查看更多>>摘要：The aluminum base microwave printed circuit board has the wide application foreground in high-tech fields. But the insulating layer of PCB is a difficult-to-machining material. In this paper, the experimental research on the wear mechanics and cutting coating comparison in high speed milling of the Rogers 6002 micro wave PCB. TiN and TiAlN coated cemented carbide cutting tool are select to milling the micro wave PCB. The effect of milling parameters and cutting length on cutting force is investigated. SEM is used to observe the wear morphology of the flank face of cutting tools. Research results show the wear mechanisms of coated tool include abrasive wear and adhesive wear. TiAIN coating is more suitable for high milling the insulating layer of microwave PCB because of its high hardness and wear resistance. The research results are contributive to choose proper high-speed cutting tools and parameters.
查看更多>>摘要：Due to the increasing threat of network attacks, network and information security is an upmost concern for CSCW. Traditional Role-Based Access made focus on the typical roles divided according to organizational roles in CSCW. It is insufficient to have role permissions based on object types for collaborative environments. An extended role-based access control model is proposed in this article to expand role to construct the hierarchy of security domain for CSCW. The total CSCW system was called security domain. Subdomain roles inherit security domain roles. Atomic domain roles inherit subdomain roles under role constrains. All extended role and role constraint are partial ordering and are uesed to restrict the range of access control for all CSCW participants.
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Trans Tech Publications Ltd