Analysis of the impact on the gravity field determination from the data with the ununiform noise distribution using block-diagonal least squares method

The block-diagonal least squares method, which theoretically has specific requirements for the observation data and the spatial distribution of its precision, plays an important role in ultra-high degree gravity field determination. On the basis of block-diagonal least squares method, three data processing strategies are employed to determine the gravity field models using three kinds of simulated global grid data with different noise spatial distri- bution in this paper. The numerical results show that when we employed the weight matrix corresponding to the noise of the observation data, the model computed by the least squares using the full normal matrix has much higher precision than the one estimated only using the block part of the normal matrix. The model computed by the block-diagonal least squares method without the weight matrix has slightly lower precision than the model computed using the rigorous least squares with the weight matrix. The result offers valuable reference to the using of block-diagonal least squares method in ultra-high gravity model determination.

Convergence Track Based Adaptive Differential Evolution Algorithm(CTbADE)

One of the challenging problems with evolutionary computing algorithms is to maintain the balance between exploration and exploitation capability in order to search global optima.A novel convergence track based adaptive differential evolution(CTbADE)algorithm is presented in this research paper.The crossover rate and mutation probability parameters in a differential evolution algorithm have a significant role in searching global optima.A more diverse population improves the global searching capability and helps to escape from the local optima problem.Tracking the convergence path over time helps enhance the searching speed of a differential evolution algorithm for varying problems.An adaptive powerful parameter-controlled sequences utilized learning period-based memory and following convergence track over time are introduced in this paper.The proposed algorithm will be helpful in maintaining the equilibrium between an algorithm’s exploration and exploitation capability.A comprehensive test suite of standard benchmark problems with different natures,i.e.,unimodal/multimodal and separable/non-separable,was used to test the convergence power of the proposed CTbADE algorithm.Experimental results show the significant performance of the CTbADE algorithm in terms of average fitness,solution quality,and convergence speed when compared with standard differential evolution algorithms and a few other commonly used state-of-the-art algorithms,such as jDE,CoDE,and EPSDE algorithms.This algorithm will prove to be a significant addition to the literature in order to solve real time problems and to optimize computationalmodels with a high number of parameters to adjust during the problem-solving process.

A Study on the Characteristics of the Yutian,Xinjiang M_S7.3 Earthquake,February 12,2014

The February 12, 2014, Ms7. 3, earthquake in Yutian, Xinjiang, China, occurred as a result of shallow strike-slip faulting in the tectonicaUy complex region of the northern Tibetan Plateau, with a depth of 17kin. This earthquake occurred several hundred kilometers north of the convergent India-Eurasia plate boundary. The epicenter location of the Yutian earthquake, 36. 1° N, 82. 5° E, is ll0km north of Yutian County, Hotan Prefecture. A large number of aftershocks from ML2. 0 to ML3. 0 occurred until 12：00 o＇clock, February 23, 2014 and the largest aftershock, Ms5. 7, occurred at 17：24 μm. , February 12, 2014. The b and h value of Yutian sequence are 0.70 and 1.29, respectively. The waiting time method reveals that the strong aftershocks above ML 4. 5 comply with a linear relationship, which is consistent with the characteristics of a mainshock-aftershock sequence. Furthermore, we calculate the source parameters and analyze the rupture process based on the empirical relationships for the Yutian earthquake, and the results indicate a frictional undershoot behavior in the dynamic source process of the Yutian earthquake, which is also in agreement with the lower and similar b values compared with the 2008 Ms 7.3 Yutian earthquake and the 2012 Ms 6. 2 Yutian earthquake.