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Koleksiyondaki öğeler
- MakaleAçık Erişim2023Scopus SJRQ4Using the Taguchi Method to Optimize the Compressive Strength of Concrete in Different Aggregates Typology; [Farklı Tipolojideki Doğal Agregalı Betonların Basınç Dayanımını Optimize Etmede Taguchi Metodunun Kullanımı]
Gönen, Tahir; Cemalgil, Selim
Concrete quality is affected by many factors such as mixing ratios, material quality, transporting, placing and curing. One of the crucial factors that changes the compressive strength of concrete is aggregate which makes up 75% of concrete during concrete production. Properties of aggregate are more unstable than other materials depending on various reasons. Granulometry, moisture or organic substance amount of the aggregates which have same origin may differ within time. This study investigates physical and mechanical properties of crushed limestone and crushed river aggregates. It is on optimum design of concrete with crushed limestone and crushed river aggregates. At first, physical and mechanical properties of the aggregates are measured, then Taguchi method is applied. Test variables are water-to-binder ratio, cement dosage, river sand ratio to limestone and air entrained agent. L16 orthogonal array as an experimental design method is applied to determine the optimum concrete design in terms of compressive strength and flexural strength. Furthermore, contribution of variables on compressive and flexure strength is determined statically by using ANOVA method. Among the 4 different aggregate ratios evaluated in the study, the best performance is from the combination of 70% stream and 30% limestone. The weakest performance is from the series that do not contain any stream material.
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İncele - MakaleAçık Erişim2022Scopus SJRQ3Investigation of rutting, fatigue and cracking resistance parameters of CR modified warm asphalt binders compare with SBS modified binders
Akpolat, Mustafa
This study compares the rutting and cracking resistance and fatigue parameters of crumb rubber (CR) modified warm asphalt binders, which were determined by viscoelastic continuum damage (VECD) theory. The effect of the combination of CR modification and Sasobit, a warm mix additive, was investigated. Performance of CR + Sasobit compound was compared with styrene-butadiene-styrene (SBS) modification. Newly developed rheological tests such as multi stress creep recovery (MSCR), lineer amplitude sweep (LAS) and conventional tests were applied to modified binders. It was determined that the CR + Sasobit modified binders improved the rutting parameter better in comparison to SBS-added binders. Although the CR additive improved the rheological properties of the binder at low and medium temperatures, this effect was reduced when used with Sasobit additive. Sasobit additive increased the stiffness and decreased the fatigue parameter at low temperatures. Besides, the results of the LAS test revealed that at high strain values (i.e.> 6%), the fatigue life of CR and Sasobit modified binders was lower than the fatigue life of the pure binder. In other words, CR and Sasobit modified binders could not preserve material integrity.
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İncele - MakaleAçık Erişim2021Scopus SJRQ1Highly Efficient Defluoridation of Water through Reusable poly(aniline-co-o-aminophenol) Copolymer Modified Electrode Using Electrochemical Quartz Crystal Microbalance
Unal, Asuman; Hillman, A. Robert; Ryder, Karl S.; Cihangir, Salih
Although the World Health Organization (WHO) recommends a limit of 1.5 mg l-1 fluoride ions in drinking water, this is not satisfied in many parts of the world. When this limit is exceeded, the electrochemically switched ion-exchange (ESIX) technique (mainly based on conductive polymers) has been identified as a promising method for removing the excess fluoride ions. The present study aimed to develop an efficient method based on the ESIX technique by using poly(aniline-co-o-aminophenol) copolymer to extract fluoride ions. Electrochemical quartz crystal microbalance (EQCM) and acoustic admittance data were utilized to assay the synthetic efficiency of copolymer deposition, and to evaluate the dependence of the defluoridation process on the proportions of the monomers in the copolymer matrix and on film thickness. The resulting films were characterised by Fourier transform infrared spectroscopy (FTIR) and scanning electrochemical microscopy (SEM) techniques. For optimized co-monomer ratio in the feedstock, poly(aniline-co-o-aminophenol) at an applied potential of 0.30 V showed excellent performance for fluoride removal from water at pH 6.6, to the extent of 20 (mg F-) (g polymer)-1. Comparison of the performance of ESIX using poly(aniline-co-o-aminophenol) with that of other techniques and materials reveal that it has significant potential for water defluoridation.
