WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Citation - WoS: 7Citation - Scopus: 7Very High Early Strength Calcium Aluminate Based Binary and Ternary Cementitious Systems: Properties, Hydration and Microstructure(Taylor & Francis Ltd, 2023-06-16) Saydan, Murat; Keskin, Ulku Sultan; Uzal, BurakCalcium aluminate cement (CAC) is a cement type that has superior properties such as rapid strength gain, high resistance to high temperatures and harmful chemicals. However, the result of the using of CACs in the production of structural elements occur strength decreases at later ages as a result of a series of chemical reactions called 'conversion reactions' seen in these cements. In this study, the hydration kinetics and the crystalline and amorphous structures formed as a result of hydration were investigated in CAC containing different amounts and types of main oxides-based binary and ternary systems. Considering the results obtained, the main hydration product seen in these specimens was ettringite. Unlike many studies in the literature, metastable structures which cause conversion reactions, such as CAH(10), C(2)AH(8), have not been observed. Instead of conversion of the phases, ettringite needles were became thin and elongate which causes the paste structure porous and thus causing expansion and strength reduction at the later stages of hydration in some mixtures produce high amounts of ettringite. On the other hand, it is understood that the formation of stratlingite was limited strength decreases in systems where high silica fume is used.Article Citation - WoS: 1Citation - Scopus: 2The Impact of Knitted Linked Seams on Comfort and Friction Perception(Taylor & Francis Ltd, 2024-08-29) Temel, Mevra; Scott, Eleanor; Cain, Rebecca; Johnson, Andrew A.Friction from knitted clothing can cause discomfort and skin issues, underscoring the importance of tactile comfort for wearers. Seamless knitted garments are assumed to be comfortable to wear, yet there is little understanding of their tactile comfort in comparison to linked seams - the most common form of knitted garment. This novel study examines the influence of a garments knitted structural architecture on clothing comfort and wearability by investigating skin friction and tactile perception across ten body regions in both male and female participants, using two commonly utilised materials and seam designs: cotton and merino wool with plain and linked seams. The impact of seam design and regional factors on skin friction and tactile perception was analysed, revealing varying levels across tested body regions. Removing seams exposed a greater surface area to skin contact, leading to higher perceived friction levels. As such, structural elements in knitted garments enhance wearer comfort. Seamless knitwear manufacturing offers a more environmentally conscious option compared to traditional cut-and-sew processes. This study investigated the impact of knitted garment material and structure on wearer comfort by analysing skin friction and tactile perception across ten upper body regions. Removing seams increased garment-to-skin contact leading to wearer discomfort.Article Citation - WoS: 11Citation - Scopus: 13The Effect of Seed Sludge Type on Aerobic Granulation via Anoxic-Aerobic Operation(Taylor & Francis Ltd, 2014-06-17) Ersan, Yusuf Cagatay; Erguder, Tuba HandeThe effects of two seed sludge types, namely conventional activated sludge (CAS) and membrane bioreactor sludge (MBS), on aerobic granulation were investigated. The treatment performances of the reactors were monitored during and after the granulation. Operational period of 37 days was described in three phases; Phase 1 corresponds to Days 1-10, Phase 2 (overloading conditions) to Days 11-27 and Phase 3 (recovery) to Days 28-37. Aerobic granules of 0.56 +/- 0.23 to 2.48 +/- 1.28mm were successfully developed from both MBS and CAS. First granules appeared on Day 9 in both reactors, indicating that there was no difference between two seed sludge types in terms of the time period for granulation initiation. The results revealed that the granules developed from MBS performed better than CAS in terms of settleability, stability, biomass retention, adaptation, protection of granular structure at high loading rates (0.86 gN/L d and 3.92 gCOD/Ld) and low COD/TAN ratio (5). Granules of MBS were also found to be capable of providing better protection for nitrifiers at toxic free-ammonia concentrations (38-46 mg/L NH3-N), thus showing better treatment recovery than those of CAS.Article Citation - WoS: 8Citation - Scopus: 11The Ascent of Geopolitics: Scientometric Analysis and Ramifications of Geopolitical Risk(Taylor & Francis Ltd, 2022-04-18) Aysan, Ahmet Faruk; Polat, Ali Yavuz; Tekin, Hasan; Tunali, Ahmet SemihIn recent years, geopolitical risk (GPR) has been a crucial factor in investment decisions and