Classification of Hybrid Quantum-Classical Computing

As quantum computers mature, the applicability in practice becomes more important. Many uses of quantum computers will be hybrid, with classical computers still playing an important role in operating and using the quantum computer. The term hybrid is however diffuse and multi-interpretable. In this work we define two classes of hybrid quantum-classical computing: vertical and horizontal. The first is application-agnostic and concerns using quantum computers. The second is application-specific and concerns running an algorithm. For both, we give a further subdivision in different types of hybrid quantum-classical computing and we coin terms for them

Transfer Function Approximations for Large Highly Coupled Elastic Boosters with Fuel Slosh

Transfer function approximations for large highly coupled flexible body launch vehicles with liquid fuel slos

Weak refinement in Z

An important aspect in the specification of distributed systems is the role of the internal (or unobservable) operation. Such operations are not part of the user interface (i.e. the user cannot invoke them), however, they are essential to our understanding and correct modelling of the system. Various conventions have been employed to model internal operations when specifying distributed systems in Z. If internal operations are distinguished in the specification notation, then refinement needs to deal with internal operations in appropriate ways. However, in the presence of internal operations, standard Z refinement leads to undesirable implementations. In this paper we present a generalization of Z refinement, called weak refinement, which treats internal operations differently from observable operations when refining a system. We illustrate some of the properties of weak refinement through a specification of a telecommunications protocol

Occurrence, synthesis and applications of natural and designed [3.3.3]propellanes

The synthetically challenging [3.3.3]propellane core has caught a lot of attention over the last 50 years. This comprehensive review details all synthetic strategies reported in the period 1978–2019 to facilitate the synthesis of carbocyclic [3.3.3]propellanes. The described strategies span from acid-catalyzed rearrangements and photo-mediated cycloadditions of ketones, heteropropellanes and dispiroundecanes to thermal rearrangements of acetylenes and alkenes. Other approaches, such as radical reactions with halogenated alkenes, domino cyclizations, the smart use of epoxide-carbonyl rearrangements and intramolecular palladium-catalyzed ring contractions are discussed as well. A special section is dedicated to triptindanes, a subclass of [3.3.3]propellanes which are of interest to material sciences