AtıfScopus9WoS8OpenAlex10İncele - MakaleAçık Erişim2022Scopus SJRQ1A Bayesian BWM and VIKOR-based model for assessing hospital preparedness in the face of disasters
Saner, Halit Serdar; Yucesan, Melih; Gul, Muhammet
Hospitals are the first point of contact for people in the face of disasters that interfere with the daily functioning of life and endanger health and social life. All preparations should be made considering the worst possible conditions and the provided service should continue without interruption. In this study, a multi-criteria decision-making model was developed to evaluate disaster preparedness of hospitals. This decision model includes Bayesian best–worst method (BBWM), the VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) and technique for order preference by similarity to ideal solution (TOPSIS) methods. With the proposed decision model, six main criteria and 34 sub-criteria related to disaster preparedness of hospitals were considered. The criteria and sub-criteria evaluated in pairwise comparison manner by the experts were weighted with BBWM. These weight values and the data obtained from the six Turkish hospitals were combined to provide inputs for VIKOR and TOPSIS. In addition, a comparative study and sensitivity analysis were carried out using weight vectors obtained by different tools. BBWM application results show that the “Personnel” criterion was determined as the most important criterion with an importance value of 26%. This criterion is followed by “Equipment” with 25%, “Transportation” with 14%, “Hospital building” and “Communication” with 12%, and “Flexibility” with 11%. Hospital-2 was determined as the most prepared hospital for disasters as a result of VIKOR application. The VIKOR Q value of this hospital was obtained as 0.000. According to the results of the comparative study, Hospital-2 was determined as the most disaster-ready hospital in all six different scenarios. This hospital is followed by Hospital-4 (Q = 0.5661) and Hospital-5 (Q = 0.7464). The remaining rankings were Hospital-6, Hospital-3 and Hospital-1. The solidity of the results was checked with TOPSIS. Based on TOPSIS application results, Hospital-2 was again found the most-ready hospital. The usage of BBWM in this study enabled the expert group’s views to be combined without loss of information and to determine the criteria and sub-criteria weights with less pairwise comparisons in a probabilistic perspective. Via the “Credal ranking”, which is the contribution of BBWM to the literature, the interpretation of the hierarchy between each criterion has been performed more precisely.
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İncele - MakaleYalnız künye2022Scopus SJRQ2Interval basic uncertain information and related aggregations in decision making
Jin, Lesheng; Mesiar, Radko; Yager, Ronald; Kaya, Sema Kayapinar
The recently proposed basic uncertain information can directly present numerical uncertainties for given real values, but it cannot handle given interval values which themselves also have uncertainties. Against this background, this work proposes the concept of interval basic uncertain information which serves as a generalization of basic uncertain information and involves two types of uncertainties. We analyze some basic operations, weighted arithmetic mean and preference transformation for interval basic uncertain information. The Rule-based decisions and the comprehensive certainty of interval basic uncertain information are also discussed. An illustrative example of multi-source multi-criteria evaluation under interval basic uncertain information environment is presented.
AtıfScopus18OpenAlex17İncele - MakaleYalnız künye2021Scopus SJRQ1Crack failure in hydrodynamically lubricated bearings: A case study hydraulic turbine
Taşgın, Yahya; Kahraman, Gökhan
This study investigates the trunnion crack of a 50 MW hydraulic turbine in the generator guide bearing. The crack area has been examined metallographically and the fixing method for the the trunnion crack has been explained. Result of the study shows that the reason for the formation of the bearing trunnion crack can be the thermal stresses that occur during the mounting of the bearing trunnion to the turbine shaft and the material fatigue that occurs during the operation of the hydraulic turbine.
