Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Akkurt, Nevzat(24)
- Gul, Muhammet(11)
- Yucesan, Melih(9)
- Alataş, Mevlüt(8)
- Aslan, Naim(8)
- Batan, Nevzat(8)
- Ezer, Tülay(8)
- Utku, Anıl(8)
- Erata, Hüseyin(7)
- Xu, Qian(7)
- Dal, Murat(6)
- Etli, Serkan(6)
- Konurhan, Zekeriya(6)
- Topal, Murat(6)
- Yeşiltepe, Akgün(6)
- Yüksekol, Özlem Doğan(6)
- Şahal, Hakan(6)
- Şahin, Aykut(6)
- Cihangir, Salih(5)
- Ding, Yulong(5)
- Işık, Erdem(5)
- Kaya, Sema Kayapinar(5)
- Kök, Mediha(5)
- Orhan, Cemal(5)
- Sengur, Abdulkadir(5)
- Serdar, Osman(5)
- Uyan, Umut(5)
- Zengin, Gokhan(5)
- Öbek, Erdal(5)
- Aslan, N.(4)
- Baltacı, Nazlı(4)
- Baş, Kazım(4)
- Başkutlu, Salih(4)
- Boyali, Handan(4)
- Eldin, Sayed M.(4)
- Erdemoğlu, Murat(4)
- Erten, Fusun(4)
- Gürler, Nedim(4)
- Hudaverdi, Burcu(4)
- Kanca, Muhammed Sait(4)
Yayınlar
- MakaleYalnız künye2023Scopus SJRQ2Does surgery cause anxiety, stress and fear in geriatric patients?
Karabulut, Neziha; Gürçayır, Dilek; Abi, Özlem; Kızıloğlu Ağgül, Beyzanur; Söylemez, Nilgün
Background: Because of physiological changes in geriatric patients, their surgical process differs from that of young adults. In this regard, the perioperative period is an extremely risky time for geriatric patients. The present study examined preoperative fear, anxiety, and perceived stress levels as well as the factors affecting them in elderly patients prior to surgical intervention. Methods: This study adopted a cross-sectional descriptive design. The study sample consisted of geriatric patients (n = 407) scheduled for elective laparoscopic cholecystectomy in a research and training hospital in northeast Turkey. Data were collected by the researchers using the personal information form, Perceived Stress Scale (PSS-10), Surgical Fear Questionnaire (SFQ) and Anxiety Specific to Surgery Questionnaire (ASSQ). In the data analysis, descriptive statistics, the t-test in independent groups, one-way analysis of variance (ANOVA), correlation analysis and Bonferroni tests for post hoc analyses were used. Results: On the PSS–10, the mean score was higher for the 75-and-older age group, single patients, patients with a disease requiring medication, and those who had previously undergone surgery (P < 0.05). On the ASSQ, the mean score was lower for patients aged 65–69, university graduates, patients without children, and those without a disease requiring medication (P < 0.05). On the SFQ, the mean score was higher for the 75-and-older age group, primary school graduates, and single patients (P < 0.05). Conclusion: It was determined that being single, having a chronic disability, and advancing age had an effect on the patients' surgery-specific anxiety, perceived stress, and fear of surgery. Long-standing chronic diseases can negatively affect both stress and anxiety levels of individuals.
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İncele - MakaleYalnız künye2023Scopus SJRQ2Engineering Properties of Geopolymer Mortars Containing Industrial Steel Shavings
Gülmez, Nihan; Koçkal, Niyazi Uğur
The purpose of using waste materials is to prevent the unnecessary use of resources and to reduce the amount of waste. Geopolymer, developed as an alternative to cementitious materials, prevents the depletion of natural resources and saves a large amount of energy. This paper presents the effect of waste steel shavings on the improvement of physical and mechanical properties of geopolymer mortars. For this purpose, geopolymer mortars were produced by using two binder types [slag (BFSb) and silica fume] as well as steel shavings in five different replacement percentages (0%, 2.5%, 5%, 7.5% and 10%) by volume instead of aggregate. A series of experiments on geopolymer mortars were carried out to determine properties such as bulk density, water absorption, apparent porosity, sorptivity coefficient, splitting tensile strength, flexural strength and compressive strength. Results showed that steel shavings recovered from metal processing and forming sector were highly effective at improving engineering properties of geopolymer mortars. Furthermore, although replacement of 20% by volume of BFSb with silica fume improved properties of geopolymer mortar, it was observed that the use of silica fume at higher ratios reduced mechanical properties by increasing porosity and sorptivity of BFSb-based geopolymer mortars.
