16,899 research outputs found
The Effect of Injection-Valve Opening Pressure on Spray-Tip Penetration
The effect of various injection-valve opening pressures on the spray-tip penetration was determined for several injection pressure. A common-rail fuel injection system was used. For a given injection pressure a maximum rate of penetration was obtained with an injection-valve opening pressure equal to the injection pressure. As the excess of the injection pressure over the injection-valve opening pressure was increased for a given injection pressure, the effect of the injection-valve opening pressure on the spray-tip penetration was increased
Perceptual-gestural (mis)mapping in serial short-term memory: The impact of talker variability
The mechanisms underlying the poorer serial recall of talker-variable lists (e.g., alternating female–male voices) as compared with single-voice lists were examined. We tested the novel hypothesis that this talker variability effect arises from the tendency for perceptual organization to partition the list into streams based on voice such that the representation of order maps poorly onto the formation of a gestural sequence-output plan assembled in support of the reproduction of the true temporal order of the items. In line with the hypothesis, (a) the presence of a spoken lead-in designed to further promote by-voice perceptual partitioning accentuates the effect (Experiments 1 and 2); (b) the impairment is larger the greater the acoustic coherence is between nonadjacent items: Alternating-voice lists are more poorly recalled than four-voice lists (Experiment 3); and (c) talker variability combines nonadditively with phonological similarity, consistent with the view that both variables disrupt sequence output planning (Experiment 4). The results support the view that serial short-term memory performance reflects the action of sequencing processes embodied within general-purpose perceptual input-processing and gestural output-planning systems
Retrieval from memory: Vulnerable or inviolable?
We show that retrieval from semantic memory is vulnerable even to the mere presence of speech. Irrelevant speech impairs semantic fluency—namely, lexical retrieval cued by a semantic category name—but only if it is meaningful (forward speech compared to reversed speech or words compared to nonwords). Moreover, speech related semantically to the retrieval category is more disruptive than unrelated speech. That phonemic fluency—in which participants are cued with the first letter of words they are to report—was not disrupted by the mere presence of meaningful speech, only by speech in a related phonemic category, suggests that distraction is not mediated by executive processing load. The pattern of sensitivity to different properties of sound as a function of the type of retrieval cue is in line with an interference-by-process approach to auditory distraction
Low Luminosity Companions to White Dwarfs
This paper presents results of a near-infrared imaging survey for low mass
stellar and substellar companions to white dwarfs. A wide field proper motion
survey of 261 white dwarfs was capable of directly detecting companions at
orbital separations between and 5000 AU with masses as low as 0.05
, while a deep near field search of 86 white dwarfs was capable of
directly detecting companions at separations between and 1100 AU with
masses as low as 0.02 . Additionally, all white dwarf targets were
examined for near-infrared excess emission, a technique capable of detecting
companions at arbitrarily close separations down to masses of 0.05 .
No brown dwarf candidates were detected, which implies a brown dwarf
companion fraction of % for white dwarfs. In contrast, the stellar
companion fraction of white dwarfs as measured by this survey is 22%,
uncorrected for bias. Moreover, most of the known and suspected stellar
companions to white dwarfs are low mass stars whose masses are only slightly
greater than the masses of brown dwarfs. Twenty previously unknown stellar
companions were detected, five of which are confirmed or likely white dwarfs
themselves, while fifteen are confirmed or likely low mass stars.
Similar to the distribution of cool field dwarfs as a function of spectral
type, the number of cool unevolved dwarf companions peaks at mid-M type. Based
on the present work, relative to this peak, field L dwarfs appear to be roughly
2-3 times more abundant than companion L dwarfs. Additionally, there is no
evidence that the initial companion masses have been altered by post main
sequence binary interactions.Comment: 149 pages, 59 figures, 11 tables, accepted to ApJ Supplement
Close Binary White Dwarf Systems: Numerous New Detections and Their Interpretation
We describe radial velocity observations of a large sample of apparently
single white dwarfs (WDs), obtained in a long-term effort to discover close,
double-degenerate (DD) pairs which might comprise viable Type Ia Supernova (SN
Ia) progenitors. We augment the WD sample with a previously observed sample of
apparently single subdwarf B (sdB) stars, which are believed to evolve directly
to the WD cooling sequence after the cessation of core helium burning. We have
identified 18 new radial velocity variables, including five confirmed sdB+WD
short-period pairs. Our observations are in general agreement with the
predictions of the theory of binary star evolution. We describe a numerical
method to evaluate the detection efficiency of the survey and estimate the
number of binary systems not detected due to the effects of varying orbital
inclination, orbital phase at the epoch of the first observation, and the
actual temporal sampling of each object in the sample. Follow-up observations
are in progress to solve for the orbital parameters of the candidate velocity
variables.Comment: 30 pages (LaTeX) + 6 figures (Postscript), aaspp4 styl
Towards the origin of the radio emission in AR Sco, the first radio-pulsing white dwarf binary
The binary system AR Sco contains an M star and the only known radio-pulsing
white dwarf. The system shows emission from radio to X-rays, likely dominated
by synchrotron radiation. The mechanism that produces most of this emission
remains unclear. Two competing scenarios have been proposed: Collimated
outflows, and direct interaction between the magnetospheres of the white dwarf
and the M star. The two proposed scenarios can be tested via very long baseline
interferometric radio observations. We conducted a radio observation with the
Australian Long Baseline Array (LBA) on 20 Oct 2016 at 8.5 GHz to study the
compactness of the radio emission. Simultaneous data with the Australian
Telescope Compact Array (ATCA) were also recorded for a direct comparison of
the obtained flux densities. AR Sco shows radio emission compact on
milliarcsecond angular scales (, or $4\
\mathrm{R_{\odot}}\approx 6.5\ \mathrm{mJy}$. A comparison with the simultaneous ATCA
data shows that no flux is resolved out on mas scales, implying that the radio
emission is produced in this compact region. Additionally, the obtained radio
light curves on hour timescales are consistent with the optical light curve.
The radio emission in AR Sco is likely produced in the magnetosphere of the M
star or the white dwarf, and we see no evidence for a radio outflow or
collimated jets significantly contributing to the radio emission.Comment: 4 pages, 2 figures, accepted for publication in A&
Continuation of theoretical and experimental research on digital adaptive control system, 16 September 1966 - 16 February 1967
Digital adaptive control syste
Some more space-group corrections
A survey of approximately 100 000 entries in recent releases of the Cambridge Structural Database (CSD) has uncovered 156 crystal structures that were apparently described in inappropriate space groups. We have revised these space groups and prepared CIFs containing the new coordinates and brief comments describing the revisions
Epitaxial silicon grown on CeO2/Si(111) structure by molecular beam epitaxy
Using electron beam evaporation, a Si/CeO2/Si(111) structure has been grown in a molecular beam epitaxy machine. In situ low energy electron diffraction, cross sectional transmission electron microscopy, selected area diffraction, and atomic force microscopy have been used to structurally characterize the overlying silicon layer and show it to be single crystalline and epitaxially oriented. Rutherford backscattering and energy dispersive x-ray analysis have been used to confirm the presence of a continuous 23 Ã… CeO2 layer at the interface. Rutherford backscattering and x-ray photoemission spectroscopy show an additional presence of cerium both at the exposed silicon surface and incorporated in low levels (~ 1%) within the silicon film, suggesting a growth mechanism with cerium riding atop the silicon growth front leaving behind small amounts of cerium incorporated in the growing silicon crystal
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