34,272 research outputs found
BIM-based safety design for emergency evacuation of metro stations
Metro stations are the hubs of urban rail transit, and large numbers of people usually gather inside them. Various types of emergency can lead to a need for evacuation. However, there are few studies on proactively reducing emergency evacuation risks through the design for safety (DFS) concept, and these risks pose serious threats to the operational safety of metro stations. Therefore, in this research, fragmented DFS pre-control measures for mitigating emergency evacuation risks were comprehensively identified and classified, and indicators for evaluating the evacuation design effect on reducing emergency evacuation risks in the operation phase were improved. Moreover, through the combination of the DFS application method and BIM platform, intelligent safety design tools were provided for metro station designers so that they may apply the DFS concept to emergency evacuation risk mitigation in real cases
Optical study of MgTiO: Evidence for an orbital-Peierls state
Dimension reduction due to the orbital ordering has recently been proposed to
explain the exotic charge, magnetic and structural transitions in some
three-dimensional (3D) transitional metal oxides. We present optical
measurement on a spinel compound MgTiO which undergoes a sharp
metal-insulator transition at 240 K, and show that the spectral change across
the transition can be well understood from the proposed picture of 1D Peierls
transition driven by the ordering of and orbitals. We further
elaborate that the orbital-driven instability picture applies also very well to
the optical data of another spinel CuIrS reported earlier.Comment: 5 pages, 6 figures, to be published in Phys. Rev.
Thermo-mechanical behaviour of a compacted swelling clay
Compacted unsaturated swelling clay is often considered as a possible buffer
material for deep nuclear waste disposal. An isotropic cell permitting
simultaneous control of suction, temperature and pressure was used to study the
thermo-mechanical behaviour of this clay. Tests were performed at total
suctions ranging from 9 to 110 MPa, temperature from 25 to 80 degrees C,
isotropic pressure from 0.1 to 60 MPa. It was observed that heating at constant
suction and pressure induces either swelling or contraction. The results from
compression tests at constant suction and temperature evidenced that at lower
suction, the yield pressure was lower, the elastic compressibility parameter
and the plastic compressibility parameter were higher. On the other hand, at a
similar suction, the yield pressure was slightly influenced by the temperature;
and the compressibility parameters were insensitive to temperature changes. The
thermal hardening phenomenon was equally evidenced by following a
thermo-mechanical path of loading-heating-cooling-reloading
(4S)-Benzyl 4-isopropyl-5-oxo-1,3-oxazolidine-3-carboxylate
In the crystal structure of the title compound, C14H17NO4, obtained by the reaction of N-benzoxycarbonyl-l-valine, paraformaldehyde and 4-methylbenzenesulfonic acid, molecules are linked by C—H⋯O hydrogen bonds, generating linear chains parallel to the a axis. C—H⋯π interactions of stacked benzene rings also provide stability for the crystal structure
Collapse of Stiff Polyelectrolytes due to Counterion Fluctuations
The effective elasticity of highly charged stiff polyelectrolytes is studied
in the presence of counterions, with and without added salt. The rigid polymer
conformations may become unstable due to an effective attraction induced by
counterion density fluctuations. Instabilities at the longest, or intermediate
length scales may signal collapse to globule, or necklace states, respectively.
In the presence of added-salt, a generalized electrostatic persistence length
is obtained, which has a nontrivial dependence on the Debye screening length.Comment: 4 pages RevTex, 3 ps figures included using epsf, final version as
appeared in PR
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