23,018 research outputs found
Thermocapillary induced breakdown of a falling liquid film
Hydrodynamic models for effects of thermocapillary instability, film thickness, and heat flux on breakdown of falling liquid film
Wetting dynamics of evaporating drops on various surfaces
Mathematical prediction of evaporating water droplet wetting dynamics on stainless steel, Lucite, Teflon, and copper surface
Effect of contact angle hysteresis on moving liquid film integrity
A study was made of the formation and breakdown of a water film moving over solid surfaces (teflon, lucite, stainless steel, and copper). The flow rate associated with film formation was found to be higher than the flow rate at which film breakdown occurred. The difference in the flow rates for film formation and film breakdown was attributed to contact angle hysteresis. Analysis and experiment, which are in good agreement, indicated that film formation and film breakdown are functions of the advancing and receding angles, respectively
Temporal expectancies driven by self- and externally generated rhythms
The dynamic attending theory proposes that rhythms entrain periodic fluctuations of attention which modulate the gain of sensory input. However, temporal expectancies can also be driven by the mere passage of time (foreperiod effect). It is currently unknown how these two types of temporal expectancy relate to each other, i.e. whether they work in parallel and have distinguishable neural signatures. The current research addresses this issue. Participants either tapped a 1Hz rhythm (active task) or were passively presented with the same rhythm using tactile stimulators (passive task). Based on this rhythm an auditory target was then presented early, in synchrony, or late. Behavioural results were in line with the dynamic attending theory as RTs were faster for in- compared to out-of-synchrony targets. Electrophysiological results suggested self-generated and externally induced rhythms to entrain neural oscillations in the delta frequency band. Auditory ERPs showed evidence of two distinct temporal expectancy processes. Both tasks demonstrated a pattern which followed a linear foreperiod effect. In the active task, however, we also observed an ERP effect consistent with the dynamic attending theory. This study shows that temporal expectancies generated by a rhythm and expectancy generated by the mere passage of time can work in parallel and sheds light on how these mechanisms are implemented in the brain
Bounce-free spherical hydrodynamic implosion
In a bounce-free spherical hydrodynamic implosion, the post-stagnation hot
core plasma does not expand against the imploding flow. Such an implosion
scheme has the advantage of improving the dwell time of the burning fuel,
resulting in a higher fusion burn-up fraction. The existence of bounce-free
spherical implosions is demonstrated by explicitly constructing a family of
self-similar solutions to the spherically symmetric ideal hydrodynamic
equations. When applied to a specific example of plasma liner driven
magneto-inertial fusion, the bounce-free solution is found to produce at least
a factor of four improvement in dwell time and fusion energy gain.Comment: accepted by Phys. Plasmas (Nov. 7, 2011); for Ref. 11, please see
ftp://ftp.lanl.gov/public/kagan/liner_evolution.gi
Tendency of spherically imploding plasma liners formed by merging plasma jets to evolve toward spherical symmetry
Three dimensional hydrodynamic simulations have been performed using smoothed
particle hydrodynamics (SPH) in order to study the effects of discrete jets on
the processes of plasma liner formation, implosion on vacuum, and expansion.
The pressure history of the inner portion of the liner was qualitatively and
quantitatively similar from peak compression through the complete stagnation of
the liner among simulation results from two one dimensional
radiationhydrodynamic codes, 3D SPH with a uniform liner, and 3D SPH with 30
discrete plasma jets. Two dimensional slices of the pressure show that the
discrete jet SPH case evolves towards a profile that is almost
indistinguishable from the SPH case with a uniform liner, showing that
non-uniformities due to discrete jets are smeared out by late stages of the
implosion. Liner formation and implosion on vacuum was also shown to be robust
to Rayleigh-Taylor instability growth. Interparticle mixing for a liner
imploding on vacuum was investigated. The mixing rate was very small until
after peak compression for the 30 jet simulation.Comment: 28 pages, 16 figures, submitted to Physics of Plasmas (2012
Precise Pressure Dependence of the Superconducting Transition Temperature of FeSe: Resistivity and ^77Se--NMR Study
We report the precise pressure dependence of FeSe from a resistivity
measurement up to 4.15 GPa. Superconducting transition temperature (T_c)
increases sensitively under pressure, but shows a plateau between 0.5-1.5 GPa.
The maximum T_c, which is determined by zero resistance, is 21 K at
approximately 3.5 GPa. The onset value reaches ~37 K at 4.15 GPa. We also
measure the nuclear spin-lattice relaxation rate 1/T_1 under pressure using
77Se--NMR measurement. 1/T_1 shows that bulk superconductivity is realized in
the zero-resistance state. The pressure dependence of 1/T_1T just above T_c
shows a plateau as well as the pressure dependence of T_c, which gives clear
evidence of the close relationship between 1/T_1T and T_c. Spin fluctuations
are suggested to contribute to the mechanism of superconductivity.Comment: 4pages, 6figures: to be published in J. Phys. Soc. Jpn. Vol.78 No.6
(2009
The main types of interlingual interference in the scientific discourse in the field of nanotechnology
В статье анализируются различные подходы к определению понятия "интерференция", освещается проблема классификации видов интерференции. На материале англоязычных и русскоязычных статей из журнала "Российские нанотехнологии / Nanotechnologies in Russia" проводится детальный анализ видов деструктивной интерференции и выявляется частотность ее проявления. В результате исследования указываются наиболее и наименее распространенные типы интерференции, присущие статьям научного стиля в сфере нанотехнологий. The article examines various approaches to the definition of the term "interference" as well as covers the problem of interference classification. The article provides an analysis of examples of each type of the destructive interference based on English and Russian articles from the journal "Rossiyskie Nanotechnologii/Nanotechnologies in Russia", and the frequency of its manifestations is detected. The study outlines the most and the least widespread types of interference which are inherent in the articles of scientific style in the field of nanotechnology
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