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Nonlinear transmission by special mechanism has been applied in the mechanical flight control system. Through approximate fitting of transmission requirements, the design parameters of the mechanism can be solved. The mechanism designed by this method cannot accurately fulfill the transmission constraint condition, so it has not been applied in the mechanical aircraft engine control system. Based on the characteristic of the mechanical aircraft engine control system, the four-bar mechanism is substituted by the five-bar mechanism to realize nonlinear transmission. The mechanism design parameters are divided into optimization decision parameters and transmission control parameters by analyzing the principle of five-bar mechanism design parameters, the mechanism solving method and optimization design method are built to directly solve the mechanism design parameters and make the transmission characteristic fulfill the constraint condition precisely. Then the maximum transmission ratio and mechanism wear factor are used as the objective function to optimize the mechanism design to improve system performance and service life. Furthermore, it is proved by the engine control system design example and ground test that this method is reasonable and practicable with practical value in engineering.

Introduction. The intestinal flora has become a promising new target in acute ischaemic stroke (AIS), and small intestinal bacterial overgrowth (SIBO) is a common pathological condition of the intestinal flora. Recently, the lactose hydrogen-methane breath test has emerged as a non-invasive and economical method for the detection of SIBO in AIS patients. Exploring the prevalence of SIBO and its associated risk factors will provide a clinical basis for the association between intestinal flora and AIS. Hypothesis/Gap Statement. Given that the prevalence of SIBO and its risk factors in patients with AIS remain to be studied, there is a need to investigate them. Aim. This study aimed to investigate the prevalence and risk factors of SIBO in patients with AIS Methodology. Eighty patients tested for SIBO using the lactulose hydrogen-methane breath test were evaluated. Patients were divided into SIBO-positive and SIBO-negative groups according to the presence or absence of SIBO, respectively. The baseline characteristics and clinical biochemical indicators of the patients were compared between the two groups. The independent risk factors and predictive value of SIBO in AIS patients were determined using multivariate logistic regression and receiver operating characteristic (ROC) curve analyses. Results. Of the 80 consecutive patients with AIS, 23 (28.8 %) tested positive for SIBO. Triglyceride (TG) and homocysteine (Hcy) levels were identified as independent risk factors for SIBO in patients with AIS using multivariate logistic regression analysis ( P <0.005). ROC curve analysis showed that the area under the curve (AUC) of TG was 0.690 (95 % CI 0.577-0.789, P =0.002). The sensitivity, specificity and optimal cut-off values were 95.7 %, 35.1 % and 1.14 mmol l -1 , respectively. The AUC of Hcy was 0.676 (95 % CI 0.562-0.776, P =0.01). The sensitivity, specificity and optimal cut-off values were 73.9 %, 59.7 % and 14.1 µmol -1 , respectively. When TG and Hcy levels were combined, the AUC increased to 0.764 (95 % CI 0.656-0.852, P <0.001). The specificity and sensitivity were 61.4 and 82.6 %, respectively. This showed that the combined detection of TG and Hcy levels had a higher predictive value Conclusion. The prevalence of SIBO in patients with AIS was 28.8 %. TG and Hcy levels are independent risk factors for SIBO in patients with AIS. Both markers had good predictive value for the occurrence of SIBO. In the future, we should actively utilize these indicators to prevent intestinal flora imbalance and the occurrence of SIBO.