WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

Browse

Filters

2010 - 201922020 - 202511

Settings

Author: search.filters.author.Tayfur, Gokmen

Search Results

Now showing 1 - 10 of 13
  • Article
    Combined Impacts of Glazing Types and Dynamic Led Lighting on Human Centric Lighting Requirements
    (Elsevier, 2025) Kose, F. Busra; Kazanasmaz, Z. Tugce; Tayfur, Gokmen; Duran, H. Engin
    As modern offices increasingly integrate smart lighting systems, understanding their combined impact with daylight on human well-being is essential. This study aims to examine how glazing properties and dynamic LED lighting jointly influence circadian metrics, cognitive performance, and subjective evaluations in office environments. An experimental methodology was applied, combining lighting measurements, circadian calculations, cognitive performance tests, surveys, and statistical analyses. Results show that illuminance below 300 lux failed to meet circadian thresholds, while levels above 750 lux enhanced circadian activation, comfort, satisfaction, and mood. Optimal visual performance occurred at 300-750 lux, and LED colour temperatures between 4000 and 5000K yielded the highest circadian-effective values, supporting faster cognitive processing, better memory, and greater comfort while reducing glare and sleepiness. Glazing analysis revealed that tinted and photovoltaic types substantially altered indoor spectrum and attenuated circadian support, whereas clear and neutral low-e glazing preserved spectral balance. Interaction effects confirmed that both light intensity and spectrum must be considered together to achieve biological and perceptual benefits. Demographic influences were minimal, and useradjustable LEDs further enhanced comfort and satisfaction. This study provides novel evidence on the integrated role of glazing and dynamic lighting, offering practical guidance for office design that balances energy efficiency with occupant health, comfort, and productivity.
  • Article
    Dam Body Sediment Movement on Rough Bed Downstream Due to Earthfill Dam Break
    (Taylor & Francis Ltd, 2025) Aksoy, Aysegul Ozgenc; Dogan, Mustafa; Tayfur, Gokmen
    This study investigated movement of flow and sediment due to earthfill dam failure induced by piping and overtopping, using 12.8 m laboratory flume. Dam (60 cm high, 202 cm base width) was built in three zones with two sediment sizes, and downstream channel included a rough bed of cubic blocks. Water levels were monitored with sensors, and final sediment profiles were mapped via laser scanning. Results showed that dam body eventually collapses (in 265 s after the piping, and in 100 s after the overtopping start) while flood flow carries a great portion of its sediment away. Sediment spreading occurred all over downstream area with significant variation in non-uniform thickness (15 cm to 1 cm). In the residential area, the sediment depth variation ranged from 12 cm to 6 cm. The blocks were submerged under muddy flow in both modes of failures. Higher flow levels (22 cm) were observed over smooth bed than rough bed (15 cm), in overtopping break. This was almost the opposite in the piping failure mode (13 cm in smooth, and 15 cm in rough bed case). These findings highlights the dominant role of failure mechanism and bed roughness in sediment transport and flood dynamics.
  • Article
    Citation - WoS: 7
    Projektiranje Nasipa Zeljezničkih Pruga Primjenom Neuronskih Mreža
    (Croatian Soc Civil Engineers-hsgi, 2013) Tayfur, Gokmen; Egeli, Isfendiyar
    The main requirement in the design of high-speed railway embankments are low values of total differential settlements. The use of cement stabilized layers in embankments, as compared to non-stabilized layers that are now most often in use, is analysed in the paper. Different cement proportions and different water/cement ratios for stabilized layers are considered. It was established that the use of cement stabilized layers in embankments can greatly reduce thickness of individual layers, while also reducing settlement. The research was conducted using the feed forward neural network.
  • Article
    In-Depth Analysis of Drought Trend in Semiarid Saïs Plateau and Middle Atlas Region in Morocco
    (Springer int Publ Ag, 2025) Qadem, Zohair; Tayfur, Gokmen; Kankal, Murat
    This study explores the spatiotemporal properties of droughts and their evolution in the semiarid Sa & iuml;s Plateau and the Middle Atlas regions in Morocco. The methodology includes the analysis of 36 years of precipitation data recorded at 16 meteorological stations, the use of the standardized precipitation index (SPI) at different temporal scales of short term (1 and 3 months), medium term (6 months), and long term (12 and 24 months) to capture historical droughts, and the application of the Mann-Kendall test to assess the drought trends. The wet and dry periods in the Sa & iuml;s Plateau and Middle Atlas regions are almost evenly distributed, with 65% in the "near-normal" condition. The "extremely dry" period, with a value of 1%, was lower than the "extremely humid" period (1.65%). There is no topographically and climatically significant difference between the Sa & iuml;s Plateau and the Middle Atlas in terms of droughts, which are found to decrease over time in both regions. The results of Mann-Kendall test reveal that the short-term trends are generally positive, except at the Boulemane station (- 0.06 for SPI-1, - 0.13 for SPI-3). The long-term precipitation increases in the Middle Atlas region, particularly at the Ait Khabach (0.33 for SPI-24) and the Imouzzer (0.36 for SPI-24) stations. On the Sa & iuml;s Plateau, the trends are positive at the stations of Fez City (0.16 for SPI-24) and Dar Elarsa (0.27 for SPI-24). Significant trends are more pronounced at longer time scales.
