Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Turk, Kadir(7)
- Akinoglu, Bulent G.(6)
- Bingol, Ozkan(5)
- Ozden, Talat(5)
- Simsek, Cemaleddin(5)
- Albayrak, Cenk(4)
- Basoglu, Mustafa Engin(4)
- Dogan, Ramazan Ozgur(4)
- Ekinci, Murat(4)
- Herencsar, N.(4)
- Kayikcioglu, Temel(4)
- Dogan, Hulya(3)
- Gedikli, Eyup(3)
- Yanarates, Cagfer(3)
- Özden, Talat(3)
- Altan, Aytac(2)
- Altas, Ismail H.(2)
- Benli, Emrah(2)
- Cakmak, Recep(2)
- Demirbag, Kubra Simsek(2)
- Essaaidi, M.(2)
- Genemo, Musa Dima(2)
- Gul, Fatih(2)
- Kucuk, Mehmet Ali(2)
- Maleki, Masoud(2)
- Manshouri, Negin(2)
- Motai, Yuichi(2)
- Sreeram, G.(2)
- Tonyali, Samet(2)
- Tugcu, Emin(2)
- Turan, Raşit(2)
- Ture, Hayati(2)
- Yazgan, Ayhan(2)
- Yildirim, Nihan(2)
- Zaz, Y.(2)
- Aiordachioaie, D.(1)
- Akkaya, Kemal(1)
- Aklnoǧlu, Bülent Gültekin(1)
- Akmoǧlu, Bülent Gültekin(1)
- Akyurek, Feyzullah(1)
Yayınlar
- MakaleYalnız künye2018The Fabrication and MOSFET-Only Circuit Implementation of Semiconductor Memristor
Babacan, Yunus; Yesil, Abdullah; Gul, Fatih
In this paper, a ZnO-based semiconductor thin film memristor (300 nm in thickness) device is fabricated using metallic top and bottom electrodes by direct-current reactive magnetron sputter. The memristive characteristics of the device were completed by time-dependent current-voltage (I-V-t) measurements, and the typical pinched hysteresis I-V loops of the memristor were observed. This paper is continued with the designing memristor emulator circuit, which has only four MOS transistors. The proposed circuit is suitable both for emulating the fabricated memristor and for using general memristor-based applications. Any circuit blocks such as a multiplier or active element are not used in the circuit to obtain memristive characteristics. All results of the proposed memristor emulator circuit are compatible with general characteristics of the fabricated semiconductor device. The MOSFET-based proposed memristor emulator circuit is laid out in the Analog Design Environment of Cadence Software using 180-nm TSMC CMOS process parameters and its layout area is 366 μm2. So as to show its performance, the dependences of the operating frequency and process corner as well as effects of radical temperature changes have been investigated in the simulation results section.
- BildiriAçık Erişim2018Performance and degradation analyses of two different pv modules in central anatolia
Ozden, Talat; Akinoglu, Bulent G.; Kurtz, Sarah
Ankara (latitude: around 40°N) is in Central Anatolia and the climate is dry continental. Due to the rapid transition to renewable energy policies of Turkey it is now a must to complete truthful feasibility analyses for solar power systems countrywide. Long term performance and degradation analyses have been carried out by the authors for three different arrays and many research results appearing in the literature are summarized. Present research analyzes the outdoor testing results of two PV modules monthly data. One of the modules has multi crystalline silicon (Poly-Si) cells and the other is thin film silicon (amorphous Si / microcrystalline Si tandem structure - a-Si/μc-Si) cells. The results showed that in five years the average yearly efficiency decreases from 14% to 11% for Poly-Si (14.72% is the nameplate Standard Test Condition (STC) efficiency) and from 8% to 6% for thin film modules (9.15% is STC efficiency). Our calculations are based on measured solar global-horizontal irradiance from which we calculated plane-of-array irradiation using an anisotropic sky model. We present the details of these analyses and degradation rates for the two types of modules to be used in long term feasibility analyses.
