Zhu Guang-xi

A fast algorithm for corner detection using the morphologic skeleton

Abstract A fast corner detection algorithm based on the morphologic skeleton is proposed in this paper. The method differs from traditional chain-code-based corner detection algorithms in that the source image is represented as a polygon, and the corners are obtained through detecting the zero radius of the maximum plate on the morphologic skeleton. The result of the corner detection is achieved by using logical hetero-OR operation between two corner sets of the source image and its complement set. In addition, the pseudo-lattice corners generated by discrete sampling can also be eliminated. Experiments show that this method leads to results of good quality and robustness to noise with a low computational cost.

Adaptive scheduling strategy for WiMAX real-time communication

Defined by the IEEE 802.16 standard, WiMax system is also called broadband wireless metropolitan area network. It supports real time and non-real time services. There is no packet-scheduling algorithms defined, which was need for the requirement of quality of service (QoS) supporting for real-time services. Normally, the service station (SS) requests for bandwidth from the base station (BS), The BS then allocates the bandwidth to SS according to priority-based request. In this paper we propose an adaptive bandwidth scheduling strategy for real time polling services (rtPS), the SS estimate the arrival of rtPS packets prior to the arrival and requests the BS for bandwidth in advance, based on the SSs request and the actual bandwidth request by past. The analytical model and simulation show that, this adaptive algorithm provided better results with respect to the number of packets waiting at SS and average delay as compared to the widely accepted weighted scheduling algorithm and other adaptive bandwidth request mechanism.

Sensor management based on fisher information gain

Abstract Multi-sensor system is becoming increasingly important in a variety of military and civilian applications. In general, single sensor system can only provide partial information about environment while multi-sensor system provides a synergistic effect, which improves the quality and availability of information. Data fusion techniques can effectively combine this environmental information from similar and/or dissimilar sensors. Sensor management, aiming at improving data fusion performance by controlling sensor behavior, plays an important role in a data fusion process. This paper presents a method using fisher information gain based sensor effectiveness metric for sensor assignment in multi-sensor and multi-target tracking applications. The fisher information gain is computed for every sensor-target pairing on each scan. The advantage for this metric over other ones is that the fisher information gain for the target obtained by multi-sensors is equal to the sum of ones obtained by the individual sensor, so standard transportation problem formulation can be used to solve this problem without importing the concept of pseudo sensor. The simulation results show the effectiveness of the method.

A New Algorithm for On-Line Handwriting Signature Verification Based on Evolutionary Computation

The paper proposes an on-line signature verification algorithm, through which test sample and template signatures can be optimizedly matched, based on evolutionary computation (EC). Firstly, the similarity of signature curve segment is defined, and shift and scale transforms are also introduced due to the randoness of on-line signature. Secondly, this paper puts forward signature verification matching algorithm after establishment of the mathematical model. Thirdly, the concrete realization of the algorithm based on EC is discussed as well. In addition, the influence of shift and scale on the matching result is fully considered in the algorithm. Finally, a computation example is given, and the matching results between the test sample curve and the template signature curve are analyzed in detail. The preliminary experiments reveal that the type of signature verification problem can be solved by EC.

A Novel Bandwidth Scheduling Strategy for IEEE 802.16 Broadband Wireless Networks

WiMax system, which is defined by the IEEE 802.16 standard, also called broadband wireless metropolitan area network, supports real time and non-real time services. It has not defined the packet-scheduling algorithms, which was need for the requirement of quality of service (QoS) supporting for real-time services. Generally, the service station (SS) requests for bandwidth from the base station (BS), The BS then allocates the bandwidth to SS according to priority-based request. In this paper we propose a novel bandwidth scheduling algorithm for real time polling services (rtPS), the SS estimate the arrival of rtPS packets prior to the arrival and requests the BS for bandwidth in advance, based on the SSs request and the indeed bandwidth request by past. The analytical model and simulation show that, this adaptive algorithm provided better results with respect to the number of packets waiting at SS and average delay as compared to the widely accepted weighted scheduling algorithm and Mukul s adaptive bandwidth request mechanism.

