Search results

1

On the SU(2)×SU(2) symmetry in the Hubbard model

100%

Jakubczyk D., Jakubczyk P.

Open Physics

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2012

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vol. 10

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issue 4

906-912

EN

We discuss the one-dimensional Hubbard model, on finite sites spin chain, in context of the action of the direct product of two unitary groups SU(2)×SU(2). The symmetry revealed by this group is applicable in the procedure of exact diagonalization of the Hubbard Hamiltonian. This result combined with the translational symmetry, given as the basis of wavelets of the appropriate Fourier transforms, provides, besides the energy, additional conserved quantities, which are presented in the case of a half-filled, four sites spin chain. Since we are dealing with four elementary excitations, two quasiparticles called “spinons”, which carry spin, and two other called “holon” and “antyholon”, which carry charge, the usual spin-SU(2) algebra for spinons and the so called pseudospin-SU(2) algebra for holons and antiholons, provide four additional quantum numbers.

2

Investigating Advantages and Disadvantages of the Analysis of a Geometrical Surface Structure with the Use of Fourier and Wavelet Transform

100%

Stępień K., Makieła W., Adamczak S.

Metrology and Measurement Systems

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2010

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issue 2

3

The vertebrate skeletal muscle thick filaments are not three-stranded. Reinterpretation of some experimental data*

88%

Skubiszak L., Kowalczyk L.

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vol. 49

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issue 4

841-853

EN

Computer simulation of mass distribution within the model and Fourier transforms of images depicting mass distribution are explored for verification of two alternative modes of the myosin molecule arrangement within the vertebrate skeletal muscle thick filaments. The model well depicting the complete bipolar structure of the thick filament and revealing a true threefold-rotational symmetry is a tube covered by two helices with a pitch of 2 × 43 nm due to arrangement of the myosin tails along a helical path and grouping of all myosin heads in the crowns rotated by 240° and each containing three cross-bridges separated by 0°, 120°, and 180°. The cross-bridge crown parameters are verified by EM images as well as by optical and low-angle X-ray diffraction patterns found in the literature. The myosin tail arrangement, at which the C-terminus of about 43-nm length is near-parallel to the filament axis and the rest of the tail is quite strongly twisted around, is verified by the high-angle X-ray diffraction patterns. A consequence of the new packing is a new way of movement of the myosin cross-bridges, namely, not by bending in the hinge domains, but by unwrapping from the thick filament surface towards the thin filaments along a helical path.

4

Stability characteristic of hypersonic flow over a blunt wedge under freestream pulse wave

88%

Tang X., Lv H., Meng X., Wang Z., Lv Q.

Open Physics

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2014

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vol. 12

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issue 1

17-31

EN

To investigate the stability characteristic of hypersonic flow under the action of a freestream pulse wave, a high-order finite difference method was employed to do direction numerical simulation (DNS) of hypersonic unsteady flow over an 8° half-wedge-angle blunt wedge with freestream slow acoustic wave. The evolution of disturbance wave modes in the boundary layer under a pulse wave and a continuous wave are compared, and the wall temperature effect on the hypersonic boundary layer stability for a pulse wave disturbance is discussed. Results show that, both for a pulse wave and a continuous wave in freestream, the disturbance waves inside the nose boundary layer are mainly a fundamental mode; the Fourier amplitude of pressure disturbance mode in the boundary layer for a pulse wave is far less than that for a continuous wave, and the band frequency of the former is wider than that of the latter. All disturbance modes decay rapidly along the streamwise in the nose boundary layer. In the non-nose boundary layer, the dominant mode is transferred from fundamental mode into second harmonic. The transformation of dominant mode for a pulse wave appears much earlier than that for a continuous wave. Different frequency disturbance modes present different changes along streamline in the boundary layer, and the frequency band narrows around the second harmonic mode along the streamwise. Keen competition and the transformation of energy exist among different modes in the boundary layer. Wall temperature modifies the stability characteristic of the hypersonic boundary layer, which presents little effect on the development of fundamental modes and cooling wall could accelerates the growth of the high frequency mode as well as the dominant mode transformation.

5

Sound Wave Radiation from Partially Lined Duct

88%

Tiryakioglu B., Demir A., Tiryakioglu B., Demir A.

Archives of Acoustics

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2019

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vol. 44

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issue 2

6

Fast High-Impedance Spectroscopy Method Using Sinc Signal Excitation

88%

Kowalewski M., Lentka G.

Metrology and Measurement Systems

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2013

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issue 4

7

Analyzing Variations in Roundness Profile Parameters During the Wavelet Decomposition Process Using the Matlab Environment

75%

Makieła W., Adamczak S.

Metrology and Measurement Systems

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2011

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issue 1

8

Anatomical and functional assessment of patency of the upper respiratory tract in selected respiratory disorders – Part 1

63%

Kukwa A., Zając A., Barański R., Nitkiewicz S., Kukwa W., Zomkowska E., Rybak A., Kukwa A., Zając A., Barański R., Nitkiewicz S., Kukwa W., Zomkowska E., Rybak A.

Metrology and Measurement Systems

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2021

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vol. 28

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issue 4

Refine search results

On the SU(2)×SU(2) symmetry in the Hubbard model

Investigating Advantages and Disadvantages of the Analysis of a Geometrical Surface Structure with the Use of Fourier and Wavelet Transform

The vertebrate skeletal muscle thick filaments are not three-stranded. Reinterpretation of some experimental data*

Stability characteristic of hypersonic flow over a blunt wedge under freestream pulse wave

Sound Wave Radiation from Partially Lined Duct

Fast High-Impedance Spectroscopy Method Using Sinc Signal Excitation

Analyzing Variations in Roundness Profile Parameters During the Wavelet Decomposition Process Using the Matlab Environment

Anatomical and functional assessment of patency of the upper respiratory tract in selected respiratory disorders – Part 1