- BildiriYalnız künye2018Power spectrum analysis of EEG for watching 2D & 3D videos and resting state
Manshouri, Negin; Maleki, Masoud; Kayikcioglu, Temel
Analysis of the brain waves has become useful over than 80 years. Along with the medical application, the brain signal is also used for other research works in the last fifteen years. In this study, by considering the depth factor in the image of a video, the effects of it are checked on EEG. A video is displayed in two-dimensional (2D) and three-dimensional (3D) format to the subjects. After recording the EEG signals in video watching, the resting state was recorded. Three states are considered for a better understanding of these effects on EEG. These states involve 2D&3D, 2D&resting and 3D&resting. Frequency analysis of the signals is evaluated by two methods. These methods are Fast Fourier Transform (FFT) and Welch method.
- BildiriAçık Erişim2018Daily and monthly module temperature variation for 9 different modules
Özden, Talat; Tolgay, Doga; Akinoglu, Bulent G.
One of the main parameter affecting the efficiency of PV modules is the module temperature. In this respect, outdoor testing of modules is very important to determine the temperature dependent performances and degradation rates. In this work, we analyzed the module temperatures of 9 different modules tested in the outdoor testing facility of METU-GUNAM, Ankara (latitude ∼40°N, in Central Anatolia and the climate is dry continental). The tested module types are two CIS (identical), one μc-Si/a-Si, one Poly-Si, three Mono-Si (two identical), one HIT and one bifacial. The module temperatures can reach up to 76°C while the ambient is around 39 °C during summer days. Monthly average module temperatures can reach up to 33.7°C (CIS) while the monthly average ambient is at 26.0°C and drops down to 1 °C while average ambient temperature is about the same as average module temperature. The results showed that the monthly averages of module temperatures differences are maximum during summer (∼3.5°C) and minimum during winter (1.1°C). It is interesting that the two CIS modules have the highest monthly average module temperature and although they are supposed to be identical their temperatures differ significantly. Bifacial and HIT module temperatures are lower than the Mono-Si modules. One of the two identical Mono-Si modules was not cleaned and its module temperature is always lower than the one that was cleaned periodically, as expected. In this work, we also present the results and discussions on the spatial variations of measured module temperatures of PV panels.
- BildiriYalnız künye2018Optimal scheduling of time shiftable loads in a task scheduling based demand response program by symbiotic organisms search algorithm
Cakmak, R.; Altas, I.H.
Demand side management is one of the key issues in smart electrical grid studies. Power demand of consumers can be managed via demand response(DR) programs. Task scheduling (TS) based demand response is one of the DR schemes. Objective of the TS approach is to schedule activation time of the appropriate time-shiftable loads to reduce power consumption in peak-demand hours. Heuristic optimization methods can be used to provide this objective. Symbiotic Organisms Search (SOS) and Cuckoo Search (CS) algorithms are two of the most recent heuristic methods. In this paper, scheduling of the time-shiftable home appliances executed by SOS and CS algorithms. Time-shiftable home appliances of the consumers and run time tolerances of them aggregated by mini public survey to achieve results which close to reality. Obtained results are indicated the superiority of the SOS algorithm and demonstrated the positive effects of the demand side management on the electrical grid.
- BildiriYalnız künye2018On the Yearly Performance of a Bifacial PV Module in Central Anatolia - Turkey
Özden, Talat; Turan, Raşit; Aklnoǧlu, Bülent Gültekin; Zaz, Y.; Essaaidi, M.
