Real-time rapid prediction of variations of Earth’s rotational rate

Real-time rapid prediction of variations of the Earth＇s rotational rate is of great scientific and practical importance. However, due to the complicated time-variable characteristics of variations of the Earth＇s rotational rate （i.e., length of day, LOD）, it is usually difficult to obtain satisfactory predictions by con- ventional linear time series analysis methods. This study employs the nonlinear artificial neural net-works （ANN） to predict the LOD variations. The topology of the ANN model is determined by minimizing the root mean square errors （RMSE） of the predictions. Considering the close relationships between the LOD variations and the atmospheric circulation movement, the operational prediction series of axial atmospheric angular momentum （AAM） is incorporated into the ANN model as an additional input in the real-time rapid prediction of LOD variations with 1-5 days ahead. The results show that the LOD prediction is significantly improved after introducing the operational prediction series of AAM into the ANN model.     

The New Detection and the Basic Characteristics of the Structural System of Taiwan Region of China—Using the Earth Satellite’s Remote-sensing Images to Explain the Structural System of Taiwan Region of China

This text uses the regional geological investigation data and the remote sensing image data of earthsatellite remote sensing to synthetically analyze the structural system of Taiwan region of China. Authors detection-marked and assurance-marked and divided 5 kinds of structural system of the Taiwan region： （ 1 ） the wreath-shaped structural system, （2） the N-N-E oriented structural system, （3） the S-N oriented structural system, （4） the N-E oriented structural system, （5） the are-shaped structural system. Combination of the texture faces and associated method were adopted to recover and reconstruct the structural evolution sequences and the formation periods. In this paper, problems such as the development process in geology etc. are also discussed, contributing new information to research the structural field of the East Asia and its tectonic plate movements and structural actions inside the land plate .     

Observation of directional change of core field inside flux ropes within one reconnection diffusion region in the Earth’s magnetotail

Two consecutive magnetic flux ropes, separated by less than 30 s （△t 〈 30 s）, are observed within one magnetic reconnection diffusion region without strong guide field in the Earth＇s magnetotail by Cluster multispacecraft. The flux ropes are characterized by bipolar signatures of the south-north magnetic field component Bz accompanied with strong core magnetic field By, intense current J and density depletions inside of them. In spite of the small but non-trivial global scale negative guide field （-By）, there exists a directional change of the core fields of two flux ropes, i.e., -By for the first one, and ＋By for the second one. The directions of the core fields are the same as the ambient cross-tail magnetic field component （By） just outside of flux ropes. Therefore, we suggest that the core field of flux ropes is formed by compression of the local preexisting By and that the directional change of core field is due to the change of local preexisting By. Such a change in ambient By might be caused by some microscale physics.     

The analysis of the Earth co-orbital motion of Chang’e-2 after asteroid flyby

After the Chang’e-2 spacecraft conducted a successful asteroid flyby,where is it flying to in interplanetary space?This question is answered via an introduction to the Chang’e-2’s flight trajectory after asteroid flyby that is termed Earth co-orbital motion.Based on preliminary analysis using the dynamical systems theory,Poincare′sections concept,and routine optimization techniques,it is now predicted that,from the point of view of orbital mechanics,Chang’e-2 is capable of returning to the vicinity of the Earth in no more than 20 a and might be recaptured by the Earth if appropriate orbital maneuvers are going to be exerted,either by itself or by another spacecraft that captures Chang’e-2.     

Effects of tectonic stress field and Poisson’s ratio on stress state within the San Andreas Fault zone

We used a mechanics conceptual model to provide another perspective to understand the mechanical environment of the San Andreas Fault(SAF),and a possible mechanism that the principal stress state in the SAF is not only affected by remote tectonic stress but also by Poisson’s ratio.For a strike-slip fault like the SAF,we found that in the fault zone with Poisson’s ratio of[0.25,effective friction coefficient and the stress ratio(minimum principal stress/maximum principal stress)are less than 0.1and 0.8–1.0,respectively,corresponding to remote tectonic stress ratio of 0.36–1.0,and that the higher the Poisson’s ratio,the greater the principal stress rotates.For hydrostatic pore pressure and a received tectonic stress ratio of 0.5around the SAF,the model predicts that the SAF has a very high Poisson’s ratio(*0.45),which accommodates extremely low effective friction coefficient(0.09)and large stress ratio(0.84)or smaller shear stress(17 MPa).