The K-Means algorithms typically utilize Euclidean distance to calculate the similarity between data points when dealing with large-scale heterogeneous data. However, this method has problems of low efficiency and high computational complexity. Inspired by the significant advantage of Hamming distance in handling data similarity calculation, a Quantum K-Means Hamming (QKMH) algorithm was proposed to calculate similarity. First, the data was prepared and made into quantum state, and the quantum Hamming distance was used to calculate similarity between the points to be clustered and the K cluster centers. Then, the Grover’s minimum search algorithm was improved to find the cluster center closest to the points to be clustered. Finally, these steps were repeated until the designated number of iterations was reached or the clustering centers no longer changed. Based on the quantum simulation computing framework QisKit, the proposed algorithm was validated on the MNIST handwritten digit dataset and compared with various traditional and improved methods. Experimental results show that the F1 score of the QKMH algorithm is improved by 10 percentage points compared with that of the Manhattan distance-based quantum K-Means algorithm and by 4.6 percentage points compared with that of the latest optimized Euclidean distance-based quantum K-Means algorithm, and the time complexity of the QKMH algorithm is lower than those of the above comparison algorithms.
Since some computation in reachability Query Preserving Graph Compression (QPGC) algorithm are redundant, a high-performance compression strategy was proposed. In the stage of solving the vertex sets of ancestors and descendants, an algorithm named TSB (Topological Sorting Based algorithm for solving ancestor and descendant sets) was proposed for common graph data. Firstly, the vertices of the graph data were topological sorted. Then, the vertex sets were solved in the order or backward order of the topological sequence, avoiding the redundant computation caused by the ambiguous solution order. And an algorithm based on graph aggregation operation was proposed for graph data with short longest path, namely AGGB (AGGregation Based algorithm for solving ancestor and descendant sets), so the vertex sets were able to be solved in a certain number of aggregation operations. In the stage of solving reachability equivalence class, a Piecewise Statistical Pruning (PSP) algorithm was proposed. Firstly, piecewise statistics of ancestors and descendants sets were obtained and then the statistics were compared to achieve the coarse matching, and some unnecessary fine matches were pruned off. Experimental results show that compared with QPGC algorithm: in the stage of solving the vertex sets of ancestors and descendants, TSB and AGGB algorithm have the performance averagely increased by 94.22% and 90.00% respectively on different datasets; and in the stage of solving the reachability equivalence class, PSP algorithm has the performance increased by more than 70% on most datasets. With the increasing of the dataset, using TSB and AGGB cooperated with PSP has the performance improved by nearly 28 times. Theoretical analysis and simulation results show that the proposed strategy has less redundant computation and faster compression speed compared to QPGC.
Concerning the problem that the network access control of Virtual Machines (VM) in the cloud computing Infrastructure as a Service (IaaS) platforms, a method of communication access control for VM in IaaS platforms was proposed. The method based on Software Defined Networking (SDN) was realized to customize the communication access control rules from Layer 2 to Layer 4. The experimental results show that the method can manage communication access permissions of tenants' VM flexibly, and ensure the security of tenants' network.
An adaptive multiple colony ant algorithm was presented to solve frenquency assignment problem of mobile communicaiton. Unlike the traditional ant colony algorithm which used only one ant colony, our algorithm used multiple ant colonies. For each ant colony, a coefficient of convergence was defined by which the ants adaptively could choose the path, update their local pheromone and exchange information between colonies. By using the adaptive strategy to update the pheromone, the balance between the diversity and convergence of every ant colony was kept. The simulation results on the fixed frequency assignment problem and minimal span frequency assignment problem show that our algorithm has global convergence and higher speed of optimization.