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Comparative analysis of era5 and era5-land reanalysis data for drought evaluation using the standardized precipitation index (SPI)
No full textIt is known that a wide variety of data sources are used in research and applicationsfor drought evaluation. It is seen that reanalysis, remote sensing, satellite, and groundmeasurement data are used the most in the literature. The data sources to be selected may varydepending on the purpose, scale, drought type, data quality, and study continuity. Each datasource has advantages and disadvantages compared to the others. In recent years, in manystudies on hydrology, ERA 5 and ERA 5-Land data sources stand out with their superioraspects, such as easy access, suitability for global and large-scale field studies, high spatial andtemporal resolutions, and long-term and continuous data provision. ERA 5-Land (9 km, ̴0.1̊)provides higher resolution compared to ERA 5 (31 km, 0.25 ̊) data. It is stated that ERA 5-Land provides an advantage due to its more detailed processing feature on land surfaces. Inthis research study, drought analyses were performed using both data sources, and the resultsobtained were compared. In order to verify the obtained drought results, drought analysisresults obtained from ground measurement data were used. Standardized Precipitation Index(SPI) methodology was preferred as the drought index. Analyses were carried out for thereanalysis data at specific grid points and ground observation data in Kocaeli province.Different performance metrics and the Innovative drought Classification Matrix (IDCM) wereused to compare and find their differences and similarities. The results will significantlyenhance the evaluation of reanalysis data, providing a foundation for more accurate and reliabledrought assessments.</p
Light-driven N2 fixation for green NH3 production in H2–N2 energy storage systems
No full textAmmonia (NH3) is considered the major compound for the chemical industry and energy sector as a prominent liquid medium for energy storage with its capability of storing 19.65 wt. % of its mass in hydrogen (H2). The main catalytic process of NH3 production—the Haber-Bosch process—led to massive carbon emissions globally. The global decarbonization goals have been made prominent for the improvement of the alternative renewable-based technologies and the adaptation of the green technologies. The green NH3 is going to play a critical role in shifting the classical high energy consumption and CO2 emissions industry with alternative pathways based on material science. Light-driven N2 fixation for green NH3 production based on the conversion of atmospheric N2 gas has been performed based on catalysts in several forms, such as type-1, type-2, z-scheme and heterostructure catalysts. This study aims to provide a comprehensive review of the transition from conventional NH3 production to sustainable, solar-driven N2 fixation methods. Specifically, it focuses on the development and optimization of heterojunction photocatalysts as a promising approach for carbon-neutral NH3 synthesis with low energy consumption. By leveraging photocatalytic N2 activation is inspired by biological processes, this work explores how advanced semiconductor materials and heterojunction interfaces can enhance charge separation, N2 adsorption, and overall catalytic efficiency. Furthermore, a bibliographic analysis has been conducted to identify the latest research trends, catalyst development strategies, and emerging innovations in this field
Life cycle environmental impact assessment and review of hydrogen fuels obtained from various sources for vehicles
No full textThis paper focuses on the Life Cycle Assessment (LCA) of passenger car (CAR) heavy duty vehicle (HDV), and sport utility vehicle (SUV) which are hydrogen fueled Fuel Cell Vehicles (FCVs), and various production methods of hydrogen fuel used in these vehicles are considered for analyses and comparative evaluations. In addition, this study includes recommendations for selecting the production method and vehicle type with economic data from the National Renewable Energy Laboratory (NREL). Eight renewable and non-renewable hydrogen production options are identified, using proton exchange membrane (PEM) electrolysis driven by the electricity obtained from solar, biomass, nuclear, chlorine plants, coal, natural gas, coke oven gas and pet coke. This study is designed to utilize the LCA method for examining the use of hydrogen fuel produced from these plants in 3 different vehicle types. The Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET), which is a potential LCA software, is employed to analyze the carbon dioxide (CO2), methane (CH4), nitrogen oxides (NOx), sulfur oxides (SOx), particulate matter pollutants (PM10), nitrous oxide (N2O) and particulate organic carbon (POC) emissions. According to the results of the analysis, the lowest emission value is obtained for the passenger car using hydrogen fuel produced by PEM electrolysis method as given in Pathway 1. The results further indicate that the highest emission value is 42.86 g/km CO2, and the lowest is 0.00065 g/km POC for the passenger car as presented in Pathway 1, where the best data are obtained. In contrast, the highest emission value of the HDV vehicle type using hydrogen fuel produced in Pathway 8 is 1921.53 g/km CO2, and the lowest emission value is 0.0076 g/km POC
Evaluation of the Buttress System of a Great Ottoman Mosque Against Gravity Loads and Horizontal Seismic Forces: The Case of the Istanbul Süleymaniye Mosque
