Notice of Retraction3-Dimensional Numerical Simulation Method for the Rock Slope Excavation in Civil Engineering
Rock slope is an unknown and complicated system; As for time series with strong randomization, application of the modified GM(1,1) was much more precise than ordinary GMs by comparison. And for time series with fluctuate positive and negative data, translation of the data and revivification after modeling was introduced to make an expansion of the application of the modified GM(1,1). The fitting and prediction precision was good by applying the modified GM(1,1) to analysis the monitoring stress of certain site of the left bank of Jinping Hydropower station. And by compassion, it was known that the prediction trend was accurate, and gave good ground work for further study. On the contrary, it was an important issue for the establishment of long-term prediction models.
Grey System Theory and Applications: A Way Forward
Grey system theory was initiated in the beginning of 1980s. Since then the research on theory development and applications is progressing. However, until today nearly all researchers of grey system theory are from Chinese speaking areas, and the theory is still hardly known nor accepted in the western world. The paper addresses the state-of-the-art development of grey system theory and its application. It aims to highlight and analyse relevant issues (i.e. obstacles, possible solutions and potential trends) for further research from the perspective both of grey system theory and of the grey system methods.
Microstructure of the solder-casting zone in bridges of dental gold alloys.
The composition and structure were studied in the cast and in the solder of bridges which had failed clinically. Both materials were gold alloys but with different contents of Pt, Ag and Zn. The metallographic investigation revealed defects mostly in the solder, situated in the subsurface layer. SEM studied of the fracture surface revealed large porosites and a structure of dense parallel lines--striations--, indicating that the material had failed from fatigue. The materials in the fractured bridges were identified by micro-probe measurements. It was stated that cast material and solder material used together, were of different composition.