Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "Voigt, J." wg kryterium: Autor


Wyświetlanie 1-5 z 5
Tytuł:
Measures to reduce the residual field and field gradient inside a magnetically shielded room by a factor of more than 10
Autorzy:
Voigt, J.
Knappe-Grüneberg, S.
Schnabel, A.
Körber, R.
Burghoff, M.
Powiązania:
https://bibliotekanauki.pl/articles/220358.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
magnetic shielding
magnetic shielded room
msr
residual field
residual field gradient
degaussing
demagnetization
Opis:
Very low residual magnetic field and field gradients are essential for a number of high resolution fundamental physical experiments and for further improvement of very sensitive magnetic measurement devices. The scope ranges from spin precession experiments, e.g. with 3He or neutrons, to biomagnetic measurements, like magnetoencephalograms, and to low field MR spectroscopy. One method of reducing environmental magnetic noise is to use a magnetically shielded room (MSR). Here, measures are demonstrated to improve residual field and field gradient inside a common MSR by a factor of more than 10 by a specific degaussing procedure, material selection of prefabricated parts and active shielding. The process is independent of the shielding factor and works also properly for heavily shielded rooms.
Źródło:
Metrology and Measurement Systems; 2013, 20, 2; 237-248
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improved contrast in ultra-low-field mri with time-dependent bipolar prepolarizing fields: theory and nmr demonstrations
Autorzy:
Nieminen, J. O.
Voigt, J.
Hartwig, S.
Scheer, H. J.
Burghoff, M.
Trahms, L.
Ilmoniemi, R. J.
Powiązania:
https://bibliotekanauki.pl/articles/220699.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
T1 dispersion
prepolarization
polarizing field
ultra-low-field MRI
Opis:
The spin-lattice (T1) relaxation rates of materials depend on the strength of the external magnetic field in which the relaxation occurs. This T1) dispersion has been suggested to offer a means to discriminate between healthy and cancerous tissue by performing magnetic resonance imaging (MRI) at low magnetic fields. In prepolarized ultra-low-field (ULF) MRI, spin precession is detected in fields of the order of 10-100 μT. To increase the signal strength, the sample is first magnetized with a relatively strong polarizing field. Typically, the polarizing field is kept constant during the polarization period. However, in ULF MRI, the polarizing-field strength can be easily varied to produce a desired time course. This paper describes how a novel variation of the polarizing-field strength and duration can optimize the contrast between two types of tissue having different T1) relaxation dispersions. In addition, NMR experiments showing that the principle works in practice are presented. The described procedure may become a key component for a promising new approach of MRI at ultra-low fields.
Źródło:
Metrology and Measurement Systems; 2013, 20, 3; 327-336
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Marshall-Peierls Sign Rule in Frustrated Heisenberg Chains
Autorzy:
Voigt, A.
Richter, J.
Powiązania:
https://bibliotekanauki.pl/articles/2013996.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Jm
75.40.Mg
75.50.Ee
Opis:
We consider the frustrated antiferromagnetic s=1 Heisenberg quantum spin chain with regard to the Marshall-Peierls sign rule. Using exact diagonalization data we investigate the breakdown of the Marshall- Peierls sign rule in dependence on frustration and compare our findings with data for s=1/2. We calculate a critical value of frustration J$\text{}_{2}^{crit}$, where the Marshall-Peierls sign rule is violated. The extrapolation of this value to the infinite chain limit holds J$\text{}_{2}^{crit}$ ≈ 0.016, lower than in the case of s=1/2 (J$\text{}_{2}^{crit}$ ≈ 0.027). T his points to a stronger influence of frustration in the case of s=1. Nevertheless, the calculation of the weight of the Ising-states violating the Marshall- Peierls sign rule shows that the latter holds approximately even for a quite large frustration and may be used for numerical techniques.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 979-982
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Study of Weak Ferromagnetism in 2D J$\text{}_{1}$-J$\text{}_{2}$ Heisenberg Model with Dzyaloshinskii-Moriya Interaction
Autorzy:
Voigt, A.
Richter, J.
Powiązania:
https://bibliotekanauki.pl/articles/1955526.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
05.50.+q
75.10.Jm
Opis:
By means of exact diagonalization we consider the groundstate of the J$\text{}_{1}$-J$\text{}_{2}$ spin 1/2 Heisenberg model with an anisotropic interaction term of Dzyaloshinskii-Moriya type. We find that a Dzyaloshinskii-Moriya interaction may create a weak ferromagnetic moment. The interplay between the quantum nature of the groundstate of the pure J$\text{}_{1}$-J$\text{}_{2}$ model and the anisotropic Dzyaloshinskii-Moriya interaction favour energetically a well-defined direction of spin alignment creating anisotropic correlations.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 371-375
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zig-zag facial total-coloring of plane graphs
Autorzy:
Czap, J.
Jendrol, S.
Voigt, M.
Powiązania:
https://bibliotekanauki.pl/articles/255827.pdf
Data publikacji:
2018
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
plane graph
facial coloring total-coloring zig-zag coloring
Opis:
In this paper we introduce the concept of zig-zag facial total-coloring of plane graphs. We obtain lower and upper bounds for the minimum number of colors which is necessary for such a coloring. Moreover, we give several sharpness examples and formulate some open problems.
Źródło:
Opuscula Mathematica; 2018, 38, 6; 819-827
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

    Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies