EXPERT SYSTEM AND ITS APPLICATION IN THE SELECTION OF PIT RETAINING STRUCTURES

This paper describes the development of an expert system(ES) on earth retaining structures for the selection and design.The ES retaining is an interactive menudriven system and consists of two main parts—the selection part,selectwall and the design part.Selectwall is developed using the knowledge base and it makes a choice of the most appropriate retaining structure.The design part is developed by three independent subprograms which perform detailed design including strength,deformation,stability of the retaining structure.The calculation results are illustrated by plotting the diagram.Using this program,the design procedure of the retaining structure can be performed automatically.

Pits and adatoms at the interface of 1-ML C_(84)/Ag(111)

We prepare a well-defined C84 monolayer on the surface of Ag （111） and study the geometric structure by scanning tunneling microscopy （STM）. The C84 molecules form a nearly close-packed incommensurate R30° lattice. The lattice is long-distance ordered with numerous local disorders. The monolayer exhibits complex bright/dim contrast; the largest height difference between the molecules can be greater than 0.4 nm. Annealing the monolayer at 380 ℃ can desorb part of the molecules, but more than sixty percent molecules stay on the Ag （111） surface even after the sample has been annealed at 650 ℃. Our analyses reveal that the 7-atom pits form beneath many molecules. Some other molecules sit at the 1-atom pits. Ag adatoms （those removed substrate atoms, accompanying the pit formation） play a very important role in this system. The adatoms can either stabilize or destabilize the monolayer, depending on the distribution manner of the adatoms at the interface. The distribution manner is determined by the co-play of the following factors： the dimension of the interstitial regions of the C84 overlayer, the number of the adatoms, and the long-distance migration of part adatoms.

Bionics-Inspired Structure Boosts Drag and Noise Reduction of Rotating Machinery

As a global concern,environmental protection and energy conservation have attracted significant attention.Due to the large carbon emission of electricity,promoting green and low-carbon transformation of the power industry via the synergistic development of clean energy sources is essential.Rotating machinery plays a crucial role in pumped storage,hydropower generation,and nuclear power generation.Inspired by bionics,non-smooth features of creatures in nature have been introduced into the structure design of efficient rotating machines.First,the concept and classification of bionics are described.Then,the representative applications of non-smooth surface bionic structures in rotating machineries are systematically and comprehensively reviewed,such as groove structure,pit structure,and other non-smooth surfaces.Finally,conclusions are drawn and future directions are presented.The effective design of a bionic structure contributes toward noise reduction,drag reduction and efficiency improvement of rotating machineries.Green and ecological rotating machinery will remarkably reduce energy consumption and contribute to the realization of the“double carbon”goal.