7 results
Search Results
Now showing 1 - 7 of 7
Article Citation - WoS: 1Citation - Scopus: 2A Miniaturized Multi-Layer Microstrip Antenna for Linear Wireless Sensor Network Monitoring Systems(Gazi Univ, 2022) Kara, Ali; Aydın, Elif; Benzaghta, Mohamed; Er, Burak; Bilgin, GulsimaThis article presents a sub-GHz ISM band microstrip patch antenna based on the use of multi-layer compact structure, which overcomes the shortcomings of typical microstrip antennas such as low gain and high resonant frequency. The antenna was simulated using an electromagnetic simulator, ANSYS HFSS, and fabricated on two different substrates: RT Duroid 5880 and FR4 epoxy with a compact size of 100 x 100 x 8 mm3 (0.29λ × 0.29λ × 0.02λ). The simulated results of the antenna were then compared with the measured ones, and the two were observed to have a reasonable agreement. The proposed antenna operates in the sub-GHz license-free ISM band (862-875 MHz), with a gain value of 2.92 dB. Two prototypes of the proposed antenna were fabricated and used in a Linear Wireless Sensor Networks (LWSNs) monitoring system. Results show that the proposed antenna is a good candidate for those types of LWSNs systems.Article Citation - WoS: 1Deposition and Characterization of ZnSnSe2 Thin-Films Deposited by Using Sintered Stoichiometric Powder(Gazi Univ, 2019) Bayrakli Surucu, Ozge; Gullu, Hasan HuseyinIn this work, ZnSnSe2 (ZTSe) thin films were deposited using crystalline powder grown by vertical Bridgman-Stockbarger technique. The deposition process was carried out by means of e-beam evaporation on the well-cleaned soda lime glass substrates and keeping them at the substrate temperature of 200 degrees C. The structural, optical and electrical properties of ternary ZTSe thin films were investigated depending on the annealing temperature at 250 and 300 degrees C. X-ray diffraction analysis showed that as-grown films were in amorphous structure, however annealing at 250 degrees C triggered the crystallization on the preferred ternary structure and annealing at 300 degrees C resulted in the changes from amorphous to the polycrystalline structure. Using the compositional analysis, the detail information about the stoichiometry and the segregation mechanisms of the constituent elements in the structure were determined for both as-grown and annealed samples. In addition, they were morphologically characterized using scanning electron microscopy technique. The electrical properties were analyzed using temperature dependent dark- and photo-conductivity measurements. From the variation of electrical conductivity as a function of the ambient temperature, the current transport mechanisms and corresponding activation energies at specific temperature intervals for each sample were determined. The optical properties for the ZTSe thin films were studied depending on the structural changes with annealing.Article Citation - WoS: 7Citation - Scopus: 10Comparison of Three Different Learning Methods of Multilayer Perceptron Neural Network for Wind Speed Forecasting(Gazi Univ, 2021) Bulut, Mehmet; Tora, Hakan; Buaisha, Dr.magdiIn the world, electric power is the highest need for high prosperity and comfortable living standards. The security of energy supply is an essential concept in national energy management. Therefore, ensuring the security of electricity supply requires accurate estimates of electricity demand. The share of electricity generation from renewables is significantly growing in the world. This kind of energy types are dependent on weather conditions as the wind and solar energies. There are two vital requirements to locate and measure specific systems to utilize wind power: modelling and forecasting of the wind velocity. To this end, using only 4 years of measured meteorological data, the present research attempts to estimate the related speed of wind within the Libyan Mediterranean coast with the help of ANN (artificial neural networking) with three different learning algorithms, which are Levenberg-Marquardt, Bayesian Regularization and Scaled Conjugate Gradient. Conclusions reached in this study show that wind speed can be estimated within acceptable limits using a limited set of meteorological data. In the results obtained, it was seen that the SCG algorithm gave better results in tests in this study with less data.Article A Modeling Approach for Designing New Acoustic Materials(Gazi Univ, 2024) Koçyiğit, Filiz Bal; Köse, Ercan; Buluklu, Hatice MehtapIn this study, mathematical modeling design based on Sound Transmission Loss measurement results of new acoustic material samples with natural content was carried out. Using the test samples in question, transfer function of acoustic materials based on electronic filter circuit design and a transition design method for the production of new acoustic materials by utilizing the transfer function is presented. Based on the experimental results of the test samples, it is the most suitable low-pass filter structure for the proposed design. In this study, active Sallen-Key low-pass filter structure is preferred and used. Sound Transmission Losses in dB (decibels) of acoustic samples were obtained experimentally for 500, 1000, 2000 and 4000 Hz. fundamental frequencies in the literature. Based on these data, transfer function simulation suppression gain results were obtained in TINA-TI program, active filter circuit designed, and MATLAB program. When the other results were compared in the experimental results, it was seen that very close values were obtained. It has been demonstrated that the proposed method