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This paper aims to investigate the cycle performance of a small size turbojet engine used in unmanned aerial vehicles at 0–5,000 m altitude and 0–0.8 Mach flight speeds with real component maps.

The engine performance calculations were performed for both on-design and off-design conditions through an in-house code generated for simulating the performance of turbojet engines at different flight regimes. These calculations rely on input parameters in which fuel composition are obtained through laboratory elemental analysis.

Exemplarily, according to comparative results between in-house developed performance code and commercially available software, there is 0.25% of the difference in thrust value at on-design conditions.

Once the on-design performance parameters and fluid properties were determined, the off-design operation calculations were performed based on the compressor and turbine maps and scaling methodology. This method enables predicting component maps and fitting them to real conditions.

A method to be used easily by researchers on turbojet engine performance calculations which best fits to real conditions.

This study aims to establish a robust evaluation framework for suppliers within the automotive supply chain, specifically in the stamping sector. The primary objectives are to elucidate the performance criteria of suppliers, identify indicators and scales for measuring these criteria and find the importance of the criteria.

The evaluation framework comprises a criteria hierarchy and indicators developed based on the evaluation criteria of major automotive manufacturers. Specific indicators and measurement scales are recommended for assessing suppliers. Importance weights for the criteria are assigned based on the input of nine experts using the Analytic Hierarchy Process (AHP). Finally, four sheet metal stamping tooling (SMST) suppliers are evaluated by four specialists using the proposed evaluation framework.

The study introduces a novel classification of criteria, encompassing financial and commercial perspectives, delivery capability, supplier facility and cultural approaches and business process necessities. The findings underscore the significance of financial and commercial stability in the selection of SMST suppliers, emphasizing their role in mitigating risks associated with disruptions, bankruptcies and unforeseen events. Additionally, several SMST evaluation factors identified in this study contribute to the development of resilience capabilities, highlighting the crucial importance of their inclusion and assessment in the proposed evaluation framework.

This research presents a comprehensive model for evaluating SMST suppliers, which tackles the multidisciplinary challenges within the automotive supply chain. Given the inadequacy or nonexistence of current SMTS selection models, this study bridges the gap by exploring potential and necessary criteria, alongside 116 specific indicators and measurement scales.

This study aims to investigate the aviation, energetic, exergetic, environmental, sustainability and exergoeconomic performances of a micro turbojet engine used in unmanned aerial vehicles at four different modes.

The engine data were collected from engine test cell. The engine performance calculations were performed for four different operation modes.

According to the results, maximum energy and exergy efficiency were acquired as 19.19% and 18.079% at Mode 4. Total cost rate was calculated as 6.757 $/h at Mode-1, which varied to 10.131 $/h at Mode-4. Exergy cost of engine power was observed as 0.249 $/MJ at Mode-1, which decreased to 0.088 $/MJ at Mode-4 after a careful exergoeconomic analysis.

The novelty of this work is the capability to serve as a guide for similar systems with a detailed approach in the thermodynamic, thermoeconomic and environmental assessments by prioritizing efficiency, fuel consumption and cost formation. This investigation intends to establish a design of the opportunities and benefits that the thermodynamic approach provides to turbojet engine systems.

This paper aims to evaluate of the microalgae potential for commercial application, in particular to conduct experimental study of biogenic compounds removal from sewage waters by microalgae, and to calculate economical benefits from biofertizers and biofuel production.

Experimental study in the concentration change of nitrogen and phosphorus compounds in the cultivation of Chlorella Vulgaris microalgae in various types of sewage water was carried out.

The efficiency wastewater treatment by microalgae was confirmed. The economic benefit from the biomass utilization as biofuel production was calculated.

Implementation of wastewater treatment technology with biomass recycling for biofuel and biofertilizers production will minimize the impact on the environment.

As a results of experimental studies, the ability of microalgae to reduce biogenic elements in wastewater was confirmed. Microalgae can be used both for wastewater treatment to biogenic elements removal, such as phosphorous and nitrogen compounds, and biofuel, biofertilizers production. Prospects of the commercial use of microalgae are obvious. They are specially adapted to an environment dominated by viscous forces.

This paper aims to present an example of the measurement of airport efficiency, a topic of great interest in civil aviation today. The methodology used is data envelopment analysis (DEA) and the Malmquist Index. The calculation of airport efficiency with up-to-date data for each period is of great importance in the context of sustainability. The study selected ten airports with high air traffic in Turkey as the sample set. The objective of this study is to evaluate the current state of airport efficiency, identify the sources of inefficiency and make appropriate policy recommendations based on the findings obtained.

The study is based on DEA and Malmquist Index Analysis. The number of personnel and terminal size data of ten selected decision-making units (DMU) are used as inputs, while passenger, cargo and aircraft traffic data are used as outputs. A five-year period, spanning from 2018 to 2022, is considered as the data set in the study.

Upon analysis of the data from the ten airports included in the study, it was found that the current input-output combination yielded efficient results, with the exception of certain characteristics, such as the impact of seasonal conditions or tourism. Concurrent with the growth in aircraft, passenger and freight traffic, the number of personnel employed at these airports has also increased. It was concluded that technological efficiency is of paramount importance for each airport, and that investments in technology should be increased.

A separate assessment was conducted for each of the ten airports included in the study sample. Each airport was evaluated in terms of its strengths and weaknesses, and areas of low efficiency were identified. Consequently, more general conclusions were reached than airport-specific evaluations.

In order to ensure the long-term sustainability of the sector, it is essential that the efficiency measurements of airports are calculated using up-to-date data on a regular basis. The results obtained from these calculations provide guidance for the strategic plans to be implemented in the long term, as well as for the solution proposals for operational problems. In this context, this study not only provides information to policymakers and airport managers about the current situation, as it includes recent data, but also contributes to the literature in this sense, as it includes policy recommendations.