Due to differences in resource endowments and industrial policies among different regions, the role of distributed production in improving the competitiveness of manufacturing enterprises is very important. How to use distributed production to enhance the flexibility of mass customization is an important problem to be solved to boost consumer confidence. Combined with the idea of minicells — small manufacturing cells, in the distributed mixed production scenario with the multi-market and multi-product characteristics, an integrated model of distributed factory construction and production scheduling was proposed with the objectives to minimize the operating costs (e.g., labor and transportation costs) and minimize the makespan. By the proposed model, the minicell construction, worker and machine configuration, as well as production strategies for each batch of products were able to be solved. With the help of the proposed model, the enterprises were able to realize the quick release of production capacity and reasonable mixed flow production, so as to realize distributed manufacturing and sales that meet the multi-region, multi-product, and differentiated needs, and reduce the operating cost in the manufacturing process while guaranteeing the throughput. In addition, a Multi-Objective Particle Swarm Optimization (MOPSO) algorithm was designed to solve the proposed model, and was compared with Non-Dominated Sorting Genetic Algorithm Ⅱ (NSGA-Ⅱ) and Multi-Objective Simulated Annealing (MOSA) algorithm. The results of extensive numerical experiments show that MOPSO algorithm outperforms NSGA-Ⅱ and MOSA algorithm with the same running time in terms of three metrics: C-Metric (CM), Mean Ideal Distance (MID) and Maximum Spread (MS). The proposed algorithm can provide a high-quality decision-making scheme of production operation for the miniaturized distributed production system.
Software testing is an effective way to ensure the quality of Android applications. Understanding the functions of Android applications is the basis of the Android testing process. It aims to deeply explore the application’s business logic and reveal its functional defects, playing an important role in testing. User behavior patterns can assist testers in understanding an Android application’s functions, thereby improving test efficiency. Based on the idea “similar Android applications share user behavior patterns”, a user behavior pattern mining and reuse method was proposed to reduce the cost of Android application testing and improve the testing efficiency. Specifically, for the Android application under test, the user behavior patterns from a similar Android application were mined. Then, the semantic-based event fuzzy matching strategy was used to search the corresponding events for the application under test, and the Graphical User Interface (GUI) model based optimal path selection strategy was used to generate target event sequences for the application under test, thereby achieving user behavior pattern reuse across similar applications. The experiments were conducted on 32 user behavior patterns of three categories of Android applications. The results show that 87.4% of user behavior patterns can be completely reused on similar Android applications, and the reused user behavior patterns can effectively cover 90.2% of important states in applications under test. Thus, the proposed method provides effective support for the testing of Android applications.
With the development of smart power grid, Unmanned Aerial Vehicles (UAVs) are more and more widely used for inspection of transmission lines. In order to effectively implement fault location and type judgment of transmission lines, UAVs are required to transmit videos and images with high resolution. Under the condition of limited bandwidth, it is necessary to improve the spectral efficiency of UAV return communication link as much as possible to meet the transmission rate requirements of high-resolution videos and images. A video image transmission communication method based on mesh network was proposed. By deploying the wireless access nodes on tower and building Mesh network, the communication devices carried by UAVs could communicate with the built Mesh network as the network nodes at any time. After capturing a video of the failure on transmission lines, the video could be quickly transmitted to the data center by UAVs. For this purpose, the communication module of the patrol UAV was equipped with a large-scale antenna array, in millimeter wave frequency band, a heuristic point-to-point directional hybrid beamforming method was adopted to improve the spectral efficiency of receiving communication link. The simulation results show that the performance of the proposed method is better than that of the Orthogonal Matching Pursuit (OMP) method and is closer to that of the fully digital beamforming method.
