Numerical Simulation of Temperature Field for Laser Rapid Prototyping
The temperature field model for laser rapid prototyping is established by the mathematical treatment of laser power input. Temperature fields with different process conditions are numerical simulated, and the temperature is Gaussian distribution as the intensity distribution on laser beam cross-section. Temperature fields for laser rapid prototyping ware measured by thermal imager in real time. The simulation results agree with the experimental measurement. Experiments show that the temperature field model can be used for computer analysis and optimizing of laser rapid prototyping processing.
A note on rapid manufacturing process of metallic parts based on SLS plastic prototype
Abstract The polystyrene prototypes were produced by selective laser sintering (SLS) rapid prototyping process. According to properties of thermal depolymerisation of prototype material, the rapid manufacturing process for metallic parts was worked out through the combination of rapid prototypes and precise casting technology. After prototypes burned out in precision shell moulds, a series of complicate thin walled Al-alloy parts have been successfully made by vacuum differential pressure casting (VDPC) process. Accuracy of parts and influencing factors were investigated and discussed. The process combines the advantages of producing high-qualified metallic parts with shortening the period of production cycle.
Air scrubbing techniques for ammonia and odor reduction at livestock operations : review of on-farm research in the Netherlands
Acid scrubbers and biotrickling filters have been developed for ammonia (NH3) removal at pig and poultry houses 
in The Netherlands over the last 20 years to prevent acidification and eutrophication of soils. Because of growing 
suburbanization, odor removal is increasingly considered important as well. In this review, we report the results of the on-farm 
research on full-scale operated scrubbers for treatment of exhaust air from animal houses with regard to NH3 and odor 
removal in The Netherlands. The NH3 removal of acid scrubbers ranged from 40% to 100% with an overall average of 96%. 
The NH3 removal of biotrickling filters ranged from -8% to +100% with an overall average of 70%. Minimum empty bed air 
residence times (EBRTs) were 0.4 to 1.1 s. For acid scrubbers, process control with pH measurement and automatic water 
discharge is sufficient to guarantee sufficient NH3 removal. For biotrickling filters, however, improvement of process control 
is necessary to guarantee sufficient NH3 removal. The odor removal of acid scrubbers ranged from 3% to 51% with an overall 
average of 27%. The odor removal of biotrickling filters ranged from -29% to +87% with an overall average of 51%. 
Minimum EBRTs were 0.5 to 2.3 s. Further research is necessary to explain this variation and to improve the odor removal 
efficiency of both acid scrubbers and biotrickling filters.