AtıfScopus9WoS7OpenAlex9İncele - MakaleYalnız künye2022Scopus SJRQ2Structural characterization and oxidative stability of black cumin oil oleogels prepared with natural waxes
Orhan, Necla Ozdemir; Eroglu, Zeynep
In this study, black cumin oil (BCO) oleogel was produced using natural waxes (beeswax: BW, sunflower wax: SFW, and carnauba wax: CW) to offer a healthy alternative to shortening. Oiling-off was observed only in the BW oleogel (3.88 ± 0.02%). The CW oleogel had the lowest Ea (354.82 kJ/mol), indicating greater resistance to thermal degradation. The highest G′ and G″ were observed in the CW oleogel, while the lowest was observed in the BW oleogel. All oleogel samples displayed weak gel properties (tan δ > 0.1), but the lowest tan δ value belonged to the CW oleogel (0.12). After 4 weeks of storage, the peroxide values of the oleogels were lower than those of bulk oil (p <.05). Finally, the oxidation results showed that the BCO structuring by the waxes effectively protected it from oxidation over eight weeks of storage. Novelty impact statement: The most important innovation of the present study was to investigate the effect of BCO oleogelation on the stability of thymoquinone, the main phenolic compound of BCO. The BCO oleogels had higher thymoquinone content during the first half of the storage period compared with bulk BCO, showing that the oleogel network provides a protective effect against oxidation and thermal degradation.
AtıfScopus14WoS11OpenAlex17İncele - MakaleAçık Erişim2021Scopus SJRQ3A novel macrofungus for the biosorption of hazardous dye and its reuse potential: Experimental design approach using response surface methodology
Ince, Olcay Kaplan; Alp, Hevidar; Ince, Muharrem; Onal, Ali
In the present study, a novel biosorbent, namely Agaricus campestris, was used for the removal of Methylene Blue (MB) from an aqueous medium. The biosorbent was characterized using fourier-transform infrared spectrometer spectra, scanning electron microscopy-energy dispersive X-ray, and thermogravimetric analysis. The influence of important process parameters including pH (4–7), temperature (25°C–35°C), contact time (15–25 min), and biosorbent amount (40–80 mg) on the uptake of MB solution were also optimized, which significantly affected the removal efficiency of MB. A central composite design (CCD) combined with response surface modeling (RSM) was carried out to maximize MB removal by A. campestris for the adsorption process. A regression model was derived using RSM to predict the responses and analysis of variance (ANOVA), and to check model adequacy lack of fit test was used. The A. campestris adsorption capacity was determined as 24.2 mg g–1. The ANOVA showed a high coefficient of determination (R2 = 0.9987). This study clearly revealed that RSM was one of the most effective and appropriate method for the optimization of operating conditions. The possibility of reusing A. campestris was also investigated and, as a result, it was found quite possible and showed high performance in the recovery of MB.
AtıfScopus2WoS1OpenAlex2İncele - MakaleAçık Erişim2022Scopus SJRQ2Chrysin and flunixin meglumine mitigate overloaded copper-induced testicular and spermatological damages via modulation of oxidative stress and apoptosis in rats
Parlak Ak, Tuba; Tatli Seven, Pinar; Gur, Seyfettin; Gul, Burcu; Yaman, Mine; Seven, Ismail
This study aimed to evaluate the possible protective actions of chrysin and flunixine meglumine on testicular and spermatological injuries experimentally stimulated by copper. We separated 36 male Sprague–Dawley rats into six equal groups: control, chrysin, flunixine meglumine, copper, copper +chrysin and copper +flunixine meglumine. Chrysin (50 mg/kg/bw/po), flunixine meglumine (2.2 mg/kg/bw/ip) and copper (500 mg/kg/bw/po) were administered day to day for 21 days. Copper administration caused significant morphological, physiological and biochemical alterations compared to the control group, which are as follows: production of oxidative stress, thanks to rise in testis lipid peroxidation and fall in antioxidant enzyme concentrations, decrease in sperm quality and increase in morphologic sperm abnormalities, suppression of spermatogenesis and prominent alterations in the testis histomorphology and induction of apoptosis in the testis tissues. On the other hand, compared to the copper group, treatment with chrysin or flunixine meglumine significantly attenuated these alterations. In conclusion, chrysin and flunixine meglumine have benefits such as antioxidant, antiapoptotic and anti-inflammatory against copper-induced testicular and spermatological damages in rats via the modulation of oxidative stress and apoptosis. Consequently, chrysin is a natural product which has comparable therapeutic actions to flunixine meglumine on the male reproductive system.