  • Article
    Developing Feasible Structural Flood Mitigation Measures for Arid Regions Using Hydrological and Hydraulic Modelling: a Case of Baledweyne City, Somalia
    (Springer Int Publ Ag, 2025) Ibrahim, Abdullahi Abdulwahid; Tayfur, Gokmen; Safari, Mir Jafar Sadegh
    Flood mitigation measures are essential in several aspects of environmental sustainability, such as environmental protection and development, infrastructure resilience, and climate change adaptation strategies. This study investigates several remedial measures such as flood and disaster risk reduction strategies to protect Baledwayne City, Somalia. The developed hydrological-hydraulic model is successfully calibrated using the 2019 flood event. Inundation maps for different mitigation measures are developed to determine the most appropriate one(s) that may reduce flood impact and protect the city, especially the residential areas, against peak discharge of a 500-year return period. The investigated mitigation measures include (1) operating the Warabole Diversion Canal, (2) building two detention ponds at the upstream sections of both right and left floodplains, (3) building levees (dikes) along both sides of Shabelle River, and (4) restoration of the river. Results show that the remedial measures for the Warabole Diversion Channel and the river restoration are insufficient to protect the city. Building ponds on the right- and left-hand sides of the river substantially protects the city from flooding by reducing the flooded area from 88.6 to 31.5 km2, which is equivalent to a reduction of 35.5%. Construction of dikes on both sides of the river does not protect the city by overflowing an area of 75.2 km2 (84.9%). A combination of several measures is also investigated and it is found that ponds must be built along with any alternative measure. When all four measures are combined, it becomes clear that the city's residential areas would be fully protected, significantly reducing the overall flooded area of the city to 27.9 km2 (31.5%). These flooded areas are behind the detention pond, which is designed to hold floodwater and gradually drain it back to the river.
  • Article
    Experimental Study of Evolution of Breach Resulting From Piping at Upper Part of Earth-Fill Dam
    (Turkish Chamber Civil Engineers, 2025) Guney, Mehmet Sukru; Tayfur, Gokmen; Bor, Asli; Okan, Merve; Dumlu, Emre; Aklık, Pelin
    Piping and overtopping are the most important causes of earth-fill dam failure. Such dams may erode under seepage, causing a reduction in the structural strength. The aim of this study was to investigate the temporal evolution of the breach and flow rate from the breach resulting from the piping in earth-fill dams. The experiments were carried out at Hydraulics Laboratory of Civil Engineering Department of İzmir University of Economics. The dam was constructed by using a mixture consisting of 85 % sand and 15 % fine (low plasticity clay). In the first scenario a circular tunnel with a diameter of 2 cm was created along the centreline at 6 cm below the dam crest whereas in the second one it was located at the upper edge. Six cameras at different locations recorded the evolution of the progress of the breach formation. The pump flow rate was measured by magnetic flow meter, and the continuity equation was used to calculate the flow rate values from the breach. The time-varied values of the total breach areas were determined using the Gauss Area formula. The image processing method was also applied in the determination of the breach areas. The time-dependent changes of water depth in the channel were also recorded. The obtained experimental findings are presented and commented, together with the universal dimensionless curves. The failure of the dams occurred mainly because of the head cut erosion developed from downstream to upstream. When breaching started, the orifice flow was converted to open channel flow where breach bottom behaved like a broad crested weir. In the second scenario, the rigid lateral side considerably influenced the flow rate and the development of the breach. The peak flow rate corresponding to the first scenario was found approximately 2.3 times greater than that of the second one. The maximum values of all the breach parameters were reached earlier in the case of the seepage along the centerline. The ratios between the values corresponding to the first and the second scenarios were found as 3.25 and 1.75 for maximum breach areas at downstream and at upstream sides, respectively. These ratios were 2.44 and 1.37 for the average breach widths at downstream and upstream sides, respectively. A very good agreement was found between the area values obtained from Gauss area method and image processing technique, in both scenarios. This fact demonstrated that either of these two approaches can be used to determine the time-dependent breach areas. These experimental findings provide the opportunities for the calibration and validation of the numerical models used in the relevant numerical investigations. This study also offers guidance for the strategies concerning emergency action plans related to the failure of homogeneous earth-fill dams when the piping starts at upper part of the homogeneous earth-fill dams.
