Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Çolak, Murat(8)
- Bayram, Sinan(5)
- Öner, Erdal(5)
- Can, Zehra(4)
- Ecem Bayram, Nesrin(4)
- Kolaylı, Sevgi(4)
- Turan, Muhittin(4)
- Demirtaş, Betül(3)
- Dispinar, Derya(3)
- Erbayrak, Engin(3)
- Gumus, Beril Eker(3)
- Kamiloğlu, Aybike(3)
- Türker, Temel(3)
- Yanik, Yusuf(3)
- Yuncuoglu, Ercument Ugur(3)
- Özdemir, Akın(3)
- Şahin, Engin(3)
- Aymelek, Abdullah(2)
- Birinci, Ahmet(2)
- Dertli, Enes(2)
- Ergün, Mustafa(2)
- Eryılmaz Türkkan, Gökçen(2)
- Gerçek, Yusuf Can(2)
- Gul, Volkan(2)
- Gıdık, Betül(2)
- Kahraman, Yusuf(2)
- Kamiloglu, Aybike(2)
- Kara, Yakup(2)
- Keskin, Merve(2)
- Kul, S.(2)
- Malgaca, Levent(2)
- Nabiyev, Vasif(2)
- Oktay, Mine Gül(2)
- Sefaoglu, Firat(2)
- Turhal, Uğur(2)
- Uslu, Emin(2)
- Uyar, Mehmet(2)
- Uzun Yaylacı, Ecren(2)
- Yaylacı, Murat(2)
- Özkök, Aslı(2)
Yayınlar
- BildiriAçık Erişim2022Experimental Active Vibration Control of a Highly Flexible Composite Manipulator with Acceleration Feedback
Uyar, Mehmet; Malgaca, Levent; Lök, Ş.İpek; Can, Seda Vatan; Herisanu, N.; Marinca, V.
In this study, vibration control of a single-link flexible smart composite manipulator (FSCM) is experimentally studied. The experimental system includes a real-time data acquisition control card, accelerometer, amplifier, servo motor, and driver. The FSCM is an epoxy-glass composite manipulator with the piezoelectric actuator and has the orientation of [0/90] lay-up. Modal analysis is experimentally conducted to find the natural frequencies by applying a chirp signal to the piezoelectric actuator. Natural frequencies are found by taking the Fast Fourier Transform (FFT) in MATLAB. Triangular motion profiles are used to drive the FSCM. Motion parameters are found by utilizing the natural frequencies of the system for different deceleration times (tdec). with different deceleration times (tdec). Residual vibrations are suppressed by using PID control with acceleration feedback. The acceleration signals at the tip point are measured by utilizing the accelerometer. The controller gains are determined with the trial and error method. Experimental residual vibration results are presented for the active control. It is observed that the suppression of vibration amplitudes further increases with active control.
AtıfScopus2OpenAlex2
İncele - MakaleAçık Erişim2022Scopus SJRQ3Functional and technological characterization of lactic acid bacteria isolated from Turkish dry-fermented sausage (sucuk)
Kamiloğlu, Aybike
In this study, 10 lactic acid bacteria were isolated from Turkish fermented sausage (sucuk) and identified as 5 Lactobacillusplantarum, 1 Pediococcus acidilactici, 1 Weissella hellenica, 1 Lactobacillus pentosus, and 2 Lactobacillus sakei. PCR screening of genes encoding plantaricin A and pediocin showed the presence of plantaricin A gene in 9 and pediocin gene in 3 of strains. All isolates showed antibacterial and antifungal effect on most of the tested microorganisms. gad gene, encoding glutamic acid decarboxylase enzyme, was detected in all isolates except Weisella hellenica KS-24. Eight of isolates were determined as gamma-amino butyric acid (GABA) producer in the presence of 53 mM mono sodium glutamate (MSG) by HPLC and TLC analysis. DPPH scavenging activity was observed for all isolates. Additionally, isolates were able to produce exopolysaccharide in the presence of sucrose. The best exopolysaccharide (EPS) production was achieved with L.plantarum KS-11 and L.pentosus KS-27. As a result, this study characterized some techno-functional properties of LAB isolates from sucuk. It was concluded that the isolates studied have the potential to be used in obtaining functional products in meat industry, as well as strain selection may be effective in providing the desired properties in the product.
