A pre-chamber ignition allows spark-ignition engines to operate in lean air-fuel settings. It improves fuel efficiency and reduces emissions. In this study, a reliability analysis of a single GE Jenbacher J620 natural gas engine was done. It was operational on continuous load in the power generation sector in Karachi, Pakistan. The bathtub curve of GE J620 pre-chamber gas valve (PCV) was generated. The three-year industrial data comprised PCV failures that occurred between two overhauls. During infant mortality, the curve revealed 7 failures during 1000 hours. This decreased to a failure for the next two cycles of thousand hours each. The mean-time-to-failure (MTTF) of the gas valve at 2500 hours and 4500 hours was calculated. There was a 50% decrease in reliability after 1500 hours. Exponential distribution revealed that the mean time-to-failure (MTTF) was 545.5 hours. This study was the first of its kind in the facility. Previously, much time was lost in breakdown maintenance. Thus, it helped to increase the system’s reliability.

The aim of this study is to compare the efficiencies of 36 OECD countries in the fight against the COVID 19 pandemic. A three-stage DEA (Data Envelopment Analysis) is proposed. While the first stage analyzes the pre-covid situation, the contagion control and medical treatment stages evaluate the current COVID status of the countries. In the three-stage model, 8 input, 3 intermediate and 3 output variables are used. Efficiency analysis was carried out using output-oriented and constant return to scale CCR model and variable return to scale BCC models. First of all, efficiency analysis was performed for all countries at each stage. Target values have been calculated for countries that are not on the efficient frontier. Considering the target values and percentage changes, suggestions were made for countries to reach the efficient frontier. It has been observed that Turkey is efficient in the pre-Covid and medical treatment stages, but inefficient in the contagion control. Suggestions have been made by comparing the countries that are in the reference position for Turkey in the contagion control stage. Afterwards, with a study that can be described as a sensitivity analysis, overall efficiency scores were calculated for each country by giving different weights to the stages. No multi-stage DEA study has been found that calculates overall efficiency scores and deals with the pre-Covid and Covid pandemic period together.

In the manufacture of machine parts, quenching is a method used in all areas of the industry in different environments and conditions. The obtained hardness values must be in the appropriate value range according to the requirements of the function of the relevant machine part. It is common to measure hardness values according to ASTM E10-01 (Standard Test Method for Brinell Hardness of Metallic Materials), which is one of the hardness measurement methods. In the study, Shewart Average (X ̅) and Range (R) quality control charts and process capability analysis were used to test the compliance of the hardness values obtained as a result of the quenching-tempering process according to the technical drawing of the relevant part in a company manufacturing machine parts. In addition, due to the approximate value of the observation values, the observation values were converted into fuzzy numbers and fuzzy quality control analyzes were performed with the "Fuzzy rules method for TFN case" method, and process adequacy was measured. According to both methods, as a result of the study, it was determined that the process variability was high and therefore the process was not sufficient.

The COVID-19 (Sars CoV-2) virus, which emerged in Wuhan city of Hubei province of China in December 2019, affected the whole world in a short time and was declared a global epidemic by the World Health Organization (WHO) as of March 11, 2020. After this date, closure measures have been implemented all over the world to prevent the spread of the virus. Due to the provisions taken, there have been changes in electrical energy consumption compared to previous years. In March, April and May 2020, when the restrictions affected human life the most, dynamic changes occurred in energy demand all over the world. This has affected international energy markets, energy production and grid load planning. Although the total electricity consumption in Turkey increased compared to the previous year, there was a decrease in the consumption in the commercial tariff. In this study, the effects of the COVID-19 pandemic on electricity consumption were analyzed by analyzing the electricity consumption of Turkey and Ýzmir, depending on the tariffs, based on time. A case study was conducted on an electricity distribution feeder to see the impact of COVID-19 on electricity distribution networks. For the case study, an electricity distribution feeder with 99% of the subscriber density in the residential and commercial tariff group was selected. For the feeder, load forecasting was made using artificial neural networks machine learning method according to 2018, 2019 and 2020 data. In the load forecasting study, 75% of the data was selected for learning and 25% for testing. As a result of the study, the actual and forecasted load data of 2020 were compared. The effects of the COVID-19 pandemic on the lad of an electricity distribution feeder were investigated. In the study, the performance values of load forecasting were determined mse as 0.0024 and R2 as 0.83.