Complement block coding scheme for reducing peak-to-average power ratio of OFDM systems

A new scheme termed as Complement Block Coding (CBC) technique is proposed to reduce the Peak-to-Average Power Ratio (PAPR) of OFDM signals. Utilizing the complement bits which are added to the original information bits, this method can effectively reduce the PAPR of OFDM systems with random frame size N and the coding rate R≤(N−κ)/N, where κ is a positive integer and κ≤N/2. The performance results obtained with CBC are given and compared with that of some well known schemes, such as Simple Block Coding (SBC), Modified Simple Block Coding (MSBC) and Simple Odd Parity Code (SOPC) for the same purpose. The results show that, at the same coding rate 3/4, the CBC can achieve almost the same performance as SBC, MSBC, but with lower complexity, and that the same performance can be obtained with higher coding rate by using CBC. At the same coding rate (N−1)/N, the PAPR reduction of CBC is almost the twice as that of SOPC when N≥16. Further more, the PAPR reductions with coding rate (N−1)/N are almost the same as that with coding rate less than (N−1)/N, so the proposed scheme CBC is more suitable for the large frame size with high coding rate and can provide error detection.A new scheme termed as Complement Block Coding (CBC) technique is proposed to reduce the Peak-to-Average Power Ratio (PAPR) of OFDM signals. Utilizing the complement bits which are added to the original information bits, this method can effectively reduce the PAPR of OFDM systems with random frame size N and the coding rate R≤(N−κ)/N, where κ is a positive integer and κ≤N/2. The performance results obtained with CBC are given and compared with that of some well known schemes, such as Simple Block Coding (SBC), Modified Simple Block Coding (MSBC) and Simple Odd Parity Code (SOPC) for the same purpose. The results show that, at the same coding rate 3/4, the CBC can achieve almost the same performance as SBC, MSBC, but with lower complexity, and that the same performance can be obtained with higher coding rate by using CBC. At the same coding rate (N−1)/N, the PAPR reduction of CBC is almost the twice as that of SOPC when N≥16. Further more, the PAPR reductions with coding rate (N−1)/N are almost the same as that with coding rate less than (N−1)/N, so the proposed scheme CBC is more suitable for the large frame size with high coding rate and can provide error detection.

A visual model weighted cosine transform for hiding watermark in images

Watermarking is a technique for labeling digital pictures by hiding secret information into images. Watermark embedding is a method to discourage unauthorized copying and identify the owner or distributor of digital data. In this paper, a new method is proposed. The watermark is processed as a visually recognizable pattern—binary image, which includes more information than the traditional symbol or ID number and is “extracted” instead of only “detected” to characterize the owner. The watermark is hidden in the host image by selectively modifying the middle-frequency part of the host image in conjunction with the human visual system(HVS) and the image discrete cosine transform(DCT). The experimental results show that this method can survive image cropping and image compression, and get better results, this is also a prospective method.

Image watermarking based on image normalization

In this paper we present a technique for watermarking digital images based on its normalized version. Some parameter in the normalized image is chosen as the watermark. And the watermarked image is a linear combination of the original image and a weighted nonlinear transformation of the original. The weight is computed such that the parameter of the watermarked image is a predefined value. Watermark detection is as simple as computing the parameter of the normalized version of the received image. The proposed algorithm has proved to be robust to many kinds of geometric manipulations that are performed as part of StirMark attacks.

Development and Evaluation of a Distance Learning System Based on CSCW

This paper described a distance learning system, which allows Internet users to conduct a lesson in real-time from any kinds- attached computers. Participants can jointly view and edit relevant multimedia information distributed through Internet. Teachers and students can also simultaneously communicate by voice and text to discuss the problems. Teacher can broadcast streaming PowerPoint presentation in real time to network users. In addition to sliders, presenters can broadcast video and audio simultaneously to deliver a live multimedia show online, and store their presentations for on-demand playback. Teachers distributed in different places can also use cooperative editing tool to edit and encode existing digital content. We discussed some important design principles of the system. Then, the system configuration and the results of evaluation are also presented. The system has proved to be applicable to the distance learning based on CSCW (Computer Support Cooperative Work) in Internet.

A watermarking method based on fractal self-similarity

The watermarking technology is a new technique of embedding hidden images and data into an original image area. A watermarking method based on fractal self-similarity is given. Our watermarking method can be used to protect aptly important images and data. Hidden images and data can be retrieved directly from the image of hiding data. Experiments have shown that data or images are embedded in the whole image area and that the hidden images and data are difficult to be discovered and removed. Hence, the method can be used to protect effectively important images and data.