Analysis of dark websites is important for developing effective combating strategies against terrorism or extremists when more and more scattered terrorist cells use the ubiquity of the Internet to form communities in virtual space with fairly low costs. Terrorists or extremists anonymously set up various web sites embedded in the public Internet, exchanging ideology, spreading propaganda, and recruiting new members. In this paper, we propose a framework to discover latent topics via analyzing contents of dark websites. The content and data from dark web sites are gathered and extracted by crawlers and exported to documents. Latent Dirichlet Allocation (LDA) algorithm is used to analyze the extracted documents so as to discover latent topics from web sites of terrorists or extremists. In contrast to the traditional Information Retrieval (IR) schemes, LDA-based analysis assigns a probability to a document and captures exchangeability of both words and documents. Our work helps to gain insights into the structure and communities of terrorists and extremists.

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The number of computers and high-speed networks connected to the Internet in large-scale organizations has grown in the last two decades. As a consequence, a large number of software applications must be installed and the quantity of data neededfor their operation is considerable. This has a high price for IT departments: distribute this content efficiently. We claim that content distribution using P2Pfile sharing systems can be used to accomplish this; we propose a solution that works even in environments that use NAT and utilizes WAN links efficiently.

Information sharing among heterogeneous databases requires increasing attention and poses a pressing need. Successful protection of information by an effective access control mechanism is a basic requirement for interoperation among heterogeneous data sources. However, most existing work on access control focuses on access control model and security related information, little effort is devoted to exploring access control on the semantic-related heterogeneous databases. No current work resolves the security challenges faced by heterogeneous databases, i.e., context-aware authorization, semantic heterogeneity of databases and policy specification at different points. This paper proposes a mediation security system that secures the information sharing among heterogeneous databases with the promise to meet the above requirements. The proposed system models the flexible access control requirements specific to mediation security while providing uniform access for heterogeneous data sources.

Product information modeling is critical to the integration of mechanical CAD/CAM systems and to the implementation of a concurrent engineering system. This paper presents a recent development of a feature-based and object-oriented concurrent engineering system with its focus on a product information modeling technique implemented in the system. The technique was developed to capture product definition data including form features and their spatial relationships and to store them as an object-oriented information model during the design process. The paper also describes the implementation of the information modeling technique and its application to manufacturing process planning in an object-oriented environment.