Adaptive terminal sliding mode control for hypersonic flight vehicles with strictly lower convex function based nonlinear disturbance observer.

In this paper, the altitude and velocity tracking control of a generic hypersonic flight vehicle (HFV) is considered. A novel adaptive terminal sliding mode controller (ATSMC) with strictly lower convex function based nonlinear disturbance observer (SDOB) is proposed for the longitudinal dynamics of HFV in presence of both parametric uncertainties and external disturbances. First, for the sake of enhancing the anti-interference capability, SDOB is presented to estimate and compensate the equivalent disturbances by introducing a strictly lower convex function. Next, the SDOB based ATSMC (SDOB-ATSMC) is proposed to guarantee the system outputs track the reference trajectory. Then, stability of the proposed control scheme is analyzed by the Lyapunov function method. Compared with other HFV control approaches, key novelties of SDOB-ATSMC are that a novel SDOB is proposed and drawn into the (virtual) control laws to compensate the disturbances and that several adaptive laws are used to deal with the differential explosion problem. Finally, it is illustrated by the simulation results that the new method exhibits an excellent robustness and a better disturbance rejection performance than the convention approach.

A novel guidance law using fast terminal sliding mode control with impact angle constraints.

This paper is concerned with the question of, for a missile interception with impact angle constraints, how to design a guidance law. Firstly, missile interception with impact angle constraints is modeled; secondly, a novel guidance law using fast terminal sliding mode control based on extended state observer is proposed to optimize the trajectory and time of interception; finally, for stationary targets, constant velocity targets and maneuvering targets, the guidance law and the stability of the closed loop system is analyzed and the stability of the closed loop system is analyzed, respectively. Simulation results show that when missile and target are on a collision course, the novel guidance law using fast terminal sliding mode control with extended state observer has more optimized trajectory and effectively reduces the time of interception which has a great significance in modern warfare.

[Relationship of TCM syndrome type of gastric mucosal epithelial growth factor, vascular endothelial growth factor and proliferative cell nuclear antigen in patients with chronic atrophic gastritis].

OBJECTIVE: To study the relationship of TCM syndrome type of gastric mucosal epithelial growth factor (EGF), vascular endothelial growth factor (VEGF) and proliferative cell nuclear antigen (PCNA) in patients with chronic atrophic gastritis (CAG) for exploring the essence of TCM type and providing a theoretical basis of clinical treatment. METHODS: TCM syndrome type of 200 patients with diagnosis of CAG confirmed by fibro-gastroscope and pathological examination were differentially classified, and the expressions of EGF, VEGF and PCNA in different types were determined using immunohistochemistry. RESULTS: Patients were differentiated as Pi-Wei deficiency type (Type I ) in 72; Gan-Wei disharmony type (Type II ) in 43; Pi-deficiency with qi stagnation type (Type III) in 32; Wei-yin deficiency type (Type IV) in 24; Pi-Wei damp-heat type (Type V) in 14; and Wei-collateral stasis obstruction type (Type VI) in 5. The difference of PCNA expression level between Type II with Type I , III and IV was significant (P < 0.05). No significant difference in expression levels of EGF and VEGF was found among the 6 types (P > 0.05). CONCLUSION: Type I and II were the dominant TCM syndrome types in CAG patients; the high expression of PCNA might be a diagnostic evidence for Gan-Wei disharmony syndrome.

Anti-inflammatory effect of Diammonium Glycyrrhizinate in a rat model of ulcerative colitis.

AIM: To explore the anti-inflammatory mechanism of Diammonium Glycyrrhizinate in a rat model of ulcerative colitis induced by acetic acid. METHODS: Spragur-Dawley female rats were divided into four groups: Diammonium Glycyrrhizinate group, dexamethasone group, acetic acid control and normal control group. Colonic inflammation was evaluated by disease activity index, gross morphologic damage, histological injury and colonic myeloperoxidase activity. Immunohistochemistry was used to detect the expression of NF-kappaB, TNF-alpha and ICAM-1 in colonic mucosa. RESULTS: Compared to the acetic acid control, both Diammonium Glycyrrhizinate and dexamethasone showed a significant anti-inflammatory effect (P < 0.01). The expression of NF-kappaB, TNF-alpha and ICAM-1 in colonic mucosa was significantly lower in the Diammonium Glycyrrhizinate group and dexamethasone group than in the acetic acid group. CONCLUSION: Diammonium Glycyrrhizinate could reduce inflammatory injury in a rat model of ulcerative colitis. This may occur via suppression of NF-kappaB, TNF-alpha and ICAM-1 in colonic mucosa.