Search results for " basis"

Comparison between the MHFEM formulation and a 2nd spatial order FV formulation of the linear ground problem

2008

Comparison of different 2nd order formulations for the solution of the 2D groundwater flow problem over irregular triangular meshes

2009

Mixed and Mixed Hybrid Finite Elements (MHFE) methods have been widely used in the last decade for simulation of groundwater flow problem, petroleum reservoir problems, potential flow problems, etc. The main advantage of these methods is that, unlike the classical Galerkin approach, they guarantee local and global mass balance, as well the flux continuity between inter-element sides. The simple shape of the control volume, where the mass conservation is satisfied, makes also easier to couple this technique with a Finite Volume technique in the time splitting approach for the solution of advection-dispersion problems. In the present paper, a new MHFE formulation is proposed for the solution …

High Performance 3D PET Reconstruction Using Spherical Basis Functions on a Polar Grid

2011

Statistical iterative methods are a widely used method of image reconstruction in emission tomography. Traditionally, the image space is modelled as a combination of cubic voxels as a matter of simplicity. After reconstruction, images are routinely filtered to reduce statistical noise at the cost of spatial resolution degradation. An alternative to produce lower noise during reconstruction is to model the image space with spherical basis functions. These basis functions overlap in space producing a significantly large number of non-zero elements in the system response matrix (SRM) to store, which additionally leads to long reconstruction times. These two problems are partly overcome by expl…

Shape staggering of midshell mercury isotopes from in-source laser spectroscopy compared with density-functional-theory and Monte Carlo shell-model c…

2019

Neutron-deficient Hg177-185 isotopes were studied using in-source laser resonance-ionization spectroscopy at the CERN-ISOLDE radioactive ion-beam facility in an experiment combining different detection methods tailored to the studied isotopes. These include either α-decay tagging or multireflection time-of-flight gating for isotope identification. The endpoint of the odd-even nuclear shape staggering in mercury was observed directly by measuring for the first time the isotope shifts and hyperfine structures of Hg177-180. Changes in the mean-square charge radii for all mentioned isotopes, magnetic dipole, and electric quadrupole moments of the odd-A isotopes and arguments in favor of I=7/2 s…

Prowadzenie pozarolniczej działalności gospodarczej jako tytuł ubezpieczeń społecznych - wybrane zagadnienia

2021

Prowadzenie pozarolniczej działalności gospodarczej stanowi szczególny tytuł ubezpieczeń społecznych. Wynika to z faktu, że w zakresie podlegania ubezpieczeniom społecznym wyłącznie przedsiębiorcy (spośród wszystkich osób prowadzących pozarolniczą działalność) posiadają uprawnienia do okresowego wyłączenia obowiązku ubezpieczeń społecznych oraz zawieszenia wykonywania działalności gospodarczej, nie tylko z powodu sprawowania osobistej opieki nad dzieckiem. Z kolei w sferze opłacania składek na ubezpieczenia społeczne istnieją trzy sposoby ustalania podstawy wymiaru składek z tego tytułu (podstawa zwykła, preferencyjna i uzależniona od dochodu). Ogólnie należy stwierdzić, że prowadzenie poza…

The existence of solutions for the modified (p(x), q(x))-Kirchhoff equation

2022

We consider the Dirichlet problem-Delta(Kp)(p(x))u(x) - Delta(Kq)(q(x))u(x) = f(x, u(x), del u(x)) in Omega, u vertical bar(partial derivative Omega) = 0,driven by the sum of a p(x)-Laplacian operator and of a q(x)-Laplacian operator, both of them weighted by indefinite (sign-changing) Kirchhoff type terms. We establish the existence of weak solution and strong generalized solution, using topological tools (properties of Galerkin basis and of Nemitsky map). In the particular case of a positive Kirchhoff term, we obtain the existence of weak solution (= strong generalized solution), using the properties of pseudomonotone operators.

Correspondence between generalized binomial field states and coherent atomic states

2008

We show that the N-photon generalized binomial states of electromagnetic field may be put in a bijective mapping with the coherent atomic states of N two-level atoms. We exploit this correspondence to simply obtain both known and new properties of the N-photon generalized binomial states. In particular, an over-complete basis of these binomial states and an orthonormal basis are obtained. Finally, the squeezing properties of generalized binomial state are analyzed.

One-loop corrections to light cone wave functions: the dipole picture DIS cross section

2018

We develop methods needed to perform loop calculations in light cone perturbation theory using a helicity basis, refining the method introduced in our earlier work. In particular this includes implementing a consistent way to contract the four-dimensional tensor structures from the helicity vectors with d-dimensional tensors arising from loop integrals, in a way that can be fully automatized. We demonstrate this explicitly by calculating the one-loop correction to the virtual photon to quark-antiquark dipole light cone wave function. This allows us to calculate the deep inelastic scattering cross section in the dipole formalism to next-to-leading order accuracy. Our results, obtained using …

Omosessualità ed esclusione sociale nella donazione di sangue: divieti permanenti e divieti temporanei come fattore di discriminazione

2016

Around the world, as a consequence of the contamination of the blood supply by HIV and Hepatitis C and B in the early 1980s, public and private blood banks have required blood donors to complete a donor health assessment questionnaire to identify various risk factors for sexually transmitted diseases including, for men, the act of having sex with a male partner. In this latter case the policy provides for a permanent or temporary ban on donation. This deferral policy, which aimed to protect recipients of blood and blood products, in recent years has been subject to criticism in so far as this exclusion seems to be an unfair discrimination against gay men on the basis of sexual orientation. …

Evaluating the performance of artificial neural networks for the classification of freshwater benthic macroinvertebrates

2014

Abstract Macroinvertebrates form an important functional component of aquatic ecosystems. Their ability to indicate various types of anthropogenic stressors is widely recognized which has made them an integral component of freshwater biomonitoring. The use of macroinvertebrates in biomonitoring is dependent on manual taxa identification which is currently a time-consuming and cost-intensive process conducted by highly trained taxonomical experts. Automated taxa identification of macroinvertebrates is a relatively recent research development. Previous studies have displayed great potential for solutions to this demanding data mining application. In this research we have a collection of 1350 …