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116 results on '"ROTH CH"'

9. Magnetic properties of Cr overlayers on Fe (invited).

Author

Jungblut, R., Roth, Ch., Hillebrecht, F. U., and Kisker, E.

Subjects
*CHROMIUM, *IRON, *PHOTOEMISSION, *MAGNETS
Abstract

Presents a study which investigated the magnetic properties of chromium overlayers deposited on iron(100) by spin-resolved photoemission. Background on studies on metallic multilayers; Polarization of valence band spectra taken after deposition of chromium; Description of valence band spectra for photon energy; Causes of the reduction of polarization evident in the valence band spectra.

Published
1991
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14. Quantifying sediment sources in lowlying sugarcane land: a sediment budget approach

Author

Dyer, FJ, Thoms, MC, Olley, JM, Visser, F, Roth, CH, Wasson, RJ, Prosser, IR, Dyer, FJ, Thoms, MC, Olley, JM, Visser, F, Roth, CH, Wasson, RJ, and Prosser, IR

Abstract

The flood plain of the Herbert River basin is predominantly used for sugarcane cultivation. Although flood plains are generally considered depositional areas, high sediment concentrations have been observed in the water draining from cane land. Erosion control measures have reduced erosion from cane fields, but other landscape elements (e.g. drains) could still be important sediment sources. For this study the total sediment output from a cane area was gauged and the contribution of a range of landscape elements was quantified with traditional erosion measurement methods. A sediment budget is used to both present and check the measurement results. The study indicates that this tropical flood plain area is a net source of sediment. Sediment loss from the cultivated cane land was 3.9 t ha(-1) between I December 1999 and 31 May 2000.

Published
2002

46. A strain-rate dependent engineering approximation of the temperature rise in plastically-deforming DP steel

Author

Li Xueyang, Roth Christian C., and Mohr Dirk

Subjects
Physics, QC1-999
Abstract

Experiments at ten strain rates ranging from 0.001/s to 4/s are carried out on uniaxial tension specimens extracted from DP800 metal sheets. Digital Image Correlation (DIC) is used to obtain surface strain fields and a high speed infrared (IR) camera is employed to measure the corresponding temperature rise due to plastic dissipation. A temperature rise of 60K is witnessed for the highest loading speed whereas minimal temperature rise (

Published
2021
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47. Plane strain tension fracture at high strain rate

Author

Adlafi Morwan, Galpin Bertrand, Mahéo Laurent, Roth Christian C., Mohr Dirk, and Grolleau Vincent

Subjects
Physics, QC1-999
Abstract

Under plane stress conditions, most micromechanical and phenomenological models predict a minimum in ductility for plane strain tension stress state. Therefore, the stress state of plane strain tension plays a crucial role in many forming and crash applications and the reliable measurement of the strain to fracture for plane strain tension is particularly crucial when calibrating modern fracture initiation models. Recently, a new experimental technique has been proposed for measuring the strain to fracture for sheet metal after proportional loading under plane strain conditions. The basic configuration of the new setup includes a dihedral punch which applies out-of-plane loading onto a Nakazima-type of discshaped specimen with two symmetric holes and an outer diameter of 60 mm. In the present work, the applicability of the test is extended to high strain rates. High strain rates of about 100/s to 200/s are obtained using a drop weight tower device with an original sensor for load measurements. Quasi static tests are also performed for comparison, keeping the same specimen geometry, image recording parameters and set-up. The effective strains at fracture are compared from quasi-static to high strain rate loading for three different materials, i.e one aluminium alloy and two steels.

Published
2021
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48. Plasticity and fracture of aluminium 7075 at high strain rates and elevated temperatures

Author

Li Xueyang, Pandya Kedar, Karathanasopoulos Nikos, Roth Christian C., and Mohr Dirk

Subjects
Physics, QC1-999
Abstract

Slow, intermediate and high strain rate experiments with UT geometries are performed on aluminum AA7075-T6 sheet metal at various temperatures. The comprehensive experimental program characterizes the plasticity response at temperatures ranging from 20°C to 360°C and at strain rates ranging from 0.001/s to 150/s. The elevated temperature - elevated strain rate experiments are performed on a hydraulic tensile testing machine and a Split Hopkinson Pressure Bar system with a Load Inversion Device along with a custom-made induction heating system. A machine learning based modified Johnson-Cook plasticity model is calibrated to capture the complex strain rate and temperature effect of the observed hardening response.

Published
2021
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49. DIFFRACTION OF SPIN-POLARIZED 3PHOTOELECTRONS.

Author

ROTH, CH., KINOSHITA, T., ROSE, H. B., HILLEBRECHT, F. U., and KISKER, E.

Abstract

We measured the spin-orbit-induced spin polarization in Cu 3p photoemission for fixed angle between light incidence and electron collection, while varying the emission angle relative to the crystal lattice. The polarization is found to vary strongly with emission direction in both sublevels. However, the ratio between the polarizations of the j=3/2 and j=1/2 sublevels is close to -1/2 for all emission directions. The spin polarization and its dependence on emission direction can both be viewed as arising from the angular momentum character of the final state wave which is imposed by the excitation conditions. [ABSTRACT FROM AUTHOR]

Published
1997
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