Brno University of Technology

About: Brno University of Technology is a education organization based out in Brno, Czechia. It is known for research contribution in the topics: Fracture mechanics & Filter (video). The organization has 6339 authors who have published 15226 publications receiving 194088 citations. The organization is also known as: Vysoké učení technické v Brně & BUT.

CDTA-C current-mode universal 2nd-order filter

Abstract: Transformation of the classical KHN (Kerwin-Huelsman-Newcomb) 2nd-order filter into the current mode structure containing the CDTA (Current-Differencing Transconductance Amplifier) active elements is described. The resulting structure consists of three CDTAs and two grounded capacitors. The proposed filter has a low-impedance current input and three current outputs, realizing three basic transfer functions (lowpass, highpass, and bandpass), which can easily be combined to implement transfer functions with various transfer zeros.

First-principles study of Co- and Cu-doped Ni2MnGa along the tetragonal deformation path

Abstract: The influence of Co and Cu doping on Ni-Mn-Ga Heusler alloy is investigated using the first-principles exact muffin-tin orbital method in combination with the coherent-potential approximation. Single-element doping and simultaneous doping by both elements are investigated in Ni${}_{50\ensuremath{-}x}$Co${}_{x}$Mn${}_{25\ensuremath{-}y}$Ga${}_{25\ensuremath{-}z}$Cu${}_{y+z}$ alloys, with dopant concentrations $x,\phantom{\rule{0.28em}{0ex}}y$, and $z$ up to 7.5 at. %. Doping with Co in the Ni sublattice decreases the ${(c/a)}_{\text{NM}}$ ratio of the nonmodulated (NM) martensite, but it simultaneously increases the cubic phase stability with respect to the NM phase. Doping with Cu in the Mn or in Ga sublattices does not change the ${(c/a)}_{\text{NM}}$ ratio significantly and it decreases the cubic phase stability. For simultaneous doping by Co in the Ni sublattice and Cu in the Mn or Ga sublattices, the effects of the individual dopants are independent and about the same as for the single-element doping. Thus, the ${(c/a)}_{\text{NM}}$ ratio can be adjusted by Co doping while the phase stability can be balanced by Cu doping, resulting in stable martensite with a reduced ${(c/a)}_{\text{NM}}$. The local stability of the cubic phase with respect to the tetragonal deformation can be understood on the basis of a density-of-states analysis.

Flatten and conquer: a framework for efficient analysis of string constraints

Abstract: We describe a uniform and efficient framework for checking the satisfiability of a large class of string constraints. The framework is based on the observation that both satisfiability and unsatisfiability of common constraints can be demonstrated through witnesses with simple patterns. These patterns are captured using flat automata each of which consists of a sequence of simple loops. We build a Counter-Example Guided Abstraction Refinement (CEGAR) framework which contains both an under- and an over-approximation module. The flow of information between the modules allows to increase the precision in an automatic manner. We have implemented the framework as a tool and performed extensive experimentation that demonstrates both the generality and efficiency of our method.