Mechanical behavior of irregular fibers part III : the flexural buckling behavior

Fiber buckling behavior is associated with fabric-evoked prickle, which affects clothing comfort and aesthetics. In this paper, the flexural buckling behavior of irregular or nonuniform fibers is studied using the finite element method (FEM). Fiber dimensional irregularities are simulated with sine waves of different magnitude, frequency, and initial phase. The critical buckling loads of the simulated fibers are then calculated from the FE model. The results indicate that increasing the level of irregularity will decrease the critical buckling load of fibers, but the effect of the frequency and initial phase of irregularity on fiber buckling behavior is complicated and is affected by fiber diameter and effective length

Estimation of glottal closure instants in voiced speech using the DYPSA algorithm

Published versio

Low Mass Stars and Brown Dwarfs around Sigma Orionis

We present optical spectroscopy of 71 photometric candidate low-mass members of the cluster associated with Sigma Orionis. Thirty-five of these are found to pass the lithium test and hence are confirmed as true cluster members, covering a mass range of <0.055-0.3M_{sun}, assuming a mean cluster age of <5 Myr. We find evidence for an age spread on the (I, I-J) colour magnitude diagram, members appearing to lie in the range 1-7 Myr. There are, however, a significant fraction of candidates that are non-members, including some previously identified as members based on photometry alone. We see some evidence that the ratio of spectroscopically confirmed members to photometric candidates decreases with brightness and mass. This highlights the importance of spectroscopy in determining the true initial mass-function.Comment: To appear in the 12th Cambridge Workshop on Cool Stars Stellar Systems and the Su

The ``Outside-In'' Outburst of HT Cassiopeiae

We present results from photometric observations of the dwarf nova system HT Cas during the eruption of November 1995. The data include the first two--colour observations of an eclipse on the rise to outburst. They show that during the rise to outburst the disc deviates significantly from steady state models, but the inclusion of an inner-disc truncation radius of about 4 $R_{wd}$ and a ``flared'' disc of semi-opening angle of $10^{\circ}$ produces acceptable fits. The disc is found to have expanded at the start of the outburst to about $0.41R_{L1}$, as compared to quiescent measurements. The accretion disc then gradually decreases in radius reaching $<0.32R_{L1}$ during the last stages of the eruption. Quiescent eclipses were also observed prior to and after the eruption and a revised ephemeris is calculated.Comment: 9 pages, 11 figures, to appear in MNRA

The discovery of a low mass, pre-main-sequence stellar association around gamma Velorum

We report the serendipitous discovery of a population of low mass, pre-main sequence stars (PMS) in the direction of the Wolf-Rayet/O-star binary system gamma^{2} Vel and the Vela OB2 association. We argue that gamma^{2} Vel and the low mass stars are truly associated, are approximately coeval and that both are at distances between 360-490 pc, disagreeing at the 2 sigma level with the recent Hipparcos parallax of gamma^{2} Vel, but consistent with older distance estimates. Our results clearly have implications for the physical parameters of the gamma^{2} Vel system, but also offer an exciting opportunity to investigate the influence of high mass stars on the mass function and circumstellar disc lifetimes of their lower mass PMS siblings.Comment: Monthly Notices of the Royal Astronomical Society, Letters - in pres

A generic synthesisable test bench

Writing test benches is one of the most frequently-performed tasks in the hardware development process. The ability to reuse common test bench features is therefore key to productivity. In this paper, we present a generic test bench, parameterised by a specification of correctness, which can be used to test any design. Our test bench provides several important features, including automatic test-sequence generation and shrinking of counter-examples, and is fully synthesisable, allowing rigorous testing on FPGA as well as in simulation. The approach is easy to use, cheap to implement, and encourages the formal specification of hardware components through the reward of automatic testing and simple failure cases.This work was supported by DARPA/AFRL contracts FA8750- 10-C-0237 (CTSRD) and FA8750-11-C-0249 (MRC2), and EPSRC grant EP/K008528/1 (REMS).This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/MEMCOD.2015.734047

Optical and ROSAT X-ray observations of the dwarf nova OY Carinae in superoutburst and quiescence

We present ROSAT X-ray and optical light curves of the 1994 February superoutburst of the eclipsing SU UMa dwarf nova OY Carinae. There is no eclipse of the flux in the ROSAT HRI light curve. Contemporaneous `wide B' band optical light curves show extensive superhump activity and dips at superhump maximum. Eclipse mapping of these optical light curves reveals a disc with a considerable physical flare, even three days into the superoutburst decline. We include a later (1994 July) ROSAT PSPC observation of OY Car that allows us to put constraints on the quiescent X-ray spectrum. We find that while there is little to choose between OY Car and its fellow high inclination systems with regard to the temperature of the emitting gas and the emission measure, we have difficulties reconciling the column density found from our X-ray observation with the column found in HST UV observations by Horne et al. (1994). The obvious option is to invoke time variability.Comment: 16 pages, 14 figures, accepted for publication in MNRA