With the tremendous increase in the photovoltaic (PV) power plants world-wide remarkable decreases in their installation prices per watt are attained mainly due to economic scale effect. This brings questioning to increase their energy yields by considering any possible way like fabricating bifacial solar modules. Present study is on the performance analysis of a bifacial PV module using one-year outdoor testing results in Ankara-Turkey. The module performed very well and reached a specific yield value of 1750 kWh/kWp. This value for Central Anatolia region is well above the values predicted (and suggested) by the local authorities. The efficiency and performance ratio variation with respect to ambient and module temperature are obtained. The calculated dependence of efficiency on the module temperature is found to be η=-0.073Tmod+18.05, and the maximum measured module temperature is about 70 °C. The results show that the bifacial modules have the potential to replace the mono facial modules that are now dominating the PV market.
- BildiriYalnız künye2018Experimental Channel Measurement for Indoor Office Visible Light Communication
Yazgan, Ayhan; Simsek, Cemaleddin; Albayrak, Cenk; Tugcu, Emin; Turk, Kadir; Herencsar, N.
Channel measurement for visible light communication (VLC) is theoretically and experimentally performed in a real office platform. Six armatures composed of phosphor based white LED arrays are fed by designed analog LED drivers. Measurements are taken in a 6m x 7.8m office room which is formed as 10×13 matrix with 60 cm grid distance for both simulation and experiment studies. The link distance between LED arrays and optical receiver is kept minimum 2.5 meters for each measurement. Experimental results are generally in good agreement with simulation results, which are obtained using Barry's theoretical channel model.
- BildiriYalnız künye2018Performance of Visible Light Communication with Colour Shift Keying Modulation and Polar Code
Simsek, Cemaleddin; Tugcu, Emin; Albayrak, Cenk; Yazgan, Ayhan; Turk, Kadir; Herencsar, N.
Visible light communication (VLC) is an emerging technology to fulfill both illumination and communication purposes considered as either an alternative or a support system for some of scenarios carried by RF communication systems. Colour shift keying (CSK) is the modulation given in IEEE 802.15.7 VLC standard which proposes Reed-Solomon as error correction code. Polar code is the first theoretically proven capacity achieving error correction code with low encoding and decoding complexities. Performance of Polar code with belief propagation decoder has not been studied under VLC CSK scheme. In this study we investigate performance of Polar code with belief propagation decoder under VLC CSK scheme and compare it with performance of Reed-Solomon code. Result show that Polar code with belief propagation decoder outperforms Reed-Solomon code by at least 1.5dB.
- BildiriYalnız künye2018Fast and accurate classifier-based brain-computer interface system using single channel EEG data
Maleki, Masoud; Manshouri, Negin; Kayikcioglu, Temel
In brain-computer interface system (BCIs), direct communication between humans and computers is performed by analyzing neural signals and transforming them into digital signals. In the continuation of our previous works, in this paper, we advanced the proposed BCI system that was based on the gaze on rotating vanes. The speed of communication and convenience of the user are very important factors in BCI systems. Therefore, in this paper, for the convenience of the user, a single EEG channel was used. Also, for to increase the speed of the system, we tried to the classification of 0.5 sec epochs with a partial least squares regression (PLSR) as a fast classifier. In addition, we computed the information transfer rate (ITR) that has proved our proposed BCI system is fast and accurate. This system could be used in real-time implementations due to having high classification rate, speed and convenience of the user.
- BildiriYalnız künye2018Seasonal Variation of the Monthly Efficiencies of Thin Film PV Modules
Özden, Talat; Turan, Raşit; Akmoǧlu, Bülent Gültekin; Zaz, Y.; Essaaidi, M.
Outdoor testing of solar photovoltaic (PV) modules must be carried out at different climates as PV power plants nowadays are installed and continues to be installed in many countries. Present study is outdoor testing results and analyses of 5 thin film modules in Ankara, Turkey. The analyses are carried out using monthly efficiencies of the modules that are derived using the energy yield and input. The average efficiencies of the CIS, CIGS and μc-Si/a-Si thin film modules are. We present the monthly and average efficiencies and discuss their variations with the parameter: input, ambient temperature and relative humidity. We also carried out seasonal analyses using Pearson's correlation coefficient and find out that the efficiencies are differently dependent on the above mentioned parameters. This arose a new open question on differentiation of the strength of the effect of each parameter on the monthly efficiencies.
