Gulen Gullu

Prof. Dr. Gulen Gullu

orcid

Research Focus & Metrics

Academic Career Length

24Years (2003-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 November 2020 in Biochemical Engineering Journal
Verified
Journal Article
Closed access
EAElmira Aghaalipour
Elmira Aghaalipour
AAAydın Akbulut
Aydın Akbulut
GGGulen Gullu
Gulen Gullu

19 October 2011 in Indoor and Built Environment
Verified
Journal Article
Closed access
SMSibel Mentese
Sibel Mentese
ARAbbas Yousefi Rad
Abbas Yousefi Rad
MAMünevver Arısoy
Münevver Arısoy
GGGulen Gullu
Gulen Gullu
Seasonal and spatial variations of both levels and characteristics of airborne bacteria and fungi in various types of non-complaint indoor environments and their outdoors were investigated. Bioaerosol samples were collected by the single-stage Andersen sampler during the winter and summer seasons in Ankara, Turkey. Indoor and outdoor temperature, relative humidity (RH) and CO2 concentrations were also monitored online during the sampling. Bacteria levels in apartments were found to be considerably elevated when people were present. Significant relationships between bioaerosol levels and RH and CO2 concentrations ( p<0.05) were found. Bacteria levels exhibited a seasonal variation, while fungi levels did not, probably due to lower fungi concentrations occurrence as a result of lower RH values (median: 30%). Measured low levels of fungi in this study may be due to geographical conditions, climatic factors, and other environmental conditions. The indoor to outdoor (I/O) ratio for bacteria levels were found to be significantly higher than 1.0, while indoor and outdoor fungi levels were similar. Winter to summer (W/S) ratios in the sampling site groups varied on a large scale for both culturable fungi concentrations (0.24–19.59) and total bacteria count (0.16–6.59). The most prominent bacteria were Micrococcus spp., Staphylococcus spp. and Bacillus spp., while the most predominant fungi were Penicillium spp., Aspergillus spp. and Cladosporium spp.

13 October 2022 in Journal of Environmental Chemical Engineering
Verified
Journal Article
Open access
AAAyse Sever Akdag
Ayse Sever Akdag
IDInés Durán
Inés Durán
GGGulen Gullu
Gulen Gullu
Covadonga PevidaCovadonga Pevida
Covadonga Pevida

4 May 2022 in Atmosphere
Verified
Journal Article
Open access
PDF file
S. Yeşer AslanoğluS. Yeşer Aslanoğlu
S. Yeşer Aslanoğlu
EPEmmanouil Proestakis
Emmanouil Proestakis
AGAntonis Gkikas
Antonis Gkikas
GGGulen Gullu
Gulen Gullu
VAVassilis Amiridis
Vassilis Amiridis
Turkey is located in the heart of complex transition geography between Eurasia and the Middle East. In the grand scheme, the so-called eastern Mediterranean Basin is located almost in the middle of the dusty belt, and is a hot spot of climate change. The downstream location of dust-carrying winds from close desert sources reveals Turkey as an open plane to particulate matter exposure throughout the year. In order to clarify this phenomenon, this paper aims to determine the desert dust climatology of Turkey via CALIPSO onboard Lidar. This prominent instrument enables us to understand clouds, aerosols and their types, and related climatic systems, with its valuable products. In this study, a 9-year CALIPSO-derived pure dust product dataset was formed to explain horizontal and vertical distributions, transport heights and case incidences. The results indicated that the pure dust extinction coefficient increased as the location shifted from west to east. Moreover, in the same direction of west to east, the dominant spring months changed to summer and autumn. Mountain range systems surrounding Anatolia were the main obstacles against lofted and buoyant dust particles travelling to northern latitudes. Even if high ridges accumulated mass load on the southern slopes, they also enabled elevated particles to reach the ground level of the inner cities.

9 September 2023 in Environmental Science and Pollution Research
Verified
Journal Article
Closed access
PDF file
PBParisa Babaei
Parisa Babaei
ANAfsoun Nikravan
Afsoun Nikravan
AMArzu Meral
Arzu Meral
BKBatuhan Kibar
Batuhan Kibar
GGGulen Gullu
Gulen Gullu

25 January 2023 in Atmosphere
Verified
Journal Article
Open access
PDF file
RRReza Rezaei
Reza Rezaei
BNBehzad Naderalvojoud
Behzad Naderalvojoud
GGGulen Gullu
Gulen Gullu
This paper investigates the effect of the architectural design of deep learning models in combination with a feature engineering approach considering the temporal variation in the features in the case of tropospheric ozone forecasting. Although deep neural network models have shown successful results by extracting features automatically from raw data, their performance in the domain of air quality forecasting is influenced by different feature analysis approaches and model architectures. This paper proposes a simple but effective analysis of tropospheric ozone time series data that can reveal temporal phases of the ozone evolution process and assist neural network models to reflect these temporal variations. We demonstrate that addressing the ozone evolution phases when developing the model architecture improves the performance of deep neural network models. As a result, we evaluated our approach on the CNN model and showed that not only does it improve the performance of the CNN model, but also that the CNN model in combination with our approach boosts the performance of the other deep neural network models such as LSTM. The development of the CNN, LSTM-CNN, and CNN-LSTM models using the proposed approach improved the prediction performance of the models by 3.58%, 1.68%, and 3.37%, respectively.