23,720 research outputs found
A Platform Independent Architecture for Virtual Characters and Avatars
We have developed a Platform Independent Architecture for Virtual Characters and Avatars (PIAVCA), a character animation system that aims to be independent of any underlying graphics framework and so be easily portable. PIAVCA supports body animation based on a skeletal representation and facial animation based on morph targets
An analysis of aircraft accidents involving fires
All U. S. Air Carrier accidents between 1963 and 1974 were studied to assess the extent of total personnel and aircraft damage which occurred in accidents and in accidents involving fire. Published accident reports and NTSB investigators' factual backup files were the primary sources of data. Although it was frequently not possible to assess the relative extent of fire-caused damage versus impact damage using the available data, the study established upper and lower bounds for deaths and damage due specifically to fire. In 12 years there were 122 accidents which involved airframe fires. Eighty-seven percent of the fires occurred after impact, and fuel leakage from ruptured tanks or severed lines was the most frequently cited cause. A cost analysis was performed for 300 serious accidents, including 92 serious accidents which involved fire. Personal injury costs were outside the scope of the cost analysis, but data on personnel injury judgements as well as settlements received from the CAB are included for reference
Cylindrical, periodic surface lattice â theory, dispersion analysis, and experiment
A two-dimensional surface lattice of cylindrical topology obtained via perturbing the inner surface of a cylinder is considered. Periodic perturbations of the surface lead to observation of high-impedance, dielectric-like media and resonant coupling of surface and non-propagating volume fields. This allows synthesis of tailored-for-purpose "coating" material with dispersion suitable, for instance, to mediate a Cherenkov type interaction. An analytical model of the lattice is discussed and coupled-wave equations are derived. Variations of the lattice dispersive properties with variation of parameters are shown, illustrating the tailoring of the structure's electromagnetic properties. Experimental results are presented showing agreement with the theoretical model
Older and wiser? Menâs and womenâs accounts of drinking in early mid-life
Most qualitative research on alcohol focuses on younger rather than older adults. To explore older peopleâs relationship with alcohol, we conducted eight focus groups with 36 men and women aged 35 to 50 years in Scotland, UK. Initially, respondents suggested that older drinkers consume less alcohol, no longer drink to become drunk and are sociable drinkers more interested in the taste than the effects of alcohol. However, as discussions progressed, respondents collectively recounted recent drunken escapades, challenged accounts of moderate drinking, and suggested there was still peer pressure to drink. Some described how their drinking had increased in mid-life but worked hard discursively to emphasise that it was age and stage appropriate (i.e. they still met their responsibilities as workers and parents). Women presented themselves as staying in control of their drinking while men described going out with the intention of getting drunk (although still claiming to meet their responsibilities). While women experienced peer pressure to drink, they seemed to have more options for socialising without alcohol than did men. Choosing not to drink alcohol is a behaviour that still requires explanation in early mid-life. Harm reduction strategies should pay more attention to drinking in this age group
Quantum Information Paradox: Real or Fictitious?
One of the outstanding puzzles of theoretical physics is whether quantum
information indeed gets lost in the case of Black Hole (BH) evaporation or
accretion. Let us recall that Quantum Mechanics (QM) demands an upper limit on
the acceleration of a test particle. On the other hand, it is pointed out here
that, if a Schwarzschild BH would exist, the acceleration of the test particle
would blow up at the event horizon in violation of QM. Thus the concept of an
exact BH is in contradiction of QM and quantum gravity (QG). It is also
reminded that the mass of a BH actually appears as an INTEGRATION CONSTANT of
Einstein equations. And it has been shown that the value of this integration
constant is actually zero. Thus even classically, there cannot be finite mass
BHs though zero mass BH is allowed. It has been further shown that during
continued gravitational collapse, radiation emanating from the contracting
object gets trapped within it by the runaway gravitational field. As a
consequence, the contracting body attains a quasi-static state where outward
trapped radiation pressure gets balanced by inward gravitational pull and the
ideal classical BH state is never formed in a finite proper time. In other
words, continued gravitational collapse results in an "Eternally Collapsing
Object" which is a ball of hot plasma and which is asymptotically approaching
the true BH state with M=0 after radiating away its entire mass energy. And if
we include QM, this contraction must halt at a radius suggested by highest QM
acceleration. In any case no EH is ever formed and in reality, there is no
quantum information paradox.Comment: 8 pages in Pramana Style, 6 in Revtex styl
Homodyne extimation of quantum states purity by exploiting covariant uncertainty relation
We experimentally verify uncertainty relations for mixed states in the
tomographic representation by measuring the radiation field tomograms, i.e.
homodyne distributions. Thermal states of single-mode radiation field are
discussed in details as paradigm of mixed quantum state. By considering the
connection between generalised uncertainty relations and optical tomograms is
seen that the purity of the states can be retrieved by statistical analysis of
the homodyne data. The purity parameter assumes a relevant role in quantum
information where the effective fidelities of protocols depend critically on
the purity of the information carrier states. In this contest the homodyne
detector becomes an easy to handle purity-meter for the state on-line with a
running quantum information protocol.Comment: accepted for publication into Physica Script
A possible mechanism of ultrafast amorphization in phase-change memory alloys: an ion slingshot from the crystalline to amorphous position
We propose that the driving force of an ultrafast crystalline-to-amorphous
transition in phase-change memory alloys are strained bonds existing in the
(metastable) crystalline phase. For the prototypical example of GST, we
demonstrate that upon breaking of long Ge-Te bond by photoexcitation Ge ion
shot from an octahedral crystalline to a tetrahedral amorphous position by the
uncompensated force of strained short bonds. Subsequent lattice relaxation
stabilizes the tetrahedral surroundings of the Ge atoms and ensures the
long-term stability of the optically induced phase.Comment: 6 pages, 3 figure
Modelling Quantum Mechanics by the Quantumlike Description of the Electric Signal Propagation in Transmission Lines
It is shown that the transmission line technology can be suitably used for
simulating quantum mechanics. Using manageable and at the same time
non-expensive technology, several quantum mechanical problems can be simulated
for significant tutorial purposes. The electric signal envelope propagation
through the line is governed by a Schrodinger-like equation for a complex
function, representing the low-frequency component of the signal, In this
preliminary analysis, we consider two classical examples, i.e. the Frank-Condon
principle and the Ramsauer effect
Decoherence and thermalization dynamics of a quantum oscillator
We introduce the quantitative measures characterizing the rates of
decoherence and thermalization of quantum systems. We study the time evolution
of these measures in the case of a quantum harmonic oscillator whose relaxation
is described in the framework of the standard master equation, for various
initial states (coherent, `cat', squeezed and number). We establish the
conditions under which the true decoherence measure can be approximated by the
linear entropy . We show that at low temperatures and for
highly excited initial states the decoherence process consists of three
distinct stages with quite different time scales. In particular, the `cat'
states preserve 50% of the initial coherence for a long time interval which
increases logarithmically with increase of the initial energy.Comment: 24 pages, LaTex, 8 ps figures, accepted for publication in J. Opt.
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