Search results for "Basis"
showing 10 items of 760 documents
Computational determination of the dominant triplet population mechanism in photoexcited benzophenone
2014
In benzophenone, intersystem crossing occurs efficiently between the S-1(n pi(star)) state and the T-1 state of dominant n pi(star) character, leading to excited triplet states after photoexcitation. The transition mechanism between S-1(n pi(star)) and T-1 is still a matter of debate, despite several experimental studies. Quantum mechanical calculations have been performed in order to assess the relative efficiencies of previously proposed mechanisms, in particular, the direct S-1 -> T-1 and indirect S-1 -> T-2(pi pi(star)) -> T-1 ones. Multiconfigurational wave function based methods are used to discuss the nature of the relevant states and also to determine minimum energy paths a…
Block Based Deconvolution Algorithm Using Spline Wavelet Packets
2010
This paper presents robust algorithms to deconvolve discrete noised signals and images. The idea behind the algorithms is to solve the convolution equation separately in different frequency bands. This is achieved by using spline wavelet packets. The solutions are derived as linear combinations of the wavelet packets that minimize some parameterized quadratic functionals. Parameters choice, which is performed automatically, determines the trade-off between the solution regularity and the initial data approximation. This technique, which id called Spline Harmonic Analysis, provides a unified computational scheme for the design of orthonormal spline wavelet packets, fast implementation of the…
Bessel sequences, Riesz-like bases and operators in Triplets of Hilbert spaces
2016
Riesz-like bases for a triplet of Hilbert spaces are investigated, in connection with an analogous study for more general rigged Hilbert spaces performed in a previous paper. It is shown, in particular, that every \(\omega \)-independent, complete (total) Bessel sequence is a (strict) Riesz-like basis in a convenient triplet of Hilbert spaces. An application to non self-adjoint Schrodinger-type operators is considered. Moreover, some of the simplest operators we can define by them and their dual bases are studied.
Coupled-Cluster study of ‘no-pair’ bonding in the tetrahedral Cu4 cluster
2011
Abstract Ab initio Coupled-Cluster calculations with single and double excitations and perturbative correction to the triple, CCSD(T), have been carried out for the high-spin electronic state, ( 5 A 2 ) , of the copper cluster Cu 4 in its tetrahedral arrangement. Like alkali metals clusters, tetrahedral Cu 4 presents a bound quintet state, i.e., a situation where all the valence electrons are unpaired. This rather exotic wavefunction, also known as no-pair bonding state, is examined in detail. The influence of the basis set is also analyzed, as well as the importance of the core correlation and the effect of the basis-set superposition errors.
Radial Basis Functions for Electronic Devices Behavioral Modeling
2006
In this paper a black-box identification technique based on the radial basis functions is used in developing global dynamic behavioural models of electronic devices from measured transient responses. This approach allows to reproduce a non-linear dynamic model of the device under modelling automatically taking into account all the physical effects relating input and output data, from measured waveform only: no knowledge of the internal structure is needed. Original application related to a bipolar junction transistor is reported and validated by comparing simulation results with measured data.
A 3D mesoscopic approach for discrete dislocation dynamics
2001
In recent years a noticeable renewed interest in modeling dislocations at the mesoscopic scale has been developed leading to significant advances in the field. This interest has arisen from a desire to link the atomistic and macroscopic length scales. In this context, we have recently developed a 3D-discrete dislocation dynamics model (DDD) based on a nodal discretization of the dislocations. We present here the basis of our DDD model and two examples of studies with single and multiple slip planes.
A Formal Model for Developing of the self-Diagosing and Self-Repairing 8-Bits Microprocessor, and Its Investigation Using Simulation
1986
Abstract The complete model of functional diagnostics is theoretically described. It specifies the conditions, which must be satisfied if the system to be self-diagnosable. The general principles of constructing self-diagnosable systems are enumerated. The model enables the realization of self-renewal, too. The model has been developed on the basis of the works by Preparata, Metze, Chien (1967) and Hakimi, Amin (1974) . The model contains a method of diagnostics completely separeted from the physical structure of the system. Recent results (Gruber, 1978; Swiatek, 1982) indicate that it is only necessary to know the set of transformations realized by the circuit. The model has been applied t…
A Criterion for Attaining the Welch Bounds with Applications for Mutually Unbiased Bases
2008
The paper gives a short introduction to mutually unbiased bases and the Welch bounds and demonstrates that the latter is a good technical tool to explore the former. In particular, a criterion for a system of vectors to satisfy the Welch bounds with equality is given and applied for the case of MUBs. This yields a necessary and sufficient condition on a set of orthonormal bases to form a complete system of MUBs. This condition takes an especially elegant form in the case of homogeneous systems of MUBs. We express some known constructions of MUBs in this form. Also it is shown how recently obtained results binding MUBs and some combinatorial structures (such as perfect nonlinear functions an…
Kollokationen in Leserbriefen der Wochenzeitschrift Die Zeit
2020
Im Rahmen der Phraseologieforschung haben Kollokationen traditionell nur wenig Beachtung gefunden. Im Gegensatz zu Idiomen sind sie in der Regel semantisch transparent und bereiten daher Fremdsprachenlernern selten rezeptive Schwierigkeiten. Bei der Textproduktion muss jedoch die Problematik der Kollokationen beachtet werden. Aus diesem Grund halten wir Kollokationen für einen wichtigen Bereich der Phraseologie. Im vorliegenden Beitrag wird die Aufmerksamkeit auf die syntaktische Struktur, den Gebrauch und die Funktion von Kollokationen in 243 Leserbriefen der Zeitschrift Die Zeit gerichtet. Nach Heranziehung zweier Kollokationswörterbücher sowie einiger anderer Quellen konnten 278 Kollokat…
Why betaine crystallizes in high local C s symmetry. An ab initio MO and DFT study of anhydrous betaine and betaine monohydrate
1999
A theoretical study of the structure, charge distribution, rotational barrier and fundamental vibrations of anhydrous betaine (CH3)3NCH2COO (trimethylglycine) was carried out and compared with available experimental data. Calculations were carried out at HF, MP2 and B3LYP levels using a 6-31+G(d,p) basis set. The calculated rotational barrier of the betaine carboxylic group is 40.5 kJ/mol at the MP4(SDQ)/6-311G(d,p)//HF/6-31+G(d,p) level of theory. The rotation of the carboxylic group changes the molecule from a highly symmetric (C s ) conformation into a twisted conformation resulting in shortening of the molecule by about 50 pm. Natural population analysis (NPA) indicates intramolecular i…