On theory and methods for advanced detonation-driven hypervelocity shock tunnels.

This study describes theory and methods for developing detonation-driven shock tunnels in hypervelocity test facilities. The primary concept and equations for high-enthalpy shock tunnels are presented first to demonstrate the unique advantage of shock tubes for aerodynamic ground-based testing. Then, the difficulties in simulating flight conditions in hypervelocity shock tunnels are identified, and discussed in detail to address critical issues underlying these difficulties. Theory and methods for developing detonation drivers are proposed, and relevant progress that has advanced the state of the art in large-scale hypersonic test facilities is presented with experimental verifications. Finally, tailored conditions for detonation-driven shock tunnels are described, laying a solid foundation to achieve long test duration. This interface-matching key issue encountered in developing shock tunnels has been investigated for decades, but not solved for detonation drivers in engineering applications.

Comparison of Smart Contract Blockchains for Healthcare Applications.

Blockchain and smart contracts (i.e., computer code that can be run on blockchain) are increasingly popular for healthcare applications. However, only very few implementations exist because of the complexity of the technologies. Although there are tutorials and reviews to introduce blockchain and smart contracts, a pragmatic comparison of such platforms is needed. In this study, we addressed practical considerations while building a healthcare blockchain and smart contract system, by (1) comparing technical features of platforms, (2) selecting three platforms, (3) constructing blockchain networks, (4) testing the blockchains, and (5) summarizing the experience and time used for implementation by students. We evaluated Ethereum, Hyperledger Fabric, and MultiChain, and confirmed that the selection of a proper platform depends on the requirements of the application. The findings of our study can accelerate the process and reduce the risk of adopting blockchain technology in biomedical and healthcare domain.

A gasdynamic gun driven by gaseous detonation.

A gasdynamic gun driven by gaseous detonation was developed to address the disadvantages of the insufficient driving capability of high-pressure gas and the constraints of gunpowder. The performance of this gasdynamic gun was investigated through experiments and numerical simulations. Much more powerful launching capability was achieved by this gun relative to a conventional high-pressure gas gun, owing to the use of the chemical energy of the driver gas. To achieve the same launching condition, the initial pressure required for this gun was an order of magnitude lower than that for a gun driven by high-pressure H2. Because of the presence of the detonation, however, a more complex internal ballistic process of this gun was observed. Acceleration of projectiles for this gun was accompanied by a series of impulse loads, in contrast with the smooth acceleration for a conventional one, which indicates that this gun should be used conditionally. The practical feasibility of this gun was verified by experiments. The experiments demonstrated the convenience of taking advantage of the techniques developed for detonation-driven shock tubes and tunnels.