Applied Mechanics and Materials Vols. 380-384

Abstract: OFDM-IDMA system with perfect performance is the key technology of 4th mobile communication. in this paper, we simulated the performance of OFDM-IDMA in AWGN and quasi-static Rayleigh channel respectively, the simulation results indicate that the performance of multi-user is close to the single use as the increase of SNR, and the error-bits curve descends obviously, which means OFDM-IDMA system can be used to the complex electromagnetic environment and high-speed data transmission.

Abstract: When medical image transmitted and stored on the Internet, it is vulnerable to many kinds of attacks, thus, the security of the patients personal information is low. A robust watermarking algorithm has been proposed to increase the security of medical images. The scheme obtains the visual feature vectors of the medical image using DWT-DFT. At the same time, applying Logistic Map to encrypt the watermarking image, which can enhance its security. The experiment results show that the scheme has strong robustness against geometrical attacks.

Abstract: According to the four array elements of Beidou satellite navigation model as the research object, put forward a kind of Compass satellite navigation signal model construction method, and using Matlab software to build the satellite navigation signal system model . Based on the power inversion principle, try to use the recursive least squares (RLS) algorithm for getting the power inversion Optimum weights, compared and evaluated in terms of this performance. The results show that the power inversion based on RLS algorithm can make the antenna array in the direction of interference to automatically generate nulling .And compared with LMS power inversion array algorithm, RLS algorithm in interference can form deeper nulling. The disadvantage is computationally intensive.

Abstract: The Inverse Synthetic Aperture Radar (ISAR) is a high resolution imaging radar. Some methods used to evaluate the jamming effect of general radar are unsuitable to ISAR. A new evaluation method of jamming effect on ISAR is presented in the paper through comparing the change of moment character and area character, The amplitude modulation (AM) noise jamming and frequency modulation (FM) noise jamming are carried out in the paper, the results of simulation prove the method is corrective and effective.

Abstract: To solve the problem of the large amount of calculation, poor robustness and do not well in image mosaic of images who are in different scales in the traditional image mosaic method ,the article arise a mosaic algorithm of different scales images registration and adaptive. Through feature point matching and automatically recognizing of transform geometric parameters between images,It achieves the match and mosaic of different scale and rotated images. First, using SIFT to extract the feature points of the images and matching feature points according to the principal of mutual information maximum. Then based on the geometric information of the matching pairs, automatically recognize the relationship of transformation parameters. In the end, obtain the projective transformation and achieve the image stable mosaic.

Abstract: This paper studies the C/S architecture, and designs a set of teaching and training for hardware-in-loop simulation system. System consists of an antenna, shelters, and other presentation models, master and client components, mainly to complete radar system functional demonstration, radar signal release and capture functions. Experimental results show that the system reaches a very good teaching training effect.

Abstract: This paper presents a method of error correcting code to improve the performance of audio information hiding. To use hadamard as error correcting code, not only makes audio information more secret, but also has higher correct error capacity to noise, compression and filter.

Abstract: Image retrieval has been a top topic in the field of both computer vision and machine learning for a long time. Content based image retrieval, which tries to retrieve images from a database visually similar to a query image, has attracted much attention. Two most important issues of image retrieval are the representation and ranking of the images. Recently, bag-of-words based method has shown its power as a representation method. Moreover, nonnegative matrix factorization is also a popular way to represent the data samples. In addition, contextual similarity learning has also been studied and proven to be an effective method for the ranking problem. However, these technologies have never been used together. In this paper, we developed an effective image retrieval system by representing each image using the bag-of-words method as histograms, and then apply the nonnegative matrix factorization to factorize the histograms, and finally learn the ranking score using the contextual similarity learning method. The proposed novel system is evaluated on a large scale image database and the effectiveness is shown.

Abstract: Informed by water pressure and gate weight balance principle, the hydraulic automatic flap dam makes use of hydraulic power together with the damping feedback system, which makes it possible to automatically open the discharge when water level at the upper stream is high and to close when the level is low. This helps to ensure that the water level at the upper stream always stays within the normal range and has been widely applied in city water regulation projects and hydropower renovation projects alike. The flap dam in the project reported here is constructed upon the existing levees of Duanmijian river. This paper discusses the design of the flap dam as well as the entire outline and its major features.

Abstract: This The draft tube is one of the main load-bearing structure of the hydropower plant, The hydropower draft tube of Xiaoshankou is an underground space structure, mainly composed by the taper pipe segment, elbows segment and diffusion segment. This paper describe the structure design and calculation process of Xiaoshankou hydropower draft tube, including the draft tube load calculation, structural mechanics just Rigid panels calculate internal force calculation and reinforcement calculation.