AtıfScopus4OpenAlex4İncele - MakaleYalnız künye2022Scopus SJRQ2Thermal analysis of a radiative nanofluid over a stretching/shrinking cylinder with viscous dissipation
Alqahtani, Aisha M.; Riaz Khan, M.; Akkurt, Nevzat; Puneeth, V.; Alhowaity, Awatif; Hamam, Haneen
This study explores the impact of thermal radiation and viscous dissipation on the stagnation point flow of a copper–water nanofluid across a convective stretching/shrinking cylinder. The copper suspension in the base fluid water enables the fluid to conduct more heat by increasing its thermal conductivity. The mathematical model that governs the flow of Cu-H2O nanofluid is formulated by the system of partial differential equations (PDEs) which are then subjected to transformation by introducing suitable similarity variables so the system is transformed to the Ordinary Differential Equations (ODEs). These equations have been solved numerically via the bvp4c package in MATLAB. The outcomes have been signified graphically in the form of heat transfer rate, temperature, skin friction and velocity which are dependent on the concerning flow parameters. For each of these result, dual solutions have been produced which are conditional on the shrinking of cylinder. These results declare that the skin friction increases for the shrinking cylinder and decreases for the stretching cylinder whereas an opposite trend is seen for the rate of heat transfer. Similarly, heat transfer is found to be decreasing for the increase in both Biot and Eckert number. Meanwhile, the existence of greater values of curvature parameter causes to enhance both first and second solution of velocity as well as the temperature is augmenting with the increase in Eckert number and volume fraction of nano particles.
AtıfScopus38OpenAlex39İncele - MakaleAçık Erişim2023Scopus SJRQ4Physicochemical and Phytochemical Properties of Different Extracts of Sumac Plant (Rhus coriaria L.) Grown in Tunceli, Türkiye; [Tunceli'de Yetişen Sumak Bitkisinin (Rhus coriaria L.) Farklı Ekstraktlarının Fizikokimyasal ve Fitokimyasal Özellikleri]
Yuksel, Esra; Ince, Olcay Kaplan
In this study, sumac plant (Rhus coriaria L.) naturally grown in Tunceli (Türkiye) was collected from 5 different provinces and investigated for their phytochemical properties. In sumac samples, pH, color, ash amount, total phenolic content (TPC), 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging capacity, metal chelating capacity, copper (II) ion reducing antioxidant capacity (CUPRAC), reducing power, mineral matter content, organic acids as tartaric acid, malic acid and citric acid, phenolic compounds as gallic acid, vanillic acid, caffeic acid, routine, resveratrol, (-)- epicatechin, and (+)- catechin hydrate contents were determined. The highest TPC was found in the acidified methanol extract (AME) and the DPPH free radical scavenging capacity was found in the acidified acetonitrile extract (AAE). It was determined that all extracts of sumac sample 5 (S5) collected from Pertek district, metal chelating capacity was higher than the other samples but lower than the metal chelating capacity of ethylene diamine tetra acetic acid (EDTA). CUPRAC was detected at the highest concentration of 118.0±3.0 mg caffeic acid equivalent kg-1 (mg CAE kg-1) in the AME, at the lowest 10.2±0.6 mg CAE kg-1 in the AAE for S5 sample. It was found that the reducing powers of all samples were found to be lower than the reducing power of synthetic antioxidants (butylhydroxytoluene (BHT), α tocopherol, and vitamin C), and the samples were rich in mineral substances, the predominant organic acid was malic acid, and phenolic compound was gallic acid.
AtıfScopus2OpenAlex2İncele - MakaleYayıncıda açık erişim2022Scopus SJRQ4Epiphytic bryophyte vegetation of Fagus orientalis trees in Hıdırnebi Plateau (Trabzon, Turkey); [Эпифитная бриофитная растительность на стволах деревьев Fagus orientalis на плато Хыдырнеби (Трабзон, Турция)]
Alataş, Mevlüt; Ezer, Tülay; Erata, Hüseyin; Batan, Nevzat
In this study, the epiphytic bryophyte vegetation of Fagus orientalis forests in Hıdırnebi Plateau (Trabzon, Turkey) was investigated. A total of 34 relevés taken from living tree trunks in the different vegetation periods of 2020 were analysed according to the Braun-Blanquet methodology. As a result of the analyses, the Leskeello nervosae–Pterigynandretum filiformis, Leskeello nervosae–Pterigynandretum filiformis lewinskyetosum rupestris subass. nov., Pseudoleskeello nervosae–Raduletum lindbergianae ass. nov. and Pseudoleskeello nervosae–Raduletum lindbergianae isothecietosum alopecuroidis subass. nov. were described and characterised as a new epiphytic syntaxa. The Leskeello nervosae–Pterigynandretum filiformis is also new to Turkey. In addition, the ecological and floristical characteristics of the syntaxa were evaluated.
