Coupling a Chlor-Alkali Membrane Electrolyzer Cell to a Wind Energy Source: Dynamic Modeling and Simulations

Renewable energy sources are becoming a greater component of the electrical mix, while being significantly more volatile than conventional energy sources. As a result, net stability and availability pose significant challenges. Energy-intensive processes, such as chlor-alkali electrolysis, can potentially adjust their consumption to the available power, which is known as demand side management or demand response. In this study, a dynamic model of a chlor-alkali membrane cell is developed to assess the flexible potential of the membrane cell. Several improvements to previously published models were made, making the model more representative of state-of-the-art CA plants. By coupling the model with a wind power profile, the current and potential level over the course of a day was simulated. The simulation results show that the required ramp rates are within the regular operating possibilities of the plant for most of the time and that the electrolyte concentrations in the cell can be kept at the right level by varying inlet flows and concentrations. This means that a CA plant can indeed be flexibly operated in the future energy system.

End-to-end Mars entry, descent, and landing modeling and simulations for Tianwen-1 guidance, navigation, and control system

On May 15, 2021, the Tianwen-1 lander successfully touched down on the surface of Mars. To ensure the success of the landing mission, an end-to-end Mars entry, descent, and landing (EDL) simulator is developed to assess the guidance, navigation, and control (GNC) system performance, and determine the critical operation and lander parameters. The high-fidelity models of the Mars atmosphere, parachute, and lander system that are incorporated into the simulator are described. Using the developed simulator, simulations of the Tianwen-1 lander EDL are performed. The results indicate that the simulator is valid, and the GNC system of the Tianwen-1 lander exhibits excellent performance.

PERFORMANCE EVALUATION OF RAILWAY BALLAST DEGRADATION USING THE MORPHOLOGICAL PROPERTIES

Ballast degradation through attrition and breakage during operations affects the structural performance of the railway track system. In an attempt to study railway ballast degradation changes due to train cyclic loading at micro-scale. This study quantified and compared the changes that occur on ballast particles due to ballast degradation using LAA test and image analysis techniques. TB/T 2328.14-2008 gradation use by china railways was adopted. Series of LAA tests were conducted to accelerate the ballast particle breakage and abrasion, in a sequence of 250 turns of the LAA test drum, after which the changes in gradation and morphological properties were quantified. The morphological properties were quantified using imaging techniques (Aggregate Image measurement system (AIMS)). At the end of the study, the overall results showed that ballast degradation has a strong correlation with the ballast particle's morphological properties. The relationships and the indices of morphological changes can be used for numerical modeling and simulations using discrete element method (DEM) to study the performance of ballast at different degradation levels.

Modeling and simulations of a Zika virus as a mosquito-borne transmitted disease with environmental fluctuations

This paper deals with the stochastic Zika virus model within the human and mosquito population. Firstly, we prove that there exists a global positive solution. Further, we found the condition for a viral infection to be extinct. Besides that, we discuss the existence of a unique ergodic stationary distribution through a suitable Lyapunov function. The stationary distribution validates the occurrence of infection in the population. From that, we obtain the threshold value for prevail and disappear of disease within the population. Through the numerical simulations, we have verified the reproduction ratio R 0 S ${R}_{0}^{S}$ as stated in our theoretical findings.