A prediction-aided routing algorithm based on ant colony optimization mode(PRACO)to achieve energy-aware data-gathering routing structure in wireless sensor networks(WSN)is presented.We adopt autoregressive moving average model(ARMA)to predict dynamic tendency in data traffic and deduce the construction of load factor,which can help to reveal the future energy status of sensor in WSN.By checking the load factor in heuristic factor and guided by novel pheromone updating rule,multi-agent,i.e.,artificial ants,can adaptively foresee the local energy state of networks and the corresponding actions could be taken to enhance the energy efficiency in routing construction.Compared with some classic energy-saving routing schemes,the simulation results show that the proposed routing building scheme can ① effectively reinforce the robustness of routing structure by mining the temporal associability and introducing multi-agent optimization to balance the total energy cost for data transmission,② minimize the total communication consumption,and ③ prolong the lifetime of networks.
We propose an image retrieval method based on interest image region by asymmetrical blocking. An image is segmented into the interest region and background region on a certain rule. For the interest image regions, the color histogram of the uneven blocks is extracted as the color characteristic. We also collect the mean and variance value of the Gabor filtering results of background blocks as texture features of the background image. Then, the images can be retrieved by synthesizing the image color and texture features. We test our approaches by analyzing the results of recall and precision indicators for the Corel image data-base. The experiment results show that the proposed method performs effectively and accurately, which is more effective to retrieve the distant-view images, and the achieved precision increases by about 10% without loss of the retrieval call compared with some other traditional search methods.
Compared with channel estimation method based on explicit training sequences,bandwidth is saved for those methods using superimposed training sequences,while it is wasted when Cyclic Prefix(CP) is added.In previous work of McLernon,the Mean Square Error(MSE) performance of Data-Dependent Superimposed Training(DDST) without CP for Single-Input Single-Output(SISO) system was analyzed under the assumption that the data-dependent sequence matrix was a circulant matrix and not interfered by others.In fact,for the system without CP,the data-dependent sequence matrix is not circulant any more and will be interfered.This paper derives the exact expression of MSE for the system without CP and also gives its extension to Multiple-Input Multiple-Output(MIMO) system without CP.
For the traditional steganographic method of Jsteg,the emmbedment of secret message is completed by dividing cover-image into nonoverlapping blocks of 8×8 pixels,discrete cosine transform(DCT) transforming,and using the standard 8×8 quantization table to quantize.In this paper,a novel steganogra-phic method based on the JPEG quantization table modification is presented.Instead of dividing cover-image into 8×8 blocks,nonoverlapping blocks of 16×16 pixels is used.Both theoretical anlysis and experiment results show that the new methods has larger steganography capacity and better stego-image quality,compared with the method of Jsteg and Chang's.
JIANG Cuiling PANG Yilin GUO Lun JING Bing GONG Xiangyu
