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Objectives: Aiming at the mixed observation data of multiple distribution forms, a expectation-maximum (EM) combined p-norm distributed model(EM_p) is established.Methods: Considering that the mixed number in the mixture model belongs to incomplete data, the EM algorithm is introduced to estimate the parameters of the mixture model and the p-model mixture model parameters are derived in detail. The estimated iteration formula and the corresponding iteration steps are given.The mixture Gaussian distribution data, Laplace distribution and Gaussian distribution mixture data, and the residual data of measured global positioning system(GPS) observations are used to verify the correctness and adaptability of the formula in this paper. Results and Conclusions: The results of the calculation examples show that, compared with the single probability distribution, the p-norm mixture model can accurately reflect the actual situation of the data distribution, and the model parameters estimated by the EM algorithm have higher accuracy. [ABSTRACT FROM AUTHOR]

In order to improve the observation accuracy and efficiency of bed load experiments, the fine experimental observations of the movement and the state transition of bed sands in open channel flow were accomplished by means of underwater photography and particle tracking (UP/PTV). The reliability of the sampling data was improved by removing the interference caused by bed sands wagging, and setting the critical threshold of particle motion state as well as adapting multiple filter screening programs. By conducting series of bed load experiments under low transport intensity conditions, data including motion trajectory, velocity and step duration of bed particle was obtained, which was analyzed using a Lagrange process and the Probability Density Function (PDF) of the particle motion elements. Experimental results indicated that, the particle velocity shows a trend that increases rapidly at first and then decays slowly during the process of one single step, which is caused by inter particle collision and sweep events of near-bed turbulence. The PDF curve of particle velocity presents the Gamma function distribution with a thin tail,while the PDF curve of particle acceleration shows the Laplace distribution characteristics, influenced by the particle wagging effect. The particle velocity is closely associated with the friction velocity u*,maintaining a ratio of 3.4 to 3.5. The joint distribution of the single step duration Ts and the single step length Ls of the particles presents an exponential function,and the exponent of the fitting curves ranges between 1.25 and 1.30. The exponent is associated with the transport intensity of bed load and the heterogeneity of the bed surface particles. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency of data scheduling and replica access in cloud computing, this paper studied the replica placement problem in replica strategy and proposed a replica placement strategy based on ant colony algorithm. According to the principle of ant colony foraging in nature, the strategy applied ant colony algorithm to the entire process of replica placement. It used the pheromone dynamic updating and Laplace probability distribution to improve the ant colony algorithm, obtained a set of optimal solutions for replica placement. Simulation was on the CloudSim platform. The experimental results show that the proposed scheme is superior to the original ant colony algorithm in average job completion time, network utilization and load balance, and reduces the copy placement time consumption and network load to a certain extent. [ABSTRACT FROM AUTHOR]