AtıfScopus23WoS21
İncele - MakaleAçık Erişim2022Scopus SJRQ3An Investigation of the Effect of Curing Temperature on the Deformation Characteristics of the Stabilized Soil Layers Treated with Lime and Tuff Wastes with Response Surface Method
Kamiloglu, Hakan Alper; Turan, Huseyin
The shallow spread foundations are one of the widely used foundation types for low-rise, low-cost or commercial buildings. However, it is not possible to use this type of foundation for soils with low bearing capacity or capable of excessive settlements. In these cases, stabilized soil layers overlying insufficient soil may be alternative to the high-cost foundation systems. As the temperature of the soils depends mostly on air temperature for shallow depths, curing conditions of the stabilized soil layers are affected by the air temperature. The effect of curing temperature on the pressure-settlement relation of the layered soil is a gap in the literature. This study investigates the effect of Bayburt tuff on pressure-settlement characteristics of layered soil for various curing temperatures. The specific objectives of this paper are to (1) examine the effect of using the waste tuffs as a stabilization agent in layered soils, (2) evaluate the usability of response surface methodology (RSM) to estimate shear strength parameters (c, ϕ), unconfined compression strength, and secant modulus of the stabilized soil with less experiment, (3) investigate the effect of dimensions of the stabilized soil block (length, with and thickness) on pressure-settlement relations under various curing temperature (T = 3 °C, 13 °C, 23 °C, 33 °C, 43 °C). This study comprises experimental and numerical parts. In the experimental part, strength parameters (c, ϕ) and secant modulus of stabilized soil samples were estimated with response surface methodology for various curing temperatures (3 °C, 23 °C, 43 °C). The effects of curing temperature on shear strength and Bulk’s modulus parameters were determined with the derived RSM model. In the numerical part of the study plate load test was simulated with the derived 2D axisymmetric FE model. The parameters required for the FE analyses were determined with the derived RSM model. As a result of the study, it was seen that it is possible to estimate experimental parameters accurately using the RSM approach with fewer tests. Bayburt tuff and lime mixtures increase the stiffness of the layered soil. The curing temperature has considerable effects on the pressure-settlement relationship up to a certain value. After a certain value increasing curing temperature has no considerable effects on the stiffness of the layered soil.
AtıfScopus3WoS1İncele - Kitap BölümüAçık Erişim2022Scopus SJRQ3Optimum Discrete Design of Steel Planar Trusses Comprising Earthquake Load Impact
Carbas, Serdar; Artar, Musa; Kim, JH; Deep, K; Geem, ZW; Sadollah, A; Yadav, A
In this study, the success of teaching–learning-based optimization (TLBO) and biogeography-based optimization (BBO) metaheuristic methods in optimum discrete sizing design of a steel planar truss comprising earthquake load impact has been investigated. To do this, a 46-element steel planar truss has been handled as a design example. Like many other stochastic optimization methods, the TLBO and BBO techniques imitate specific natural events. In TLBO, the processes are carried out by mimicking a class consisting of teachers and students; on the other hand, the BBO simulates the distribution of species in nature based on biodiversity. The stress and displacement constraints in American Institute of Steel Construction-Allowable Stress Design (AISC-ASD) provisions are considered as structural behavior constraints. Both algorithms select design profiles from a discrete list containing steel W-shaped sections. For obtaining the minimum weighted optimum structural design, the algorithms encoded in MATLAB are supplied with open application programming interface (OAPI) functions that enable mutual data transfer with a structural analysis software (SAP2000) to practically get the structural responses under the effect of load combinations containing earthquake load. The optimal truss designs yielded with TLBO and BBO algorithms are compared with those already existed in the literature. Accordingly, it has been concluded that the TLBO and BBO algorithms give successful solutions.