Focusing on the unbalance issue between local optimization and global optimization and the inability to jump out of the local optimum of Artificial Fish Swarm Algorithm (AFSA), an Adaptive AFSA utilizing Gene Exchange (AAFSA-GE) was proposed. Firstly, an adaptive mechanism of view and step was utilized to enhance the search speed and accuracy. Then, chaotic behavior and gene exchange behavior were employed to improve the ability of jumping out of the local optimum and the search efficiency. Ten classic test functions were selected to prove the feasibility and robustness of the proposed algorithm by comparing it with the other three modified AFSAs, which are Normative Fish Swarm Algorithm (NFSA), FSA optimized by PSO algorithm with Extended Memory (PSOEM-FSA), and Comprehensive Improvement of Artificial Fish Swarm Algorithm (CIAFSA). Experimental results show that AAFSA-GE achieves better results in local and global search ability than those of PSOEM-FSA and CIAFSA,and better search efficiency and better global search ability than those of NSFA.
Focused on the issue that the traditional interest area based visualization method can not pay attention to the details in the process of analyzing pilot eye movement data, a visual analysis method of eye movement data based on user-defined interest area was proposed. Firstly, according to the specific analysis task, the self-divison and self-definition of the background image of the task were introduced. Then, multiple auxiliary views and interactive approaches were combined, and an eye movement data visual analysis system for pilot training was designed and implemented to help analysts analyze the difference of eye movement between different pilots. Finally, through case analysis, the effectiveness of the visual analysis method and the practicability of the analysis system were proved. The experimental results show that compared with the traditional method, in the proposed method, the analysts' initiative in the analysis process is increased. The analysts are allowed to explore the local details of the task background in both global and local aspects, making the analysts' analyze the data in multi-angle; the analysts are allowed find the flight students' cognitive difficulties in the training process as a whole, so as to develop more targeted and more effective training courses.
In order to deal with the cache pollution attacks in Content Centric Networking (CCN), a defense scheme based on cache diversification was proposed. To reduce the attack scope, the in-network content services were divided into three categories and different cache strategies were used for different services. For private and real-time services, contents were directly delivered without being cached; for streaming media services, contents were pushed to be cached in the edge of network according to probablity; for document services, the priority was caching contents in the upstream, then pushing them to the downstream. Then different defense methods were configured on different nodes. For the edge nodes, attacks were detected by observing the request probability variation of different contents; for the upstream nodes, contents with low request rate were ruled out from the cache space by setting filter rules. The simulation results show that the network average hit ratio under service diversification mechanism is 17.3% higher than that under CCN with traditional caching strategies.The proposed scheme can effectively improve the defense capability of the network for the cache pollution attack.
Aiming at the capacity P-median problem of continuous domains under the dense demand, the Centroidal Capacity Constrained Power Diagram (CCCPD) theory was proposed to approximately model the continuous P-median problem and accelerate the solving process. The Power diagram was constructed by extended Balzer's method, centroid restriction was imposed to satisfy the requirements of P-median, and capacity constraint was imposed to meet the capacity requirements of certain demand densities. The experimental results show that the proposed algorithm can quickly obtain an approximate feasible solution, having the advantages of better computing efficiency and capacity accuracy compared to Alper Murata's method and Centroidal Capacity Constrained Voronoi Tessellation (CCCVT) respectively. Additionally, the proposed method has excellent adaptability to complex density functions.
To overcome the shortcoming that the Non-negativity And Support constraint Recursive Inverse Filtering (NAS-RIF) algorithm is noise-sensitive and time-consuming, an improved NAS-RIF algorithm for blind restoration was proposed. Firstly, a new cost function of the NAS-RIF algorithm was introduced, and then the noise resistance ability and the restoration effect were both improved. Secondly, in order to enhance computational efficiency of the algorithm, after decomposed by Haar wavelet transform, only degraded image in low frequency sub-bands was restored with the NAS-RIF algorithm, while information in high frequency sub-bands was predicted from the restored image of low frequency sub-bands by interband prediction. Finally, an interband prediction based on Minimum Mean Square Error (MMSE) was presented to guarantee the accuracy of the predicted information in high frequency sub-bands. The experiments on synthetic degraded images and real images were performed, and the Signal-to-Noise Ratio (SNR) gain by proposed algorithm were 5.2216 dB and 8.1039 dB respectively. The experimental results demonstrate that the proposed algorithm not only preserves image edges, but also has good performance in noise suppression. In addition, the computational efficiency of the proposed algorithm is greatly enhanced.
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.