The Hamiltonian size reduction method or the mode space applicable to general heterogeneous structures is developed in this work. effectiveness and accuracy of are demonstrated for four example devices GaSb/InAs tunnel field effect transistor (FET), MoTe2/SnS2 bilayer vertical FET, InAs nanowire FET with a defect, Si rough surfaces. reduced around 5 % original full without losing calculated tra...

Nanostructured semiconducting alloys obtain ultra-low thermal conductivity as a result of the scattering phonons with wide range mean-free-paths (MFPs). In these materials, long-MFP are scattered at nanoscale boundaries whereas short-MFP high-frequency impeded by disordered point defects introduced alloying. While this trend has been validated simplified analytical and numerical methods, an ab-...

We study the damping of internal gravity waves in a stably stratified fluid with constant viscosity in twoand three-dimensional bounded domains. For the linearized Navier-Stokes equations for incompressible flow with no-slip boundary conditions that model this fluid, we prove there are non-oscillatory normal modes with arbitrarily small exponential decay rates. The proof in a twoand three-dimen...

We analyse the spectrum of perturbations of the de Sitter space on the one hand, while on the other hand we compute the location of the poles in the Conformal Field Theory (CFT) propagator at the border. The coincidence is striking, supporting a dS/CFT correspondence. We show that the spectrum of thermal excitations of the CFT at the past boundary I − together with that spectrum at the future b...

A theory of flexibility and rigidity is developed for general infinite bar-joint frameworks (G, p). Determinations of nondeformability through vanishing flexibility are obtained as well as sufficient conditions for deformability. Forms of infinitesimal flexibility are defined in terms of the operator theory of the associated infinite rigidity matrix R(G, p). The matricial symbol function of an ...

In this paper we investigate a class of combined discrete-continuous mechanical systems consisting of a continuous elastic structure and a nite number of concentrated masses, elastic supports and linear oscillators of arbitrary dimension. After the motion equations for such combined systems are derived, they are formulated as an abstract evolution equation on an appropriately deened Hilbert spa...