AtıfScopus1OpenAlex1İncele - MakaleAçık Erişim2023Scopus SJRQ3Rotor Field-Oriented Control of Doubly Fed Induction Generator in Wind Energy Conversion System
Omac, Zeki; Erdem, Irfan
In this study, robust and high-performance vector control of a rotor side converter (RSC) was performed for stability and efficient operation doubly fed induction generator (DFIG) based on the variable speed wind turbine (VSWT). The mathematical model of the DFIG is simulated in the computer. Amplitude and frequency of the voltage in the DFIG were controlled for different values of load and variable speeds. In the experimental study, a DFIG-based wind turbine system was set up in the laboratory. The field position of the stator was detected from stator voltages by a phase-locked loop (PLL) circuit. The rotor position was measured with an incremental encoder connected to the rotor shaft of the DFIG. The angular position of the slip was calculated by the difference between the rotor and the stator field positions. The frequency and amplitude of rotor currents were determined with the angular position of slip. To generate output voltages of converter feeding rotor windings, the space vector pulse width modulation (SVPWM) technique was used. In the experimental study, the RSC was controlled with the DS1103 board. The prepared experiment set was tested at different operating speeds.
AtıfScopus4WoS3OpenAlex4
İncele - MakaleAçık Erişim2023Scopus SJRQ1PatchResNet: Multiple Patch Division–Based Deep Feature Fusion Framework for Brain Tumor Classification Using MRI Images
Muezzinoglu, Taha; Baygin, Nursena; Tuncer, Ilknur; Barua, Prabal Datta; Baygin, Mehmet; Dogan, Sengul; Tuncer, Turker; Palmer, Elizabeth Emma; Cheong, Kang Hao; Acharya, U. Rajendra
Modern computer vision algorithms are based on convolutional neural networks (CNNs), and both end-to-end learning and transfer learning modes have been used with CNN for image classification. Thus, automated brain tumor classification models have been proposed by deploying CNNs to help medical professionals. Our primary objective is to increase the classification performance using CNN. Therefore, a patch-based deep feature engineering model has been proposed in this work. Nowadays, patch division techniques have been used to attain high classification performance, and variable-sized patches have achieved good results. In this work, we have used three types of patches of different sizes (32 × 32, 56 × 56, 112 × 112). Six feature vectors have been obtained using these patches and two layers of the pretrained ResNet50 (global average pooling and fully connected layers). In the feature selection phase, three selectors—neighborhood component analysis (NCA), Chi2, and ReliefF—have been used, and 18 final feature vectors have been obtained. By deploying k nearest neighbors (kNN), 18 results have been calculated. Iterative hard majority voting (IHMV) has been applied to compute the general classification accuracy of this framework. This model uses different patches, feature extractors (two layers of the ResNet50 have been utilized as feature extractors), and selectors, making this a framework that we have named PatchResNet. A public brain image dataset containing four classes (glioblastoma multiforme (GBM), meningioma, pituitary tumor, healthy) has been used to develop the proposed PatchResNet model. Our proposed PatchResNet attained 98.10% classification accuracy using the public brain tumor image dataset. The developed PatchResNet model obtained high classification accuracy and has the advantage of being a self-organized framework. Therefore, the proposed method can choose the best result validation prediction vectors and achieve high image classification performance.
AtıfScopus103OpenAlex101İncele - MakaleAçık Erişim2023Scopus SJRQ2The Epiphytic Bryophyte Vegetation of Buxus sempervirens L. forests in the Fırtına Valley (Rize, Turkey); [Végétation de bryophytes épiphytes des forêts de Buxus sempervirens L. dans la vallée de Fırtına (Rize, Turquie).]
