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An essential device for managing the vectoring nozzle’s thrust direction is the thrust-vectoring nozzle adjusting mechanism. The attitude of an aircraft’s flight may be changed by adjusting the vectoring nozzle’s airflow, which affects the direction of thrust. The adjusting mechanism’s motion precision and operational stability are crucial in this procedure. In this paper, the influence of the clearance of the motion joint on the dynamic characteristics of the thrust-vectoring nozzle adjusting mechanism under different flight conditions are studied. First, a dynamic model of the thrust-vectoring nozzle adjusting mechanism that takes into account the clearance and friction properties of the motion joint is constructed by combining the Lagrange equation of the first sort with the mixed contact force model and the LuGre friction model. Second, the variation law of nonlinear contact stiffness is explored, and the precision of the dynamic model is confirmed by contrasting the results of the numerical simulation with those of the Simulink simulation. Finally, the simulation results reveal that while the motion joint’s clearance causes the adjusting blade’s velocity and acceleration to vibrate violently and momentarily during early operation, this clearance has minimal effect on the precision of blade motion throughout the stable phase.

CFRP/Ti pinned joints are widely applied on main load-bearing structures of aircrafts. Understanding the dynamic behavior of the joints is important for optimal joint designs. Therefore, a dynamic test platform based on electromagnetic loading method was developed to investigate the dynamic behavior of CFRP/Ti single-lap pinned joints under tensile dynamic loading. Bearing and failure loads of the joints were evaluated, and the dynamic failure mechanism was discussed. The test results demonstrated that both bearing and failure loads decreased with impact velocity, which is consistent with the literature. Failure modes of the joints were dominated by CFRP failure. High-rate joints failed first in bearing failure mode, but ultimately experienced tearing-out failure. Moreover, much fiber and matrix fracture was observed during dynamic loading progress. A study of interference size also revealed a correlation with the dynamic behavior of the joints, which will help to optimize joint designs.

Protease-activated receptor 2 (PAR-2) has been demonstrated to promote invasion and metastasis of certain cancer cells. This study aimed to investigate the mechanism by which PAR-2 regulated invasion and migration of esophageal cancer (EC) cells EC109. A successfully constructed PAR-2 shRNA lentiviral vector (Lenti-PAR-2 shRNA) was stably transfected into EC109 cells, and the expression of PAR-2 in infected cells was detected by quantitative real-time PCR (qRT-PCR) and western blotting. Specific inhibitors, PD98059 (for MEK/ERK) and LY294002 (for PI3K/Akt), were used to confirm the role of MEK/ERK and PI3K/Akt signaling pathways, respectively, in PAR-2-regulated invasion and migration of EC109 cells. A significant decrease in PAR-2 mRNA and protein expression was detected in EC109 cells stably transfected with Lenti-PAR-2 shRNA. The PAR-2 agonist could dramatically promote cell invasion and migration, up-regulate the expression of MMP-9 and TM4SF3, and activate MEK/ERK and PI3K/Akt signaling pathways. However, PAR-2 gene silencing attenuated PAR-2-mediated enhancement of invasion and migration of EC109 cells, significantly down-regulated the mRNA and protein expression of MMP-9 and TM4SF3, and inhibited ERK (Try202/204) and Akt (Ser473) phosphorylation. An effect similar to PAR-2 silencing could be achieved with the two specific MEK/ERK and PI3K/Akt pathway inhibitors. Consequently, these results demonstrated that PAR-2 promoted invasion and migration of esophageal cancer cells EC109 by activating MEK/ERK and PI3K/Akt signaling pathways, which was accompanied by up-regulation of MMP-9 and TM4SF3 expression. Hence, PAR-2 may be a potential candidate for anti-metastasis treatment of EC.