AtıfScopus3WoS2İncele - MakaleAçık Erişim2022Scopus SJRQ2Extraction of low-dimensional features for single-channel common lung sound classification
Engin, M. Alptekin; Aras, Selim; Gangal, Ali
In this study, feature extraction methods used in the classification of single-channel lung sounds obtained by automatic identification of respiratory cycles were examined in detail in order to extract distinctive features at the lowest size. In this way, it will be possible to design a system for the detection of lung diseases, completely autonomously. In the study, automatic separation and classification of 400 respiratory cycles were performed from the single-channel common lung sounds obtained from 94 people. Leave one out cross validation (LOOCV) was used for the calibration and validation of the classification model. The Mel frequency cepstrum coefficients (MFCC), time domain features, frequency domain features, and linear predictive coding (LPC) were used for classification. The performance of the features was tested using linear discriminant analysis (LDA), k-nearest neighbors (k-NN), support vector machines (SVM), and naive Bayes (NB) classification algorithms. The success of combinations of features was explored and enhanced using the sequential forward selection (SFS). As a result, the best accuracy (90.14% in the training set and 90.63% in the test set) was acquired using the k-NN for the triple combination, which included the standard deviation of LPC and the standard deviation and the mean of MFCC. Graphical abstract: [Figure not available: see fulltext.]
AtıfScopus15WoS9OpenAlex14İncele - MakaleYalnız künye2022Scopus SJRQ3Comparison of Statistical Methods to Graphical Method in Precipitation Trend Analysis, A Case Study: Coruh Basin, Turkey
Hırca, Tuğçe; Eryılmaz Türkkan, Gökçen
It is a known fact that the precipitation characteristics will become irregular as a result of climate change resulting from global warming. Trend analysis is one of the most effective methods of observing the effects of climate change on precipitation. This study compares the changes in precipitation with traditional trend analysis methods and graphical method (divided into subcategories using the Z-Score Index). Some preliminary analyzes (missing data estimation, homogeneity check, autocorrelation, and removal of the autocorrelation), which are lacking in many studies in the literature, have been performed. In this context, the monthly total precipitation data of the precipitation stations belonging to the Coruh Basin, one of the most important basins of Turkey, for the period 1972–2011 were used. As a result of the study, it was determined that all the stations’ data were homogeneous, and 92% of them were at the Class A level. While 100% trend is determined in Innovative Trend Analysis in total annual precipitation, this rate was just 40% at Mann–Kendall and Spearman's rho at 95% confidence. An increasing trend was determined in the “high” group of total spring precipitation at all stations.
AtıfScopus5WoS4OpenAlex5İncele - MakaleYalnız künye2022Scopus SJRQ2Determination of the gas/particle phase concentrations of PCBs in urban and rural atmosphere in Erzurum, Turkey
Paloluoğlu, Cihan; Bayraktar, Hanefi
Active sampling was conducted for the first time in Erzurum, Turkey, between August 2012 and January 2013, in order to investigate the presence of 82 polychlorinated biphenyls (PCBs) congeners. Urban and rural ambient air samples, including gas and particle phase atmospheric concentrations (GAPPACs) of PCBs, were collected simultaneously using high volume air sampler (HVAS) at two different sampling points of Erzurum. GAPPACs of PCB samples taken using HVAS in Palandöken Mountain Region (2565 m) and Ataturk University Campus (1870 m) were analyzed in GC–MS following appropriate extraction steps. Throughout the sampling period, total ambient air concentrations (gas phase + particulate phase) were 10 ± 6 and 27 ± 13 pg/m3 (mean) for Palandöken Mountain Region (PMR) and Atatürk University Campus (AUC), respectively. Low molecular weighted PCBs were found to be dominant in both rural an urban sampling sites. Meteorological parameters especially temperature (from Clausius–Clapeyron equation), wind direction, wind velocity, and precipitation were found to be effective on PCB concentration and distribution. The gas-particle distributions of PCBs in the summer and winter period were found to be 82% (gas phase) and 18% (particle phase) in the PMR and 90% (gas phase) and 10% (particle phase) in AUC, through Junge-Pankow adsorption model. In the light of these findings, total PCB concentrations detected in urban atmosphere (due to possible PCB sources) were observed to be higher than those determined in rural area.