Alataş, Mevlüt; Ezer, Tülay; Erata, Hüseyin; Batan, Nevzat; Ursavaş, Serhat
The Fırtına Valley forests are of the 100 forests in the world whose conservation is a priority due to the natural old forests they have. In this study, the epiphytic bryophyte vegetation of the Buxus sempervirens L. forests located in the Fırtına Valley (Rize, Northern Turkey), which is one of the nine hotspots in Turkey and Turkey’s only boxwood forest, was investigated. The relevés taken from living tree trunks in 2020 were analyzed according to the Braun-Blanquet methodology, and ordinated and classified using the Detrended Correspondence Analysis (DECORANA) and the Two-Way Indicator Species Analysis (TWINSPAN). As a result of the analyses, Exsertotheco crispae-Allenielletum besseri ass. nov. subass. typicum and leucodontetosum sciuroidis subass. nov., and Alleniello besseri-Palamocladietum euchloronis ass. nov. were described and characterized. All syntaxa were presented by analyzing them in terms of their ecological and floristic classifications.
AtıfScopus2OpenAlex4İncele - MakaleAçık Erişim2023Scopus SJRQ4Single and combined effects of dimethoate and malathion on oxidative stress biomarkers in the non-target freshwater mussel Dreissena polymorpha
Serdar, Osman; Yildirim, Numan; Yildirim, Nuran Cikcikoglu
This study evaluates the single and combined effects of dimethoate (DI) and malathion (MA) on oxidative stress biomarkers in the freshwater mussel Dreissena polymorpha, estimating the potential harm of these pesticides on aquatic ecosystems. Superoxide dismutase (SOD) and catalase (CAT) activities, and glutathione (GSH) and lipid peroxidation (TBARS) levels were determined in D. polymorpha exposed to sublethal concentrations of DI, MA and a combination of the two during 24 and 96 h periods. The results showed that the GSH levels were decreased but the TBARS levels were increased in all the exposure groups after 24 and 96 h compared to the control. It was observed that SOD activity decreased but CAT activity increased in all the DI exposure groups after 24 h compared to the control. At the end of 96 hours, it was observed that CAT and SOD activities increased again in some exposure groups compared to the control. Exposure time also had an effect on biomarkers in different levels. According to the results, the cytotoxicity of DI and MA combination depended on their concentrations. DI or/ and MA, in sub-lethal concentrations, induced oxidative damages in D. polymorpha. Combined exposure of the pesticides can alter their toxicity and may be evidence of increased toxicity and oxidative stress.
AtıfScopus3WoS3OpenAlex2İncele - DüzeltmeAçık Erişim2023Correction to: A new approach based on convolutional neural network and feature selection for recognizing vehicle types(Iran Journal of Computer Science, 10.1007/s42044-022-00125-6)
Doğan, Gürkan; Ergen, Burhan
The sentence beginning 'Bu nedenle bu …' in this article should have read 'Therefore, in this study, a combination of OMobileNetv1, OMobileNetv2, ONASNetMobile CNN methods for feature extraction, LSVC method for feature selection and SVM method for classification is proposed.' The original article has been corrected.
- MakaleYayıncıda açık erişim2023Scopus SJRQ2The Symptom Experience and Functioning of Non-Hospitalized COVID-19 Patients Within the First 20 days
Tütün Yümin, Eylem; Sürmeli, Mahmut; Topcuoğlu, Ceyhun; Başol Göksülük, Merve; Yümin, Murat
The adverse physical, psychological, and mental health consequences associated with COVID-19 illness are well-documented. However, how specific symptoms change over time and how COVID-19 affects one’s day-to-day activities of daily living (ADL), Quality of Life (QoL), sleep quality, and fatigue severity are not well described. This longitudinal and descriptive study examined the changes in COVID-19 symptoms, ADL, QoL, sleep quality, and fatigue severity within the first 20 days. A convenience sample (n = 41) of non-hospitalized SARS-CoV-2 positive patients were recruited and followed for 20 days. Participants completed self-report measures: COVID-19 symptoms, ADL, QoL, sleep quality, and fatigue severity at days: 1, 10, and 20 following a diagnosis. Findings revealed that symptoms decreased over 20 days (p <.001). In parallel with the decrease in symptoms, QoL and ADL improved over 20 days (p <.05). However, sleep quality and fatigue severity did not improve within 20 days (p >.05). Our findings contribute to the growing evidence that COVID-19 symptoms can linger, especially fatigue and sleep quality, that affect overall day-to-day functioning for at least 20 days after diagnosis. To mitigate the effect of COVID-19 on QOL and ADL, findings underscore the need for clinicians to work collaboratively with patients to develop a symptom management plan for a variety of symptoms including fatigue and sleep quality. Beginning to repurpose existing self-management strategies for the longer term COVID-19 symptoms could be beneficial and help to optimize patient outcomes. Future work should examine these variables over a longer timeframe and among different samples of non-hospitalized patients.