AtıfScopus3OpenAlex2İncele - MakaleAçık Erişim2021Scopus SJRQ1Influences of sample shape, voltage gradient, and electrode surface form on the exergoeconomic performance characteristics of ohmic thawing of frozen minced beef
Çokgezme, Ömer Faruk; Döner, Deniz; Çevik, Mutlu; Kemahlıoğlu, Ali Varsın; İçier, Filiz
In the present study, it was aimed to investigate the exergoeconomic performance of ohmic thawing (OT) system during the thawing of frozen minced meat (lean beef). The effects of the sample shape (X: 13 × 4 × 3 cm, Y: 13 × 6 × 2 cm, Z: cylinder with a height of 13 cm and diameter of 3.91 cm), electrode surface form (titanium foil with smooth surface, titanium electrode with needle-type surface and titanium electrode with pyramid-type surface), and voltage gradients (10, 13, and 16 V/cm) were investigated. Lower exergoeconomic values were obtained for the cylindrical shape compared to the rectangular prism. The lowest exergy efficiency value (12.45 ± 0.42), is was obtained for the cylindrical shape at 10 V/cm voltage gradient with titanium foil electrode. The needle-type surface electrodes had higher performance values than other electrodes. The exergoeconomic performance increased as the voltage gradient increased. The lowest unit exergy cost (72.40 ± 2.8) was obtained for rectangular prism shape at 16 V/cm with needle-type electrode. The comprehensive exergoeconomic evaluation in this study exhibited the energy utilization effectiveness and unit exergy cost of OT.
AtıfScopus32WoS28OpenAlex30İncele - MakaleAçık Erişim2021Scopus SJRQ3A MCDM Based on Goal Programming and GIS-Based Risk Assessment for the Evaluation of Educational Locations in Conflict Areas
Hallak, Jamil; Polat, Elifcan Göçmen
Conflict is recognized as a major barrier in socio-economic development. In conflict situations, most sectors such as health, food, shelter and education are adversely affected. The provision of education services to conflict-affected children saves them from becoming a lost generation and contributes to community building. Thus, we conducted this research to investigate the potential of a GIS (Geographic Information Systems) approach and risk assessment based multi-criteria decision making (MCDM) for the allocation of displaced dropped-out children to the most appropriate educational centres, taking into account multiple goals related to cost, distance, risk, etc. A two-stage approach was adopted, utilizing a risk assessment approach, and a location-allocation approach. The risk assessment approach was carried out using GIS and F-AHP (Fuzzy Analytic Hierarchy Process) to determine the risk value of each candidate educational centre in the conflict area. In the location-allocation stage, a mathematical model was developed to allocate all demands to the chosen centres. All presented methods were computationally conducted on real case data provided by direct beneficiaries and stakeholders in the 26 sub-districts in the Idleb governorate, Syria. The computational results demonstrate that the proposed approaches ensure practical and theoretical impacts.
AtıfScopus8WoS5OpenAlex7İncele - Kitap BölümüYalnız künye2023Determining the Criterion Weights for the Selection of Volunteers in Humanitarian Organizations by the Best-Worst Method
Ozdemir, Umit; Mete, Suleyman; Gul, Muhammet
Today, it is vital for humanitarian organizations operating in many different fields to select volunteers from the determining criteria according to the needs of the institution. Failure to select volunteers in accordance with the institution's needs may cause the volunteers to be unable to continue their duties and interrupt the institution's work. When choosing volunteers, it is essential for effective volunteer management to classify (expert, experienced, inexperienced, and insufficient) them according to the institution’s needs and assign them starting from the volunteer in the best class volunteer when necessary. The aim of this study is to determine the criteria weights in the classification of volunteers who want to participate in search and rescue activities in humanitarian aid organizations according to the criteria determined before their assignment. In this study, a questionnaire is applied to field experts in Turkey to determine the most important and least important criteria, then criteria weights are calculated by using the Best-Worst Method (BWM). The findings obtained as a result of our study are evaluated and suggestions are made on how to improve it for future studies.