Despite the advances in technology, electrical energy needs in rural and less developed regions is not yet fully met in terms of cost and sustainability. Nowadays, small-scale Photovoltaic (PV) systems can be transported to other regions and easily reinstalled so that these systems can be used in areas where needed for home usage and humanitarian purposes. There is no doubt that a PV-based microgrid is needed in rural and remote areas where energy is often important, and grid energy is not available or unstable. Mobility microgrid design studies can reduce time, effort, and costs significantly in such cases. Therefore, the design, modeling, and technical simulation of an isolated system based on solar energy are investigated and analyzed in this paper. This study also highlights the future trends of transportable-based isolated (off-grid) microgrid design which provides a sustainable solution for small-scale PV power generation. Additionally, an optimal solution approach for power management with Energy Storage (ES) and PV energy technologies is presented in the developed of an off-grid PV system. Aside from the designed system's cost-benefit analysis, important criteria such as lifespan, battery performance, and energy production have been evaluated. The Distributed Energy Resources (DER) with the load flow in 24-hour scenario is modeled, and simulated, also the findings are presented. Specifically, an application study for a 60.75kWp isolated (off-grid) PV system with the 105.60kWh ES, and 16kVA diesel generator is discussed in terms of financial, regional, and technical parameters as well as numerical modeling, and MATLAB simulation for the province of Sanliurfa in Turkey.

One of the most common cyber-attacks that users encounter on the internet are phishing websites. In the attacks that are performed on phishing websites, real websites are duplicated and published on different domain names, and users are directed to these fake websites through various social engineering techniques. Through to the website to which users are directed, they transmit some personal and confidential data such as credit card, username-password details to attackers. In this study, the establishment of the infrastructure and content of phishing internet sites has been explained, a tool named PhisherHunter created, and four different methods have been developed so as to detect such websites. Through the examination of newly registered websites, which is the main detection method, a successful detection rate of 95.4% has been achieved. Three different methods have been used in the active defense part of the study. Firstly, the hosting company has been automatically determined to stop the publication of the phishing website and a notification has been sent with a success rate of 98%. As the second active defense method, the active honeypot technique has been developed. The active honeypot method aims to enter a marked information on the phishing website and to track this information on the real website. And as the last active defense method, the method of poisoning phishing websites by using fake data has been developed. It has been observed that poisoning methods by using the techniques of active honeypot and fake data have achieved a success of 92%.

Recently, researchers have started to be interested in population-based swarm-based algorithms in optimization due to their simple structure, high optimization performance, and ease of adaptation. Although swarm-based algorithms solve continuous optimization problems, they can also be used to solve binary optimization problems. In continuous optimization, the search space variables try to approach the optimal value, while in discrete optimization, the search space variables are fixed and expressed with real values. In binary optimization, the decision variables take values of 0 and 1 and are basically in the discrete optimization class. In this paper, the proposed Rat Swarm Algorithm (RSA) to solve continuous optimization problems is examined. RSA is an algorithm based on swarm intelligence. RSA was developed by imitating the chasing and attacking behaviors of rats. In this study, the original RSA was updated again to solve binary optimization problems and Binary RSA (BinRSA) was proposed. In BinRSA, four U-shaped and four T-shaped transfer functions are used while converting the continuous search field values to binary values. Thus, eight variants of BinRSA were obtained. These are named as BinRSA1, BinRSA2, BinRSA3, BinRSA4, BinRSA5, BinRSA6, BinRSA7 and BinRSA8. Among these variants, the most successful variant of BinRSA was determined as BinRSA6. Then the BinRSA6 variant was developed by adding crossover and mutation operators and was named GBinRSA. GBinRSA's performance has been tested in knapsack problems. In addition, the success of GBinRSA was compared with different heuristic algorithms selected from the literature. According to the results obtained, it has been seen that the solution quality of the proposed algorithm is effective and comparable. The results showed that GBinRSA is a preferred heuristic for binary optimization problems.

