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ObjectivesThe maritime navigation environment is random, complex and changeable, and intelligent autonomous navigation is an important trend in the development of large ocean-going transport ships, for which a new adaptive control method is proposed. MethodsFirst, the linear quadratic regulator (LQR) control method is integrated with the first-order dynamic integral sliding mode control method based on the grasshopper optimization algorithm (GOA). A nonlinear passive estimator with real-time monitoring of wave disturbance forces is then combined to separate the high and low-frequency motion signals of the ship. Finally, the simulation results of the proposed method are compared with those of the LQR control method and first-order dynamic integral sliding mode control method. ResultsThe results show that the new control method has better transient and steady-state tracking performance, and is able to overcome the effects of random waves under different sea conditions with strong robustness. ConclusionsThe new control method has such abilities as self-adjustment in complex environments, fast control response, high precision and less redundant steering, enabling it to greatly improve the navigation efficiency, safety and stability of large transport ships.

In order to improve the quality of dried beef products, the impact of protease-producing lactic acid bacteria on the degradation of beef protein was clarified. Three lactic acid bacteria (LAB) strains with high protease-producing ability were inoculated in the dried beef, namely Lactococcus lactis (S-1), Lactococcus gracilis (S-2) and Pediococcus pentosaceus (S-3). The samples without adding starter were used as control group (CK). Instrumental analysis and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were used to detect the protein degradation of dried beef. The results showed that the contents of non-protein nitrogen, amino acid nitrogen and TCA-soluble peptide increased gradually with the extension of fermentation time, and the inoculation group was significantly higher than the CK group (P 0.05). The total free amino acids in the samples of S-1 and S-2 groups were significantly increased (P < 0.05). SDS-PAGE results showed that the protein degradation degree of the inoculation group was significantly higher than that of the CK group. In the process of dried beef production, inoculation of protease-producing lactic acid bacteria could significantly improve the degree of protein degradation, and S-1 group had the most obvious effect on protein degradation.

Objectives The electro-hydraulic servo valve operates in a harsh working environment but lacks integrated testability. In order to improve the usability and maintainability of electro-hydraulic servo valves, it is necessary to design a built-in test (BIT). Methods A BIT method involving the characteristics of the valve amplifier is proposed. On this basis, the implementation of BIT software/hardware and the concrete design of anti-false alarm measures are given, and a closed-loop electro-hydraulic servo system is constructed for verification. Results The verification test results show that this design method is feasible and can quickly detect faults online. Conclusions The BIT method is an effective way to reduce the maintenance cost of the electro-hydraulic servo system life cycle, giving it certain engineering application value.

Background Hypoparathyroidism is one of the common complications of radical thyroidectomy, but there are few studies on differentiated thyroid cancer. Objective To investigate the influencing factors of hypoparathyroidism in patients with differentiated thyroid carcinoma after radical thyroidectomy. Methods A total of 166 patients with differentiated thyroid carcinoma who underwent radical thyroidectomy from 940 Hospital of PLA Joint Logistics Support Force from June 2018 to December 2020 were included, and their clinical data were collected, including gender, age, body mass index (BMI), tumor site, tumor size, blood supply of lesion, whether there is capsule invasion, surgical method, scope of lymph node dissection, whether there is use of carbon nanoparticles, parathyroid gland resection. Also, this study monitors preoperative and postoperative serum PTH and follow-up monitoring levels of Ca2+. Results Among the 166 patients, the incidence of postoperative hypoparathyroidism was 28.31% (47/166), among which the incidence of temporary hypoparathyroidism was 21.68% (36/166) and the incidence of permanent hypoparathyroidism was 6.63% (11/166). There were statistically significant differences between patients with normal parathyroid function and patients with hypoparathyroidism in gender, age, tumor location, membranous invasion, surgical method, lymph node dissection and the use of carbon nanotube (P