Design of a Modified Tracking Differentiator

A modified tracking differentiator is proposed. Firstly, a nonlinear odd exponent continuous function is adopted which is only stable at one equilibrium point and proved the global asymptotic stability of the modified tracking differentiator by select a Lyapunov function. Through combining of the nonlinear and linear function properly, it can be sure that the state converges to the equilibrium point with high speed automatically no matter that the state was far away from the equilibrium point or near to it, and it can prevent the chattering.?Simulation results show that the modified tracking differentiator tracking results?are?superior to the classical nonlinear tracking differentiator, and the response?of state variables tracking differentiator estimated?is?almost coincide with the real state of the variables of the given system.

Experimental Study of the Vibration Phenomenon of Compressor Rotor Blade Induced by Inlet Probe Support

An experimental investigation was conducted in order to understand the installation effects of inlet measurement probes on the vibration characteristics of the rotor blades in two axial compressors.The vibration signal of the rotor blades was analyzed for different layouts of the inlet measurement probes.For the three-stage axial compressor,the first-order resonance occurs on the first stage of the rotor blades at an engine order excitation condition,which is induced by the cylindrical probe support with a diameter of 10 mm.When the size of the probe support is decreased,the vibration level reduces evidently.In contrast,for the six-stage axial compressor,the first-order resonance occurs on the first stage of the rotor blades at an excitation source of 6th order,which is triggered by the inlet measurement probes and the upstream struts.When the number of the inlet measurement probes is changed,the resonance of the rotor blades vanishes.

Analysis on Chinese Airline Network Invulnerability

Air transportation systems are often subject to failures or attacks induced by unexpected abominable weather or temporal airspace occupation, while complex networks have been springing up as a convenient yet efficient tool to represent and analyze various realistic complex systems such as realistic airline system. In terms of Chinese airline network formed during the spring festival timespan, structural empirical research and invulnerability simulation analysis against various deliberate attack strategies were made using complex network theory, where nodes and edges denotes domestic airports and direct flights between them respectively. The analysis results indicate: The presented airline network is a small net-work with scale-free characteristics, and correlation shows remarkable hierarchical structure and obvious assortative characteristics;The network shows obvious invulnerability under deliberate node attack, while shows partly robustness under edge attack even with obvious attack effects against various attack strategies.