Irregular Repeat Accumulate (IRA) codes' decoding usually adopts Belief Propagation (BP) decoding algorithm, but BP decoding algorithm needs hyperbolic tangent calculation, so its hardware implementation is very difficult because of the high complexity. A decoding algorithm combining the early detection mechanism and offset polyline was put forward. Its performance would approach to BP algorithm via non-uniform error compensation for polyline approximation decoding algorithm. And the early detection method was introduced which observed the transmitted information of check nodes in advance, judged the lines' log-likelihood value which had negligible influence on the next iteration and moved it out of the iteration. So the computational complexity of next iterations was reduced. The simulation results show that the proposed algorithm greatly reduces the computational complexity through the offset polyline approximating the hyperbolic tangent, and the decoding performance is close to BP algorithm.
Because the existing Web quality assessment approaches rely on trained models, and users' interactions not only cannot meet the requirements of online response, but also can not capture the semantics of Web content, a data Quality Assessment based on Simulated Annealing (QASA) method was proposed. Firstly, the relevant space of the target article was constructed by collecting topic-relevant articles on the Web. Then, the scheme of open information extraction was employed to extract Web articles' facts. Secondly, Simulated Annealing (SA) was employed to construct the dimension baselines of two most important quality dimensions, namely accuracy and completeness. Finally, the data quality dimensions were quantified by comparing the facts of target article with those of the dimension baselines. The experimental results show that QASA can find the near-optimal solutions within the time window while achieving comparable or even 10 percent higher accuracy with regard to the related works. The QASA method can precisely grasp data quality in real-time, which caters for the online identification of high-quality Web articles.
Addressing the issue of computer processing in the internal spherical screen projection, an internal spherical screen projection algorithm was proposed based on virtual spherical transform and virtual fisheye lens mapping. Concerning the spherical screen output distortion caused by irregular fisheye projection, a sextic polynomial of distortion correction algorithm based on the equal-solid-angle mapping function was presented to approximate any fisheye mapping function to eliminate the distortion. The six coefficients of the polynomial could be obtained via solving a linear algebra equation. The experimental results show this method is able to completely eradicate the spherical screen projection distortion. Addressing the illumination distribution modification stemming from the spherical screen projection, an illumination correction algorithm based on the cosine of the projecting angles was also proposed to eliminate the illumination distribution change. The experimental results show the illumination distribution correction method successfully recovers the originally severely modified illumination distribution into the illumination distribution almost identical to the original picture. This algorithm has theoretical instructive importance and significant practical application values for design and software development of the spherical projection systems.