8,905 research outputs found
Evaluation of high temperature structural adhesives for extended service, phase 4
The evaluation of three phenylquinoxaline polymers as high temperature structural adhesives is presented. These included an experimental crisskubjabke oiktner (X-PQ) and two experimental materials (PPQ-2501) and (PPQ-HC). Lap shear, crack extension, and climing drum peel specimens were fabricated from all three polymers, and tested after thermal, combined thermal/humidity, and stressed Skydrol exposure. All three polymers generally performed well as adhesives at initial test temperatures from 219K (-67 F) to 505K (450 F) and after humidity exposure. The 644K (700 F) cured test specimens exhibited superior Skydrol resistance and thermal stability at 505K (450 F) when compared to the 602K (625 F) cured test specimens
BiSON data preparation: A correction for differential extinction and the weighted averaging of contemporaneous data
The Birmingham Solar Oscillations Network (BiSON) has provided high-quality
high-cadence observations from as far back in time as 1978. These data must be
calibrated from the raw observations into radial velocity and the quality of
the calibration has a large impact on the signal-to-noise ratio of the final
time series. The aim of this work is to maximise the potential science that can
be performed with the BiSON data set by optimising the calibration procedure.
To achieve better levels of signal-to-noise ratio we perform two key steps in
the calibration process: we attempt a correction for terrestrial atmospheric
differential extinction; and the resulting improvement in the calibration
allows us to perform weighted averaging of contemporaneous data from different
BiSON stations. The improvements listed produce significant improvement in the
signal-to-noise ratio of the BiSON frequency-power spectrum across all
frequency ranges. The reduction of noise in the power spectrum will allow
future work to provide greater constraint on changes in the oscillation
spectrum with solar activity. In addition, the analysis of the low-frequency
region suggests we have achieved a noise level that may allow us to improve
estimates of the upper limit of g-mode amplitudes.Comment: Accepted for publication in MNRAS; 10 pages, 7 figure
Performance of the Birmingham Solar-Oscillations Network (BiSON)
The Birmingham Solar-Oscillations Network (BiSON) has been operating with a
full complement of six stations since 1992. Over 20 years later, we look back
on the network history. The meta-data from the sites have been analysed to
assess performance in terms of site insolation, with a brief look at the
challenges that have been encountered over the years. We explain how the
international community can gain easy access to the ever-growing dataset
produced by the network, and finally look to the future of the network and the
potential impact of nearly 25 years of technology miniaturisation.Comment: 31 pages, 19 figures. Accepted by Solar Physics: 2015 October 20.
First online: 2015 December 7. Open Acces
Using humanoid robots to study human behavior
Our understanding of human behavior advances as our humanoid robotics work progresses-and vice versa. This team's work focuses on trajectory formation and planning, learning from demonstration, oculomotor control and interactive behaviors. They are programming robotic behavior based on how we humans âprogramâ behavior in-or train-each other
The Sun in transition? Persistence of near-surface structural changes through Cycle 24
We examine the frequency shifts in low-degree helioseismic modes from the
Birmingham Solar-Oscillations Network (BiSON) covering the period from 1985 -
2016, and compare them with a number of global activity proxies well as a
latitudinally-resolved magnetic index. As well as looking at frequency shifts
in different frequency bands, we look at a parametrization of the shift as a
cubic function of frequency. While the shifts in the medium- and highfrequency
bands are very well correlated with all of the activity indices (with the best
correlation being with the 10.7 cm radio flux), we confirm earlier findings
that there appears to have been a change in the frequency response to activity
during solar cycle 23, and the low frequency shifts are less correlated with
activity in the last two cycles than they were in Cycle 22. At the same time,
the more recent cycles show a slight increase in their sensitivity to activity
levels at medium and higher frequencies, perhaps because a greater proportion
of activity is composed of weaker or more ephemeral regions. This lends weight
to the speculation that a fundamental change in the nature of the solar dynamo
may be in progress.Comment: 9 pages, 6 figures. Accepted by MNRAS 24 May 201
Advancing the time of ripeness of grapes by the application of methyl 2-(ureidooxy) propionate (a growth retardant)
Methyl 2-(ureidooxy) propionate (MUP), a plant growth retardant, hastened the ripening of grape berries of Vitis vinifera L. cultivars Mataro and Sultana by about 2 weeks and 1 week, respectively. The vines were sprayed with 0.1 % solution of MUP about halfway :through the first rapid growth phase of the fruit and again 2 weeks later. Terminal and lateral shoot growth was inhibited. Ripening of berries was advanced as measured by development of colour, and changes in titratable acid and reducing sugar content. The earlier ripening of the berries may have been due to hormonal changes but the advancement was much greater than that found previously with abscisic acid or ethylene applied during the slow growth stage of berry development.Die Beschleunigung des Reifezeitpunktes von Trauben durch die Anwendung vonMethyl-2-(ureidooxy)-Propionat, einen WachstumsdĂ€mpferMethyl-2-(ureidooxy)-Propionat (MUP), welches das Pflanzenwachstum verlangsamt, beschleunigte bei den Vitis-vinifera-Sorten Mataro und Sultana die Beerenreife um etwa 2 Wochen bzw. 1 Woche. Die Reben wurden etwa in der Mitte der ersten raschen Wachstumsphase der Beeren und ein weiteres Mal 2 Wochen spĂ€ter mit einer 0,1%igen MUP-Lösung besprĂŒht. Das terminale und laterale Triebwachstum war gehemmt. Die Beerenreife war beschleunigt, wie die Entwicklung der Beerenfarbe und die VerĂ€nderungen im Gehalt an titrierbarer SĂ€ure und reduzierenden Zuckern zeigten. Die frĂŒhzeitigere Beerenreife könnte auf hormonale VerĂ€nderungen zurĂŒckgehen; allerdings war die Reife viel stĂ€rker beschleunigt als im Fall frĂŒherer Versuche, in denen wĂ€hrend der langen Wachstumsphase der Beerenentwicklung AbscisinsĂ€ure oder Ăthylen angewandt worden waren
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