AtıfScopus1WoS1İncele - MakaleAçık Erişim2021Scopus SJRQ2Modeling and solving assembly line worker assignment and balancing problem with sequence-dependent setup times
Yilmaz, Hamid
Assembly lines appear with various differentiations in order to better include the disabled in the labor market and to increase production efficiency. In this way, the optimal workforce assignment problem that emerges heterogeneously is called assembly line worker assignment and balancing problem (ALWABP). This paper addresses the ALWABP where the simple version is enriched by considering sequence-dependent setup times between tasks. A mixed integer linear programming model is presented, and a simulated annealing algorithm is developed such as an NP-hard problem. In order to test the proposed solutions, 640 benchmark problems in the literature were combined and used. The solutions obtained through using the proposed algorithm are compared with the mixed integer programming model on the small-size test problems. Experimental results show that the proposed algorithm is more effective and robust for a large set of benchmark problems.
AtıfScopus14WoS12OpenAlex16İncele - MakaleAçık Erişim2021Scopus SJRQ2An Experimental and Numerical Determination on Low-Velocity Impact Response of Hybrid Composite Laminate
Erbayrak, Engin; Yuncuoglu, Ercument Ugur; Kahraman, Yusuf; Gumus, Beril Eker
In this study, experimental and numerical investigations were carried out in order to determine the mechanical properties and impact response of hybrid composite laminate. The hybrid composite laminate was formed from plain woven carbon fiber reinforced epoxy (CFRE) and plain woven glass fiber reinforced epoxy (GFRE) fiber using VARTM (vacuum-assisted resin transfer molding) process. The mechanical properties of the hybrid composites were determined using tensile test device with a 1 mm/min loading rate at room temperature. In addition, hybrid composites were subjected to low-velocity impact test under different impact energy levels (10, 20, 30, 40 J) for determining the impact response. Moreover, mechanical properties and impact responses of CFRE and GFRE laminates were also determined to compare to those of hybrid composite (HCGFRE). Microstructure analysis was performed to investigate the damage surfaces of the fiber and matrix in the composite material subjected to impact and tensile forces. In numerical analyses, composite damage model (Mat 54) was utilized in LS-DYNA® explicit finite element program to simulate the impact behavior of CFRE, GFRE and HCGFRE laminates. Consequently, the tensile test results showed that hybrid composite laminate behaved more ductile than carbon composite laminate and it exhibited more brittle behavior than glass composite laminate. Also, it was determined that absorbed energy and impact load capacity of HCGFRE composite laminate are between absorbed energy and impact load capacity of CFRE and GFRE composite laminate. It was determined that numerical results indicate a similar tendency with the experimental results.
AtıfScopus12WoS13OpenAlex14İncele - MakaleAçık Erişim2021Scopus SJRQ2Production, purification, and characterization of Streptomyces sp. strain MPPS2 extracellular pyomelanin pigment
Bayram, Sinan
Melanins are natural pigments widely distributed in nature from bacteria to humans. These complex, negatively charged, amorphous, high molecular mass natural biopolymers have many different bioactive properties such as antimicrobial, antiviral, antioxidant, liver protective effects, etc. In this study, some chemical and physical properties of the purified extracellular pyomelanin pigment were investigated via XRD (X-ray diffraction), FT-IR (Fourier transform infrared), and 1H NMR (Nuclear magnetic resonance). Additionally, the melanin pigment producer Streptomyces sp. strain MPPS2 was characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS) and 16S rDNA sequence analysis. 16S rDNA nucleotide sequence analysis result was deposited in NCBI GenBank® under accession number MT825616.
