Search results for " basis"

Un solutore pseudospettrale basato su RBF per l'equazione di Helmoltz

2012

On a topology optimization problem governed by two-dimensional Helmholtz equation

2015

The paper deals with a class of shape/topology optimization problems governed by the Helmholtz equation in 2D. To guarantee the existence of minimizers, the relaxation is necessary. Two numerical methods for solving such problems are proposed and theoretically justified: a direct discretization of the relaxed formulation and a level set parametrization of shapes by means of radial basis functions. Numerical experiments are given. peerReviewed

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.

Analysis of inhomogeneously filled waveguides using a bi-orthonormal-basis method

2000

A general theoretical formulation to analyze inhomogeneously filled waveguides with lossy dielectrics is presented in this paper. The wave equations for the tranverse-field components are written in terms of a nonself-adjoint linear operator and its adjoint. The eigenvectors of this pair of linear operators define a biorthonormal-basis, allowing for a matrix representation of the wave equations in the basis of an auxiliary waveguide. Thus, the problem of solving a system of differential equations is transformed into a linear matrix eigenvalue problem. This formulation is applied to rectangular waveguides loaded with an arbitrary number of dielectric slabs centered at arbitrary points. The c…

How can hepatitis C be prevented in the long term?

2007

Abstract Significant advances have been made in preventing HIV infection among injectors but we still know little about preventing hepatitis C (HCV). Both prevalence and incidence of hepatitis C can remain high among IDUs even in the context of widespread implementation of harm reduction programmes. We need to develop new ways to fill the knowledge gap regarding HCV prevention. One way is to learn from the experts—those IDUs who, after long-term injection in social milieus of high hepatitis C prevalence, nonetheless remain uninfected. We describe a recently commenced program of research that focuses on understanding the strategies, behaviours, and environmental factors associated with "stay…

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…

Performance of revised STO(1M)-3G basis set for prediction of 5-fluorocytosine chemical shifts.

2019

Nuclear shieldings and chemical shifts of 5-fluorocytosine (5FC) were predicted in the gas phase and DMSO solution modeled by polarizable continuum model using B3LYP density functional and revised STO(1M)-3G basis set. For comparison, eight arbitrary selected basis sets including STO-3G and medium-size Pople-type and larger dedicated Jensen-type ones were applied. The former basis sets were significantly smaller, but the calculated structural parameters, harmonic vibrational frequencies, were very accurate and close to those obtained with larger, polarization-consistent ones. The predicted 13 C and 1 H chemical shieldings of 5FC and cytosine, selected as parent molecule, were acceptable (ro…

Adjuvant Imatinib in Patients with GIST Harboring Exon 9 KIT Mutations : Results from a Multi-institutional European Retrospective Study

2022

[Purpose] The effect of high-dose imatinib (800 mg/day) on survival in the adjuvant treatment of patients with resected KIT exon 9–mutated gastrointestinal stromal tumors (GIST) is not established. Here, the association of dose and other clinicopathologic variables with survival was evaluated in a large multi-institutional European cohort.

A mesh less approch based upon Radial basis function Hermite collocation method for predicting the cooling and the freezing times of foods

2005

This work presents a meshless numerical scheme for the solution of time dependent non linear heat transfer problems in terms of a radial basis function Hermite collocation approach. The proposed scheme is applied to foodstuff's samples during freezing process; evaluation of the time evolution of the temperature profile along the sample, as well as at the core, is carried out. The moving phase-change zone is identified in the domain and plotted at several timesteps. The robustness of the proposed scheme is tested by a comparison of the obtained numerical results with those found using a Finite Volume Method and with experimental results.

Referenceless thermometry using radial basis function interpolation

2014

The Proton Resonance Frequency (PRF) shift provide a method for temperature change measurements during thermotherapy. Conventional PRF thermometry works subtracting one or multiple baseline images. The method leads to artifacts caused by tissue motion and frequency drift. Various works estimating the background phase from each acquired image phase are present in literature. These algorithms are called “referenceless” because they don’t require any subtraction of baseline images for calculating temperature increment. Conventional referenceless methods estimate baseline image by fitting the background phase outside the heated region through a polynomial approach. In this work a background pha…