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Building contractors have many risks to face. we took the multi-level comprehensive evaluating method of gray relational analysis and effectively resolved the problem of index weight in system, the comprehensive relational degree from this study gave a basis to evaluate building contractors' risks scientifically.
This paper investigates the modeling and control problem of a novel piezoelectric-actuator (PZT) driven nanopositioner. The physical model of the nanopositioning stage is first discussed with the hysteresis nonlinearity of the PZT actuator. For the purposes of eliminating the hysteresis impact and various disturbances, an active disturbance rejection control (ADRC) algorithm is proposed, where the...
This paper studies the anti-disturbance control for ultra-high precision positioning of a piezoelectric-actuator driven nano-positioner, subjects to nonlinear dynamics and various external disturbances. In this particular study, the multiple-disturbance is supposed to have two parts. One is the undesired vibration resonance, which could be described by an exogenous dynamical system. The other includes...
In this paper, we consider the discrete time case of a time-varying internal model-based control design for high precision tracking of frequency-varying reference trajectories. Thanks to a recently proposed parallel time-varying internal model structure, the asymptotic tracking conditions for the design of internal model units are developed, and a low order robust stabilizer is synthesized. In a discrete...
In view of traditional hydrauLic micro-displacement mechanisms in honing, complexity of structure, low control resolution and low efficiency have greatly Limited appLications and the popularization of honing. These micro-displacement feeding mechanisms are unfit to be appLied in multi-channel feeding for large diameter parts because of their low efficiency. So, in this paper, a new strategy for micro-displacement...
This paper studies the integration of VRML and Ja-va3D in the Web3D core technology, and adopts Java3D to implement the virtual scene displaying and the users and virtual scene interactive roaming function, promoting users to experience the 3D stereo model displaying way online without leaving home.
Web service matchmaking is an important aspect of interaction between modern enterprises. At present, many service matchmaking methods are proposed. However, most of them only consider function compatibility of service, yet ignoring the compatibility of task circumstance. In fact, a service description should contain semantics of task circumstance, which can improve the precision of service matchmaking...
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