The data in internet social media has the characteristics of fast transmission, high user participation and complete coverage compared with traditional media under the background of the rise of various platforms on the internet.There are various topics that people pay attention to and publish comments in, and there may exist deeper and more fine-grained sub-topics in the related information of one topic. A survey of sub-topic detection based on internet social media, as a newly emerging and developing research field, was proposed. The method of obtaining topic and sub-topic information through social media and participating in the discussion is changing people’s lives in an all-round way. However, the technologies in this field are not mature at present, and the researches are still in the initial stage in China. Firstly, the development background and basic concept of the sub-topic detection in internet social media were described. Secondly, the sub-topic detection technologies were divided into seven categories, each of which was introduced, compared and summarized. Thirdly, the methods of sub-topic detection were divided into online and offline methods, and the two methods were compared, then the general technologies and the frequently used technologies of the two methods were listed. Finally, the current shortages and future development trends of this field were summarized.
Due to the high radiation dose to the patient when acquiring lung four Dimensional Computed Tomography (4D-CT) data, this paper proposed a method for deriving the phase-binned 4D-CT image sets through deformable registration of the images acquired at some known phases. First, Active Demons registration algorithm was employed to estimate the motion field between inhale and exhale phases. Then, images at an intermediate phase were reconstructed by a linear interpolation of the deformation coefficients. The experiment results showed that the images at intermediate phases could be reconstructed efficiently. The quantitative analysis of landmark point displacements showed that 3 mm accuracy was achievable. The different maps of reconstructed and acquired images illustrated the similar level of success. The proposed method can accurately reconstruct images at intermediate phases of lung 4D-CT data.
Aiming at the problem of extracting the useful signal in the complex background of chaotic noise rapidly and accurately, the phase space reconstruction theory based on complex nonlinear system was proposed, and the method of improved Extreme Learning Machine (ELM) was used to predict the single step error and detect the weak signal. The improved K-means clustering algorithm was used to select the optimal family as training set, the improved extreme learning machine chose the weight value and the offset to improve the detection accuracy and speed. The one step prediction model of chaotic noise sequence with Lorenz system was established, and the weak target signals (including periodic signal and transient signal) that lost in the chaotic noise were detected, then the IPIX radar data of Canada Mc Master University were used, and the floater signal in sea clutter noise was extracted to do the experimental research. The results show that the method can effectively detect the very weak signal in chaos background noise, at the same time, the influence of noise was restrained to the chaotic background signal, compared with the traditional algorithms such as Radial Basis Function (RBF), the prediction accuracy is increased by 25%, the detection threshold is increased by -5 dB, the training time is reduced by 77.1 s, it has more obvious advantages in practical application.
Maximizing customer satisfaction is directly related to the enterprise profit and market competitiveness for the supermarket as a service enterprise, so it is important to optimize the retail checkout operation. Firstly, the retail checkout scheduling problem was described by a triplet of α/β/γ, maximizing customer satisfaction was taken as the first goal and minimizing operating cost was taken as the second goal with machine usage restriction and the rule of First In First Out (FIFO). The corresponding mathematical model was established, and then an algorithm was designed using plant growth simulation algorithm. 〖BP(〗Finally, the actual data was used to simulate, and the results prove that the study has effectiveness and feasibility. 〖BP)〗Finally, a numerical simulation of actual cases was used to verify the effectiveness and feasibility of the method.