Robust stability of linear time-varying delta-operator formulateddiscrete-time systems

Some earlier results on robust stability of continuous-time and discrete-time control systems are extended to a class of linear time-varying delta-operator formulated discrete-time systems     

Modern Approaches for Calculating Flow Parameters during a Laminar–Turbulent Transition in a Boundary Layer

We analyze modern methods for calculating heat and hydrodynamic flow parameters in a boundary layer during the laminar–turbulent transition. The main approaches for describing the phenomenon of laminar–turbulent transition are examined. Each approach is analyzed. The manner in which different factors influence the laminar–turbulent transition is studied. An engineering model of the laminar–turbulent transition in a high-velocity flow is presented.     

Averaging of Random Sets Based on Their Distance Functions

A new notion of expectation for random sets (or average of binary images) is introduced using the representation of sets by distance functions. The distance function may be the familiar Euclidean distance transform, or some generalisation. The expectation of a random set X is defined as the set whose distance function is closest to the expected distance function of X. This distance average can be applied to obtain the average of non-convex and non-connected random sets. We establish some basic properties, compute examples, and prove limit theorems for the empirical distance average of independent identically distributed random sets.     

Non‐iterative Second‐order Approximation of Signed Distance Functions for Any Isosurface Representation

Signed distance functions (SDF) to explicit or implicit surface representations are intensively used in various computer graphics and visualization algorithms. Among others, they are applied to optimize collision detection, are used to reconstruct data fields or surfaces, and, in particular, are an obligatory ingredient for most level set methods. Level set methods are common in scientific visualization to extract surfaces from scalar or vector fields. Usual approaches for the construction of an SDF to a surface are either based on iterative solutions of a special partial differential equation or on marching algorithms involving a polygonization of the surface. We propose a novel method for a non‐iterative approximation of an SDF and its derivatives in a vicinity of a manifold. We use a second‐order algebraic fitting scheme to ensure high accuracy of the approximation. The manifold is defined (explicitly or implicitly) as an isosurface of a given volumetric scalar field. The field may be given at a set of irregular and unstructured samples. Stability and reliability of the SDF generation is achieved by a proper scaling of weights for the Moving Least Squares approximation, accurate choice of neighbors, and appropriate handling of degenerate cases. We obtain the solution in an explicit form, such that no iterative solving is necessary, which makes our approach fast.     

The diagnostic potentials for the consulting surgeon in a medical aviation department

Three cases of cri du chat syndrome with varying ages of presentation are compared and contrasted to highlight the clinical features and evolution of the phenotype with time.