Study on process parameter of high performance laser cutting machine tool for copper sheet
A high performance NC laser cutting machine tool for copper sheet is designed, emphasis discussing the components of NC laser cutting machine tool and design points. Performance of high power semiconductor pulse micro-cutting of copper sheet is studied and several key parameters are given by changing assistant gas and process parameters. The experimental results show that the best cutting quality can be obtained when argon is used as assistant gas, and oxygen is on the contrary. Also, in a certain range, improving laser power and cutting speed can help in decreasing laser cutting gap, minishing heat affected area, and achieving better cutting quality.
Laser Cutting Technology In Process of Sheet Metal
Introduce the course of laser cutting technology in process of sheet metal,expound the advantage of laser cutting technology.Based on the fact of production,expound the experience of laser cutting technology from processing range,precision and cost.
The risk of Listeria monocytogenes infection in beef cattle operations
Aim:  To determine the prevalence of Listeria monocytogenes and associated risk factors among beef operations (cow‐calf and feedlot) in central and southern California.