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The benchmarking of CO2 emissions serves as the foundation for the accurate assessment of the environmental impact of air traffic. To calculate the environmental benchmarks of arrival traffic flows with Point Merge System (PMS) patterns, this study proposes a 4D trajectory optimization method that combines data-driven and optimal control models. First, the predominant arrival routes of traffic flows are identified using the trajectory spectral clustering method, which provides the horizontal reference for 4D trajectory optimization. Second, an optimal control model for vertical profiles with point merging topology is established, with the objective of minimizing the fuel–time cost. Finally, considering the complex structure of the PMS, a flexible and adaptable genetic algorithm-based vertical profile nonlinear optimization model is created. The experimental results demonstrate that the proposed method is adaptable to variations in aircraft type and cost index parameters, enabling the generation of different 4D trajectories. The results also indicate an environmental efficiency gap of approximately 10% between the actual CO2 emissions of the arrival traffic flow example and the obtained benchmark. With this benchmark trajectory generation methodology, the environmental performance of PMSs and associated arrival aircraft scheduling designs can be assessed on the basis of reliable data. [ABSTRACT FROM AUTHOR]

To better understand the mechanism of air traffic delay propagation at the system level, an efficient modeling approach based on the epidemic model for delay propagation in airport networks is developed. The normal release rate (NRR) and average flight delay (AFD) are considered to measure airport delay. Through fluctuation analysis of the average flight delay based on complex network theory, we find that the long-term dynamic of airport delay is dominated by the propagation factor (PF), which reveals that the long-term dynamic of airport delay should be studied from the perspective of propagation. An integrated airport-based Susceptible-Infected-Recovered-Susceptible (ASIRS) epidemic model for air traffic delay propagation is developed from the network-level perspective, to create a simulator for reproducing the delay propagation in airport networks. The evolution of airport delay propagation is obtained by analyzing the phase trajectory of the model. The simulator is run using the empirical data of China. The simulation results show that the model can reproduce the evolution of the delay propagation in the long term and its accuracy for predicting the number of delayed airports in the short term is much higher than the probabilistic prediction method. The model can thus help managers as a tool to effectively predict the temporal and spatial evolution of air traffic delay., 1. Introduction Flight delays are one of the most important performance indicators of air transportation system. It has become increasingly more serious, which directly causes huge damage to the quality [...]

The agricultural soils were polluted by the chemical fertilizer for a long time, which led to changing of the soil engineering properties. The strength, compressibility and permeability of red clay contaminated by different concentration solution of ammonium carbonate were tested by the direct shear testing, one-dimensional consolidation testing and variable head permeability test, respectively. The test results show that the cohesion values and the permeability of red clay increase, but the failure strength, internal friction angle and modulus of compressibility under the same load decrease with increasing of the concentration of ammonium carbonate solution. The hydrated film thickness in the red clay is calculated by the theory of double electric layer. And the mechanism of the engineering properties of red clay contaminated by the ammonium carbonate solution is analyzed. The thickness of hydrated film changed by ammonium carbonate solution is the key to influence of the strength, compressibility and permeability of red clay. [ABSTRACT FROM AUTHOR]

Abstract: A novel Pt–IrO2 electrocatalyst was prepared using the dip-coating/calcinations method on titanium substrates. Titanium electrodes coated with oxides were investigated for oxygen evolution. Experimental results showed that Ti/Pt–IrO2 electrode containing 30mol% Pt in the coating exhibited significantly higher electrocatalytic activity for oxygen evolution compared to Ti/IrO2 prepared by the same method, which is also supported by the electrochemical impedance data. Stability tests demonstrated Pt–IrO2 electrocatalyst had a service cycle of 10,000 times in 0.1M H2SO4 solution. And the anode surface had hardly discovered cracks and had compact structures, which contributed to stable nature of the electrode together with good conductivity and specific interaction between Pt and IrO2 formed during the calcination. Furthermore, the enhanced catalytic activity for O2 evolution at Ti/Pt–IrO2 electrode is preliminarily discussed using the Mott–Schottky analysis. [ABSTRACT FROM AUTHOR]