In Event-Based Social Network (EBSN), the recommendation work starts from the user historical preferences to model user preferences, which hinders the scope and ways for users to access new things. Aiming at the above problems, an unexpectedness metric-based social event recommendation model was proposed, namely UER(Unexpectedness-based Event Recommendation). UER model included two sub-models, Base and Unexpected. Firstly, based on the interaction sequence characteristics of users, events, and user historical events, the Base sub-model used the attention mechanism to measure the weights of events in user historical preferences, and finally predicted the probabilities of users participating in events. Secondly, multiple interest representations of the user were extracted by Unexpected sub-model through the self-attention mechanism to calculate the unexpectedness of the user itself and the unexpectedness value of the candidate event to the user according to the multiple interest representations of the user, so as to measure the unexpectedness of the recommended event. Experimental results on Meetup-California dataset show that compared with Deep Interest Network (DIN) and Personalized Unexpected Recommender System (PURS), the recommendation Hit Ratio (HR) of the UER model is increased by 22.9% and 30.3%, the Normalized Discounted Cumulative Gain (NDCG) is increased by 27.5% and 42.3%, and the unexpectedness of recommended events is increased by 54.5% and 21.4% respectively. On Meetup-NewYork dataset, the recommendation HR of the UER model is increased by 18.2% and 21.8%, the NDCG is increased by 26.9% and 32.0%, and the unexpectedness of recommended events is increased by 52.6% and 20.8% respectively.
To solve the problem that the two-tower neural network in the recommendation system is difficult to learn the interaction information between the user side and the item side and the graph connection information, a new algorithm TSN (Two-stage Siamese graph convolutional Neural network recommendation algorithm) was proposed. First, a heterogeneous graph based on user behavior was built. Then, a graph convolutional Siamese network was designed between the two-tower neural networks, so as to achieve information interaction while learning the connection information of the heterogeneous graph. Finally, by designing a special structure of two-stage information sharing mechanism, the neural networks on the user side and the item side could transmit information dynamically and bidirectionally during the training process, and neural network cascading was effectively avoided. In comparative experiments on MovieLens and Douban movie datasets, the NDCG@10, NDCG@50, NDCG@100 of the proposed algorithm are 11.39% to 23.98% higher than those of the optimal benchmark algorithm DAT (Dual Augmented Two-tower model for online large-scale recommendation). The results show that the proposed algorithm can alleviate the problem of lack of information interaction in the two-tower neural network; and significantly improves the recommendation performance compared with the previous algorithms.
When the image is blurred due to rapid camera movement or in low-texture scenes, the Simultaneous Localization And Mapping (SLAM) algorithm using only point features is difficult to track and extract enough feature points, resulting in poor positioning accuracy and matching robustness. If it causes false matching, even the system cannot work. To solve the problem, a low-texture monocular SLAM algorithm based on point-line feature fusion was proposed. Firstly, the line features were added to enhance the system stability, and the problem of insufficient extraction of point feature algorithm in low texture scenes was solved. Then, the idea of weighting was introduced for the extraction number selection of point and line features, and the weight of point and line features were allocated reasonably according to the richness of the scene. The proposed algorithm ran in low-texture scenes, so the line features were set as the main features and the point features were set as the auxiliary features. Experimental results on the TUM indoor dataset show that compared with the existing point-line feature algorithms, the proposed algorithm can effectively improve the matching precision of the line features, has the trajectory error reduced by about 9 percentage points, and has the feature extraction time reduced by 30 percentage points. As the result, the added line features play a positive and effective role in low-texture scenes, and improve the overall accuracy and reliability of the data.
To effectively solve overhead computing and bandwidth, high complexity problems about user access privileges revoking in cloud-storage service, a cloud-storage privilege revoking optimization mechanism based on dynamic re-encryption (DR-PRO) was proposed. Firstly, based on ciphertext access control scheme of Ciphertext Policy Attribute Based Encryption (CP-ABE), by using (k,n) threshold algorithm of secret sharing scheme, data information was divided into a number of blocks, and then a data information block was dynamically selected to realize re-encryption. Secondly, the user access privilege revoking was finished by the sub-algorithms, including data cutting, data reconstructing, data publishing, data extracting and data revoking. The theoretical analysis and test simulation showed that, based on high security of user information in cloud-storage service, compared with lazy re-encryption mechanism, the average computing and bandwidth decrease of user access privileges revoking was 5% when data file changed; compared with full re-encryption mechanism, the average computing and bandwidth decrease of user access privileges revoking was 20% when shared data block changed. The experimental results show that DR-PRO effectively improves the performance and efficiency of user access privileges revoking in cloud-storage service.
The virtual machines in cloud computing platform exchange data in the shared memory of physical machine. In view of the problem that the traffic cannot be captured and detected in firewall or other security components, the OpenFlow technology was analyzed, and a traffic redirection method based on OpenFlow was presented. To control traffic forwarding process and redirect it to security components, the method provided network connection for virtual machines with OpenFlow controller and virtual switches instead of physical switches, and built a traffic detection system composed of four modules including virtual switch, control unit, intrusion detection and system configuration management. The experimental results show that the proposed scheme can realize traffic redirection and the subsequent detection processing, and the system can provide switch-level and host-level control granularity. It also solves traffic detection problem under cloud computing environment in traditional scene by traffic redirection, and provides great expansion of the traffic processing based on OpenFlow.
To ensure the integrity and accuracy of the meteorological data, combined with automatic weather station's daily average temperature data which contained discontinuous noise, three types of membership functions were submitted. A compensation algorithm of Fuzzy Support Vector Machine (FSVM) based on root-mean-square membership function was designed and the compensation model was established too. Finally, the FSVM method was compared with the traditional Support Vector Machine (SVM) method. The experimental results show that the proposed algorithm has good recognition capability for noise points. After interpolation, the data precision was 1.4℃, better than 1.6℃ of the traditional SVM method. Moreover, the whole data precision was 1.13℃, superior to 1.42℃ of the traditional SVM method.