Towards a Trusted and Unified Consortium-Blockchain-Based Data Sharing Infrastructure for Open Learning—TolFob Architecture and Implementation

Open learning is now facing a complex higher education ecosystem that involves a variety of heterogeneous information systems and comprises decentralized stakeholders, such as universities, professors, students, and software vendors. Authentic, non-repudiable, and fast available data sharing among open learning information systems and stakeholders is a key issue that remains unresolved. To solve this problem, this paper proposes a consortium blockchain extended architecture featuring integration and cross-chain functions to provide a unified and trusted data-sharing infrastructure for open learning. The overall architecture consists of three elements: a blockchain-integrated open learning scenario schema; a blockchain-integrated open learning application model; and a pragmatic blockchain integration framework. The proposed blockchain integration framework is implemented based on Hyperledger Fabric 1.4. A trusted open-learning behavior and achievement management application is developed as a proof-of-concept which integrates two educational institutions’ four productional learning systems into a blockchain network and has stably run over six months. A suite of experiments is designed and executed to verify our blockchain system’s viability and scalability. The test result shows the implementation of the blockchain system is competent for the production environment and outperforms related works investigated. However, it does have limitations and optimization potential, which will be studied in the future.

The effect of tourism source market structure on international tourism revenues in Turkey

The current study calculates an indicator of tourism source market structure and investigates its impact on international tourism revenues in Turkey. This structure may influence the tourism performance through its consequences on the competitiveness and risk structure of the sector. The calculation of tourism source market structure in this study is based on the normalized Herfindahl–Hirschman Index and number of tourists by nationality. The ARDL co-integration framework is the method used and the estimation covers the period between January 2008 and September 2019. The calculated tourism source market structure indicator showed decreasing trend in the research period indicating that the tourism source market diversified in some extent. The co-integration is supported, and in the long-term model a 1% decrease in the tourism source market concentration found to increase international tourism revenues by 1.9078%. Furthermore, the error correction model indicated that it takes 7.16 months for deviations from the long-run relationship to return to the equilibrium.

Mass Integration for Rigorous Process Modelling: A Sequential Approach for Direct Recycling

Mass integration has been used for reducing the amount of process waste and environmental impact. Despite its long history, new challenges constantly arise with the use of process simulation tools offering platforms for rigorous process models. Therefore, the typical mass integration framework requires modifications to accurately account for the process performance. In this work, a novel sequential methodology is presented to realize a recycle network with rigorous process models. Initially, under the hypothesis of constant compositions of the process sources, an optimal ranking of the process sinks is determined. The optimal recycling network thus obtained is then used for a sequential methodology considering rigorous process models. The violations of process constraints are handled at each sequential step through the concept of “tightening constant”. The application of the sequential methodology to two case studies proves its ability to provide good approximations of the global optima with low computational effort.