No full textHistorical mosques are some of the most valuable structures in Islamic societies. It is of primary importance to protect these structures and ensure their safe transmission to future generations. This study investigates the adequacy of the buttress system of the Süleymaniye Mosque in Istanbul, regarded as the ‘symbol structure of Ottoman Architecture’, against gravity and horizontal earthquake loads. Although several structural studies have been conducted on this unique building, the absence of any research on the buttress system, which clearly plays a significant role in its survival through many earthquakes, served as the main motivation for this study. After presenting the material properties, a finite element model of the structure was created. Finite element models were also developed for two hypothetical scenarios in which the outer depths of the buttresses were reduced by fifty percent or eliminated. The models and all analyses were performed using ABAQUS software. Gravity load analyses indicated that the mosque does not face any issues related to stresses or displacements. Nonlinear static analyses revealed that, with the current buttress dimensions, the structure can resist horizontal loads up to about 70% of self-weight along the Qibla axis and about 90% along the axis perpendicular to the Qibla. These findings are some of the most significant results obtained thus far in studies investigating the horizontal earthquake resistance of the mosque. Through performance analyses, it was determined that the structure can meet the limited damage performance criterion only with the current buttress depths; however, it cannot satisfy this performance level with reduced buttress dimensions. In conclusion, the study demonstrated that the buttress system of the Süleymaniye Mosque is highly effective against gravity loads and transverse seismic forces and that it was designed not only with practical experience but also with a solid understanding of structural behavior
Hardening Behavior's Effect on Deformation of Materials with Geometrical Discontinuities
No full textKrizler Çağında Sürdürülebilir Ulaşım Tercihleri: Dirençli Kentler ve Toplumlar için Yenilikçi Yaklaşımlar
No full textInfluence of seed concentration and storage time on the rheological, textural, and microscopic crystallization attributes of Apis mellifera honey
No full textThis study aimed to evaluate the impacts of seed honey supplementation at concentrations of 5, 10, and 15 % (w/w) and storage time (up to 12 days at 14 °C) on the rheological, textural, crystallization, and colour attributes of honey. The rheological properties, including the apparent viscosity, loss modulus, and storage modulus, were assessed using a rheometer. Textural properties, such as hardness and spreadability, were measured using a texture analyzer. The L* values were determined to assess the crystallization process, and microscopic imaging was used to observe the size and formation of the sugar crystals. Results showed that the apparent viscosity increased significantly (p < 0.05) from 13.1 Pa.s to 38.5 Pa.s (194 % ↑) as both the seed concentration and storage time increased from 0 %–15 % and 0–12 days, respectively. The highest G" value (2756 Pa) was observed on the 9th day for the 15 % seed concentration. The work of shear decreased with increasing seed concentrations but increased over storage time. L* values, an indicator of crystallization, showed a significant increase across concentrations and storage time. Microscopic examination of seed crystals anticipated zero crystals at 0–12th day in control; however, 6th and 12th days of storage at 10 % and 15 % addition of seeds increased size and magnitudes of crystals than 5 %. Conclusively, adding seed honey at levels up to 10 % and allowing 9 days of storage effectively promotes the shear-thinning behaviour desirable in spreadable honey products. Creamed honey offers improved texture and user convenience, enhancing product versatility without compromising flavour. These results provide a practical basis for optimizing processing conditions in commercial honey formulation to meet diverse consumer and market needs
Comparative Study of Open-Loop, PID, and MPC Control Strategies for Hydrogen Production from Waste Heat in Cement Plants
No full textThis paper presents a comparative study of three control strategies for optimizing hydrogen production from waste heat in cement plants: open-loop (no control), Proportional-Integral-Derivative (PID) control, and Model Predictive Control (MPC). The study uses simulation-based results to evaluate the energy efficiency, emission reductions, and operational stability of the system. The open-loop system, lacking feedback control, exhibited fluctuations in hydrogen production rate and temperature regulation, leading to inefficiency and instability. PID control stabilized the production rate but still showed minor fluctuations and occasional overshooting of the temperature, which limited its effectiveness under dynamic conditions. In contrast, MPC demonstrated clear advantages, maintaining hydrogen production at the desired setpoint while optimizing the system's overall efficiency. By anticipating future system behavior and adjusting control inputs dynamically, MPC showed exceptional disturbance rejection, particularly in handling variations in waste heat availability and external temperature changes. The results indicate that MPC leads to significant improvements in system performance, providing more reliable control, better efficiency, and enhanced environmental performance compared to both open-loop and PID strategies. This study highlights the potential of integrating advanced control strategies like MPC to optimize complex systems, offering a sustainable approach to energy management in energy-intensive industries. </p