Search results for "ESA"

Design and Implementation of a Tool for Analysing Student Products When They Solve Fermi Problems

2017

In this chapter, we present a tool for analysing the work of secondary-level students from two different schools when they solve a type of Fermi problem. The tool is based on the characterisation of the concepts, procedures and language used to construct the models. Our results show that the proposed tool is useful to describe the models and to distinguish different aspects between the models produced by students without any previous modelling experience and those obtained by students who were already acquainted with working on modelling activities.

Optimal control of the Schrödinger equation with two or three levels

2007

In this paper, we present how techniques of “control theory”, “sub-Riemannian geometry” and “singular Riemannian geometry” can be applied to some classical problems of quantum mechanics and yield improvements to some previous results.

Paschen β line shape studies in low-temperature plasmas

2003

Line shape calculations and measurements of the Paschen β line of hydrogen (λ=12818 Å) are reported. Measurements were performed at electron densities of the plasma between 1015 cm-3 and 1016 cm-3. A wall-stabilized arc operated at atmospheric pressure in a helium-hydrogen gas mixture was applied as the excitation source. The radiation of the plasma, originating from nearly homogeneous plasma layers, in the end-on direction, was analyzed. A grating spectrometer equipped with a CCD detector was used for the radiation detection. The measured line profiles are compared with results of available experimental and theoretical Stark broadening data e.g. based on simulation techniques, applied also…

Optical study of gallium and nitrogen polarity layers of GaN grown on sapphire

2003

A confocal Raman spectroscopic study was carried out on either side of an intentionally grown GaN inversion domain boundary between a pair of strips with opposite (Ga- or N-) polarity. It is shown that the Raman spectra on the N-polarity side displays an A1(TO) mode, prohibited by symmetry considerations, meanwhile on Ga-polarity material this peak is absent, indicating a lower density of defects present in this region. The Raman spectra reveal that in the lateral direction, the change in structural quality accross the inversion domain boundary is rather continuous and extends along 4 ± 1 μm. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Emmy Noether’s Triumphal Years

2020

When Emmy Noether returned from the September 1929 conference in Prague – where she and Hasse surely spoke about their mutual mathematical interests – she belatedly answered a postcard he had sent here.

Appendix: Feynman rules

2010

Multiparametric Rational Solutions of Order N to the KPI Equation and the Explicit Case of Order 3

2021

We present multiparametric rational solutions to the Kadomtsev-Petviashvili equation (KPI). These solutions of order N depend on 2N − 2 real parameters. Explicit expressions of the solutions at order 3 are given. They can be expressed as a quotient of a polynomial of degree 2N(N +1)−2 in x, y and t by a polynomial of degree 2N(N +1) in x, y and t, depending on 2N − 2 real parameters. We study the patterns of their modulus in the (x,y) plane for different values of time t and parameters.

Hadronic light-by-light contribution to $(g-2)_\mu$ from lattice QCD with SU(3) flavor symmetry

2020

We perform a lattice QCD calculation of the hadronic light-by-light contribution to $(g-2)_\mu$ at the SU(3) flavor-symmetric point $m_\pi=m_K\simeq 420\,$MeV. The representation used is based on coordinate-space perturbation theory, with all QED elements of the relevant Feynman diagrams implemented in continuum, infinite Euclidean space. As a consequence, the effect of using finite lattices to evaluate the QCD four-point function of the electromagnetic current is exponentially suppressed. Thanks to the SU(3)-flavor symmetry, only two topologies of diagrams contribute, the fully connected and the leading disconnected. We show the equivalence in the continuum limit of two methods of computin…

Efficacy of the cloud computing technology in the management of communications and business processes of the companies

2016

W artykule zbadano tendencje rozwoju i stosowania różnych klas systemów informatycznych w zarządzaniu w relacji do rodzajów procesów biznesowych. Zaprezentowano krótki przegląd aktualnego stanu wykorzystania technologii chmury obliczeniowej na świecie i na Ukrainie. Korzyści wynikające z zastosowania modelu "SaaS - Software as a Service" zostały wyjaśnione na przykładzie innowacji międzynarodowego projektu "Bitrix 24", w którym zrealizowane zostały główne cele systemów CRM w połączeniu z szerokimi możliwościami koordynacji procesów komunikacyjnych i biznesowych nowoczesnych firm. Projekt ten został przetłumaczony na większość języków europejskich i wykorzystuje narzędzia społecznego środowi…

Vecāku zaudējušu pusaudžu sēru komunikācija ar galveno aprūpētāju saistībā ar piesaisti un sēru reakcijām

2020

Pētījuma mērķis ir noskaidrot, kā pusaudža un galvenā aprūpētāja sērošanas komunikācijas atvērtība saistīta ar pusaudža sērošanas intensitāti, kā arī pārbaudīt vai droša piesaiste mediē attiecības starp komunikāciju un sērošanu. Pētījumā piedalījās 51 pusaudzis, kurš zaudējis vienu vai abus vecākus pēdējo sešu gadu laikā. Izmantojot šķērsgriezuma pētījuma dizainu, pusaudži aizpildīja pašnovērtējuma aptaujas: pētījuma ietvaros latviski adaptētu kompleksās sērošanas traucējumu aptauju jauniešiem, vecāku un vienaudžu piesaistes aptauju bērniem, kā arī pētījumam izveidotu pusaudža – aprūpētāja sērošanas komunikācijas izvērtējuma aptauju. Korelācijas analīze starp mainīgajiem atklāja, ka augstāk…