Kırşehir Ahi Evran Üniversitesi Kurumsal Akademik Arşivi
DSpace@Kırşehir, Kırşehir Ahi Evran Üniversitesi tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve yayınların etkisimi artırmak için telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
Theoretical İnvestigations on Structural, Electronic, Mechanical, Optical, Dynamic, Thermal, and Hydrogen Storage Properties of Mgah4 (M = Li, Na, K, Rb, Cs)
(Springer, 2025) Kürkçü, Cihan; Yamçıçıer, Çağatay
This study presents a comprehensive first-principles investigation of the structural, electronic, mechanical, optical, dynamical, thermal, and hydrogen storage properties of MGaH4 (M = Li, Na, K, Rb, Cs) hydrides using density functional theory. The optimized crystal structures reveal that LiGaH4 and NaGaH4 crystallize in the Cmcm space group, while KGaH4, RbGaH4, and CsGaH4 crystallize in the Pnma space group. All compounds exhibit thermodynamic stability with negative formation enthalpies ranging from − 0.154 eV/atom (LiGaH4) to − 0.248 eV/atom (CsGaH4). Cohesive energies vary between 3.110 and 3.173 eV/atom, confirming strong internal bonding. Mechanical analysis demonstrates mechanical stability for all compounds, with elastic constants satisfying Born–Huang criteria. The polycrystalline bulk moduli (8.26–16.33 GPa), shear moduli (5.47–11.46 GPa), and Young’s moduli (13.44–27.54 GPa) indicate relatively soft and brittle behavior (B/G < 1.75). Hardness calculations yield average Vickers hardness values of 0.88–2.87 GPa, confirming their soft nature. Phonon dispersion spectra show no imaginary frequencies, confirming dynamical stability. Electronic band structures reveal wide band gaps, confirming semiconducting behavior: 4.57 eV (LiGaH4), 4.68 eV (NaGaH4), 5.00 eV (KGaH4), 5.00 eV (RbGaH4), and 4.93 eV (CsGaH4). Optical analysis demonstrates high ultraviolet absorption (maximum absorption coefficient up to 13.1 × 105 cm−1 for CsGaH4), high reflectivity in the UV region (maximum 36% for NaGaH4), and optical transparency in the visible range. Thermal properties reveal Debye temperatures between 168.26 K (CsGaH4) and 352.04 K (LiGaH4), while melting temperatures range from 428.38 to 553.64 K. Minimum thermal conductivities are found between 0.29 and 0.72 W/m·K. Hydrogen storage analysis shows that LiGaH4 possesses the highest gravimetric (5.00 wt%) and volumetric (92.81 gH2L−1) storage capacities, approaching the U.S. DOE 2025 gravimetric target (5.5 wt%) and exceeding the volumetric target (40 gH2L−1). The desorption temperatures range from 113.70 K (LiGaH4) to 183.01 K (CsGaH4), suggesting relatively low hydrogen release energy barriers. Among the studied compounds, LiGaH4 demonstrates superior performance owing to its high storage capacity, strong bonding (Ecoh = 3.173 eV/atom), high Debye temperature (352.04 K), and wide band gap (4.57 eV). Overall, the results highlight LiGaH4 as the most promising candidate for lightweight solid-state hydrogen storage, while providing systematic insights into the role of alkali cation size on the stability, mechanical robustness, electronic band gap, optical absorption, and storage performance of MGaH4 hydrides.
A New Type of Soft Multi Rough Sets
(Walter de Gruyter GmbH, 2025) Güzel Ergül, Zehra
Soft multi rough sets which are a hybrid model combining rough sets with soft multisets are defined by using soft multi rough approximation operators. Soft multi rough sets can be seen as a generalized rough set model based on soft multisets. In this paper, we contribute to a recent modelization of uncertainty. To be precise, in order to approach the uncertainty issue, we introduce a novel type of soft multi rough set by means of soft multi neighborhoods and then we use it to improve decision making in a multicriteria group environment. The motivation and method of this paper are as follows. Firstly we establish a soft multi covering approximation space. Secondly we define the soft multi neighborhood of the objects. We also introduce a new type of soft multi upper approximation operator by using soft multi neighborhood of the objects. Based on this new type of soft multi upper approximation operator, we propose a new kind of soft multi rough set. We present its basic properties and provide some illustrative examples. Thirdly, we show that our soft multi upper approximation operator is smaller than other multi upper approximation operator. Finally, we present an application of multicriteria group decision making using new type of soft multi covering rough approximation operators.