Seismic codes are updated by taking into account the information obtained as a result of scientific studies and the observations after earthquakes about the behavior of the building. In Turkey, the Turkish Building Earthquake Codes (TBEC) has also been published in 2019, instead of the Turkish Earthquake Codes (TEC). Both seismic codes contain definitions for nonlinear dynamic analysis for the design and/or evaluation of structures. However, in TBEC, both the definition of the design spectrum and the spectral parameters used to obtain the design spectrum for any location in Turkey have changed. In order to evaluate the effects of these changes on the drift demands, nonlinear dynamic analyzes of single degree of freedom (SDOF) systems with different periods and lateral strength ratios were made according to both TBEC and TEC. Then, mean of the maximum and residual drift demands and the scattering of these demands were compared. For this purpose, totally 72 different TSD systems were considered. For the analysis of these systems, 84 and 168 ground motion record sets were used according to TEC and TBEC (different earthquake zones, ground class and cities), respectively. When the results are examined, it is seen that a) the design spectrums change according to the ground class and cities, b) the maximum and residual drift demands change depending on the earthquake levels and soil classes, c) in some cities, the demands obtained with TBEC, and in some cities, the demands obtained with TBEC are greater, d) drift demands scattering within the set is high and e) the scattering between the sets is low for the maximum drift demand and high for the residual drift demand.

Tons of fly ash are released every year due to the coal burned in thermal power plants that meet 80% of Türkiye's electrical energy needs. Especially considering the low-quality lignite reserves in Türkiye, the recycling rate of the high sulfate fly ash is relatively low. In concrete production, the use of ash containing high SO3 is not allowed due to the limitation of SO3 ratios of fly ash by regulations. Herein, the usability of fly ash, which has a high sulfate content due to the low-quality lignite reserves in Türkiye, and is therefore wholly waste, as a clinker replacement material was investigated. Fly ash, which has been used as a clinker replacement material, was obtained from Afþin Elbistan thermal power plant. Binders were obtained by grinding together the high sulfate fly ash, clinker and gypsum at different rates. The setting times of the mixtures in the fresh cement paste were determined, and the compressive strengths of the hardened samples were examined. As a result of the study, it was concluded that although the high sulfate fly ash extended the setting time by approximately 29% compared to the reference specimen, it increased the 28-day compressive strength of the hardened specimens up to 14%

This study examines the use of rubber particle (RP) recycled from waste vehicle tires, which is one of today's most serious environmental problems in concrete. For this purpose, studies on rubber aggregate concrete (RAC) were compiled and analyzed. The physical, mechanical and durability properties of RAC were investigated. When the results were analyzed, the addition of rubber decreased the compressive and flexural strength, and the modulus of elasticity. The porosity percentage, water absorption, sorptivity and water permeability of RAC generally increased with increasing rubber percentage and rubber size. The addition of rubber aggregate to the concrete increased the toughness of the concrete up to 3 times because of the energy absorbing property of the rubber particles (RPs). Besides, the addition of rubber had positive effects on the properties of concrete such as abrasion resistance and freeze-thaw resistance. Drying shrinkage of RAC varies depending on the percentage, size and stiffness of RPs. The findings reveal that less than 10% of RPs should be used in concrete for structural applications where strength is important.

In urban areas, dust accumulated on the surface is one of the most used sampling methods used to evaluate environmental pollution, due to the effectiveness of meteorology and topography in the transport and accumulation of atmospheric pollution. The heavy metal concentration of surface dust collected from stadium seats was examined in this study. 22 different heavy metals namely Si, Fe, Al, Ti, Mn, Zn, Sr, Ba, Cr, Pb, Co, V, Ni, Sn, Sc, Bi, Sb, Ag, As, Mo, Hg and Cd concentrations were determined by ICP-MS and ICP-OES techniques, and SEM image was examined to determine its morphological structure. Heavy metal concentrations, except Zn and Bi, were found to be lower than those found in the earth crust. The shape and size of the particles indicated that the environment could be influenced by the natural soil source and anthropogenic sources. In addition, two separate assessments were conducted in terms of exposure to dust toxicity for normal daily activity and sporting activity coupled with normal daily activity. The results were considered acceptable because the health risk and cancer risk assessments were below the limit values.

