Concerning the problem that severe signal multipath effect, low accuracy of sensor node positioning, etc. in narrow space, a new method using Weighted Centroid Localization (WCL) algorithm based on Received Signal Strength Indicator (RSSI) was proposed. The algorithm was used in scenarios with characteristics of long and narrow strip space, and it could dynamically acquire the decline index of path by RSSI and distance of neighbor beacon node signal, improve the environmental adaptation of RSSI distance detection algorithm. In addition, the algorithm based on environment improved weight coefficient of weighted centroid algorithm by introducing correction factor, which improved the accuracy of localization. Theoretical analysis and simulation results show that the algorithm has been optimized to adapt to narrow space. As compared with the Weighted Centroid Localization (WCL) algorithm, in roadway environment with the width of 3 m, 5 m, 8 m, 10 m respectively and 10 beacon nodes, positioning precision increases 22.1%, 19.2%, 16.1% and 16.5% respectively, the stability increases 23.4%, 21.5%, 18.1% and 15.4% respectively.
In applications of Wireless Mesh Networks (WMN), users can access Internet through mesh gateways. This architecture is prone to cause traffic unbalance between mesh routers located at different places, make some mesh routers become bottleneck and hence affect network performance and user's Quality of Service (QoS). To solve this problem, a traffic balancing routing algorithm based on Grover quantum search algorithm was presented. In this algorithm, the parallel character of quantum computation was utilized. The operation matrix was constructed according to model of traffic balancing function. The traffic balancing paths were gotten by Grover iteration. Simulations show that the paths selected by the algorithm can balance traffic of WMN effectively and make the minimum bandwidth every user got maximized. The executive efficiency of the algorithm is also better than the similar ones.
Gama nonlinearity and random noise caused by optical devices are two main phase errors on structured light projection. Double three-step phase-shifting algorithm has the unique advantage on inhabiting both of them, but there remains two drawbacks in its measuring result including higher nonlinear error and lower measuring pecision. A double four-step route phase-shifting average algorithm was proposed for resolving above questions, which applied the idea of phase-aligning average in four-step phase-shifting algorithm to lower the effect of nonlinear error, and put forward a phase average method of phase-field space transform in multi-frequency heterodyne to weaken random noise and improve meauring precision. The experimental results show that the proposed method has higher accuracy and adaptability in phase unwrapping.
Concerning the phenomenon that common parking service could not satisfy the increasing demand of the private vehicle owners, an intelligent parking guidance system based on ZigBee network and geomagnetic sensors was designed. Real-time vehicle position or related traffic information was collected by geomagnetic sensors around parking lots and updated to center sever via ZigBee network. On the other hand, out-door Liquid Crystal Display (LCD) screens controlled by center sever displayed information of available parking places. In this paper, guidance strategy was divided into 4 levels, which could provide clear and effective information to drivers. The experimental results prove that the distance detection accuracy of geomagnetic sensors was within 0.4m, and the lowest loss packet rate of the wireless network in the range of 150m is 0%. This system can possibly provide solution for better parking service in intelligent cities.
Resampling is a typical operation in image forgery, since most of the existing resampling tampering detection algorithms for JPEG images are not so powerful and inefficient in estimating the zoom factor accurately, an image resampling detection algorithm via further resampling was proposed. First, a JPEG compressed image was resampled again with a scaling factor less than 1, to reduce the effects of JPEG compression in image file saving. Then the cyclical property of the second derivative of a resampled signal was adopted for resampling operation detection. The experimental results show that the proposed algorithm is robust to JPEG compression, and in this manner, the real zoom factor may be accurately estimated and thus useful for resampling operation detection when a synthesized image is formed from resampled original images with different scaling factors.
Bernstein’s Batch-factor algorithm can test B-smoothness of a lot of integers in a short time. But this method costs so much memory that it’s widely used in theory analyses but rarely used in practice. Based on splitting product of primes into pieces, a hierarchical batch-factor algorithm cloud framework was proposed to solve this problem. This hierarchical framework made the development clear and easy, and could be easily moved to other architectures; Cloud computing framework borrowed from MapReduce made use of services provided by cloud clients such as distribute memory, share memory and message to carry out mapping of splitting-primes batch factor algorithm, which solved the great cost of Bernstein’s method. Experiments show that, this framework is with good scalability and can be adapted to different sizes batch factor in which the scale of prime product varies from 1.5GB to 192GB, which enhances the usefulness of the algorithm significantly.
This paper introduced the research works on all kinds of chain code used in image processing and pattern recognition and a new chain code named Improved Compressed Vertex Chain Code (ICVCC) was proposed based on Compressed Vertex Chain Code (CVCC). ICVCC added one code value compared with CVCC and adopted Huffman coding to encode each code value to achieve a set of chain code with unequal length. The expression ability per code, average length and efficiency as well as compression ratio with respect to 8-Directions Freeman Chain Code (8DFCC) were calculated respectively through the statistis a large number of images. The experimental results show that the efficiency of ICVCC proposed this paper is the highest and compression ratio is ideal.
Feature point matching is of central importance in feature-based image registration algorithms such as Scale-Invariant Feature Transform (SIFT) algorithm. Since most of the existed feature matching algorithms are not so powerful and efficient in mismatch removing, in this paper, a mismatch removal algorithm was proposed which adopted the depth information in an image to improve the performance. In the proposed approach, the depth map of an acquired image was produced using the clues of defocusing blurring effect, and machine learning algorithm, followed by SIFT feature point extraction. Then, the correct feature correspondences and the transformation between two feature sets were iteratively estimated using the RANdom SAmple Consensus (RANSAC) algorithm and exploiting the rule of local depth continuity. The experimental results demonstrate that the proposed algorithm outperforms conventional ones in mismatch removing.