AtıfScopus28WoS22OpenAlex27İncele - MakaleAçık Erişim2021Scopus SJRQ1Development of a Fuzzy Exponentially Weighted Moving Average Control Chart with an α-level Cut for Monitoring a Production Process
Kaplan Göztok, Kader; Uçurum, Metin; Özdemir, Akın
Statistical quality control is a useful approach that applies to statistical techniques for monitoring a production system. These charts are effective to monitor the process under certain conditions. On the other hand, the fuzzy set theory is an appropriate tool to deal with an uncertain situation. This paper is fourfold. First of all, triangular fuzzy numbers with an α-level cut technique are used for each sample. The α-level cut technique is sensitive to satisfy the process requirement. Second, a fuzzy exponentially weighted moving average (FEWMA) control chart is proposed with the α-level cut technique. The proposed FEWMA detects small shifts under uncertain situations while using a unity technique for samples. Third, the fuzzy target-focused process capability index (FCpm) index is proposed to measure the fuzzy process performance. Then, a case study is presented to monitor a pumice block plant using the FEWMA control chart with the α-level cut and measure the process performance with the FCpm index. Comparative studies are also presented. By using the proposed FEWMA control chart with the α-level cut, the accuracy and the flexibility of control specification limits are reported for the case study.
AtıfScopus9WoS8OpenAlex7İncele - MakaleYalnız künye2021Scopus SJRQ2Asymmetric reduction of aromatic heterocyclic ketones with bio-based catalyst Lactobacillus kefiri P2
Baydaş, Yasemin; Kalay, Erbay; Şahin, Engin
Abstract: Chiral heterocyclic secondary alcohols have received much attention due to their widespread use in pharmaceutical intermediates. In this study, Lactobacillus kefiri P2 biocatalysts isolated from traditional dairy products, were used to catalyze the asymmetric reduction of prochiral ketones to chiral secondary alcohols. Secondary chiral carbinols were obtained by asymmetric bioreduction of different prochiral substrates with results up to > 99% enantiomeric excess (ee). (R)-1-(benzofuran-2-yl)ethanol 5a, which can be used in the synthesis of pharmaceuticals such as bufuralols potent nonselective β-blockers antagonists, Amiodarone (cardiac anti-arrhythmic), and Benziodarone (coronary vasodilator), was produced in gram-scale, high yield and enantiomerically pure form using L. kefiri P2 biocatalysts. The gram-scale production was carried out, and 9.70 g of (R)-5a in enantiomerically pure form was obtained in 96% yield. Also, production of (R)-5a in terms of yield and gram scale through catalytic asymmetric reduction using the biocatalyst was the highest report so far. This is a cost-effective, clean and eco-friendly process for the preparation of chiral secondary alcohols compared to chemical processes. From an environmental and economic perspective, this biocatalytic method has great application potential, making it a green and sustainable way of synthesis. Graphical Abstract: [Figure not available: see fulltext.]
AtıfScopus8WoS8OpenAlex9İncele - MakaleAçık Erişim2021Scopus SJRQ1Removal of Cu(II) from aqueous solutions using modified sewage sludge ash
Kul, S.
