87 research outputs found
On the Initial-Value Problem to the Quantum Dual BBGKY Hierarchy
We develop a rigorous formalism for the description of the evolution of
observables in quantum systems of particles. We construct a solution of the
initial-value problem to the quantum dual BBGKY hierarchy of equations as an
expansion over particle clusters whose evolution are governed by the
corresponding-order dual cumulant (dual semi-invariant) of the evolution
operators of finitely many particles. For initial data from the space of
sequences of bounded operators the existence and uniqueness theorem is proved.Comment: 22 page
Different Approaches for Multiband Transport in Semiconductors
We compare the well-known Kane model with a new multiband envelope function model, which presents many advantages with respect to the first one.Добре відому модель Кане порівняно з новою моделлю багатокомпонентної обвідної функції i продемонстровано багато переваг останньої
Quantum Kinetic Evolution of Marginal Observables
We develop a rigorous formalism for the description of the evolution of
observables of quantum systems of particles in the mean-field scaling limit.
The corresponding asymptotics of a solution of the initial-value problem of the
dual quantum BBGKY hierarchy is constructed. Moreover, links of the evolution
of marginal observables and the evolution of quantum states described in terms
of a one-particle marginal density operator are established. Such approach
gives the alternative description of the kinetic evolution of quantum
many-particle systems to generally accepted approach on basis of kinetic
equations.Comment: 18 page
Towards Rigorous Derivation of Quantum Kinetic Equations
We develop a rigorous formalism for the description of the evolution of
states of quantum many-particle systems in terms of a one-particle density
operator. For initial states which are specified in terms of a one-particle
density operator the equivalence of the description of the evolution of quantum
many-particle states by the Cauchy problem of the quantum BBGKY hierarchy and
by the Cauchy problem of the generalized quantum kinetic equation together with
a sequence of explicitly defined functionals of a solution of stated kinetic
equation is established in the space of trace class operators. The links of the
specific quantum kinetic equations with the generalized quantum kinetic
equation are discussed.Comment: 25 page
Antipersonnel Landmines Detection by Holographic Radar Imaging: An Experimental Study of Soil Effects
A stationary criticality problem in generalL p -space for energy dependent neutron transport in cylindrical geometry
Studio per lo sviluppo di nuovi rivestimenti ceramico compositi impiegabili in sistemi abradibili
Una strategia per l’incremento delle prestazioni delle turbine a gas consiste nella riduzione del trafilamentodei gas nella zona ad alta temperatura della turbomacchina grazie alla riduzione della distanza tra lasommità delle palette e la copertura protettiva della cassa della turbina. A tal fine sono stati studiati sistemiabradibili realizzati mediante diverse tecniche. Sono stati realizzati sistemi compositi compositi a baseCoNiCrAlY/Al2O3 mediante tecnica Air Plasma Spray (APS), a base NiCrAlY/graphite mediante tecnica LaserCladding e barriere termiche spesse e porose. Le resistenze all’ossidazione e alla fatica termica dei rivestimentisono state valutate per mezzo di prove di ossidazione isoterma e ciclica. I rivestimenti compositiCoNiCrAlY/Al2O3 e NiCrAlY/graphite dopo 1000 ore a 1100°C non hanno mostrato rilevanti modificazionimicrostrutturali. La resistenza all’ossidazione dei nuovi rivestimenti compositi soddisfa le specifiche deiproduttori, gli “Original Equipment Manufacturer” (OEM). Le barriere termiche spesse e porose superano i testdi fatica termica imposti dalle procedure degli OEM. La durezza di tali rivestimenti suggerisce il loro uso incombinazione con palette dotate di rivestimento abrasivo sull’estremità. Le barriere termiche hanno mostratobuone caratteristiche di abradibilità
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