- BildiriAçık Erişim2018Determining photovoltaic module performance and comparisons
Karaveli, Abdullah Bugrahan; Ozden, Talat; Akinoglu, Bulent G.
Knowing electricity production potential of a photovoltaic (PV) system prior to installation is very beneficial for the investor to see the feasibility of the investment. There are three procedures that can be followed to calculate the potential electricity production of any system under different conditions. These are installation of sample systems and gathering data over time, the use of some databases/software programs to reach the performances and developing new model/methodology to make these estimations. It is obvious that installation of PV systems everywhere is neither technically nor economically conceivable. On the other hand, global software programs may not reflect local conditions to calculations. Consequently, there is a need to develop methodology that is able to derive location specific equations and coefficients and make accurate estimations. Its accuracy can be controlled by validating the results for some locations with the measured values from already installed PV power plants (PV PP). So, in this study we initially develop a methodology to calculate efficiency and electricity production performance of some modules for Ankara and compare the results with the measured values owing to the system installed on the roof of the Middle East Technical University Solar Energy Research Center (METU GUNAM) in Ankara/Turkey. The methodology initially calculates solar irradiation falling on the modules that is the input. Then the performance of the module is calculated by using developed methodology. There are also some online software programs to calculate the performances, such as EU PVGIS and PV WATTS. We analyzed and used these software programs and compare their results with the results of newly developed methodology. As proven through mean-bias error (MBE), root-mean-square error (RMSE) and mean absolute error (MAE) statistical comparison methods, the methodology of this study has given the most accurate results.
- BildiriAçık Erişim2018Impacts of a photovoltaic power plant for possible heat island effect
Demirezen, Emre; Ozden, Talat; Akinoglu, Bulent G.
Today, solar energy conversion technologies take a significant place within the efforts of obtaining renewable and sustainable energy around the world, and show a rapid progress. One of the most common technologies is photovoltaic power plants (PVPP) which are built using PV modules that provide electricity directly from sunlight. These plants are qualified as one of the pioneering applications among clean energy production methods. However, as the modules cover large areas and as they are produced by mostly dark-colored solar cells, an environmental debate has already been opened via some recent studies in the literature: Do they alter the solar reflectivity (albedo) of the region's surface where they are installed, and in turn affect the typical microclimate characteristics of that region such as the local air temperatures, humidity, pressure and wind speed? Considering also the additional heat that the modules radiate while producing electricity, the main probable result should be expected as Heat Island Effect (HIE). HIE has been particularly discussed for about last 10 years. Basically, this effect defines the day-night and inter-seasonal variations of local temperatures due to artificial changes on the natural land surface. Accordingly, when an urbanized area is compared with the neighboring rural areas, the difference is specifically named as Urban Heat Island (UHI) effect. In the present work, we are conducting a field research with in-situ measurements taken by the two weather monitoring stations inside and outside a PVPP in the district Tavsanli (Kutahya, Turkey). We also provide the meteorological data of Tavsanli station from Turkish State Meteorological Service (TSMS), which is the nearest weather monitoring station to the PVPP under inspection. These stations have been collecting the data of air temperature, relative humidity, average wind speed and atmospheric pressure every 10 minutes since October 2017. We used two statistical methods to compare and interpret the first 8-month data of all the three stations. We considered the statistical significance tests for both the first 8 months as a whole and dividing it into two 4 months before and after the PVPP becomes operational. We found that the measurements of the three stations differ significantly for most of the weather parameters. We also carried out pairwise tests and showed that each pair has significant differences for most parameters.
- BildiriYalnız künye2017Artificial intelligent models for thermodynamic properties of R152a and R134a refrigerants in automobile air conditioning systems
Kalkisim, Ahmet Tahir; Bilen, Kadir; Hasiloglu, Abdussamet; Sobh, T.; Elleithy, K.