AtıfScopus1WoS1İncele - MakaleYalnız künye2023Scopus SJRQ2Replacement of Cu with One-Step Production of CuAg (Ag0.04Cu3.96): Superior Conductivity, Corrosion Resistance, and Hardness
Cihangir, Salih
Copper is the forefront of the fundamental metals used in various industries. It is utilized as bulk or electrodeposited on PCBs or interconnects. However, poor corrosion resistance and hardness reduce copper performance and limit its applicability in the fields that require mechanical strength, such as probing applications. Facile electrochemical deposition of Cu(Ag) films was examined in a deep eutectic solvent known for its green nature. SEM–EDS technique was applied for morphostructural and crsytal plane analysis. XRD analysis revealed Cu3.96Ag0.04 phase, and 2% Ag was identified in the Cu(Ag) film in EDS. Four-prope point resistivity analysis was performed via galvano-impedance spectroscopy. Obtained resistivity value of 5 µm thick Cu(Ag) coating was lower than the compliance limit of International Technology Roadmap for Semiconductors. Corrosion analysis was carried out via electrochemical impedance spectroscopy technique, and Cu(Ag) films demonstrated better resistance. Hardness tests also revealed that Cu(Ag) was approximately two times harder than Cu. Graphical Abstract: [Figure not available: see fulltext.]
AtıfScopus6WoS6OpenAlex6İncele - MakaleAçık Erişim2023Scopus SJRQ1Modeling and numerical simulation of non-Newtonian arterial blood flow for mild to severe stenosis
Nadeem, Sohail; Ali, Shahbaz; Akkurt, Nevzat; Ben Hamida, Mohamed Bechir; Almutairi, Shahah; Ali Ghazwani, Hassan; Eldin, Sayed M; Khan, Zareen A.; Al-Shafay, A.S.
The fundamental cause of coronary heart disease is thought to be atherosclerosis. Blood flow in arteries under plaque formation is widely studied using both experimental and theoretical methods in literature. This paper presents a comprehensive study on the mathematical modelling and numerical simulation of non-Newtonian blood flow in an idealized stenosed artery. Non-Newtonian behavior of blood flow is assumed by Casson and Quemada fluid models. An analysis is performed for four forms of stenosis, 50%, 60%, 70%, and 80%, which are defined by a narrowing of the artery's diameter. The mathematical model for non-Newtonian fluid transport is presented in the form of highly nonlinear coupled partial differential equations. A finite-volume approach is used to solve the system of equations numerically. The solutions are obtained using a hybrid mesh with hexahedron and tetrahedron control volumes. Numerical solutions are validated first with experimental results from the literature for a Newtonian fluid, and then the results are extended to non-Newtonian fluid models. It can be observed that the non-Newtonian nature of the fluid model influences flow dynamics and is a significant aspect to consider for arteries with small diameter. The velocity and pressure drop rise as the degree of stenosis develops. Wall shear is substantially larger in stenotic passages and severity of stenosis is directly related with this increasing behavior.
AtıfScopus32OpenAlex33İncele - MakaleAçık Erişim2023Scopus SJRQ3Effect of Spectrogram Parameters and Noise Types on The Performance of Spectro-temporal Peaks Based Audio Search Method
Koseoglu, Murat; Uyanik, Hakan
Audio search algorithms are used to detect the queried file in large databases, especially in multimedia applications. These algorithms are expected to perform the detection in a reliable and robust way within the shortest time. In this study, based on spectral peaks method, an audio fingerprint algorithm with a few minor modifications was developed to detect the matching audio file in target database. This method has two stages as the audio fingerprint extraction and matching. In the first stage, fingerprint features are extracted from spectral peaks on the spectrograms of audio files by hash functions. This state-of-art technique reduces the processing load and time considerably compared to traditional methods. In the second stage, fingerprint data of the queried file are compared with the data created in the first stage in the database. The algorithm was demonstrated, and the effect of spectrogram parameters (window size, overlap, number of FFT) was investigated by considering reliability and robustness under different noise sources. Also, it was aimed to contribute to new audio retrieval studies based on spectral peaks method. It was observed that the variation in the spectrogram parameters significantly affected the number of matchings, reliability and robustness. Under high noise conditions, the optimal spectrogram parameters were determined as 512 (window size), 50% (overlap), 512 (number of FFT). It was seen in general that the algorithm successfully detected the queried file in the database even in high noise conditions for these parameters. No significant effect of music genre was observed.
