4 sonuçlar
Arama Sonuçları
Listeleniyor 1 - 4 / 4
Yayın Measurement of perceived psychological safety: integration, review and evidences for the scale in the context of Turkiye(İstanbul Üniversitesi Yayınevi, 2022-06-22) Bülbül, Seçil; İşiaçık, Serin; Aytaç, SerpilPsychological safety can predict many positive individual and organizational outcomes at work, and previous research addressed how psychological safety contributes to positive work attitudes and behaviors. In Turkey, there is quite an amount of research showing the contributing role of psychological safety perception on employees' positive performance behaviors and organizational effectiveness and innovativeness. However, previous research in Turkey does not adequately show the reliability and validity of the psychological safety scale, which was developed by Edmondson (1999). Based on the suggested requirement this study aimed to investigate the psychological safety perceptions of individuals who work in various sectors in Turkey. The adapted version of the psychological safety scale was used to gain evidence for the reliability and validity of the instrument in Turkey. In total, 585 individuals working in various industries and from various occupational groups participated in the research. Both exploratory factor analysis and the confirmatory factor analysis showed that Turkish adapted version of the psychological safety scale was valid and reliable.Yayın Numerical modelling of energy dissipative steel cushions(Korean Soc Steel Constructiın-KSSC, 2019-08) Güllü, Ahmet; Smyrou, Eleni; Khajehdehi, Arastoo; Özkaynak, Hasan; Bal, İhsan Engin; Yüksel, Ercan; Karadoğan, Hüseyin FarukEnergy dissipative steel cushions (EDSCs) are simple units that can be used to join structural members. They can absorb a substantial amount of seismic energy due to their geometric shapes and the ductile behavior of mild steel. Large deformation capability and stable hysteretic behavior were obtained in monotonic and cyclic tests of EDSCs in the framework of the SAFECLADDING project. Discrete numerical modeling strategies were applied to reproduce the experimental results. The first and second models comprise two-dimensional shell elements and one-dimensional flexural frame elements, respectively. The uncertain points in the preparation of the models included the mesh density, representation of the material properties, and interaction between contacting surfaces. A zero-length nonlinear link element was used in the third attempt in the numerical modeling. Parameters are recommended for the Ramberg-Osgood and bilinear models. The obtained results indicate that all of the numerical models can reproduce the response, and the stiffness, strength, and unloading and reloading curves were fitted accurately.Yayın Drying of PAAm hydrogels at various temperatures: A fluorescence study(Taylor & Francis Group, 2007-05) Aktaş, Demet Kaya; Evingür, Gülşen Akın; Pekcan, Mehmet ÖnderThe steady-state fluorescence (SSF) technique was employed for studying the drying of polyacrylamide (PAAm) hydrogels. Disc-shaped hydrogels were prepared by free-radical crosslinking copolymerization of acrylamide (AAm) with N,N'-methylene bisacrylamide (BIS) as crosslinker in the presence of ammonium persulfate (APS) as an initiator. Pyranine (P) was introduced as a fluorescence probe and the intensity of pyranine was monitored during in situ drying at various temperatures. It was observed that the fluorescence intensity of pyranine increased during the drying process. A supporting, gravimetrical experiment was also performed. A phenomenological equation was introduced to determine the desorption coefficient, D, of water molecules from the drying hydrogels at various temperatures. The desorption activation energy, triangle E-d, values were measured for the drying processes and found to be 91.08 and 36.82 kJ mol(-1) by fluorescence and gravimetrical methods, respectively. This difference most probably originates from the origin of the techniques; the fluorescence technique measures the parameters at a molecular level, whereas the gravimetrical technique measures a parameter in the bulk.Yayın Measurement and assessment of fatigue life of spot-weld joints(Asme-Amer Soc Mechanical Eng, 2009-01) Ertaş, Ahmet Hanifi; Vardar, Öktem; Sönmez, Fazıl Önder; Solim, ZaferSpot-weld joints are commonly used to fasten together metal sheets. Because fatigue fracture is the most critical failure mode for these joints under fluctuating loads, understanding their fatigue failure behavior and assessment of their fatigue lives are crucial from the viewpoint of failure prevention in design. In this study, a series of experiments was conducted to study the fatigue failure of spot-welded modified tensile-shear specimens made of a low carbon steel. Two different types of resistance spot welding were investigated (manual and automated). Tests were repeated under different load ranges, and the corresponding fatigue lives were determined. The specimens were also examined under an optical microscope. In the numerical part of this study, a finite element analysis was carried out using commercial software, ANSYS, to determine the stress and strain states within the specimens. The material nonlinearity, local plastic deformations around the welds during loading, and the residual stresses and strains developed after unloading as a result of plastic deformations were taken into account. Based on the predicted stress and strain states, fatigue analyses were performed using several models for life assessment. Then, the measured and predicted fatigue lives were compared, and the suitability of the models was discussed. Among the strain-based models, Coffin-Manson and Morrow's means stress models yielded the best predictions.
