Advanced Materials Research Vols. 989-994

Abstract: Presents the working principle of Integrated PLL chip Si4133, this paper presents the implementation of a 375MHz local oscillator for a super heterodyne transmitter/receiver by using Si4133.Using programming method to set the divider register Internal chip. In addition, this paper discuss the methods for decreases the phase noise. Debugging circuit using ICCAVR software , and show the debugging results. Facts show that the phase noise and spurious of the frequency synthesizer is low, and it is practical.

Abstract: The problem of scheduling for electronic satellites is a serious problem involving a lot of complex constraints. Considering the specific constraints of electromagnetic detection electronic satellite, on the basis of rational hypothesis, a multi-objective mathematic model was established. Several basic scheduling strategies were proposed. Based on the roulette method and hierarchical optimization method, a heuristic algorithm based on the rules was designed. A comprehensive evaluation with Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) for the algorithm was offered. Finally, some experiments are conducted to verify the correctness and practicability of our scheduling model and algorithm.

Abstract: The target of this paper is to introduce the improvement of the technique of image retrieval. At first, it comes up with the concept of image retrieval and shows the importance of this technique. As the techniques of multimedia and Internet are developing rapidly, the resources of images that users obtain are also extended. And then this paper gives the problem about the image retrieval, namely the information of images are disordering. As the result, it is significant to do the effective organization, management and retrieval based on the increasingly extensive image information storage. After that, this paper presents the concept of TBIR and CBIR and gives the definitions of them. It proposes an issue that CBIR is the improvement of TBIR. Based on CBIR, there are also some disadvantages that need to be improved. In terms of the main point of CBIR, the paper raises that the annotation is one of the most difficult techniques that need to be promoted. Then it describes some algorithms about the technique of automatic image annotation. After these algorithms, the paper shows the challenges and developing direction of the technique of image retrieval. At last, it presented the conclusion to emphasize the main points of this paper.

Abstract: Otsu is one of better image segmentation algorithm, which obtains optimum threshold by maximizing the between-class variance of an image. However, computation time will sharply increase as the threshold increase. In order to greatly improve the problem, a new segmentation algorithm called firefly algorithm based on Otsu’s method is presented in this paper, and applied the algorithm to segmentation of mineral belt image of shaking table, which lay the foundation for automation of shaking table. Experimental results show that the new algorithm can accurately segment different mineral belts and can obtain the same optimal thresholds and fitness values with Otsu’s method.

Abstract: The IEEE 802.11 and IEEE 802.15.4 are two of the most popular wireless network protocols. And it is very important to look into the differences between IEEE 802.11 MAC and IEEE 802.15.4 MAC. The main goal of this paper is to look into the hidden terminal problem of the MAC layers of 802.11 and 802.15.4 based on NS2 platform. Through a dedicated experiment, the author compares the results based on the NAM animation and throughput and then explains the reasons respectively.

Abstract: Halftone is the key technique for low-resolution equipment like fax machines and printers to reconstruct grayscale images with black and white binary data. Images produced by classic error diffusion algorithm have more abundant color than those made by ordered dithering method. But the problems still exits that there can distortions and false contour phenomenon and fuzzy edges. This paper puts forward an advanced error diffusion algorithm based on bidirectional feedback and improves its feedback type through adding correction factors. The simulation results show that the bidirectional feedback error diffusion algorithm with correction factors better inhibited the phenomenon of distortions and false contour. Directional texture is also improved greatly.

Abstract: With the rapid development of communication technology and Internet technology, as well as the popularization of computer, the application of digital multimedia technology is more and more widely, video, voice and image gathering, editing, storage, and dissemination of digital information has become more and more convenient. However, it is because of the computer and the network popularization and the fragility of the digital information itself, digital multimedia data are more vulnerable to attack, digital products is also very easy to forged and tampered with. According to these digital multimedia data more easily by illegal processing problem, people put forward the concept of digital watermark. Digital watermark technology is used to realize the protection of digital information. In this paper, the digital watermark technology research starting from the practical application, the digital image watermark based on DCT domain is studied.

Abstract: In this paper, Gabor filtering and linear local tangent space alignment algorithm and its improved algorithm are used on face recognition. The Gabor wavelet transform can detect the image information in different directions and scales, according to its selective direction and frequency characteristics. The LLTSA reduces the dimension of the sample while the LLTSA and the other improved algorithms extract secondary feature. Experiment and analyze the average recognition rate of the LLTSA and its improved algorithms with the variation of dimension. The experiment results show the effectiveness of the method, increasing the face recognition accuracy.

Abstract: A new way to optimize the degree profiles for irregular LDPC codes in MAC is presented. The combination technology of differential evolution and density evolution is applied in the optimizing of degree distributions. By using a greedy algorithm we show the differential evolution method to seek the maximum noise threshold in MAC channels under different degree number and maximum degree condition.

Abstract: The characteristics of remote sensing image are big data volume and high resolution. It is difficult to meet actual demands by using traditional techniques for transmission and storage. This paper studies and designs remote sensing image compression encoder with FPGA technology and three-layer feedforward BP neural network. The neural network can parallelly process large amounts of data, and has a structural characteristic of self-learning and self-organizing. The encoder has a simple structure, safety, fast speed, good reconfiguration. It overcomes shortcomings of conventional compression techniques which compress high-resolution images ineffectively. The study has some theoretical values in the field of image compression.