10,562 research outputs found
Guidance methods for low-thrust space vehicles Cumulative progress report, 1 Jan. 1969 - 31 Jan. 1970
Guidance and control schemes for optimal low-thrust Earth-Mars transfer mission
Nucleosynthesis in the early history of the solar system
Nucleosynthesis in early history of solar syste
Topological code Autotune
Many quantum systems are being investigated in the hope of building a
large-scale quantum computer. All of these systems suffer from decoherence,
resulting in errors during the execution of quantum gates. Quantum error
correction enables reliable quantum computation given unreliable hardware.
Unoptimized topological quantum error correction (TQEC), while still effective,
performs very suboptimally, especially at low error rates. Hand optimizing the
classical processing associated with a TQEC scheme for a specific system to
achieve better error tolerance can be extremely laborious. We describe a tool
Autotune capable of performing this optimization automatically, and give two
highly distinct examples of its use and extreme outperformance of unoptimized
TQEC. Autotune is designed to facilitate the precise study of real hardware
running TQEC with every quantum gate having a realistic, physics-based error
model.Comment: 13 pages, 17 figures, version accepted for publicatio
Subglacial floods beneath ice sheets.
Subglacial floods (jökulhlaups) are well documented as occurring beneath present day glaciers and ice caps. In addition, it is known that massive floods have occurred from ice-dammed lakes proximal to the Laurentide ice sheet during the last ice age, and it has been suggested that at least one such flood below the waning ice sheet was responsible for a dramatic cooling event some 8000 years ago. We propose that drainage of lakes from beneath ice sheets will generally occur in a time-periodic fashion, and that such floods can be of severe magnitude. Such hydraulic eruptions are likely to have caused severe climatic disturbances in the past, and may well do so in the future
Simple models for the shuttle remote manipulator system
The investigation is aimed at establishing a series of simple models which can be used to study the forces and moments which occur due to the reaction control system (RCS) jet plume firings during a deployment or retrieval of an IUS type payload. The models considered in this investigation are primarily planar in nature. In this study primary attention is given to the roles the payload play in determining the overall moments on the remote manipulator system arm
Perimeter ring currents in benzenoids from Pauling bond orders
It is shown that the ring currents in perimeter hexagonal rings of Kekulean benzenoids, as estimated
within the Randić conjugated-circuit model, can be calculated directly without tedious pairwise
comparison of Kekulé structures or Kekulé counting for cycle-deleted subgraphs. Required are only
the Pauling bond orders of perimeter bonds and the number of Kekulé structures of the benzenoid,
both readily available from the adjacency matrix of the carbon skeleton. This approach provides easy
calculation of complete current maps for benzenoids in which every face has at least one bond on the
perimeter (as in the example of cata-condensed benzenoids), and allows qualitative evaluation of the
main ring-current contributions to 1H chemical shifts in general benzenoids. A combined Randić-
Pauling model for correlation of ring current and bond length through bond order is derived and shown
to be consistent with resilience of current under bond alternation
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