The study aims to determine Cu(II) adsorption from wastewater in the laboratory condition using modified sewage sludge ash as adsorbent which was obtained from a thermal drying and incineration facility. This procedure was completed with an inexpensive pollutant material which has high metal-binding capacity and is available in abundant amounts. During experiments, the effects of particle size, pH, stirring speed, initial ion concentration, adsorbent dosage and temperature were investigated. Adsorption equilibrium was obtained in 10 min. Maximum Cu(II) removal was calculated as 83.63% with 20 mg L−1 initial Cu(II) ion concentration and 5 g L−1 adsorbent dosage. Kolmogorov–Smirnov normality test was performed to test the conformity of the data obtained as a result of the study to variance analysis, and it was determined that the data were distributed normally (p > 0.05). Levene test was performed for homogeneity test, and it was determined that the data were distributed homogeneously (p > 0.05). Langmuir was determined as the most suitable isotherm model for Cu(II) adsorption. Adsorption kinetics abided by the pseudo-second-order model. Based on kinetic studies, the adsorption process was endothermic with maximum adsorption capacity calculated as 7.53 mg g−1. The results of thermodynamic research showed the adsorption reaction was spontaneous (ΔG° < 0), endothermic (ΔH° > 0) and reversible (ΔS° > 0 and close to zero).
AtıfScopus10WoS10OpenAlex12İncele - Kitap BölümüAçık Erişim2021Scopus SJRQ4The Importance of Foreign Direct Investments in Turkey’s Export: A New Strategy for Low and Medium Tech Firms
Adalı, Zafer; Bilgin, Tuba
This research investigates the relationship between Foreign Direct Investment (FDI) and export operated by low-, medium low-, and medium high-tech firms in Turkey. For this purpose, a hidden cointegration approach developed by Hatemi and Iraoundaoust Hidden cointegration is conducted on data covering the period between 2006:Q1 and 2018:Q3. According to Hatemi and Irandoust (Asymmetric interaction between government spending and terms of trade volatility. Journal of Economic Studies 39(3):368–378, 2012), hidden cointegration, there is no long-run relationship between the cumulative positive shocks of Low Tech Export (LTX) and cumulative positive shocks of FDI; the same existence is obtained for the cumulative negative shock between the variables. The outcomes identify that LTX and FDI respond to shocks differently in Turkey. Moreover, the same results were found for Medium Low-Tech Export (MLTE) and FDI. In another saying, a positive and negative shock in MLTX does not proceed with positive and negative shocks in FDI. Nonetheless, a long-run relationship between Medium High-Tech Export (MHTE) and FDI concerning both the positive and negative cumulative shocks is also found. A positive shock in MHTX is associated with the influence of positive in FDI. Furthermore, a negative shock in MHTX is also linked to the impacts of negative in FDI. Thus, it is recommended that Companies and governments manage cooperatively with foreign investors, sustain and create locational advantages, and implement policies that lower costs because low and medium low-tech export plays a ruling role in export performance.
AtıfScopus1OpenAlex1İncele - MakaleAçık Erişim2021Scopus SJRQ1Modal identification and fatigue behavior of Eynel steel arch highway bridge with calibrated models
Sunca, Fezayil; Ergün, Mustafa; Altunişik, Ahmet Can; Günaydin, Murat; Okur, Fatih Yesevi
In this paper, modal parameters of the Eynel steel arch highway bridge are identified and the fatigue behavior of the bridge is investigated. Modal parameters were extracted from three ambient vibration tests carried out over the period since the bridge came into service. The bridge became operational in 2009, and experimental measurements were taken in 2010, 2019, and 2021. The Enhanced Frequency Domain Decomposition (EFDD) method in the frequency domain and the Stochastic Subspace Identification (SSI) method in the time domain were used. Modal parameters were compared and any differences found over time in the measurement test results were investigated. Comparison of the results shows that changes in the natural frequencies were very limited and there was no change between the mode shapes. When experimental natural frequencies were compared, the maximum difference between the first and second measurements was calculated as 2.827%. Similarly, the maximum difference between the first and third measurements was 5.587% for the second mode, and around 3% for the other modes. This result is as expected because: (i) the bridge is not subject to heavy vehicle traffic and only connects village roads; (ii) no significant earthquake occurred during this period in the region which might have caused structural damage; (iii) no corrosion was found in the structural system elements as there was no contact with the reservoir water; (iv) no settlement or sliding occurred in the ground and boundary conditions remained unchanged. Moreover, the fatigue behavior of the bridge was investigated using the stress life method and AASHTO LRFD Bridge Design Specifications. To rationalize the results against the fatigue effects, the verified finite element model was used. From the fatigue analyses, it was concluded that the fatigue life of the bridge was within safe limits.
