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Exploring mixed-mode fracture behavior and mechanical properties of selective laser sintered polyamide 12 components
No full textPurposeThis study aims to comprehensively investigate the mixed-mode fracture behavior and mechanical properties of selective laser sintering (SLS) polyamide 12 (PA12) components, considering different build orientations and layer thicknesses. The primary objectives include the following. Conducting mixed-mode fracture and mechanical analyses on SLS PA12 parts. Investigating the influence of build orientation and layer thickness on the mechanical properties of SLS-printed components. Examining the fracture mechanisms of SLS-produced Arcan fracture and tensile specimens through experimental methods and finite element analyses.Design/methodology/approachThe research used a combination of experimental techniques and numerical analyses. Tensile and Arcan fracture specimens were fabricated using the SLS process with varying build orientations (X, X-Y, Z) and layer thicknesses (0.1 mm, 0.2 mm). Mechanical properties, including tensile strength, modulus of elasticity and critical stress intensity factor, were quantified through experimental testing. Mixed-mode fracture tests were conducted using a specialized fixture, and finite element analyses using the J-integral method were performed to calculate fracture toughness. Scanning electron microscopy (SEM) was used for detailed morphological analysis of fractured surfaces.FindingsThe investigation revealed that the highest tensile properties were achieved in samples fabricated horizontally in the X orientation with a layer thickness of 0.1 mm. Additionally, parts manufactured with a layer thickness of 0.2 mm exhibited favorable mixed-mode fracture behavior. The results emphasize the significance of build orientation and layer thickness in influencing mechanical properties and fracture behavior. SEM analysis provided valuable insights into the failure mechanisms of SLS-produced PA12 components.Originality/valueThis study contributes to the field of additive manufacturing by providing a comprehensive analysis of the mixed-mode fracture behavior and mechanical properties of SLS-produced PA12 components. The investigation offers novel insights into the influence of build orientation and layer thickness on the performance of such components. The combination of experimental testing, numerical analyses and SEM morphological observations enhances the understanding of fracture behavior in additive manufacturing processes. The findings contribute to optimizing the design and manufacturing of high-quality PA12 components using SLS technology.Scientific Research Coordination Unit of Adana Alparslan Turkescedil; Science and Technology University [22103006]This research received support from the Scientific Research Coordination Unit of Adana Alparslan Turke & scedil; Science and Technology University under project number 22103006. The authors extend the sincere gratitude for the valuable technical assistance provided by the Additive Manufacturing Research Center, GOETHELAB, FH Aachen
An alternative approach to total economy of the late Ottoman Empire
No full textThe Ottoman Empire until the eve of the First World War gave the impression of an agrarian society with modest manufacturing activities, mainly based on craft-based production. A major difficulty was to supply food for the army for a long time in total war conditions. This was an important indicator for the new leaders of Ottoman bureaucracy to develop a nationalist economic view. With an intention to enhance further argument, this study implies that the Ottoman officials with their strong ties to Young Turk Movement would have pursued a nationalist economy regardless of the total war status. So, this study proposes that the war and rising nationalism were not the sole reasons for creating a national economy, but merely footsteps along the way
Industry 4.0 and food sustainability: role of automation, digitalization, and green technologies
No full textCurrently, agrifood systems find themselves at an unprecedented crossroads of challenges stemming from climate change, dwindling resources, the rapid growth of the global population, and the emergence of pandemics and conflicts, among other factors. These global challenges underscore the urgent necessity to seek novel and alternative approaches for tackling or, at the very least, alleviating the profound environmental, social, and economic dilemmas they pose. As a result, Industry 4.0 and its enabling technologies have attracted tremendous attention from researchers and the academic community in recent times. This chapter is intended to provide a general overview of recent applications of Industry 4.0 and green technologies in different food sectors and to show how these technological innovations can be used to foster automation and digitalization. A special focus will be put on the role of this technologies in providing innovative solutions to enhance food sustainability and circular economy. © 2024 Elsevier Inc. All rights reserved