Interference fit can significantly enhance the tensile and fatigue strength of CFRP/Ti bolted joints, however, the damage can occur during interference fit bolt installation progress. Therefore, an experimental study was conducted to understand damage behaviors of the joint during the interference fit bolt installation progress using dynamic installation method based on electromagnetic dynamic force. The installation resistance was evaluated and the damage mechanism was discussed. Moreover, the influence of interference size on damage behaviors was also studied. The test results demonstrated that the installation resistance exhibited two typical stages and mainly generated by Ti plate, which agreed with theoretical analysis. Damage modes of the joint were dominated by CFRP damage and significantly influenced by interference size. The internal damage mainly occurred in the entrance and the exit of the hole in CFRP, especially, the first ply along the installation direction was the most critical ply, on which a typical damage ring was observed. The dynamic installation method can reduce the damage and the layer deflection of CFRP, which is suggested to be used to improve joint designs.

Interference fit can lead to better fatigue behavior of mechanical fastened joints. To explore the fatigue enhancement mechanism of interference fit, an analytical model of an interference-fit pinned sheet under subsequent tensile loading is presented. This model is employed to correlate the bypass load with the external longitudinal tensile load of the sheet, and the range of the two forces. Three-dimensional (3D) finite element (FE) analysis is performed using ABAQUS and comparison between the results of the two models shows a good agreement. Analytical results reveal that the key to the reduction of the bypass load amplitude lies in the elastic deformation of connected members of interference-fitted joints and the contact between them. This effect is accomplished through the automatic adjustment of the contact at the interfaces of the pin and sheet. For a specific joint, the effective affecting range (EAR) of interference for external loading is dependent on the interference and stiffness of its members. Specifically, the bypass load amplitude can be reduced only when external loads intersect EAR with a nonempty subset. If exerted loads are entirely within EAR, the bypass load amplitude can be minimized and the reduction ratio depends solely upon the stiffness of the connected members. It is also concluded that taking into consideration the external loads, especially its maximum value, is essential in the optimizing of interference. Finally, the optimum interference is deduced via the analytical model.

Based on three-point supported automatic leveling platform, this paper first establishes the mathematical model of leveling platform, and determines the kinematic relationship between front&rear pitching, left&right lifting and its supporting leg action, then tests and analyzes different leveling control methods on the platform through the experiment, finally explores the coordinated control strategy of signal acquisition system and platform support leg servo system and leveling control system according to the test data, and presents flow chart of the control strategy in the working process of the automatic leveling platform. The control strategy can guarantee the fast response of the automatic leveling platform during the leveling process.

Applications of microparticles and nanoparticles have been found in the fields of microelectronics, micro-electro-mechanical systems (MEMS), material engineering, chemical engineering, biomedical engineering and others. In most of the applications, the interfacial interactions of microparticles and nanoparticles with surfaces play a significant role. Currently, there are a very limited number of techniques capable of characterizing the properties of both the particles and the particle-surface interactions in real time with high sensitivities. In this thesis, a novel method using a thickness shear mode (TSM) acoustic wave sensor is devised to characterize the interactions of microparticles with surfaces and the properties of microparticles.Interfacial forces between a single microparticle and a surface, including Van der Waals forces, the gravitational force and capillary force, are analyzed. A mechanical model is developed to describe the interfacial interaction of a single microparticle with a piezoelectric quartz crystal TSM sensor. An important parameter, interfacial coupling coefficient, is proposed to characterize the particle-surface interactions. Equivalent electrical circuits are built to study the effects of a loading of a single or multiple particles on the electrical characteristics of a TSM sensor. The dependence of the change in the resonant frequency of a TSM sensor on the diameter of a particle is obtained. The mass sensitivity of 5 MHz and 10 MHz TSM sensors are experimentally determined. The interfacial coupling coefficients obtained from the TSM measurements are compared with the results obtained from the measurements of the interaction forces between a particle and a surface by using an atomic force microscope (AFM).This study shows that TSM sensors can be used as a very promising tool for the real-time characterization of the interactions of microparticles with a surface and the properties of the microparticles.