Precipitation of struvite or magnesium ammonium phosphate (MgNH4PO4.6H2O, MAP) in wastewater treatment plants where nitrogen (N) and phosphorus (P) treatment is carried out causes very important operational problems. Also, since MAP has commercial value, its control and recovery is important.
Therefore, batch experiments were conducted to examine the effects of pH, Magnesium (Mg): N and N: P molar ratio, different Mg2+ sources and the presence of calcium (Ca2+) on MAP crystallization. Experimental results showed that at a constant Mg: N: P=1: 1: 1 ratio, the optimum pH was 9, and the N and P removal efficiencies at this pH were 79.4% and 88.4% respectively. These removal efficiencies for N and P increased to 87.6% and 99.1%, respectively, by increasing the Mg: N ratio to 1.25: 1. By increasing the N: P ratio to 1: 1.15, the N removal efficiency increased to 96.4%, but the P removal efficiency decreased to 96.1%. The most effective source of Mg2+ was found to be MgCl2.6H2O, with N and P removal efficiencies of over 96%. It was found that the N removal efficiency was significantly reduced in the presence of Ca2+ in the solution. It was determined that the N removal efficiency, which was >96% in the absence of Ca2+, decreased to 68.6% at 1000 mg/L Ca2+ concentration. In the XRD analysis performed on the sediment, it was determined that the formation was a MAP crystal, and in the addition of Ca2+, an amorphous structure rich in Ca2+ was formed instead of MAP.

In this study, almond shell waste (ASW) as filling material, pure (ER), and waste polystyrene modified bisphenol-A type epoxy resin (ER-PS) were used to obtain biobased composite materials. The modification of ASW was carried out with NaOH and linoleic acid (LnA). Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Particle size distribution analyses were used in the characterization of ASW. Composites were prepared at filling ratios of 10-20-30-40-50% by mass using the casting technique. The morphology of the composites was characterized by SEM. The effects of epoxy matrix type and BK filling ratio on composites' mechanical, thermal, and water sorption properties were investigated. Tensile strength and modulus of elasticity (e-modulus) values of ER-PS/ASW composites were lower, and tensile elongation values were higher than ER/ASW composites. The highest tensile strength values of 95-129 MPa were obtained for LnA modified ASW composites. The order of the tensile strength of the prepared ER matrix composites according to the filler type is: linoleic acid-modified ASW (LnA-ASW) > NaOH treated ASW (NaOH-ASW) > unmodified ASW. The most suitable ASW ratio was found as 30% by mass. e-modulus values of all modified ASW composites were higher than the epoxy matrix. According to the hardness test results, there was no significant difference between the composites. The water sorption of the composites increased depending on the ASW ratio and had a weakening effect on the mechanical properties.

Nickel and titanium-based alloys are commonly used for engineering or medical applications. NiTi alloys are recycled as additive materials at the end of their lifetime. Separate recovery of metals present in NiTi alloy is possible via hydrometallurgical methods; however, NiTi alloys are highly resistant to corrosion. Various mineral acids (H2SO4, HCl, HNO3, H3PO4) have been investigated, and the effect of H2O2 in the leaching medium has also been explored. Different leaching yields have been observed, and correlations between them according to acid treatment conditions have been established. SEM, XRF, and EDS techniques characterized alloys' microstructure and chemical properties. Among mineral acids, H2SO4 and HCl illustrated the highest extraction efficiencies. However, the addition of hydrogen peroxide decreased this efficiency severely. The kinetics of dissolution was obtained through decreased leaching efficiency with the addition of hydrogen peroxide.

In the present study, a comparative study was conducted on drying characteristics, physicochemical (color, texture, rehydration ratio, total phenolic content, and antioxidant activity), and microstructural (SEM and XRD) properties of mushroom slices using conventional (control, 50˚C at atmospheric pressure) and high temperature (75°C-10 min)-vacuum treatments (-90 kPa) (HT-VT) at a different stage of conventional drying. HT-VT is carried out in the beginning (PRE), intermediate (MID70 and MID110), and final (POST) stages of hot air drying. HT-VT at low moisture content led to having similar drying and physicochemical properties to hot-air dried counterparts. MID and POST samples were more comparable with control, while PRE samples were completely different from control. According to SEM and XRD analyses, these differences can be associated with the decomposition of the cell wall and mannitol content within the tissue cells. PRE samples had a softer texture, darker color, and less rehydration ratio with the lowest total phenolic content and antioxidant activity among the others (p<0.05). The hardness, total color change, rehydration ratio, and total phenolic content of POST were similar (p>0.05) and the antioxidant activity was significantly different from the control (p<0.05). This study showed that drying duration can be shortened with desirable physicochemical properties by application combined high temperature and vacuum at lower moisture content levels.