AtıfScopus16WoS16OpenAlex16İncele - MakaleAçık Erişim2021Scopus SJRQ2Relationship between hydraulic and geoelectrical parameters for alluvial aquifers in Bursa, Turkey—a case study
Eryılmaz Türkkan, Gökçen; Korkmaz, Serdar
This research aims at analyzing the relationship between the hydraulic conductivity and the formation factor in alluvial aquifers. The study was conducted on the alluvial aquifers within the province of Bursa, Turkey. Field surveys were carried out on 12 different locations each having alluvial formation. Initially, slug tests were applied at the wells and hydraulic conductivity values were calculated by using Bouwer-Rice and Dagan analytic methods. Afterwards, vertical electrical sounding method with Schlumberger array was applied on these locations to obtain apparent resistivity. These values were then converted to real resistivity under IPI2WIN software. Water samples were taken from the wells, and their electrical conductivity values were measured in the laboratory which were converted to water resistivity. Finally, formation factor was calculated as a ratio of real resistivity to water resistivity. The variations of hydraulic conductivity and transmissivity values against the formation factor were examined, and a linear relation was observed. Furthermore, their variations against modified formation factor and modified aquifer resistivity were also investigated and similarly linear relationships were observed. The graphs obtained conform to the results of similar studies in literature and will serve as a guideline for prospective groundwater research in the study area.
AtıfScopus3OpenAlex2İncele - MakaleAçık Erişim2021Scopus SJRQ1Pb (II) biosorption from the aqueous solutions by raw and modified tea factory waste (TFW)
Nuhoğlu, Y.; Ekmekyapar Kul, Z.; Kul, S.; Nuhoğlu, Ç.; Ekmekyapar Torun, F.
The study is aimed to determine Pb (II) biosorption from synthetic wastewaters using natural and modified tea factory waste as biosorbent material. This process is carried out with this waste matter, which is found in large quantities, so cheap and has high metal adsorption ability. The sorption kinetic studies were determined as variations of initial pH value, particle size, initial Pb (II) and tea factory waste concentrations, stirring speed and temperature. Biosorption reached the equilibrium in 15 min. Zeta potential values of the biosorbent were defined in the range of pH 2 to 4. The adsorption isotherm models give the experimental values, and the thermodynamic characteristics of the patterns generally give insight about the sorption mechanism depending on the surface characteristics and affinity of the biosorbent. The biosorption mechanism was searched considering to Freundlich, Langmuir, BET and Temkin isotherm model, and the experimental adsorption values were conformed to Freundlich adsorption model. The optimum experimental conditions were investigated as pH 3.5, particle size of 0.125–0.25 mm, stirring speed of 200 rpm, biosorbent concentration of 7 g L−1 and 25 °C. In these conditions, the highest efficiency of biosorption was obtained as 94.07% and after the activating process the efficiency was reached to 97.73% at 70 mg L−1. The maximum Pb (II) removal capacity of raw tea factory waste was found to be 22.111 mg g−1 at 200 mg L−1. The biosorption kinetics has complied with the pseudo-second-order model. Thermodynamic studies stated that this biosorption phenomenon was an endothermic process.
