Wu Ai

An Improved Neural Network for Solving Optimization of Quadratic Programming Problems

For the quadratic programming problems with both equality and inequality constraints, an improved neural network is proposed based on the Lagrange function reconstructed based on the saddle point theorem of optimization theory. The proposed neural network has less neuron quantity than the traditional method with slack variables does. The stability and convergency of the proposed neural network is investigated. The feasibility of the neural network is verified with computation examples are discussed. The simulation results illustrate the proposed neural network have an effective computational capability and performance for optimization of the quadratic programming problems

An improved fuzzy system for position control of permanent magnet linear motor

In this paper, a fuzzy system with stable value is proposed to promote the traditional fuzzy controller and to be applied to position control of the permanent magnet linear motor. By a partition of error and change of error, the proposed fuzzy system can be used in a traditional fuzzy controller and can be switched to preceding a stable output control smoothly. For PMLM control system, the output of position control can be divided into a stable value and a changing one when the controlled system is close to stable state. A stable parameter value is acquired from the output of a traditional fuzzy controller when the controlled system comes into the stable state. And the stable parameter value can be tuned by a designed integral part so as to alleviate the static error. Simulation results show the improved fuzzy system has a higher performance than the traditional PID and the traditional fuzzy controller. The experiment results also verify that it has high precision in position control of PMLM.

A Nanofluidic Biosensor Based on Nanoreplica Molding Photonic Crystal

A nanofluidic biosensor based on nanoreplica molding photonic crystal (PC) was proposed. UV epoxy PC was fabricated by nanoreplica molding on a master PC wafer. The nanochannels were sealed between the gratings on the PC surface and a taped layer. The resonance wavelength of PC-based nanofluidic biosensor was used for testing the sealing effect. According to the peak wavelength value of the sensor, an initial label-free experiment was realized with R6g as the analyte. When the PC-based biosensor was illuminated by a monochromatic light source with a specific angle, the resonance wavelength of the sensor will match with the light source and amplified the electromagnetic field. The amplified electromagnetic field was used to enhance the fluorescence excitation result. The enhancement effect was used for enhancing fluorescence excitation and emission when matched with the resonance condition. Alexa Fluor 635 was used as the target dye excited by 637-nm laser source on a configured photonic crystal enhanced fluorescence (PCEF) setup, and an initial PCEF enhancement factor was obtained.

Hierarchical fuzzy neural controller based on error iterative and approach

In this paper, a fuzzy neural networks based on hierarchical approach reasoning is proposed. The construction combining model is described by the fuzzy logic technology. The output of the antecedent part of the fuzzy logic is expressed as the input of the consequent part. The consequent part is a simple linear equation of the variables corresponding to the rule strength of the antecedent network and the output variables of the consequent network. So, the physical meaning of the proposed fuzzy neural network is clearer and its structure is simpler. We present a learning algorithm based on hierarchy error approach which utilizes a fuzzy logic function to aggregate the weight coefficients of the neural network, so the output can rapidly converge to the desired tolerable error range. Simulation results show the fuzzy neural network based on fuzzy hierarchy error approach have very good approach ability of for the complex functions through learning and training of the rule weight.

CMOS-Compatible Fabrication for Photonic Crystal-Based Nanofluidic Structure

Photonic crystal (PC)-based devices have been widely used since 1990s, while PC has just stepped into the research area of nanofluidic. In this paper, photonic crystal had been used as a complementary metal oxide semiconductors (CMOS) compatible part to create a nanofluidic structure. A nanofluidic structure prototype had been fabricated with CMOS-compatible techniques. The nanofluidic channels were sealed by direct bonding polydimethylsiloxane (PDMS) and the periodic gratings on photonic crystal structure. The PC was fabricated on a 4-in. Si wafer with Si3N4 as the guided mode layer and SiO2 film as substrate layer. The higher order mode resonance wavelength of PC-based nanofluidic structure had been selected, which can confine the enhanced electrical field located inside the nanochannel area. A design flow chart was used to guide the fabrication process. By optimizing the fabrication device parameters, the periodic grating of PC-based nanofluidic structure had a high-fidelity profile with fill factor at 0.5. The enhanced electric field was optimized and located within the channel area, and it can be used for PC-based nanofluidic applications with high performance.

Accurate tracking control of a linear fast tool servo unit for noncircular cutting

In this paper, an accurate position tracking control scheme is proposed for a moving-coil-type linear DC motor driven fast tool servo unit for noncircular cutting application. A sliding mode tracking controller is designed to ensure the system has a fast tracking characteristic to the position command. Moreover a disturbance observer is used to estimate and compensate exogenous disturbance to improve robustness and stability of the fast tool servo unit. Because the reference input is approximately periodic in noncircular cutting process. Therefore, the periodic error can he further reduced by augmenting an iterative learning controller to the existing sliding mode controller for repetitive position tracking. The experimental results of noncircular cutting adopting the proposed control method, including tracking performance and robustness of the system, are much improved.