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A novel adaptive backstepping controller is developed to achieve the asymptotic synchronization. The designed controller only contains the values of system states, and doesn’t contain any other prior knowledge of system. Firstly, the designed controller regards the unknown system nonlinearities and the disturbance of state time-delay as “disturbance-like” terms, which are guaranteed to be bounded by using the pre-set barrier functions, such that any prior knowledge of system nonlinearities and state time-delay are released. Then, the “disturbance-like” terms are compensated adaptively by designing the novel compensator at each step, such that the synchronization errors are eliminated to zero eventually for each agent. It is proved that our developed controller guarantees the convergence on the basis of Lyapunov stability theory. Some simulations are shown to demonstrate the effectiveness and advantages of the developed method.

Today, with increase in the demand for higher quality communication, a kind of long adaptive filter is frequently encountered in practical application, such as the acoustic echo cancellation. Increase of adaptive filter length from decades to hundreds or thousands causes the conventional adaptive algorithms encounter new challenges. Therefore, a new variable step-size normalized least-mean-square algorithm combined with Partial update is proposed and its performances are investigated through simulations. The proposed step size method takes into account the instantaneous value of the output error and provides a trade-off between the convergence rate and the steady-state coefficient error. In order to deal with this obstacle that the large number of filter coefficients diminishes the usefulness of the adaptive filtering algorithm owing to increased complexity, the new algorithm employing tap-selection partial update schemes only updates subset of the filter coefficients that correspond to the largest magnitude elements of the regression vector. Simulation results of such applications in acoustic echo cancellation verify that the proposed algorithm achieves higher rate of convergence and brings significant computation savings compared to the NLMS algorithm.

We demonstrate, for the first time to the best of our knowledge, fabrication of three-dimensional microfluidic channels with arbitrary lengths and configurations inside glass by femtosecond laser direct writing. The main fabrication process includes two steps: (1) direct formation of hollow microchannels in a porous glass substrate immersed in water by femtosecond laser ablation and (2) postannealing of the glass substrate at ∼1150°C by which the porous glass can be consolidated. We show that a square-wavelike channel with a total length of ∼1.4cm and a diameter of ∼64μm can be easily produced ∼250μm beneath the glass surface.

We report the direct fabrication of a microfluidic chip composed of two high-aspect ratio microfluidic channels with lengths of 3.5 cm and 8 mm in a glass substrate by femtosecond laser micromachining. The fabrication mainly consists of two steps: 1) writing microchannels and microchambers in a porous glass by scanning a tightly focused laser beam; 2) high-temperature annealing of the glass sample to collapse all the nanopores in the glass. Migration of derivatized amino acids is observed in the microfluidic channel by applying electric voltage across the long-migration microchannel.