Zhou Zhaoying

Shape recognition using complex nonlinear exponential autoregressive model

In this paper, the closed boundary of an arbitrary 2-0 shape is considered to be physically related to the trace of a 2-0 orthogonal nonlinear vibrafion with equal period, and hence a complex exponential autoregressive (CEAR) model is proposed to describe the 2-0 closed boundary. The model coefficients are invariant to translation, rotation, scale and choice of the starting point in tracing a boundary, additionally, they are not invariant to mirroring transformafion. Due to the nonlinearity of the model, the local information of boundary is also reflected in the coefficients. Experimental results indicate that this model has superior performance in recognizing similar shapes and some dgferent patterns with mirroring similarity. Furthermore, this model has good prospect for the recognition of constrained handwritten numerals and characters.

Adaptive filtering of color noise using the Kalman filter algorithm

In the view of the drawbacks of the conventional Kalman filtering, a kind of adaptive Kalman filtering approach of color noise based on the correlative method of the system output is proposed. This approach builds the Kalman filtering model of color noise by adopting the equivalent measurement equation in order to avoid complicated computation and the expansion of the dimension of the filter. It is unnecessary to know the variance of the measurement noise beforehand so that it is closer to the actual situation. The correlative method of the system output is presented to estimate the variance of the measurement noise. The adaptive filtering of color noise using the Kalman filter algorithm is applied to solve the cephalometric images of stomatology. Several experimental results demonstrate the feasibility and good performance of the approach.

A cold 87Rb atomic beam

We demonstrate an experimental setup for the production of a beam source of cold 87Rb atoms. The atoms are extracted from a trapped cold atomic cloud in an unbalanced three-dimensional magneto—optical trap. Via a radiation pressure difference generated by a specially designed leak tunnel along one trapping laser beam, the atoms are pushed out continuously with low velocities and a high flux. The most-probable velocity in the beam is varied from 9 m/s to 19 m/s by varying the detuning of the trapping laser beams in the magneto—optical trap and the flux can be tuned up to 4×109 s−1 by increasing the intensity of the trapping beams. We also present a simple model for describing the dependence of the beam performance on the magneto—optical trap trapping laser intensity and the detuning.

Self-Aligned Growth of Single-Walled Carbon Nanotube Bridging Two Electrodes

An integrated method for the fabrication of electrical contacts to the single-walled carbon nanotubes (SWNTs) by gas-flowing techniques is reported. Bridge structures containing single SWNT channels are successfully fabricated through the CVD process. Raman spectra of the grown nanowires exhibit typical radial breathing modes which can be associated with the vibrational features of SWNT. Atomic force micrograph (AFM) and scanning electronic microscopy (SEM) images demonstrate that the as-growth SWNTs are indeed bridging two electrodes. I-V curves of such a structure confirm that the SWNTs are electronically linked with the Mo electrodes. This research provides a parallel method for the large-scale integration of SWNTs into electronic, optoelectronic, and sensing systems.

Electrical characteristics and optoelectronic properties of metal?semiconductor?metal structure with zinc oxide nanowires across Au electrodes

This paper reports on a method of assembling semiconducting ZnO nanowires onto a pair of Au electrodes to construct a metal?semiconductor?metal (MSM) structure by dielectrophoresis and studying on its electrical characteristics by using current-voltage (I ? V) measurements. An electronic model with two back to back Schottky diodes in series with a semiconductor of nanowires was established to study the electrical transport of the MSM structures. By fitting the measured I ? V characteristics using the proposed model, the parameters of the Schottky contacts and the resistance of nanowires could be acquired. The photoelectric properties of the MSM structures were also investigated by analysing the measurements of the electrical transports under various light intensities. The deduced results demonstrate that ZnO nanowires and their Schottky contacts with Au electrodes both contribute to photosensitivity and the MSM structures with ZnO nanowires are potentially applicable for photonic devices.

Vision-based flight parameter extraction for micro air vehicles

The autonomous flight of MAVs (Micro Air Vehicles) is a very important feature of the vehicles. Due to the limitation of the size. weight and energy of MAVs, the automatic pilot technologies with sensors utilized on larger aircrafts are not currently available for MAVs. As the first step towards MAV autonomic flight, a robust, vision-based flight parameter extraction algorithm is proposed in this paper. Four flight parameters-the pitch angle, the roll angle, the flight height and the relative heading of the MAVS-are extracted in this paper. The algorithm has been demonstrated at 5 H z on PentiumIII750 PC. The height error is below 10m. The parameter extraction algorithm is suitable in different weather conditions and altered circumstances. And the experimental results show the effectiveness of the algorithm. Index Termparameter estimation, vision-based , MAVs, image processing

A novel centrifugal miniature pump and its medical application

A miniature pump based on a high precision machining technique is described. The working principle of the pump is centrifugal. The blades of the pump are driven by a micromotor to rotate at very high speed, so the fluids from the axial direction of the pump are thrown out to the tangential direction of the pump. The available back pressure of the pump is 0 to 10 kPa (1 mH/sub 2/O). Its highest flow rate is relatively very large, so by using throttle tubes of different length and different inner diameter, variable flow rates of less than 1 /spl mu/l/min and up to 100 ml/min can be achieved easily. It is of very useful in medical and other applications.

Approximation to Boolean functions by neural networks with applications to thinning algorithms

In this paper, a theorem on approximation to Boolean functions by neural networks and its proof are proposed. A Boolean function, f:{0,1}n/spl rarr/{0,1} is proved to be approximated by a three layer neural network with 2/sup n/ hidden nodes. With the theorem, a thinning algorithm using the neural network technique is concluded. A hard processor implementing the thinning algorithm is designed to raise the thinning efficiency, which can meet the practical needs better. This makes the algorithm suitable for real-time image processing.

Research on adaptive filtering of colored noise and its application

In the view of the drawbacks of conventional Kalman filtering, a kind of adaptive Kalman filtering approach for colored noise based on the correlative method of the system output is proposed to solve the cephalometric images of stomatology. This approach builds a Kalman filtering model of colored noise by adopting the equivalent measurement equation in order to avoid complicated computation and the expansion of the dimension of the filter. It is also unnecessary to know the variance of measurement noise beforehand so that it is closer to the actual situation. Results of several experiments are presented to demonstrate the feasibility and good performance of this approach.

Spectral response of carbon nanotube-based device

Being direct band-gap materials, carbon nanotubes have a potential to be efficient spectrum detection material. By depositing the carbon nanotubes on the substrate surface using chemical vapor deposition growth methods, a carbon nanotube-based device is fabricated with micromachined techniques. The structure of the carbon nanotube-based device is characterized using scanning electron microscope image. The spectra of carbon nanotube-based device are measured. The photocurrent as a function of wavelength reveals a broad absorption at wavelength from 500 to 1000 nm, showing the potential application in wide-range spectrum detection.