AtıfScopus1OpenAlex1İncele - MakaleAçık Erişim2022Scopus SJRQ3Economic analysis of rare earth element processing methods for Mountain Pass ore
Uysal, T.
The increasing demand for rare earth elements (REE) in highly strategic sectors such as hybrid electric vehicles, renewable energy, communication technologies, and the defense industry has made REE production methods important. In recent years, studies on REE have increased rapidly; however there are many studies on REE, there are not enough studies in the literature on the economics of the beneficiation process. RE ores are generally leached after beneficiation by gravity, magnetic and flotation methods. In this study, direct leaching, attrition scrubbing and leaching, and flotation and leaching methods are evaluated economically based on the data for the Mountain Pass (MP) facility. According to the sensitivity analysis performed as a function of capital cost (CAPEX), operating cost (OPEX), and rare earths oxides (REO) recovery, REO recovery has the biggest effect on the process economies. Although the flotation method entails additional investment and operating costs, transportation and operating costs are significantly reduced result of the higher grade and recovery. The flotation method is more profitable, with larger NPV and IRR values and a shorter payback period.
AtıfScopus8WoS8OpenAlex10İncele - MakaleAçık Erişim2021Scopus SJRQ2Fabrication of porous-Ti6Al4V alloy by using hot pressing technique and Mg space holder for hard-tissue biomedical applications
Aslan, N.; Aksakal, B.; Findik, F.
Porous-Ti6Al4V (P-Ti6Al4V) alloys were produced using the hot pressing and spacer methods for hard tissue biomedical applications and in particular, the effects of porosity on the mechanical and morphological properties of the structures were investigated. P-Ti6Al4V structures having the homogeneously distributed porosities at 41.08, 52.37 and 64.10% were fabricated by adding 40, 50 and 60% spherical magnesium (Mg) powder with 350 μm particle sizes in average as spacers and evaporating magnesium via the atmosphere-controlled sintering. The obtained porous structures were characterized by SEM, XRD and EDS. Furthermore, the strength and elastic modulus were evaluated by performing compression tests. Elastic modulus and densities were found to be 40–171 MPa, 2–5 GPa and 1.59–2.61, respectively and these values have been shown to decrease with an increase in porosity. The achieved density and mechanical property values, in particular, elastic modulus are close to human bone and within acceptable ranges for with biomedical application purposes. In addition, it was also found out from the analysis of produced P-Ti6Al4V that macropores were responsible for mechanical anisotropy contributed to formation of homogeneous and inter-connected open pores. [Figure not available: see fulltext.]
AtıfScopus40WoS37OpenAlex39İncele - MakaleAçık Erişim2022Scopus SJRQ2Effects of silver/selenium/chitosan doped hydroxyapatite coatings on REX-734 alloy: Morphology, antibacterial activity, and cell viability
Aksakal, B.; Say, Y.; Sinirlioglu, Z.A.
The goal of this study was to improve the antibacterial activity and cell viability of the Rex-734 alloy in biomedical applications. Various biocomposite coatings, such as single-layer hydroxyapatite (HAp), HAp/silver(Ag), and HAp/selenium(Se)/chitosan(Chit), were applied to Rex-734 alloy at various film thicknesses. The surface coatings were characterized by scanning electron microscopy, SEM, EDX, XRD and coating thickness and hardness of surface coatings were measured. The in vitro antibacterial activities of the coated and uncoated substrates were tested against Esherichia coli JM 103 and Staphylococcus aureus ATCC29293. In vitro cell–material interactions using Saos-2 osteoblast cells were characterized by the 3-(4,5-dimethylthiazol2-yl)− 2,5-diphenyltetrazolium bromide (MTT) assay for cell viability. The post-coating sintering parameters were shown to have a significant effect on the surface morphology. When compared to single HAp and HAp/Ag coatings, Se and Chit additions to HAp powders revealed good crack-free coating surfaces. Crack-free coating morphologies were achieved with a sintering speed of 3 °C/min. While single-HA coatings had an antimicrobial efficiency of 83% against E. coli, this value increased to 94% with Ag additive and to 85% with Se additive. Similarly, Ag and Se additives improved HAp's antimicrobial efficiency against Staphylococcus aureus. Cell viability decreased in the HAp/Ag coating at 86.5% and 90.93%, but increased significantly (p < 0.05) in the HA/Se-Chit coating at 137,43% and 158.23% at the end of the first and seventh days of incubation, respectively. The addition of Ag/Se/Chit to HAp increased the viability of the Rex-734 cells. Furthermore, it was revealed that the HAp-doped Se/Chit duplex biocomposite coating groups increased bone cell viability at much higher rates than the single-layer HAp coatings.
