756 research outputs found
Kondo Behavior of U in CaB
Replacing U for Ca in semiconducting CaB at the few at.% level induces
metallic behaviour and Kondo-type phenomena at low temperatures, a rather
unusual feature for U impurities in metallic hosts. For
CaUB, the resistance minimum occurs at = 17 K. The
subsequent characteristic logarithmic increase of the resistivity with
decreasing temperature merges into the expected dependence below 0.8 K.
Data of the low-temperature specific heat and the magnetization are analyzed by
employing a simple resonance-level model. Analogous measurements on LaB
with a small amount of U revealed no traces of Kondo behavior, above 0.4 K.Comment: 4 pages, 4 figures, submitted for publication to Europhysics Letter
Sedimenttransport en sedimentatieprocessen ter hoogte van de polders van Kruibeke, Bazel en Rupelmonde
How present am I: three virtual reality facilities testing the fear of falling
Virtual reality environments have long been used in studies related to architecture simulation. The main objective of this paper is to measure the sense of presence that different virtual reality devices provide to users so as to evaluate their effectiveness when used to simulate real environments and draw conclusions of people’s behaviours when using them. The study also aims at investigating, in a quantitative way, the influence of architectural elements on the comfort of use of a built environment, namely considering the fear of falling reported by adults while using these architectural elements. Using a between-subjects design randomly distributed between two experimental conditions (safe and unsafe), a set of three studies were conducted in three different virtual reality environments using a 5-sided-CAVE, a Powerwall or a Head Mounted Display. The study shows that immersive virtual reality devices give users a higher sense of presence than semi-immersive ones. One of the conclusions of the study is that a higher sense of presence helps to enhance the building spaces perceived impacts on users (in this case the fear of falling).info:eu-repo/semantics/publishedVersio
Fluctuation-induced phase in CsCuCl3 in transverse magnetic field: Theory
CsCuCl3 is a quantum triangular antiferromagnet, ferromagnetically stacked,
with an incommensurate (IC) structure due to a Dzyaloshinskii-Moriya
interaction. Because of the classical degeneracy caused by the frustration,
fluctuations in CsCuCl3 have extraordinarily large effects, such as the phase
transition in longitudinal magnetic field (normal to the planes, parallel to
the IC wavenumber q) and the plateau in q in transverse field (perpendicular to
q). We argue that fluctuations are responsible also for the new IC phase
discovered in transverse field near the Neel temperature T_N, by T. Werner et
al. [Solid State Commun. 102, p.609 (1997)]. We develop and analyse the
corresponding minimal Landau theory; the effects of fluctuations on the
frustration are included phenomenologically, by means of a biquadratic term.
The Landau theory gives two IC phases, one familiar from previous studies;
properties of the new IC phase, which occupies a pocket of the
temperature-field phase diagram near T_N, agree qualitatively with those of the
new phase found experimentally.Comment: 12 pages, revtex, 4 postscript figures, submitted to J. Phys:
Condens. Matte
Flow equation analysis of the anisotropic Kondo model
We use the new method of infinitesimal unitary transformations to calculate
zero temperature correlation functions in the strong-coupling phase of the
anisotropic Kondo model. We find the dynamics on all energy scales including
the crossover behaviour from weak to strong coupling. The integrable structure
of the Hamiltonian is not used in our approach. Our method should also be
useful in other strong-coupling models since few other analytical methods allow
the evaluation of their correlation functions on all energy scales.Comment: 4 pages RevTeX, 2 eps figures include
Oblique triangular antiferromagnetic phase in CsCuCoCl
The spin-1/2 stacked triangular antiferromagnet CsCuCoCl with
undergoes two phase transitions at zero field. The
low-temperature phase is produced by the small amount of Co doping. In
order to investigate the magnetic structures of the two ordered phases, the
neutron elastic scattering experiments have been carried out for the sample
with . It is found that the intermediate phase is identical to
the ordered phase of CsCuCl, and that the low-temperature phase is an
oblique triangular antiferromagnetic phase in which the spins form a triangular
structure in a plane tilted from the basal plane. The tilting angle which is
42 at K decreases with increasing temperature, and becomes
zero at K. An off-diagonal exchange term is proposed as the
origin of the oblique phase.Comment: 6 pages, 7 figure
Comparison of Different Combined Multiple Tunnel Complexes in Soft Soil under Seismic Vibrations
The resilience of underground tunnels has gained paramount importance recently, driven by the need to ensure the safety and functionality of critical transportation and infrastructure systems during seismic events. Underground tunnels are prone to severe damage when the soil condition is poor and located in a high seismic zone. While the behavior of individual tunnels has been extensively studied, the concept of multiple tunnels combined into a large tunnel complex is relatively new, with limited available research focusing on rectangular-shaped tunnel complexes and requiring a more detailed examination. This study parametrically analyzes two novel and unconventional structures in soft soil, i.e., twin and triple tunnel complexes resulting from the combination of closely spaced circular twin and triple individual tunnels. Seismic records from Coyote (US, 1979), Kobe (Japan, 1995), and Kocaeli (Turkey, 1999) have been used to determine the produced surface displacements, tunnel distortions, lateral stresses on the tunnel structures, and the induced seismic forces, including thrusts, shear forces, and bending moments. The results are then compared with the conventional rectangular-shaped tunnel complex, which is also analyzed under the same conditions. The comparison shows that the twin and triple tunnel complexes are comparatively better seismic performers than the conventional rectangular tunnel complex, with reduced ground displacements produced, lesser incurred structural distortions, experienced lateral stresses, and induced seismic forces. Doi: 10.28991/CEJ-2023-09-12-01 Full Text: PD
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