AtıfScopus9WoS6OpenAlex11TR Dizin1İncele - MakaleYalnız künye2023Scopus SJRQ1An integrated hybrid MCDM approach to evaluate countries’ COVID-19 risks
Mete, Suleyman; Yucesan, Melih; Gul, Muhammet; Ozceylan, Eren
To enable planning and early reaction efforts, it is important to identify the nations most at risk from COVID-19's health and humanitarian effects, which could exceed present national response capabilities. INFORM COVID-19 Risk Index developed by European Commission is one of the initiatives to meet the aforementioned need. However, the Index has 40 conflicting and comprehensive indicators (e.g., health system capacity, hygiene, vulnerability) and different countries that lead to a need for multicriteria decision-making (MCDM) approaches. This paper offers an integrated MCDM approach with two phases to re-assess the countries' COVID-19 risks based on INFORM COVID-19 Risk Index. In the first phase, the 40 indicators are prioritized using the Entropy-based multi-choice best-worst method (MC-BWM) to provide multiple viewpoints for the preferences values. In the second phase, 29 countries from different geographical regions are ranked using the COPRAS (Complex Proportional Assessment) method. Applying these three methods together on the COVID-19 risk assessment of countries is the most significant novelty for the relevant literature. The proposed approach has undergone a thorough comparative evaluation with the released INFORM COVID-19 Risk Index, and recommendations are provided based on different scenario analyses.
AtıfScopus21WoS16OpenAlex18İncele - MakaleAçık Erişim2023Scopus SJRQ1Detailed investigation of zinc coating behaviours in various deep eutectic solvents
Cihangir, Salih; Ryder, Karl S.; Unal, Asuman
Determining the optimum conditions of a metal coating is significant for its possible applications in many fields. The present work described the electrodynamic process of zinc coating from six different deep eutectic solvents (DESs), especially type-III DES systems prepared with a quaternary ammonium salt and hydrogen bond type. Non-reversible processes without oxidation were found in DES systems prepared with choline chloride and zinc nitrate salts, and also, propylene glycol and zinc nitrate salts, termed as type-II and type-IV, respectively. The most attracted type-III DES prepared by a mixture of 1 molar choline chloride and 2 molar ethylene glycols, commercially known as Ethaline (E200), were examined for its electronucleation and possible reactions for zinc electrodeposition. For the first time, the Pt working electrode was investigated under high-resolution optical microscopy to visualize the in-situ morphology change during oxidation and reduction in E200. Furthermore, the morphological change during the anodic dissolution of zinc was also investigated in situ under a high-resolution microscope. It was found that insoluble species forming during anodic dissolution blocks the surface. Bulk electrolysis was performed in these solvents to investigate the formed zinc nucleates' morphological differences. XRD analysis was performed to differentiate the crystal planes of each deposition obtained from six DESs. It was found that the type-II and type-IV DESs consisting of zinc nitrates revealed zinc hydroxy nitrate dominated zinc deposition, which can be helpful in various applications.
AtıfScopus14WoS11OpenAlex15İncele - MakaleAçık Erişim2023Scopus SJRQ4The influence of microwave curing on the strength of silica fume-added fly ash-based geopolymer mortars
Yilmazer Polat, Berivan
Geopolymer concretes a substitute for traditional Portland cement as a more environmentally sustainable alternative. In addition, one of the most significant advantages of geopolymer concrete is the high setting speed that can be achieved with thermal curing, that is, the short curing period. Research on geopolymer concrete has focused on curing, where curing is usually done with conventional ovens. Microwave curing initiates heat generation at the molecular level, which results in a minimal heat increase on the surface of the specimens compared to traditional thermal curing methods. In addition, it provides internal, rapid, and homogeneous heating and rapid strength development. This study is based on research that examined the effect of microwave cure on the compressive strength of silica füme-modified geopolymer mortar. In the study, sodium silicate and sodium hydroxide were used for activation, and first of all, fly ash substituted geopolymer mortar specimens were subjected to conventional thermal curing in an oven. On the other hand, the mortar specimens with the same composition were subjected to short-duration (10 minutes) microwave curing at power levels of between 200-600 W. When the results were compared regarding compressive strength, void and per-cent water absorption, UPV, and SEM-internal structure examination, it was revealed that microwave curing could be used faster than the conventional oven curing method in silica füme-added fly ash-based geopolymer mortars. This research can be considered an essential step for further optimizing and popularising geopolymer concrete and microwave curing and proposes a method that should be considered in the future development of more sustainable construction materials.
