Numerical Study on the Recoating Process in Microstereolithography

Microstereolithography is a promising RP-based micro-fabrication technique that aims to meet the demands for complex geometry micro-scale parts. Projection microstereolithography incorporates a Dynamic Pattern Generator to obtain high resolution in the parallel plane. However, its lateral resolution has been always limited by the final layer thickness and the long resin settling time, both of which rely on the recoating process. In order to find the critical factors behind the recoating process, a numerical simulation method (Computational Fluid Dynamics, CFD) has been used to investigate the relationships among final layer thickness, settling time, resin viscosity and ratio of object/container size. These results are helpful for the selection of resin characteristics and the design of the microstereolithography machine.Mechanical Engineerin

Shape of Proton and the Pion Cloud

Proton-proton differential and total cross sections provide information on the energy dependence of proton shape and size. We show that the deviation from exponential behavior of the diffraction cone observed near $t=-0.1$ GeV$^2$, (so-called break), both at the ISR and the LHC follows from the $t$-channel two-pion loop contributions, imposed by unitarity. By using a simple Regge-pole model, we extrapolate the "break" from the ISR energy region to that of the LHC. This allows us to answer two important questions: 1) To what extent is the "break" observed recently at the LHC a "recurrence" of that seen at the ISR (universality)? 2) What is the relative weight of two-pion effect to the vertex coupling (Regge residue) compared to expanding size (pomeron propagator) in producing the "break"? We find that the effect comes both from the Regge residue (proton-pomeron coupling) and from the Regge propagator. A detail analyses of their balance, including the correlation between the relevant parameters is presented.Comment: 9 pages, 7 figures, 3 table

Relaxation of a high-energy quasiparticle in a one-dimensional Bose gas

We evaluate the relaxation rate of high-energy quasiparticles in a weakly interacting one-dimensional Bose gas. Unlike in higher dimensions, the rate is a nonmonotonic function of temperature, with a maximum at the crossover to the state of suppressed density fluctuations. At the maximum, the relaxation rate may significantly exceed its zero-temperature value. We also find the dependence of the differential inelastic scattering rate on the transferred energy. This rate yields information about temperature dependence of local pair correlations