5,588 research outputs found
Viscoelastic evaluation of biological soft tissue in crush process at subsonic level for anti-bird strike technology of airplane
Miniaturization and lightening of airplane are advanced to improve its economic efficiency, and the safety technology of airplane design becomes difficult while the accident of bird-strike is increasing year by year. Then a system of shock impact test by using airsoft rifle is developed to evaluate the design technology of anti-bird strike structure of airplane. The viscoelastic characteristics of specimen is evaluated by analyzing stress response using the modified Hertz contact theory and the wave equation at the moment when simple ball bullet is shot to specimen by the airsoft rifle. In the results of experiment, the obvious relationship is observed subjectively between quasi-static and impact responses of specimen. The evaluated viscoelastic relationship is applied to simulate the impact test by using LSDYNA with fundamental viscoelastic constitutive equation and the material parameters derived from the impact test, and the well similar behavior has been simulated by the constitutive equation. By using the developed technology here, the phantom imitating real bird will be developed as standard specimen for an anti-bird strike test in future
Thermal Instability of Advection-Dominated Disks against Local Perturbations
Thermal instability is examined for advection-dominated one-temperature
accretion disks. We consider axisymmetric perturbations with short wavelength
in the radial direction. The viscosity is assumed to be sufficiently small for
the vertical hydrostatic balance to hold in perturbed states. The type of
viscosity is given either by the -viscosity or by a diffusion-type
stress tensor. Optically thick disks are found to be in general more unstable
than optically thin ones. When the thermal diffusion is present, the optically
thin disks become stable, but the optically thick disks are still unstable. The
instability of the advection-dominated disks is different from that of the
geometrically thin disks without advection. In the case of no advection, the
thermal mode behaves under no appreciable surface density change. In the case
of advection-dominated disks, however, the thermal mode occurs with no
appreciable pressure change (compared with the density change), when local
perturbations are considered. The variations of angular momentum and of surface
density associated with the perturbations lead to a thermal instability. The
astrophysical implications of this instability are briefly discussed.Comment: PASJ, in press 1996, Feb; uuencoded, compressed, PS file; also
available on WWW at http://fy.chalmers.se/~chen
Microscopic Description of Nuclear Wobbling Motion -- Rotation of traxially deformed nuclei --
The nuclear wobbling motion in the Lu region is studied by the microscopic
cranked mean-field plus RPA method. The Woods-Saxon potential is used as a
mean-field with a new parameterization which gives reliable description of
rapidly rotating nuclei. The prescription of symmetry-preserving residual
interaction makes the calculation of the RPA step parameter-free, and we find
the wobbling-like RPA solution if the triaxial deformation of the mean-field is
suitably chosen. It is shown that the calculated out-of-band of the
wobbling-like solution depends on the triaxial deformation in the same way as
in the macroscopic rotor model, and can be used to probe the triaxiality of the
nuclear mean-field.Comment: 10 pages, 8 figures, talk at International Conference on Nuclear
Structure Physics, Shanghai, June 200
Self-learning Multiscale Simulation for Achieving High Accuracy and High Efficiency Simultaneously
We propose a new multi-scale molecular dynamics simulation method which can
achieve high accuracy and high sampling efficiency simultaneously without
aforehand knowledge of the coarse grained (CG) potential and test it for a
biomolecular system. Based on the resolution exchange simulations between
atomistic and CG replicas, a self-learning strategy is introduced to
progressively improve the CG potential by an iterative way. Two tests show
that, the new method can rapidly improve the CG potential and achieve efficient
sampling even starting from an unrealistic CG potential. The resulting free
energy agreed well with exact result and the convergence by the method was much
faster than that by the replica exchange method. The method is generic and can
be applied to many biological as well as non-biological problems.Comment: 14 pages, 6 figure
Self-written waveguides in photopolymerizable resins
We study the optically-induced growth and interaction of self-written
waveguides in a photopolymerizable resin. We investigate experimentally how the
interaction depends on the mutual coherence and relative power of the input
beams, and suggest an improved analytical model that describes the growth of
single self-written waveguides and the main features of their interaction in
photosensitive materials.Comment: 3 pages, 3 figure
Matrix product states approach to the Heisenberg ferrimagnetic spin chains
We propose a new version of the matrix product (MP) states approach to the
description of quantum spin chains, which allows one to construct MP states
with certain total spin and its z-projection. We show that previously known MP
wavefunctions for integer-spin antiferromagnetic chains and ladders correspond
to some particular cases of our general ansatz. Our method allows to describe
systems with spontaneously broken rotational symmetry, like quantum
ferrimagnetic chains whose ground state has nonzero total spin. We apply this
approach to describe the ground state properties of the isotropic ferrimagnetic
Heisenberg chain with alternating spins 1 and 1/2 and compare our variational
results with the high-precision numerical data obtained by means of the quantum
Monte Carlo (QMC) method. For both the ground state energy and the correlation
functions we obtain very good agreement between the variational results and the
QMC data.Comment: 4 pages, RevTeX, uses psfig.sty, submitted to Phys. Rev.
Cryobanking potentials of marine shrimp gametes
For developing marine shrimp industry through aquaculture technology, one of the major
constraints is non-availability of sufficient seed and spawners to produce seed at the desired
time. Cryopreservation of gametes of aquatic animals in contrast to the situation in other
vertebrates particularly mammals has met with a very limited success. Very few attempts have been made on cryopreservation of sperms in decapod crustaceans in general and marine shrimps in particular. Efforts are now being made continuously on cryopreservation and cryobanking of penaeid gametes. The viable spermatozoa of P. indicus and P. monodon havebeen successfully preserved in CMFRI
Construction of Video On Demand (VOD) Systems for Real Time Monitoring of a Local Island Divertor (LID) Head
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