With the development of space technology, the functions of lunar vehicles are constantly enriched, and the structure is constantly complicated, which puts forward more stringent requirements for its ground micro-low-gravity simulation test technology. This paper puts forward a high-precision and high-dynamic landing buffer test method based on the principle of magnetic quasi-zero stiffness. Firstly, the micro-low-gravity simulation system for the lunar vehicle was designed. The dynamic model of the system and a position control method based on fuzzy PID parameter tuning were established. Then, the dynamic characteristics of the system were analyzed through joint simulation. At last, a prototype of the lunar vehicle’s vertical constant force support system was built, and a micro-low-gravity landing buffer test was carried out. The results show that the simulation results were in good agreement with the test results. The sensitivity of the system was better than 0.1%, and the constant force deviation was 0.1% under landing impact conditions. The new method and idea are put forward to improve the micro-low-gravity simulation technology of lunar vehicles.

Porous air journal bearings (PAJBs) with O-rings mounted are regarded as a potential choice to offer air levitation with a large load capacity and optimal start/stop characteristics, which are required in small-size and high-efficiency turbomachinery. However, the coupling of the mechanical properties of the O-rings and lubrication induce strong nonlinear characteristics, thereby affecting the dynamic responses of the rotor. In this study, a numerical model is presented, which is coupled with the excitation frequency-influenced stiffness and damping characteristics of O-rings, the Darcy’s laws, air motion equations established by the air lubrication model, and the rotor and bearing motion equations. The model is well verified by the experimental results. The effect of the different system parameters on the performance of the rotor-PAJB system (RPS) is studied by analyzing the bifurcation diagrams, orbit, Poincaré maps, and FFT plots. Results show that the motion of the rotor is changed between periodic and quasi-periodic with the variation in rotational speed, external supply pressure, bearing clearance, and porous permeability. With O-rings mounted, the stability of RPS can be increased to hinder the rotor motion from changing from periodic to quasi-periodic. The effectiveness in increasing the stability of the RPS for the O-rings with SBR as the material is better than that with NBR but weaker than that with VMQ. Moreover, only a few number of O-rings have better effects on improving the stability of the RPS.

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In this paper we present WSProxy, an analysis system for malicious websites that focuses on detecting attacks through behavior of web programs. The system uses Webkit which is an open script engine to execute page scripts. We detect malicious codes from web pages using static analysis and dynamic analysis technology. In contrast to previous work, this approach combines generality with usability, since the system is executed directly in the web browser before the web page is displayed. We show that we can achieve false positive rates below 5% and false negative rates below 10% with a performance overhead of only a few seconds, which affords a great potential for future versions of our tool.

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