An evaluation of spatiotemporal changes of meteorological drought in the Mediterranean sub-basins in Türkiye using discrepancy precipitation and standardized precipitation index
No full textDetecting dry and wet periods is crucial for regions susceptible to drought impacts. The present study analyzed the dry and wet periods using precipitation data obtained from 8 gauging stations along the Central Mediterranean coast of T & uuml;rkiye. A span of 52 years, from 1970 to 2021, was examined utilizing three distinct methods: the Standardized Precipitation Index (SPI-Gamma, SPI-Lognormal), Discrepancy Precipitation Index (DPI), and Reconnaissance Drought Index (RDI). Initially, the study discussed the changes in dry and wet periods observed at the respective stations. Subsequently, it determined the transition probabilities associated with classifications of drought. The results showed that SPI-G values exhibit greater precision in detecting wet periods, while the SPI-L method yields more specific outcomes in identifying dry periods. Notably, the DPI method demonstrates a higher frequency of dry periods than the SPI method. Additionally, findings from the SPI method suggest that reductions in drought indices correspond to an increased occurrence of drought. The DPI method's outputs indicate fewer occurrences of wet periods across all stations in contrast to the results obtained through the SPI method. The study stands out by addressing the assessment of drought development in the Mediterranean coastal regions of T & uuml;rkiye using the DPI method, which has recently garnered attention in the literature, presenting a novel contribution within the scope of this research
Legitimizing Mediated Islamophobic Actions: Example “X”
No full textThe media plays an active role in spreading Islamophobia, with an increase in Islamophobic content and discourses in new media in recent years leading academic studies to focus on this issue. New media tools offer free and unlimited sharing opportunities to their users, becoming platforms where hate speech against religious groups is developed and spread. One such platform where freedom of speech is violated is X, formerly known as Twitter. It is crucial to determine the approach of content on social media platforms towards Islam, Muslims, and their sacred values. This study discusses posts made through burning/tearing actions on the X platform, covering the first 9 months of 2023. The findings, based on posts from 23 X accounts analyzed using qualitative-oriented content analysis, reveal that concepts related to Islam and Muslims with negative connotations were frequently used. The posts framed a narrative portraying Islam and Muslims as pro-violence, intolerant, and hostile. Acts of burning and tearing the Holy Quran were largely justified as freedom of speech, with a narrative of exclusion, accusation, distortion, and disdain towards Muslims who disagreed
The failure of Islamization policies in Turkey: a Victory of Secularization Theory?
No full textRecep Tayyip Erdo & gbreve;an's aim to raise a pious generation has failed to achieve its objectives. On the contrary, relevant academic studies reveal that Turkish society is secularizing. Therefore, the present study seeks to explain the reasons why Erdo & gbreve;an's policy of Islamizing Turkish society failed despite him having the whole state apparatus at his disposal. Recent studies argue that this transformation is a reaction to the repressive policies of the Justice and Development Party (Adalet ve Kalk & imath;nma Partisi - AKP) and that the dissatisfaction with Erdo & gbreve;an and AKP has turned into a parallel dissatisfaction with religion. However, this article argues that the secularization debates centering on hot politics are only a small part of the picture and that the modernization process, as the secularization theory claims, is behind the young generations' disaffection with religion in Turkey. The article argues that Turkey has been experiencing a demographic transition and religious change similar to what occurred in regions where scientific developments, industrialization and urbanization, i.e., modernization, had occurred
Dynamic analysis of viscoelastic FGM shells with porosities on elastic foundation
No full textThis study investigates free and damped vibration behaviours of porous functionally graded shells supported by Winkler-Pasternak foundation, considering different geometries. Utilizing a higher-order shear deformation theory, the displacement field is determined. The equations of motion are formulated using Hamilton's principle, and the solutions are obtained Navier's method employing double Fourier series. Parametric studies regarding the effects of porosity, material distribution, elastic foundation, shell geometry and damping are carried out. Results are given in tabular and graphical form for the free and forced vibration analyses, respectively
