Results 181 to 190 of about 12,379 (262)

Ensemble reliability and the signal‐to‐noise paradox in ECMWF subseasonal forecasts

open access: yesQuarterly Journal of the Royal Meteorological Society, EarlyView.
We derive a general expression for the ratio of predictable components (RPC) in terms of correlation, spread–error ratio, and total variance ratio. Physical constraints on the admissible solutions (i.e., real‐valued and non‐negative variances) provide a mechanism to identify statistically paradoxical sample combinations of reliability and correlation ...
Christopher D. Roberts, Frederic Vitart
wiley   +1 more source

New views of some invariants associated with the Cartesian 2D velocity gradient tensor

open access: yesQuarterly Journal of the Royal Meteorological Society, EarlyView.
Vorticity and divergence of horizontal flow are fundamental quantities in meteorology; both are linear functions of the four elements of the 2D velocity gradient tensor and both are formally unchanged under coordinate rotation. We explore four quadratic functions of the elements that are geometrically invariant in this sense, finding some novel ...
I. Roulstone, S. A. Clough, A. A. White
wiley   +1 more source

Adaptive Sliding Mode Control Design for Interval Type‐2 T–S Fuzzy Systems With Time Delay: An Event‐Triggered Approach

open access: yesInternational Journal of Robust and Nonlinear Control, EarlyView.
ABSTRACT In this work, a new event‐triggered adaptive first‐order sliding mode control method is proposed for nonlinear systems with constant time delays, modeled by interval type‐2 Takagi–Sugeno (T–S) fuzzy systems. To handle matched disturbances with unknown upper bounds, a non‐overestimating adaptation strategy for the control coefficient is ...
Rodrigo Possidonio Noronha   +1 more
wiley   +1 more source

A Superintegrable Quantum Field Theory. [PDF]

open access: yesCommun Math Phys
De Clerck M, Evnin O.
europepmc   +1 more source

Sliding Mode Control in Aerospace Applications: A Survey

open access: yesInternational Journal of Robust and Nonlinear Control, EarlyView.
ABSTRACT Sliding mode control (SMC) enjoys robustness to matched and unmatched (in the case of minimum phase input‐output dynamics) bounded perturbations, and finite time convergence. Second‐order and higher‐order sliding mode control systems (2‐SMC/HOSMC) retain all the advantages of sliding mode control, but in addition can be applied to systems of ...
Yuri Shtessel, Christopher Edwards
wiley   +1 more source

Discrete Implementations Modify the Intuition of Final Set Adjustment in Barrier Function Based Control

open access: yesInternational Journal of Robust and Nonlinear Control, EarlyView.
ABSTRACT This paper establishes an implementation‐aware framework for Barrier Function Adaptation (BFA) and shows that discrete‐time realizations fundamentally alter the logic of final‐set adjustment. In particular, sufficient conditions are derived to preserve the key benefits of BFA (predefined performance, gain adaptation with uncertain perturbation
Luis Ovalle   +3 more
wiley   +1 more source

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