can be used effectively in the design and examination of new acoustic materials.Article Citation - WoS: 1Citation - Scopus: 1A New Multi-Target Compiler Architecture for Edge-Devices and Cloud Management(Gazi Univ, 2022) Gokcay, ErhanEdge computing is the concept where the computation is handled at edge-devices. The transfer of the computation from servers to edge-devices will decrease the massive amount of data transfer generated by edge-devices. There are several efficient management tools for setup and connection purposes, but these management tools cannot provide a unified programming system from a single source code/project. Even though it is possible to control each device efficiently, a global view of the computation is missing in a programming project that includes several edge-devices for computation and data analysis purposes, and the devices need to be programmed individually. A generic workflow engine might automate part of the problem using standard interfaces and predefined objects miming on edge-devices. Nevertheless, the approach fails in fine-tuning each edge-device since the computation cannot be moved easily among devices. This paper introduces a new compiler architecture to control and program edge-devices from a single source code. The source code can be distributed to multiple edge-devices using simple compiler directives, and the transfer and communication of the source code with multiple devices are handled transparently. Fine-tuning the source code and code movement between devices becomes very efficient in editing and time. The proposed architecture is a lightweight system with fine-tuned computation and distribution among devices.Article Citation - WoS: 2Citation - Scopus: 3Low-Cost Alpha Cabin Like Test Box Proposal for the Development of New Acoustic Sound Insulation Materials(Gazi Univ, 2023) Koçyiğit, Filiz Bal; Köse, Ercan; Buluklu, Hatice MehtapExperimental criteria for sound insulation material recommendation and design have an important share in indoor acoustic control. Among these criteria, laboratories with devices such as impedance tubes, alpha cabins and reverberation rooms used to measure and analyze parameters such as sound transmission loss and sound absorption coefficient have been investigated. In literature, it has been observed that there are studies on acoustic materials and the tests applied to these materials, but the application is more limited. According to research data, an Alpha Cabin model system design that can be used to develop new types of acoustic sound materials has been proposed. In addition to the fact that a large number of experimental measurements can be performed at lower costs using the designed Alpha Cabin model system, many tests can be performed easily for different material designs in a very short time. To perform these tests, the Alpha Cabin system has been designed based on noise and sound insulation. For example, floating flooring, ribbed connection, and so on. Afterward, different insulation materials were used for insulation purposes and standards were achieved. The Alpha Cabin test system, which was designed and developed, overlaps the experimental and theoretical data for 500, 2000, and 4000 Hz when compared with the values of 29.1 dB for 500 Hz, 38.6 dB for 2000 Hz, and 49 dB for 4000 Hz measured in the Acoustic Facade Panel Test Room, and it has been observed that it can be used in the development of new sound insulation materials.Article Citation - WoS: 4Betonarme Binaların Yapım Maliyeti ve Deprem Davranışında Döşeme Tipinin Etkisi(Gazi Univ, 2023) Tunç, Gökhan; Azizi, Abdul Basir; Tanfener, TuğrulTürkiye’de betonarme çerçeveli binalar diğer tür yapı taşıyıcı sistemlerine göre en çok tercih edilmektedir. Bu tür binalarda kullanılan yaygın döşeme türleri ise kirişli, kirişsiz, kaset ve nervürlü olanlarıdır. Bir bina tasarımında, yatay ve düşey yükler altında en iyi performansı gösteren ve aynı zamanda en az maliyet gerektiren döşeme türünün belirlenmesi istenir. Ancak, kirişler, kolonlar ve perde duvarlar gibi diğer yapı elemanlarına analitik çalışmalarda öncelik verildiğinden, döşeme türünün uygun seçimi genellikle tasarımcı tarafından göz ardı edilir. Bu nedenle, döşemelerin bina tasarımına ve yapısal davranışına sağlayacakları katkılar yeterince irdelenmemiş olur. Ortaya çıkan bu eksikliğin ise binanın tasarım aşamasından itibaren detaylı olarak irdelenmesi gerekmektedir. Bu çalışmada çok katlı betonarme binalar üzerinde farklı döşeme türlerinin etkileri incelenirken aynı zamanda toplam maliyetin de optimumda kılınması hedeflenmiştir. Bu amaç doğrultusunda toplamda 36 bina modeli hazırlanarak, analiz ve tasarımları mevcut Türkiye bina yönetmelik ve standartlarına uygun olarak yapılmıştır. Bu kapsamda yapılan analitik çalışmalarda incelenen parametreler şu şekildedir: döşeme türleri (kirişli, kirişsiz, kaset ve nervürlü), toplam kat sayıları (10, 20 ve 30) ve tip döşeme açıklıkları (6, 7.5 ve 9 metre). Binaların tümünün iş yeri kullanımına uygun olarak İstanbul’un deprem tehlikesi içeren bir bölgesinde yer aldığı kabul edilmiştir. Yapılan analitik çalışmalara göre 6 metre açıklığa sahip binalarda en ekonomik sonucun kirişli, 7.5 metre açıklığa sahip olanlarda ise kaset döşemelerde olduğu görülmüştür. Ele alınan tüm modeller içerisinde en maliyetli çözümü üreten döşeme türü kirişsiz döşeme olarak belirlenmiştir. İncelenen tüm döşeme türleri arasında, kirişli döşemeye sahip binaların en iyi deprem performansına, kaset ve kirişsiz döşeme türlerine sahip binaların ise en olumsuz deprem performansına sahip oldukları görülmüştür.
