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An access control model for multidomain collaborative environments based on shared permittions is presented. The model can realize secure resource sharing and interoperation among different domains. It classifies permissions of an administrative domain into two categories: private permissions that can only be accessed by subjects within the domain, and sharing permissions which can be shared by other...
The focus of existing researches on RBAC constraints has been predominantly on the specification of constraints, the detection and resolution of constraint conflicts have been overlooked and remain a significant research challenge. To address these concerns, we propose a set of detection rules for these conflicts. Furthermore, a flexible approach is provided to resolve internal constraint conflicts...
A virtual learning environment is a system that creates an environment designed to facilitate teachers in the management of educational courses for their students, especially a system using computer hardware and software, which involves distance learning. It is often referred to as a learning management system. E-learning refers to the strategies that use the company network to deliver training courses...
Using the very complete, high-quality observational data of the 1992-10-27 flare and through an analysis of its optical, soft X-ray and hard X-ray images and of its spectra thermal and non-thermal processes are diagnosed. The results show that, for this event, thermal and non-thermal processes coexisted and showed different features in their temporal and spatial evolutions.
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