AtıfScopus26WoS26OpenAlex27İncele - Kitap BölümüAçık Erişim2021Parallel Assembly Lines with Heterogeneous Workforce: A Cost-Driven Mathematical Model and Simulated Annealing Approach
Kökhan, Serhan; Baykoç, Ömer Faruk; Xu, J; Marquez, FPG; Hassan, MHA; Duca, G; Hajiyev, A; Altiparmak, F
In recent years it has become possible for people, machines and robots to work collaboratively in most production environments. Collaborative working models, which are diversified with the concept of Industry 4.0, have become an important issue in Assembly Line Problems (ALP). In this study, a cost-driven mathematical model which combines Parallel Assembly Line Problems and human and robot collaborative workforce which is an important parameter of Industry 4.0 philosophy is proposed. The mathematical model was tested for new data sets derived from existing data sets in the parallel assembly lines literature and the results were analyzed. Because of the NP-hardness of ALP, a heuristic approach based Simulated Annealing (SA) algorithm was proposed to solve for larger sized problems. For this purpose, the same data sets were solved with SA and the results were compared and analyzed. The results show that the mathematical model gives better results up to Tonge data set (140 task), but feasible solutions can only be obtained by SA algorithm for the rest. Since there are very few studies with heterogeneous workforce in Parallel Assembly Line Balancing Problems (PALBP), this study is believed to provide a significant contribution to related literature.
AtıfScopus5WoS5OpenAlex8İncele - MakaleAçık Erişim2020Scopus SJRQ2Investigations of Strain Rate Effects on the Mechanical Properties of Hybrid Composite Laminate Under Varying Temperatures
Erbayrak, Engin; Gumus, Beril Eker; Yuncuoglu, Ercument Ugur; Kahraman, Yusuf
The mechanical behavior of hybrid composite laminates under varying strain rates and temperatures was investigated in this study. The hybrid composite laminate is constituted as a sequential stacking sequence of plain-woven carbon-fiber-reinforced epoxy (CFRE) and plain-woven glass-fiber-reinforced epoxy (GFRE) laminates. Vacuum-assisted resin transfer molding (VARTM) process was used to fabricate the composite laminates. Hybrid composite laminates (HCGFRE) were tested under four different strain rates (0.05 min−1, 0.5 min−1, 2.5 min−1, 5 min−1) and three different temperatures (RT, 60 °C, 100 °C). Microstructure analysis was performed to observe the voids, fiber delamination and matrix failure occurring in the composite laminate. In numerical analyses, continuum damage mechanics material model (MAT 58) was utilized in LS-DYNA® explicit finite element program to simulate the mechanical properties of CFRE, GFRE and HCGFRE laminates. It was determined that the tensile strength of all composite laminates is increasing by increasing the strain rates in all temperatures. The continuous damage mechanics material model (MAT 58) was found to be suitable for simulating woven composite laminate under different strain rates and temperatures. In microstructural study, it was not observed significant changes in the microstructure of composite laminates by changing strain rates.
AtıfScopus1WoS1OpenAlex3İncele - MakaleAçık Erişim2020Scopus SJRQ2Bioproduction, structure elucidation and in vitro antiproliferative effect of eumelanin pigment from Streptomyces parvus BSB49
Bayram, Sinan; Dengiz, Cagatay; Gerçek, Yusuf Can; Cetin, Idil; Topcul, Mehmet R.
In this study, the structure of the purified extracellular eumelanin pigment isolated from Streptomyces spp. was elucidated by detailed analysis via two different spectroscopic techniques (FT-IR and NMR). In vitro antiproliferative effects of eumelanin were evaluated on HeLa cell line. These experiments were carried out with the evaluation of the parameters including cell viability, cell index, and mitotic index. With the cell viability and cell index, IC50 concentration of eumelanin was determined as 10 μM. This result showed that the IC50 concentration of eumelanin decreased the values of cell viability, cell index and mitotic index. These changes are statistically significant (p ' 0.01). The ability of the dissolved eumelanin (250 μg mL−1) to scavenge free radicals was determined via DPPH and ABTS and was shown to be about 87.73% and 75.2%, respectively, compared with standard antioxidants. It was observed that dry weights of eumelanin yield among the selected strains ranged from 160 to 240 mg L−1. The strain with the highest production potential was selected for 16S rDNA sequence analysis and, accordingly, the selected strain BSB49 was identified as Streptomyces parvus and the sequence analysis results were deposited in NCBI under accession number MK894155.
AtıfScopus47WoS40OpenAlex48İncele