Polyaniline-Functionalized Nanosized Cobalt Ferrite-Decorated MoS2 Composites for Broadband Electromagnetic Wave Absorption
No full textThis study presents the synthesis of polyaniline (PANI)-coated cobalt ferrite-decorated molybdenum disulfide (MoS2@CoFe2O4); a composite architecture engineered to combine unique morphological, magnetic, and dielectric properties for the electromagnetic wave/radar absorption applications. MoS2 and CoFe2O4 were produced separately using a one-step hydrothermal process. Then, the CoFe2O4 nanoparticles were integrated into the flower-like MoS2 nanosheets using the sonication method. Finally, PANI was synthesized through in situ polymerization of aniline on the surface of MoS2@CoFe2O4 to create the final design as well as to boost the dielectric performance. Structural analysis confirmed the existence of the 2H phase and a minor trace of the 1T phase in MoS2, while CoFe2O4 displayed a cubic structure without any detectable impurities. Scanning electron microscopy verified the successful distribution of CoFe2O4 particles within the MoS2 nanosheets, aligning with the design's intended configuration. The electromagnetic wave (EMW) characteristics of the composites were analyzed by using a vector network analyzer. The MoS2@CoFe2O4 demonstrated a broad effective absorption bandwidth, spanning from the X-band to the Ku-band with a minimum matching thickness of just 2 mm. The reflection loss minimum value (RLmin) reached -22.82 dB at 8.96 GHz, corresponding to a 99.47% absorption of the incident EMWs. The addition of PANI at 50% by weight further increased the RLmin value to approximately 99.999% absorption (-50 dB), indicating enhanced impedance matching and absorption efficiency.Scientific and Technological Research Council of Turkey (TUBITAK) [121F367]; TUBITAKThis study was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under grant no. 121F367. The authors thank TUBITAK for their support
Concluding Remarks
No full textThe COVID-19 1, 2 pandemic has shattered the world economies. The challenges posed by the pandemic and the impact of new waves have dragged all economic instruments and investors into an uncertain territory. It has resulted in several repercussions like decreasing growth rates, falling demand, supply-chain disruptions and accompanying income inequalities. Despite the time that has passed since the spread of the pandemic, its socio-economic, political, and psychological effects continue to persist, albeit to a lesser extent. Although it is not known when the economies will be able to come out of the post-COVID challenges, there is no doubt that they will be talked about for many years to come. © 2025 selection and editorial matter, Shilpa Deo and Fatma Feyza Gündüz; individual chapters, the contributors
Effect of dilatancy on tension response of completely rough piles embedded in granular soils
No full textPile surface roughness is an important characteristic determining the displacement response of piles under various loading conditions since it leads to surface friction resistance. Considering that no capacity contribution is acquired from the pile tip, the effect of surface friction becomes more pronounced for tension piles. Pile surfaces can be classified as smooth, rough, or completely rough according to the normalized surface roughness value (Rn) of piles, and this paper focuses only on the uplift capacity of piles with normalized surface roughness values greater than 0.1 (i.e., completely rough) by employing the PLAXIS3D code verified against results of twelve physical modelling tests reported in the literature. The reason of selecting piles with completely rough surfaces in this study is that dilatancy behaviour can be only observed in the uplift load-displacement relationships of such piles, unlike the piles with smooth or rough surfaces. While numerical simulations are repeated for different normalized surface roughness values (Rn = 0.2, 0.5, 1.0, and 2.0) and different relative densities of sandy backfill (Dr = 25%, 50%, and 75%), the effect of the pile surface friction resistance on the uplift capacity, which occurs as a result of the interaction between the pile surface and sandy soil grains, is studied with special emphasis on soil dilatancy. It is observed that the numerical results are quite compatible with the physical test results. In addition, increasing the pile surface roughness and relative density of sandy soil causes an increase in the uplift capacity, and those capacity increments can only be modelled properly by increasing the dilatancy angle of sandy soil in finite element analyses