stock markets. Therefore, we explore the research on the GPR by employing bibliometric and scientometric analytical techniques. We find 366 scientific contributions in December 2021 from the Scopus database by searching 'Geopolitical risk' in abstracts, keywords, and titles. Our findings show that GPR research has gained momentum in the last three years. Specifically, the journal Defence and Peace Economics has one of the highest numbers of research and citation on GPR. Authors in Asia also dominate the GPR literature. Overall, this study contributes to the literature by presenting the existing research that may give new insights for prospective studies in GPR.Article Citation - WoS: 6Citation - Scopus: 6Low-Speed Bending Impact Behaviour of Adhesively Bonded Dissimilar Single-Lap Joints(Taylor & Francis Ltd, 2021-10-11) Atahan, M. Gokhan; Apalak, M. KemalThis study investigates the low-speed bending impact behaviour of adhesively bonded dissimilar single-lap joints and the effects of both strength and plastic deformation capability of adherend material on adhesive failure. Dissimilar adhesive single-lap joint specimens, such as Al 2024-T3 (top adherend)-Al 5754-0 (bottom) and Al 5754-0 (top)-Al 2024-T3 (bottom), were tested at two impact energy levels (3 and 11 J) for two overlap lengths (25 and 40 mm). The progressive failure analysis of the adhesive layer was also conducted by the non-linear explicit finite element method. The adhesive layer was modelled with a 3D cohesive layer along with the upper and lower adhesive interfaces and a non-linear continuum adhesive region between two cohesive layers. The continuum adhesive region had elasto-plastic adhesive properties whilst the cohesive layers obeyed 3D cohesive rules. The experimental and predicted contact force-time, contact force-displacement diagrams, axial separation lengths of the failed adhesive region, permanent deflection of the bonded region, fracture surfaces were in good agreement. The strength and plastic deformation capability of adherend materials and impact energy levels affected the progressive adhesive failure behaviour. The proposed finite element model was successful reasonably in predicting the initiation and propagation of the adhesive failure.Article Citation - WoS: 12Citation - Scopus: 12Low-Speed Bending Impact Behavior of Adhesively Bonded Single-Lap Joints(Taylor & Francis Ltd, 2016-12-26) Atahan, M. Gokhan; Apalak, M. Kemal; Gokhan Atahan, M.; Kemal Apalak, M.This study addresses the low-speed impact behavior of adhesively bonded single-lap joints. An explicit dynamic finite element analysis was conducted in order to determine the damage initiation and propagation in the adhesive layers of adhesive single-lap joints under a bending impact load. A cohesive zone model was implemented to predict probable failure initiation and propagation along adhesive-adherend interfaces whereas an elasto-plastic material model was used for the adhesive zone between upper and lower adhesive interfaces as well as the adherends. The effect of the plastic deformation ability of adherend material on the damage mechanism of the adhesive layer was also studied for two aluminum materials Al 2024-T3 and Al 5754-0 having different strength and plastic deformation ability. The effects of impact energy (3 and 11 J) and the overlap length (25 and 40 mm) were also investigated. The predicted contact force-time, contact force-central displacement variations, the damage initiation and propagation mechanism were verified with experimental ones. The SEM and macroscope photographs of the adhesive fracture surfaces were similar to those of the explicit dynamic finite element analysis.Article Citation - WoS: 39Citation - Scopus: 38Loading-Rate Effect on Tensile and Bending Strength of 3D-Printed Polylactic Acid Adhesively Bonded Joints(Taylor & Francis Ltd, 2021-05-18) Atahan, M. Gokhan; Apalak, M. KemalAdditive manufacturing provides the production of many machine parts and components with complex geometries. The adhesive bonding technique can be alternative method for joining parts produced with additive manufacturing. This experimental study investigates the applicability of the adhesive bonding technique for PLA (polylactic acid) adherends produced with additive manufacturing and especially the effects of loading rate on the strength of 3D-printed PLA adhesive single-lap joints under tensile, three-point bending (with shear) and four-point bending (no shear effect) loadings. Both PLA and adhesive tensile test specimens exhibited a better strength but lower failure strain with increasing loading rate. PLA had better mechanical behaviour in the raster orientation than those in the layer-build direction. The strength of adhesive single-lap joints improved slightly with increasing loading rate for the tensile and three-point bending tests whilst a decrease of strength