  • Article
    Numerical Study of Breaching at Upper Parts of Homogenous Earthen Dams
    (Springer Heidelberg, 2025) Dumlu, Emre; Guney, Mehmet Sukru; Okan, Merve; Ozden, Guerkan; Tayfur, Gokmen
    In this study, time-dependent finite element analyses of the breaching process in two homogenous earth-fill dams were performed using the finite element method. Breaching was initiated at the middle and corner sections of the upper part of the dam bodies. The numerical results were compared with the findings of the experiments realized on dams 60 cm high, 2 m wide at bottom, 20 cm wide at crest with 1 V:1.5H side slopes at upstream and downstream faces. This numerical study combines time-dependent hydraulic gradient distributions and groundwater flows to assess breach areas, velocities, and flow rates. A Python algorithm was integrated with the Jupyter console, allowing the simulation of the breach mechanism in multiple runs to determine breach parameters. Both numerical and experimental analyses revealed that the dams were exposed to backward erosion, starting at the downstream side of the dam and progressing inward. The compatibility between experimental and numerical results was sought by means of the parameters RMSE, MAE and the statistical performance of the numerical approach was evaluated by using RSR, NSE, and PBIAS. A fairly good agreement was obtained between the experimental and numerical results.
  • Correction
  • Conference Object
    Decoding and Predicting the Attributes of Urban Public Spaces With Soft Computing Models and Space Syntax Approaches
    (Ecaade-education & Research Computer Aided Architectural design Europe, 2023) Yonder, Veli Mustafa; Dogan, Fehmi; Cavka, Hasan Burak; Tayfur, Gokmen; Dulgeroglu, Ozum
    People spend a considerable amount of time in public spaces for a variety of reasons, albeit at various times of the day and during season. Therefore, it is of utmost importance for both urban designers and local authorities to try to gain an understanding of the architectural qualities of these spaces. Within the scope of this study, squares and green parks in Izmir, the third largest city in Turkey, were analyzed in terms of their dimensions, landscape characteristics, the quality of their semi-open spaces, their landmarks, accessibility, and overall aesthetic quality. Using linear predictor, general regression neural networks, multilayer feed-forward neural networks (2-3-4-5-6 nodes), and genetic algorithms, soft computing models were trained in accordance with the results of the conducted analyses. Meanwhile, using space syntax methodologies, a visibility graph analysis and axial map analysis were conducted. The training results (i.e., root mean square error, mean absolute error, bad prediction rates for testing and training phases, and standard deviation of absolute error) were obtained in a comparative table based on training times and root mean square error values. According to the benchmarking table, the network that most accurately predicts the aesthetic score is the 2-node MLFNN, whereas the 6-node MLFN network is the least successful network.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 3
    Sediment Transport Modelling in Densly Populated Urban Areas Due To Earthfill Dam Break
    (Taylor & Francis Ltd, 2024) Zhang, Yaoxin; Tayfur, Gokmen
    This study simulates two dimensional sediment transport, as a result of overtopping earthfill dam break, in urban areas. The model can consider breaching, removal of sediment from dam body, and transport of sediment. The model is first validated by simulating laboratory experimental data that involved measurements of levels, and longitudinal sediment profiles, and sediment distribution. Downstream side of the experimental canal is designed as; (1) smooth bed, and (2) rough bed with concrete blocks. For both cases, the model simulations are found to be satisfactory. The model is then applied to simulate artificial overtopping break scenarios of two real earthfill dams. The AW3D30 is used as the source data for representing the topographic surfaces and the LULC dataset is generated from the ESA's Sentinel-2 imagery. The results reveal that downstream of the dams can be subject to both scour, at onset of the dam break, and substantial deposition after having reservoir completely emptied. The cut can go all the way to dam bed. The scoured areas can be refilled after peak discharge recedes. Sediment depths can reach up to 1.5 m in the case of Urkmez Dam break in some areas in the vicinity of Urkmez Town and up to 3 m at the downstream area of Alibey Dam in Istanbul, implying disastrous consequences for the settlement areas.