From Trauma to Recovery: A Systematic Review and Meta-Analysis on the Effectiveness of Psychosocial Interventions Applied to War Victims
(John Wiley and Sons Ltd, 2025) Ediz, Çiçek; Uzun, Sevda
Purpose: Trauma survivors in warring countries may show intense traumatic symptoms as they are forced to repeatedly experience severe traumatic experiences. Psychosocial intervention and support activities are of great importance in order to repair the deep psychological traumas caused by war. This study was conducted with the aim of demonstrating the effectiveness of psychosocial interventions applied to war victims. Method: For this systematic review and meta-analysis study, studies were obtained by searching PubMed, Web of Science, EBSCOhost, Google Scholar and YÖK Thesis Center databases without any year limitation. After the reviews, 13 studies were included in the study. Results: This systematic review and meta-analysis analysed the effects of psychosocial interventions on depression (SMD: −0.502; 95% CI: −0.966 to −0.037; Z = −2.117, p = 0.037 [I2 = 87.32%]) and psychological well-being (SMD: −0.030; 95% CI: −0.721 to 0.660; Z = −0.886, p = 0.931 [I2 = 97.99%]). Conclusion: This study demonstrated that psychosocial interventions for war victims can play a beneficial role on individuals' mental health. These findings highlight the importance of early and targeted psychosocial intervention programs for war victims.
Thermodynamic and Environmental Assessment of Apple Production in Türkiye: Regional Comparison and Agrivoltaic İntegration
(Nature Research, 2025) Öztürk, Müjdat; Kayabaşi, Ramazan; Yıldızhan, Hasan; Ameen, Arman
This study presents a comprehensive thermodynamic and environmental assessment of apple cultivation across three major production regions in Türkiye: Antalya, Isparta and Niğde. This study is the first to provide an integrated energy, exergy and environmental assessment of agricultural voltaic systems by conducting a resource efficiency and sustainability assessment for open field apple production in Türkiye. Using a functional unit of one ton of apple production, the analysis integrates cumulative energy consumption (CEnC), cumulative exergy consumption (CExC) and cumulative carbon dioxide emissions (CCO2E) to reveal the sustainability performance of regional farming systems. The results indicate significant spatial variations linked to climatic and operational factors. Niğde exhibited the highest total energy (3098 MJ/ton) and exergy (2975 MJ/ton) consumptions, mainly due to diesel-powered irrigation and mechanization, resulting in a cumulative carbon footprint of 125 kg CO2/ton. Conversely, Antalya recorded the lowest total emissions (33 kg CO2/ton) with a balanced energy profile dominated by fertilizers and electricity use. Isparta demonstrated the most thermodynamically efficient and renewable system, achieving the highest cumulative degree of perfection (CDP) (3.80) and Renewability Index (RI) (0.74) values. The integration of agrivoltaic systems (AVS) has further enhanced sustainability across all provinces, particularly in Niğde, by increasing CDP by up to 97%. These findings highlight the significant role that renewable energy integration plays in reducing carbon intensity and increasing resource efficiency in apple cultivation. By providing a region-specific perspective on agricultural thermodynamics, the study provides strategic insights into the transition to sustainable and climate-resilient food production systems in Türkiye.
Resource Efficiency and Environmental Sustainability of Wheat Production in Türkiye
(Nature Research, 2025) Öztürk, Müjdat; Yıldızhan, Hasan; Ameen, Arman
The environmental impact of agricultural production varies depending on input levels. This study provides a comparative sustainability assessment of wheat production in two different provinces of Türkiye, Samsun and Tokat, by examining the energy, exergy and environmental performance on a per ton basis. Based on exergy consumption, Cumulative Degree of Perfection (CDP) and Renewability Index (RI) indicators were determined. The results show that Cumulative Energy Consumption (CEnC) is 7262.93 MJ/ton in Samsun and 3502.97 MJ/ton in Tokat. This indicates that wheat production in Samsun is approximately twice as energy intensive as in Tokat. Cumulative Exergy Consumption (CExC) was calculated as 10514.76 MJ/ton in Samsun and 5400.88 MJ/ton in Tokat. Here, the largest component of the exergy load is irrigation, followed by diesel consumption. From an environmental perspective, Cumulative CO₂ Emissions (CCO2E) was found to be 957.5 kg/ton in Samsun and 562.27 kg/ton in Tokat. The sustainability metrics, CDP and RI values, were calculated as 2.13 and 0.53 for Samsun and 4.14 and 0.76 for Tokat, respectively. Based on these findings, it is evident that Samsun has lower exergetic efficiency and a limited degree of renewability due to higher fuel and irrigation inputs. These results suggest that Tokat presents a more sustainable model for wheat production.