AtıfScopus7OpenAlex7TR Dizin4İncele - MakaleAçık Erişim2023Scopus SJRQ2A Fuzzy Hybrid MCDM Approach for Assessing the Emergency Department Performance during the COVID-19 Outbreak
Ortíz-Barrios, Miguel; Jaramillo-Rueda, Natalia; Gul, Muhammet; Yucesan, Melih; Jiménez-Delgado, Genett; Alfaro-Saíz, Juan-José
The use of emergency departments (EDs) has increased during the COVID-19 outbreak, thereby evidencing the key role of these units in the overall response of healthcare systems to the current pandemic scenario. Nevertheless, several disruptions have emerged in the practical scenario including low throughput, overcrowding, and extended waiting times. Therefore, there is a need to develop strategies for upgrading the response of these units against the current pandemic. Given the above, this paper presents a hybrid fuzzy multicriteria decision-making model (MCDM) to evaluate the performance of EDs and create focused improvement interventions. First, the intuitionistic fuzzy analytic hierarchy process (IF-AHP) technique is used to estimate the relative priorities of criteria and sub-criteria considering uncertainty. Then, the intuitionistic fuzzy decision making trial and evaluation laboratory (IF-DEMATEL) is employed to calculate the interdependence and feedback between criteria and sub-criteria under uncertainty, Finally, the combined compromise solution (CoCoSo) is implemented to rank the EDs and detect their weaknesses to device suitable improvement plans. The aforementioned methodology was validated in three emergency centers in Turkey. The results revealed that the most important criterion in ED performance was ER facilities (14.4%), while Procedures and protocols evidenced the highest positive D + R value (18.239) among the dispatchers and is therefore deemed as the main generator within the performance network.
AtıfScopus28OpenAlex29İncele - MakaleAçık Erişim2023Scopus SJRQ3The biosorption of Co(II) by Homalothecium sericeum from aqueous solutions under batch conditions: response surface methodology optimization and Daphnia magna bioassay
Tanyol, Mehtap; Korkmaz, Volkan; Yildirim, Numan; Erguven, Gokhan Onder; Ayhan, Nagihan Karaaslan; Alatas, Mevlut
In the present work, Homalothecium sericeum biomass was used for removal of Co(II) from aqueous solution. The effects of process parameters (contact time, biosorbent amount, and initial Co(II) con-centration) on the response (Co(II) % removal) were investigated using a batch adsorption system optimized with response surface methodology/central composite design method. Under optimized conditions the maximum Co(II) removal efficiency achieved is 94.07% at an initial Co(II) concentration of 2.05 mg/L, a H. sericeum amount of 0.34 g/50 mL, and a process time of 36.09 min. In this study, the toxicity of the medium after biosorption carried out under optimized conditions was also tested with Daphnia magna bioassay. When mortality results with D. magna were evaluated, although a removal efficiency of 94.07% was obtained after biosorption, this was not sufficient to reduce mortality of D. magna.
AtıfScopus1WoS2İncele - MakaleAçık Erişim2023Scopus SJRQ3Impact of electron concentration on the transformation temperature and important physical properties of NiMnSnFe ferromagnetic shape memory alloys
Malkoç, Türkan; Kanca, Muhammed Sait; Işık, Erdem; Kök, Mediha
This study aimed to explore the influence of electron concentration on the NiMnSn alloy, which is a crucial ferromagnetic shape memory alloy (FSMA). The alloy was doped with various amounts of iron element to assess its effect. According to DSC measurement, iron doping has resulted in a general decrease in the transformation temperature value of NiMnSn alloy, as well as a decrease in the transformation enthalpy value. The orthorhombic martensite phase of NiMnSn alloy was replaced by L21 austenite crystal structure in X-ray measurements. Martensite, austenite, and precipitate phases were observed in SEM images. Iron doping significantly increased the magnetic saturation value of NiMnSn alloy, according to magnetic measurements, and thermomagnetic measurements revealed similar results. Graphical Abstract: [Figure not available: see fulltext.]
