Blockchain for Business Process Enactment: A Taxonomy and Systematic Literature Review

Blockchain has been proposed to facilitate the enactment of interorganisational business processes. For such processes, blockchain can guarantee the enforcement of rules and the integrity of execution traces - without the need for a centralised trusted party. However, the enactment of interorganisational processes pose manifold challenges. In this work, we ask what answers the research field offers in response to those challenges. To do so, we conduct a systematic literature review (SLR). As our guiding question, we investigate the guarantees and capabilities of blockchain-based enactment approaches. Based on resulting empirical evidence, we develop a taxonomy for blockchain-based enactment. We find that a wide range of approaches support traceability and correctness; however, research focusing on flexibility and scalability remains nascent. For all challenges, we point towards future research opportunities.Comment: Preprint, Accepted at BPM 2022, Blockchain Foru

Modeling the Block Verification Time of Zcash

An important aspect of the propagation delay in blockchain networks is the block verification time, which is also responsible for the so-called verifier's dilemma. Models for the block verification time can help to understand and improve the verification process. Moreover, modeling the verification time is necessary for blockchain network simulations. In this paper, we present JOIST, a new model for the block verification time of Zcash. We identify computationally complex operations in the verification process of Zcash, and derive our model based on characteristic transaction features. We evaluate JOIST and show that the model is consistently more accurate than existing models, which consider the block size only.Comment: Preprint, Submitted to IEEE S&B 2021 Security & Privacy on the Blockchai

Environmental Flight Acceptance Tests of the Small Earth Observation Satellite Flying Laptop

Since mid-2014, the fully integrated small satellite Flying Laptop is in the system testing phase at the Institute of Space Systems located at the University of Stuttgart in Germany. The satellite’s mass is 120 kg and it is designed to conduct multi-spectral earth observation as well as to demonstrate new technologies. A part of the acceptance tests prior to launch is the environmental testing in order to verify spacecraft functionality under environmental conditions during launch and in orbit. The following three main environmental tests were successfully conducted: Tests of Electromagnetic Compatibility (EMC): The EMC test of the Flying Laptop covered the verification of electromagnetic compatibility as well as interference of the various electromagnetic signals generated on-board. Vibration test: For the structural acceptance of the spacecraft sine and random vibration tests were performed for each satellite axis. Thermal Balance / Thermal Vacuum test: The thermal vacuum test was conducted to verify the functionality of the entire satellite at hot and cold temperatures. A similar test setup was used to perform the thermal balance test that allowed the validation of the thermal model. The environmental test campaign was completed successfully in December 2014. All system requirements were met according to the defined specifications