THE NEW SOLUTION FOR THE AXIALLY SYMMETRICAL LAMINAR BOUNDARY LAYER EQUATIONS BETWEEN TWO PARALLEL SPHERICAL SURFACES

The transformations, which are similar to Mangler's transformations, are given in this paper. They change the entrance region flow of axially symmetrical laminar boundary layer between two parallel spherical surfaces into the flow of two-dimensional boundary layer, and simplify the problems. The simplified equations can be solved by the two-dimensional boundary layer theory and numerical methods. Therefore, a new way is opened up to solve the diffusive laminar flow in the entrance region between two parallel spherical surfaces.

Investigation into Metal Flow Rule during Extrusion of Spherical Surface Parts

A new process of extrusion forming was used to replace the traditional drilling technics.This kind of forming method may improve the structure of materials and anti-deforming capacity,enhancing the life of parts.It is shown by numerical simulations on the forming process of spherical extrusion on bolt-hole.Effects of technological parameters were discussed on spherical surface of extrusion and the diameter of pre-punching hole was determined.It is revealed that the smaller diameter of pre-punching hole,the larger deforming measurement of hole after extrusion.The extrusion stress determines the development trend of pre-punch hole becomes bigger or smaller and the pre-punching hole diameter is the key to control the size of deforming measurement of hole after extrusion.

A PSEUDOSPECTRAL METHOD FOR VORTICITY EQUATIONS ON SPHERICAL SURFACE

The pseudospectral method for solving vorticity equations on spherical surface is discussed. An interpolation procedure, which is different from the usual onesl is proposed. Based on such an interpolation, the pseudospectral scheme is constructed. Its generalized stability and convergence are analyzed rigorously. The theoretical analysis and computational skills can also be applied to other nonlinear partial differential equations defined on spherical surface.

METHOD FOR CALCULATION AND SIMULATION ON PROPAGATION OF SURFACE CRACK ON SPHERICAL VESSELS MADE OF STEELS

To avoid leaking or bursing by crack on surface of preddure vessels made of streels,a method for analyzing the principle of propagation of a surface crack is established,and used on a spherical vessel with program calculation and simulation,the program is written in QBASIC and the reaults are provided and discussed.

Cage-like radiotherapy system for noncoplanar radiotherapy

The aim of this study was to design a cage-like radiotherapy system(CRTS)to further promote the clinical application of noncoplanar radiotherapy.The CRTS comprises two stands,two O-rings,several arc girders,an X-ray head,an imaging subsystem,and a treatment couch.The X-ray head rotates with O-rings around the patient’s body and slides along the arc girder.Compared with the C-arm linear accelerator(C-Linac),the clinically available spatial irradiation angle ranges(SIARs)of the CRTS for the head,chest,and abdomen were 33%,63.6%,and 62.6%larger,respectively.Moreover,according to a preliminary planning comparison based on the dose distribution simulation method,the CRTS achieved much better protection of normal tissue than the C-Linac.Furthermore,the CRTS enabled accurate noncoplanar irradiation without movement of the body being irradiated,allowed automatic control of the movements of different parts without risk of collisions,and provided continuous radiation over an angle that considerably exceeded a full turn.These advantages make CRTS very promising for noncoplanar radiotherapy.

Research on Positioning Error Compensation for Micro Milling Machine Tool

Micro milling has many advantages in fabricating three-dimensional(3D) structure in micrometer scale. The micro milling machine tool with high positioning accuracy is of great importance for getting micro structure with high profile precision and good surface quality. Meanwhile, the method of position error compensation is a good way to improve the accuracy of the micro milling machine tools. In this paper,a software method is adopted to compensate the positioning error and improve the positioning accuracy. According to error cancellation theory,the compensation values are generated and compensation tables are built to adjust the positioning error in the NC system based on Industrial Motion and Automation Control( IMAC). The positioning accuracy of linear motor is ± 0. 3 μm without backlash after compensation. In order to verify the effectiveness of compensation on the machining performance,concave spherical surfaces are processed on the micro milling machine tool. The experimental results show that the profile radius error of the spherical surface machined with compensation decreases more than 60%.

Batch Preparation and Characterization of Electrospun Porous Polylactic Acid‑Based Nanofiber Membranes for Antibacterial Wound Dressing

A good wound dressing needs to promote wound healing and tissue repair when the skin is injured.In this study,a self-made spherical section free surface electrospinning device was used to produce large quantities of electrospun porous polylactic acid(PLA)/chitosan(CS)/aloin nanofiber membranes(NFMs)for antibacterial wound dressing.The porous structures of PLAbased nanofibers were controlled by adjusting the weight ratios of mixed solvent and solute.The results showed that highquality porous PLA/CS/aloin(PCA)NFMs were obtained when the weight ratios of chloroform/N,N-dimethylformamide and PLA:CS were 90/10 and 7:1,respectively.The porous PCA NFMs exhibited high porosity,acceptable mechanical properties,moderate hydrophobicity,good swelling property,and high water vapor transmission rate.Moreover,they also showed excellent blood coagulative,antibacterial,biocompatible properties,which had the potential to be used in the application of antibacterial wound dressings.