Wyniki wyszukiwania - BazTech

1

Variableloading conditions and consequences for wave phenomena

Bogacz B., Frischmuth K., Konowrocki R.

TTS Technika Transportu Szynowego

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2015

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R. 22, nr 12

168--171, CD

EN

In land transport, we observe an increase of loads as well as of speeds of travel, which leads to considerable stresses and strains in constructions like tracks, bridges and tunnels. The wave propagation caused by constant and harmonic loads moving at constant speed along straight lines has been well covered in the recent literature. Problems including other types of variable loading conditions are much less understood. In the article, some problems of this type are posed and discussed together with applications in vehicle mechanics. In particular, motion of out-of-the-round wheels on rails and some problems of brake disk dynamics are presented.

PL

W transporcie lądowym, zwłaszcza szynowym, obserwuje się tendencję do coraz wyższych prędkości i większych obciążeń, skąd wynikają między innymi znaczne naprężenia wtakich konstrukcjach jak szyny, mosty i tunele.Efekty falowe z tym związane dobrze są zbadane w przypadku stałych prędkości ruchu prostolinijnego i harmonicznych obciążeń. Zagadnienia uwzględniające innego typu zmienności sił czy warun-ków brzegowych dotąd nie znalazły odpowiednio dużo uwagi w literaturze. W obecnej pracy kilka zadań tej klasy zostało postawionych i przedyskutowanych, między innymi problem związany z kołami skorugowanymi i problem dynamiki dysku hamulcowego jako przykłady z zakresu mechaniki pojazdów szynowych.

2

Spin reorientation phenomena in Er2-xRxFe14B (R = Gd, Th) – Mössbauer and calorimetric study

Wojciechowska A., Pędziwiatr A., Bogacz B., Wróbel S.

Nukleonika

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2007

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Vol. 52, supl. 1

77-79

EN

The Er2 xGdxFe14B (x = 0.5, 1.0, 1.5) and Er2 xThxFe14B (x = 0.0, 0.5, 1.0, 1.5, 2.0) polycrystalline compounds have been investigated with 57Fe Mössbauer spectroscopy and differential scanning calorimetry (DSC). A comparison of results related to spin reorientation phenomena obtained for Gd- and Th-substituted compounds is presented in this paper. Spin reorientation phenomena (changes from planar to axial spin arrangements) have been studied extensively by a narrow step temperature scanning in the neighbourhood of the spin reorientation temperature, TSR. From the analysis of Mössbauer spectra, it was deduced that in the region of transition each subspectrum was split into two Zeeman sextets, which were characterised by different hyperfine magnetic fields and quadrupole splittings. A consistent way of fitting the spectra in the wide range of temperatures was proposed. The composition and temperature dependencies of hyperfine interaction parameters and subspectra contributions were derived from fits and the transition temperatures were determined for all the compounds studied. DSC studies proved that the spin reorientations were accompanied by thermal effects for all compositions of the Gd- and for x = 0.5 of the Th-series. Transformation enthalpy and TSR were determined from these studies and the two-stage character of transition was confirmed. Magnetic spin arrangement diagrams for R = Th and Gd series were constructed and compared using combined data obtained with both methods.

3

Mössbauer studies of spin reorientations in Er2-xGdxFe14B

Wojciechowska A., Bogacz B., Pędziwiatr A.

Nukleonika

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2004

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Vol. 49,suppl.3

71-73

EN

The Er2 xGdxFe14B (x = 0.5, 1.0, 1.5) polycrystalline compounds have been investigated with 57Fe Mössbauer spectroscopy in the 80 330 K temperature range. The spin reorientation phenomena (changes from planar to axial spin arrangements) have been studied extensively by a narrow step temperature scanning in the neighbourhood of the spin reorientation temperature. From the analysis of the spectra it was deduced that in the region of transition each subspectrum was split into two Zeeman sextets, which were characterized by different hyperfine magnetic fields and quadrupole splittings. A consistent way of describing the Mössbauer spectra in the wide range of temperatures was proposed. The composition and temperature dependencies of hyperfine interaction parameters and subspectra contributions were derived from experimental spectra. The transition temperatures were determined for all the compounds studied.

4

Spin arrangement diagrams for Er2-xRxFe14B (R = Y, Ce) obtained with Mössbauer spectroscopy and phenomenological model

Pędziwiatr A., Bogacz B., Gargula R.

Nukleonika

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2003

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Vol. 48,suppl.1

59-63

EN

Two isostructural series of polycrystalline compounds: Er2-xYxFe14B and Er2-xCexFe14B have been studied by 57Fe Mössbauer spectroscopy in the temperature range 80-370 K. The spin reorientation phenomenon (a transition from basal plane to axial easy magnetisation direction) has been studied extensively by a narrow step temperature scanning in the vicinity of the transition. Using the procedure of subtracting the Mössbauer spectra taken for the same compound at different temperatures, it was possible to follow the influence of transition on the shape of spectra. From this procedure it was concluded that in the region of transition each subspectrum splits into two Zeeman sextets, which are characterised by different hyperfine magnetic fields and quadrupole splittings. The consistent way of describing the Mössbauer spectra was proposed. The spin reorientation temperatures have been established for all compositions and compared with the values obtained from theoretical calculations of spin orientation angle based on phenomenological model. The spin arrangement diagrams have been constructed.