with the rise in temperature of the reinjected geothermal brine, but the net power of the ORC decreases. For the maximum net power output of the ORC, which is 217.6 kW, TEGs are able to produce 43.42 W for the temperature difference of 41.98°C that corresponds to this status. Therefore, TEGs must be used with lower power outputs to achieve more energy production from this hybrid energy system. For the high inlet temperature values of cooling water, the net power of the ORC decreases, and the power output of the TEGs also goes down. TEGs are able to produce 84.29 W for the temperature difference of 60.6°C for the ORC's maximum net power output of 260 kW. Therefore, it is clear that using TEGs in the power plant for low inlet temperature values of cooling water can be considered. In conclusion, this study demonstrates that waste thermal energy in reinjected geothermal brine can be harvested through TEGs, and this energy could be used to feed the electrical equipment of the power plant with low energy consumptions such as lighting, sensors, instrumentation, and control systems. However, TEGs should be used carefully, since they may affect the overall performance of the geothermal power plant.Öğe Development and characterization of a handheld radiation detector for radio-guided surgery(Elsevier, 2020) Bedir, Muhammed Emin; Thomadsen, B. R.; Bednarz, B. P.The current state-of-the-art breast surgery uses radioactive brachytherapy sources to indicate the center of the tumor and possibly a few points on the periphery as seen on mammography. Since such guidance is very coarse, tumor free margins are not achievable in many cases and a re-excision procedure is often required. Better radiation guidance (radio-guidance) could come from labelling cancer cells directly with a radionuclide, such as the agent CLR1404. The agent CLR1404 is taken up by breast cancer cells but not normal cells and, labelled with radioactive I-123, could image the whole tumor, not just points. Tc-99m-labelled nanoparticles are used to locate sentinel lymph nodes. Simultaneous detection and differentiation of the photon energies 159 keV from I-123 and 141 keV from Tc-99m requires a radiation detector with high energy resolution and sufficient efficiency. This report involves the design, development and characterization of such a handheld radiation detector. Following the design and integration of the detector, the main characteristics of the detector, such as energy resolution, photopeak efficiency and response at different source-to-detector distances were investigated experimentally. Energy resolution of the detector was found to be less than 10 keV (FWHM) at energies below 159 keV, which allowed discerning the radiation from the two radionuclides. Energy spectra of the radioactive sources acquired experimentally were compared to those simulated in Monte Carlo N-Particle Transport Code (MCNP6X). The detector developed was found to be promising for radiation-guided surgery applications.Öğe The age-related decrease in material properties of BALB/c mouse long bones involves alterations to the extracellular matrix(Elsevier, 2020) Creecy, Amy; Uppuganti, Sasidhar; Girard, Madeline R.; Amah, Chidi; Ünal, MustafaOne possibility for the disproportionate increase in fracture risk with aging relative to the decrease in bone mass is an accumulation of changes to the bone matrix which deleteriously affect fracture resistance. In order to effectively develop new targets for osteoporosis, a preclinical model of the age-related loss in fracture resistance needs to be established beyond known age-related decreases in bone mineral density and bone volume fraction. To that end, we examined long bones of male and female BALB/c mice at 6-mo. and 20-mo. of age and assessed whether material and matrix properties of cortical bone significantly differed between the age groups. The second moment of area of the diaphysis (minimum and maximum principals for femur and radius, respectively) as measured by ex vivo micro-computed tomography (mu CT) was higher at 20-mo. than at 6-mo. for both males and females, but ultimate moment as measured by three-point bending tests did not decrease with age. Cortical thickness was lower with age for males, but higher for old females. Partially accounting for differences in structure, material estimates of yield, ultimate stress, and toughness (left femur) were 12.6%, 11.1%, and 40.9% lower, respectively, with age for both sexes. The ability of the cortical bone to resist crack growth (right femur) was also 18.1% less for the old than for the young adult mice. These decreases in material properties were not due to changes in intracortical porosity as pore number decreased with age. Rather, age-related alterations in the matrix were observed for both sexes: enzymatic and non-enzymatic crosslinks by high performance liquid chromatography increased (femur), volume fraction of bound water by H-1-nuclear magnetic resonance relaxometry decreased (femur), cortical tissue mineral density by mu CT increased (femur and radius), and an Amide I sub-peak ratio I-1670/I-1640 by Raman spectroscopy increased (tibia). Overall, there are multiple matrix changes to potentially target that could prevent the age-related decrease in fracture resistance observed in BALB/c mouse.