With the increase in environmental awareness, the quest for alternative refrigerants for automobile air conditioning systemsis a necessity for the protection of the ozone layer and the prevention of global warming. Therefore, it is important that the refrigerant to be used as an alternative must be at least thermodynamically sufficient and within specified environmental limits. In this study, R152a refrigerant which is an alternative gas for R134a that's use in automobile air conditioning systems will be removed within a certain schedule has been examined thermodynamically. Artificial intelligent model was generated and compared by using data obtained from the examination. Through this model, system was tested with untrained data. The generated model has been very close to test data and successful in high precision.
- BildiriYalnız künye2017Detecting and removing repetitive errors from PPP time series by means of adaptive filter
Yalvaci, Sefa; Ustun, Aydin; Berber, Mike Mustafa
PPP (Precise Point Positioning) is a relatively new GNSS (Global Navigation Satellite System) method that enables position determinations using a single receiver. Being able to survey with a single receiver makes this approach more attractive and affordable than other GNSS positioning techniques. Since a single receiver is used, a drawback of this technique is propagation of errors such as orbit and clock uncertainties, atmospheric disturbances etc. Due to these errors, precision of point positioning may reach up to decimeter levels. Fortunately, some of these error sources such as orbital errors, multipath etc. are repetitive errors and therefore can be detected by using digital filters. Adaptive noise canceling filters are used to detect the correlated part of the time series. These filters optimize themselves using the Least Mean Square (LMS) algorithm which is a powerful tool for Geosciences and are also used for many engineering applications. In this study, it is aimed to detect repetitive errors on coordinate time series by using adaptive noise canceling filter. For the application, four stations have been selected from NGS CORS (National Geodetic Survey Continuously Operating Reference Station) network. Two of these stations are highly affected by multipath error and the other two are not. The coordinate time series of the GNSS sites have been obtained using PPP technique on kinematic mode (epoch by epoch) for several consecutive days. The cross-correlation analysis has been performed and up to 92% correlation has been detected between the daily time series. The correlated part of the data set has been captured by means of adaptive noise canceling filter and removed from the data set. After the filtration process, up to 50% precision improvement has been achieved on coordinate time series, especially for the stations affected by multipath.
- BildiriYalnız künye2017Hardware optimization for belief propagation polar code decoder with early stopping Criteria using high-speed parallel-prefix ling adder
Simsek, Cemaleddin; Turk, Kadir; Herencsar, N.
Belief propagation (BP) polar code decoder is well-studied from many aspects. This study proposes a hardware optimization to improve performance of polar BP decoder by modifying both processing element (PE) and early stopping criterion (ESC). PE is optimized by using high-speed parallel-prefix Ling adder instead of carry ripple adder and WIB ESC introduced in literature is optimized by removing unnecessary adder array. FPGA implementation is made to verify the idea behind this study. The results show that throughput of polar code belief propagation decoder can be increase significantly by using proposed approach. More accurate comparison can be made by application specific chip design with same parameters. This part of the study will be held in future.
- BildiriYalnız künye2017A day ahead hourly solar radiation forecasting by artificial neural networks: A case study for Trabzon province; [Yapay Sinir Aǧlari ile Gün Öncesi Saatlik Güneş Radyasyonu Tahmini: Trabzon İli Örneǧi]
Çevik, Sibel; Çakmak, Recep; Altaş, Ismail Hakki
The integration of renewable energy sources to the electrical grid leads to some issues in the grid because of intermittent and variable characteristics of renewable energy sources such as wind and solar. It has been predicted that the solar based electricity production will has highest annual increase rate among the other renewable sources. Due to the intermittent and volatile nature of the solar energy in an electricity grid where photovoltaic systems are intensive, load planning is essential. Therefore, day ahead solar radiation forecasting will contribute to the load planning studies. Artificial neural networks are one of the methods that are applied frequently and successfully in forecasting studies. In this study, a cause effect based artificial neural network (ANN) has been designed and performed for day ahead hourly solar radiation forecasting in Trabzon province. A similar day selection algorithm has been utilized to get more accurate forecasting by the ANN. The designed ANN has been trained and tested in MATLAB simulation environment without using ready codes of MATLAB ANN toolbox. The obtained results reveal that the designed ANN forecasts the solar radiation with acceptable error for a place such as Trabzon which has rainy and cloudy weather conditions.
