A novel 4-UPU parallel manipulator mechanism that can perform three-dimensional translations and rotation about Z axis is presented. The principle that the mechanism can perform the above motions is analyzed based on the screw theory, the mobility of the mechanism is calculated, and the rationality of the chosen input joints is discussed. The forward and inverse position kinematics solutions of the mechanism and corresponding numerical examples are given, the workspace and the singularity of the parallel mechanism are discussed. The mechanism having the advantages of simple symmetric structure and large stiffness can be applied to the developments of NC positioning platforms, parallel machine tools, four-dimensional force sensors and micro-positional parallel manipulators.

During ultra-precision cutting of brittle materials, the wear of diamond tool seriously affects the quality of machined surface. By molecular dynamics modeling of nanometric cutting, the generation of graphitization and its formation process at the cutting edge of tool are observed. By analyzing the process, the reason of the graphitization wear is mainly thermo-chemical reactions. By calculating the changes of coordination numbers of the tool atoms, graphitization conversion rate keeps increasing along the cutting process but gets stable after a certain length, which indicates the graphitization wear will occur in the same process.

No surface in engineering is absolutely smooth. It is important to analyze and calculate the real contact area for a better understanding of friction, wear, lubrication and thermal conductance. To obtain the accurate real contact area between rough surface and smooth surface, a rough-non-rigid-smooth surface contact finite element model is proposed in which the rough surface is characterized by fracture theory. In finite element modeling and analyzing process, MATLABEXCEL and AutoCAD are used to process data, and the smooth surface is considered to be non-rigid body. Compared with the traditional modeling, this method can obtain data quickly and is closer to the actual situation.

In nanometric cutting process, the actual material removal can take place at atomic level, which makes the observation of machining phenomena and the measurement of cutting parameters difficult or impossible in experiments. However, it is crucial to investigate the cutting process in nanoscale. In this work, molecular dynamics (MD) is used to study effects of cutting parameters on nanometric cutting process with the aid of EAM potential. The result of the simulation shows that higher cutting speed leads to a rough machined surface with a relative large deformation in workpiece. It is found that a smaller cutting depth results in less plastic deformation and fewer dislocations in workpiece, and also results in a smoother machined surface. Rake angle has big effect on the chip formation, potential energy and the machined surface.

After the water flooding sandstone oilfield entering the ultra-high water-cut developing phase, the remaining oil distribution has become increasingly fragmented, how to quantitative distinguish the remaining oil potential is the key to influence oilfield development, using multilevel fuzzy comprehensive evaluation mathematics method, comprehensive analyzed the classification reservoir’s producing conditions during the ultra-high water-cut developing phase, established a quantitative evaluation method from geological and develop factors, solved the problem of analyzing remaining oil in deferent kinds of reservoirs, realized the quantitative characterization of remaining oil in the ultra-high water-cut oilfield.