The Thermomyces lanuginosus lipase (TLLs) was successfully immobilized within a novel hydrogel matrix through a two-step crosslinking method. TLLs were initially crosslinked through the Schiff base reaction by oxidized carboxymethyl cellulose (OCMC). The water-soluble OCMC@TLLs complex was subsequently crosslinked by carboxymethyl chitosan (CMCSH) in a microfluidic apparatus to form the CMCHS/OCMC@TLLs microspheres. The CD (Circular Dichroism, CD) and FT-IR (Fourier Transform infrared spectroscopy, FT-IR) spectra demonstrated that the crosslinking of TLLs with OCMC resulted in a less significant impact on their structure compared to that with glutaraldehyde. CMCHS/OCMC@TLLs showed decreased catalytic performance due to the mass transfer resistance, while its thermal stability was greatly improved. The CMCHS/OCMC@TLLs were used to catalyze the lauroylation of arbutin in tetrahydrofuran. After 12 h of reaction under optimal conditions, the yield of 6′-O-lauryl arbutin reached an impressive 92.12%. The prepared 6′-O-lauryl arbutin has high lipophilicity and exhibits similar tyrosinase inhibitory activity and higher antioxidant activity compared to its parent compound. Graphical Abstract

To enhance the comprehensive performance of a low-infrared turbofan engine with CCFCS in throttling state, a rapid calculation method for infrared signature integrating with the component-level model was established. Based on the results analyzed by this method, two distinct nozzle regulation schemes were devised for diverse flight missions. Nozzle regulation scheme 1 is tailored for subsonic cruising, with the primary objective of minimizing fuel consumption, while concurrently mitigating the infrared signature of the tail jet. In this scheme, the nozzle throat area is closed-loop controlled through LP rotor speed, facilitating bypass flow at the mixer inlet nearing choke conditions. On the other hand, regulation scheme 2maintains the nozzle throat area equivalent to the central cone’s cross-sectional area, emphasizing infrared stealth in the rearward direction of the fighter, making it suitable for penetration or combat missions. During the subsonic cruise, scheme 1exhibits an average fuel consumption rate 6.15

This paper conducts a study on closed-loop control of engine performance parameters during mode transition process of TBCC engine based on artificial intelligence method. Firstly, a composite modeling method based on stepwise regression analysis and batch normalization-depth neural network is proposed to establish the on-board model during mode transition to estimate the thrust and inlet airflow in real-time. Secondly, based on the hybrid penalty function-particle swarm optimization algorithm, a mode transition control schedule applicable to the closed-loop control of thrust and inlet airflow is developed. Finally, a data processing method based on similarity conversion is proposed to extend the applicable envelope range of the mode transition control system. The transition time is shortened by 33.3 %, and the fluctuations of thrust and inlet airflow are reduced by 1.33 % and 10.77 %, respectively. When the control system is applied to the off-design mode transition process, a satisfactory mode transition performance is also obtained.

In the current study, a novel chitosan-based composite, carboxymethyl chitosan (CMCHS)/oxidized carboxymethyl cellulose (OCMC) was fabricated and characterized. The composite film (CMCHS 1.5%w/v + OCMC 0.8%w/v) was more uniform and had better tensile properties, UV blocking, water vapor permeability, and antifungal properties than pure CMCHS film. Preservation experiments showed that the CMCHS/OCMC film was more efficient for retaining the quality decrease of strawberry during storage. By the end of 7 days' storage, the hardness, contents of organic acid, soluble solids, and reducing sugar of coated strawberries were increased by 35.1%, 38.5%, 14.1%, and 3.5%, respectively, compared to the control group; and the decay rate of strawberries in CMCHS/OCMC group also dropped to 36%, about 42% decrease than that in control, suggesting the promising application of CMCHS/OCMC composite in coating preservation.