- MakaleYalnız künye2017Low-complexity early termination method for rateless soft decoder
Albayrak, Cenk; Simsek, Cemaleddin; Turk, Kadir
We propose a new early termination method (ETM) with low computational complexity for Luby transform belief propagation (BP) decoder. The proposed method, which we call least reliable messages (LRM) ETM, observes only sign alterations of a small cluster in log-likelihood ratio messages passing between nodes in BP decoder. Simulation results and complexity analyzes show that LRM ETM has quite low computational complexity and small average iteration amounts without any performance degradation compared with conventional ETMs in literature. The method can be applied to code families which can be decoded by BP such as low density parity check codes, polar codes, and Raptor codes.
- MakaleYalnız künye2016Simplified Early Stopping Criterion for Belief-Propagation Polar Code Decoders
Simsek, Cemaleddin; Turk, Kadir
As the first theoretically proven capacity-achieving error correction code, polar codes have become a milestone in information theory field, which draw serious attention by its low complexity encoding and decoding structures. For the decoding section, studies are focused on efficient and low complex algorithms based on successive cancellation and belief-propagation (BP) decoders. To reduce computational complexity of BP-based decoders further, early stopping methods that avoid unnecessary iterations can be used. In this letter, we propose a reduced complexity early stopping method for BP-based polar code decoders. The proposed method is based on the hypothesis that observing only a small cluster of information bits polarized to the highest error probabilities is enough to detect successful decoding. Simulation results show that the proposed early stopping criterion significantly reduces the computational complexity of successful decoding detection as well as the total operation numbers of the whole decoding process compared with previous methods in the literature.
- BildiriYalnız künye2016Scheduling of domestic shiftable loads via Cuckoo search optimization algorithm
Cakmak, Recep; Altas, Ismail H.; Cetin, A.; Camurcu, A.Y.
Electrical power systems have been developed to more advanced structures called as smart grids. Among many other issues, demand side management (DSM) is one of the important instruments of the smart grids. DSM techniques increase the efficiency of the grid, and modify consumer's electrical demand via demand response (DR) programs using financial incentives. In this study, shiftable domestic loads scheduled by Cuckoo search algorithm (CSA) to ensure balanced load curve as much as possible while considering the consumers' preferences. The main motivation of this paper is scheduling the usage hours of the shiftable household appliances in a neighborhood by applying the recently developed metaheuristic CSA. This paper proposes an approach to increase the efficiency and lifetime of utility network by scheduling and operating shiftable domestic loads while considering consumer's demand in terms of financial benefits. Proposed CSA based scheduling mechanism is compared with that of Genetic algorithm (GA). The results reveal positive effects of the scheduling and the performance of the CSA over GA.
- BildiriAçık Erişim2015Convergence in local press
Tingoy, Ozhan; Isikli, Sevki; Gumushane, Ali Ozcan
Improvements in information and communication technologies have evolved the way of traditional broadcasting. This evolvement is currently being experienced in press, eliminating the specific and clear lines of every kind of medium. Changing news production/distribution process as well as readers' consumption tendencies have brought up some kind of negative presumptions related with the future of press. Taken into consideration on the level of widespread newspapers, this evolvement is siginificant in respect of the future of local newspapers which count around 1400 in Turkey, trying to survive financial reasons. Fullfilling the evolvement triggered by information and communication technologies successfully, local newspapers are now expected to fulfill their alternative journalism mission against global media contents with the help of new media environment.