AtıfScopus12WoS8OpenAlex8İncele - MakaleYalnız künye2021Scopus SJRQ3Investigation of the effect of baffle cut on heat transfer and pressure drop in shell-and-tube heat exchangers using CFD
Işık, Erdem; Tuğan, Volkan
The shell-and-tube heat exchanger (STHE) is one of the most widely used types of heat exchangers in industry. For this reason, studies conducted to improve the performance of STHEs are of great importance. In this study, a single-shell- and double-tube-pass STHE was designed, and a three-dimensional and steady-state flow analysis of this heat exchanger was conducted using the CFD method. The purpose of the analysis was to investigate the effect of baffle cut and mass flow rate of the fluid on the shell side on heat transfer and pressure drop by using the ANSYS Fluent, which is a type of computational fluid dynamics (CFD) software. For this aim, oil and water are used as working fluids in the shell and tubes of the STHE, respectively. Four different mass flow rates (0.6 kg/s, 0.8 kg/s, 1.0 kg/s, and 1.2 kg/s) are used for the fluid in the shell. In the analysis, three different STHEs with baffle cuts of 20%, 30%, and 40% are compared. According to the results of the CFD analysis, baffle cut plays an important role in heat transfer and pressure drop. The highest heat transfer per pressure drop was achieved for the STHE with 40% baffle cut and the lowest was achieved for the STHE with 20% baffle cut.
AtıfScopus13WoS8OpenAlex11İncele - MakaleAçık Erişim2022Scopus SJRQ1A multicriteria approach to integrating occupational safety & health performance and industry systems productivity in the context of aging workforce: A case study
Ortiz-Barrios, Miguel; Silvera-Natera, Esnela; Petrillo, Antonella; Gul, Muhammet; Yucesan, Melih
Aging represents one of the greatest challenges that mankind will have to face in the 21st century. In this regard, there is a need to deepen the technical and organizational aspects for rebalancing the job/employee relationship. Nevertheless, there are no robust approaches assisting decision-makers in the effective management of Occupational Safety & Health Performance (OSHP) and Industry Systems Productivity (ISP) convergence with a focus on Aging Workforce (AW). There is no single and unique solution. Therefore, in a win-to-win logic that favors the characteristic of the reference scenario, the aim of this paper is to propose a multicriteria approach to integrate OSHP and ISP in the context of AW. More specifically, Intuitionistic Fuzzy Analytic Hieararchy Process (IF-AHP) was used to elicit the criteria and sub-criteria under uncertainty considering degree of belongingness and non-belongingness. Decision Making Trial and Evaluation Laboratory (DEMATEL) was applied to evaluate the presence and strength of the interrelations and feedback among OSHP and ISP criteria and sub-criteria. Finally, Combined Compromise Solution (CoCoSo) was implemented to calculate a Working Suitability Index (WSI) per aging. Based on this index, interventions on each worker are proposed to underpin redesign of the company while to provide a flexible management propelling high performance in terms of OSHP and ISP. A real case study in Colombia is presented. The results revealed that Efficiency and Quality with 0.162 were found to be the most important factors in evaluating the performance of aging electrical engineers while Psychosocial risk and Occupational Safety were concluded to be the main drivers for a joint OSHP-ISP aging workforce management. The model can be an useful tool for policy and business decision-makers from the electrical sector and can be replicated with slight changes in other industries.
AtıfScopus17WoS11OpenAlex23İncele