AtıfScopus5WoS5OpenAlex5İncele - MakaleAçık Erişim2023Scopus SJRQ2Seasonal monitoring of microbial activity using conventional approaches in a full-scale urban biological wastewater treatment plant
Demirbilek, Deniz; İpek, Ubeyde; Yetis, Ulku
Activated sludge processes contain various groups of microorganisms with different metabolic properties, which are responsible for contaminants removal. Therefore, it is important to elucidate the general structure and functional properties of biomass in activated sludge processes. For this purpose, a full-scale domestic biological wastewater treatment plant in Tunceli (Turkey), Tunceli WWTP (wastewater treatment plant), was monitored to observe seasonal variations in process performance and biomass properties for a year. It was observed that nitrifying bacteria developed abundantly in the rainy and cool spring season as they were suppressed in summer because their large losses took place due to an environment containing high alkalinity values. In September, aerobic heterotrophic, nitrify, denitrify, and anaerobic activities increased. It can be said that the biomass contained young and mature microorganism in this environment in which the sludge volume index (SVI) value increased to 196 mL/g. As a result of the improvement in the structural and functional properties of biomass, the nitrogen removal efficiency reached 99%. Throughout the whole study, the structural improvement observed in biomass was reflected in its removal activity. The amount of biomass and removal activity decreased with the abundance of organic matter in the influent at the period in which biomass was closer to being categorized in the aged sludge class. The results showed that as the lowest mixed liquid suspended solids (MLSS) and mixed liquid volatile suspended solids (MLVSS) values of the year were 530 and 400 mg/L, respectively, in November 2017, MLSS and MLVSS values reached the highest amount (1700 and 1400 mg/L, respectively) in December 2017 when aerobic heterotrophic activity accelerated with a decrease in organic matter level.
AtıfScopus7WoS7OpenAlex7İncele - MakaleAçık Erişim2023Scopus SJRQ1Case study of thermal and solutal aspects on non-Newtonian Prandtl hybrid nanofluid flowing via stretchable sheet: Multiple slip solution
Shamshuddin, MD.; Raizah, Zehba; Akkurt, Nevzat; Patil, Vishwambhar S.; Eldin, Sayed M.
The effect of multiple slip boundary conditions is one more important physical parameter on the flow investigation and have been studied in this analysis. Further, the effect of Ohmic heating and varying chemical reaction on non-Newtonian Prandtl hybrid nanofluid with water based nanofluids to an extending of leading edge was also investigated to this current analysis. An inclined magnetic field is introduced to fluid flow to regulate the fluid stream. Hybrid nanomaterial is synthesized by the dispersion of Cu and Cofe2O4 nanoparticles in Prandtl fluid. All chemical science specifications of nanofluid are measured as constant. Due to the nanofluid particles motion, the fluid concentration is inspected underneath chemical implications. A mathematical model is developed by assuming the flow as incompressible and purely cartesian coordinate system and appropriate non-dimensional variables are introduced for problem simplifications and dimensional analysis. The scheme for semi analytical study named Homotopy Analysis Method (HAM) is implied to get solutions to the equations. The procedure is then displayed pictorially where fluid velocity, temperature and concertation against various pertinent parameters are examined. It was found that, the Concentration field profiles have been shown to deteriorate because molecule diffusivity reduces as the chemical reaction parameter rises in both cases. In order to maintain thermal balance management in tiny heat density equipment and gadgets, current research may also be helpful in enhancing the thermal efficiency of heat exchangers.
AtıfScopus41WoS38OpenAlex44İncele - MakaleYalnız künye2023Scopus SJRQ2Computer-aided Optimization of Geopolymer Mortars
Gülmez, Nihan; Koçkal, Niyazi Uğur
The optimum mix design of geopolymers involves the purpose of determining which mixture will have high engineering properties without compromising the importance of each variable. This experimental study aimed to investigate the effects of some critical geopolymer mixture parameters on engineering properties by using historical data design in response surface methodology (RSM). Statistical models were developed between factors (binder and aggregate content, curing conditions and aggregate type) and their response surfaces (oven dry (OD) bulk density, water absorption, compressive strength and flexural strength). The final mathematical models for the response surfaces were constructed in terms of coded factors defined as dimensionless. In addition, a multipurpose optimization technique was used to achieve the desired design with the desired maximum strength.