To improve the anti-interference ability of engine afterburning control, the afterburning closed-loop control based on direct performance value as the controlled quantity has attracted a lot of research. Under the condition of afterburner fuel closed-loop control, the instability of the control system caused by the nonlinearity of the afterburner fuel actuator is more prominent. Traditional afterburning control system inevitably exhibits oscillation phenomenon in the nonlinearity intervals of the actuator. In this paper, the phenomenon of engine state oscillation caused by nonlinear characteristics of the afterburner fuel zonal supply system (FZSS) actuator is studied, and a compound control system based on neural network and μ modification control algorithm is proposed to eliminate the oscillation phenomenon. First, the mathematical model of the afterburner FZSS actuator is established on the Simulink platform to simulate the fuel flow discontinuity interval characteristics of the real afterburning system. Second, for the FZSS actuator combined with the mixed exhaust turbofan engine model, a direct performance control system named the compound μ correction adaptive control (CCAC) system is proposed with engine thrust as the controlled quantity to control the afterburner fuel flow in closed-loop way. The CCAC system contains multi μ modification controllers in the controller group module. If the FZSS actuator works in the fuel flow discontinuity intervals, the CCAC system can modify the engine thrust command and switch the controllers through the design of the controller switching strategy and the adaptive control law of each μ modification controller parameter, thus the nonlinear discontinuity intervals can be avoided to realize the smooth transition of turbofan engine states. Finally, the closed-loop numerical simulation is carried out for the designed control system. The simulation results show that the control system can effectively avoid the fuel flow discontinuity intervals and realize the smooth transition of the engine states in the whole operating range of the FZSS actuator. Meanwhile, the control system can improve the control effect adaptively for the engine with degraded performance.

Abstract The Thermomyces lanuginosus lipase (TLLs) was successfully immobilized within a novel hydrogel matrix through a two-step crosslinking method. TLLs was initially crosslinked through the Schiff-base reaction by oxidized carboxymethyl cellulose (OCMC). The water-soluble OCMC@TLLs complex was subsequently crosslinked by carboxymethyl chitosan (CMCSH) in a microfluidic apparatus to form the CMCHS/OCMC@TLLs microspheres. The CD (Circular Dichroism, CD) and FTIR (Fourier Transform infrared spectroscopy, FTIR) spectra demonstrated that the crosslinking of TLLs with OCMC resulted in a less significant impact on their structure compared to that with glutaraldehyde. CMCHS/OCMC@TLLs showed decreased catalytic performance due to the mass transfer resistance, while its thermal stability was greatly improved. The CMCHS/OCMC@TLLs were used to catalyze the lauroylation of arbutinin tetrahydrofuran. After 12 h of reaction under optimal conditions, the yield of 6′-O-laurylarbutin reached an impressive 92.12%. The prepared 6′-O-laurylarbutin has high lipophilicity and exhibits similar tyrosinase inhibitory activity and higher antioxidant activity compared to its parent compound.

A thrust augmentation control schedule was designed for turbo-ramjet engine during mode transition process to achieve high thrust performance. First, a mathematical model of turbo-ramjet engine was established, analyzing the reason for the existence of an insufficient thrust working range under conventional mode transition control schedule. On this basis, a thrust augmentation control schedule was devised for the thrust insufficient range considering the matching between the air inlet available airflow and the engine demand airflow. The control schedule could increase the flow capacity of the engine and reduce the overflow drag of air inlet by opening the ramjet bypass while keeping the turbofan components working at the maximum state, which could improve the maximum installation thrust performance of the engine and achieve a better air inlet/engine matching. By further designing the optimal regulation rule for the rear variable area bypass injector (RVABI), the installed thrust of the engine could be increased by more than 37.93% at most, while simultaneously reducing the fuel consumption by 0.16%. Finally, the turbo-ramjet engine was simulated along the isobaric flight path. The simulation results revealed that under conventional mode transition control schedule, the thrust insufficient occurred when Mach number is above 2.7. The designed thrust augmentation control schedule could effectively improve the maximum thrust of the thrust drop zone and provide sufficient thrust margin for engine during the whole working process. At the same time, considering the smooth thrust and thrust augmentation requirements, a compromise mode transition control schedule between the thrust augmentation control schedule and the conventional mode transition schedule is proposed. This control schedule could address the problem of insufficient thrust at high Mach numbers while the smoothness transition of engine total thrust could be guaranteed.

To improve the infrared stealth performance of the engine, an infrared characteristics real-time prediction model suitable for the overall design/control system simulation of small bypass ratio turbofan engine with typical exhaust system structure was developed. First, the accuracy and calculation speed of the model was proved to meet the requirements after comparing with CFD results; Then, the influence of the cycle parameters on the infrared characteristics was analyzed by the model. Steady-state numerical simulations were carried out for different flight missions, and the variation law of the engine infrared characteristics in the flight envelope was obtained. Finally, the dynamic response of infrared characteristics in transient state was studied. The results show that the infrared radiation intensity in the afterburner state increased by 1–2 orders of magnitude compared with the cruise state; The response speed of lateral infrared radiation intensity was basically consistent with that of thrust, while the response of backward infrared radiation intensity lagged greatly. Some useful implications from this study include turbofan overall optimized design and performance seeking control.