and an improvement of bending stiffness were observed for the four-point bending test. Failure initiated at the free edge of the top adherend-adhesive interface for all tests, and propagated along this interface for both bending tests whilst a sudden through-the-thickness failure of top adherend occurred for tensile load after a small interfacial damage propagation. The failure propagation appeared in a wavy form for the three-point bending test whilst it was along the top adherend-adhesive interface for the four-point bending test. Digital Image Correlation (DIC) method for tensile tests showed that the peeling and shear strains were more critical and concentrated around both free edges of adherend-adhesive interfaces; thus, at the right free edge of the top adherend-adhesive interface and at the left free edge of the bottom adherend-adhesive interface.Article Citation - WoS: 46Citation - Scopus: 52Life Cycle Assessment of Lightweight Concrete Containing Recycled Plastics and Fly Ash(Taylor & Francis Ltd, 2020-06-05) Ersan, Yusuf Cagatay; Gulcimen, Sedat; Imis, Tuba Nur; Saygin, Osman; Uzal, NigmetResearchers put significant effort to decrease the environmental impact of concrete by using industrial by-products as an alternative binder. However, the considerable environmental impact still exists due to the consumption of natural resources as aggregates. Natural aggregates are the most used resources by volume in the construction sector. Therefore, it is necessary to investigate by-products as an alternative to natural aggregates as well. This study presents the environmental impact of lightweight concrete (LWC) produced by replacing natural aggregates with recycled waste plastic (polyethylene) (RWP) and partially replacing Portland cement with Class F fly ash (FA). Life Cycle Assessment (LCA) was performed to compare a conventional LWC, containing pumice as natural aggregate and Portland cement as a binder, with green LWC, containing 30% RWP as pumice replacement and 20% FA as cement replacement. These scenarios were evaluated in terms of global warming potential, abiotic depletion, ozone layer depletion, terrestrial ecotoxicity, photochemical oxidation, acidification and eutrophication. LCA was coupled with mechanical tests at 7 days and 28 days. RWPs were found to be an environment-friendly replacement material for natural lightweight aggregates with an overall decrease in all CML-IA impacts except eutrophication. Tested green mix design also provided sufficient strength for nonstructural applications.Article Citation - WoS: 4Citation - Scopus: 3Experimental and Numerical Investigation of Hyper-Elastic Submerged Structures Strengthened With Cable Under Seismic Excitations(Taylor & Francis Ltd, 2020-10-23) Dincer, A. ErsinThis study presents dynamic responses of submerged highly elastic structures, strengthened with cable elements and the fluid interacting with the structure. For this purpose, fluid and structure are modelled with smoothed particle hydrodynamics and finite element methods, respectively. The interaction is satisfied with contact mechanics. In order to simulate the cable, a finite element model with a two-node cable element is used. The stiffness obtained from the cable is added to the structure and the whole fluid-structure system is solved together. The novel contribution of the present study is the coupling a two-node cable element model with the fluid-structure interaction method. In order to validate the numerical method, a set of novel experiments is carried out. In the experiments, cable elements are attached to an elastic structure that is placed in a water tank. Near-fault and earthquake excitations are applied to the tank and the displacement of the structure and the free surfaces of the water are recorded. All the results show that the proposed two-dimensional numerical model is capable of modelling the submerged elastic structure strengthened with the cable under the seismic excitations.Article Citation - WoS: 17Citation - Scopus: 21Evaluation of Geochemical Behaviour of Flooded Cemented Paste Backfill of Sulphide-Rich Tailings by Dynamic-Tank Leaching Test(Taylor & Francis Ltd, 2020-10-13) Yilmaz, Tekin; Ercikdi, Bayram; Deveci, HaciThis research elucidates the geochemical behaviour of cemented paste backfill (CPB) of sulphide-rich tailings (S-rT). The dynamic-tank leaching test was performed on the CPBs for up to 360 days. The CPBs with the alkaline industrial by-products (AIPs) produced relatively lower acidity, Ec and SO(4)(2-)than the Control. The AIPs replacement appeared to considerably mitigate the release of heavy metals (HMs) including As. Only Mo and As in CPBs of AIPs exceeded the limit-values for ground-water. These findings demonstrated that a suitable CPB mixture design to control the release of all HMs in CPB is of practical importance for ground-water quality.