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1
Lisak-Gębala, Dobrawa. "Glitchem opętanie. Poetyka cyfrowych usterek w wierszach drukowanych." Sztuka Edycji 22, no. 2 (December 1, 2022): 65–74. http://dx.doi.org/10.12775/se.2022.00028.
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Glitch w obszarze mediów elektronicznych definiuje się jako nacięcie w powierzchni jednego systemu otwierające chwilowy wgląd w cyfrowe struktury zwykle ukryte głęboko. Obcy element widoczny na ekranie z powodu samorodnych błędów w działaniu komputerów lub oprogramowania często jest interpretowany w perspektywie posthumanizmu. Ten sposób myślenia wpływa na funkcjonowanie digitalnych defektów, które są świadomie wykorzystywane w ramach glitch poetry, także tej wydrukowanej na papierze, która wiąże się z fenomenem remediacji wstecznej. Przykładami takich utworów w ramach artykułu stają się w zdecydowanej większości ogłaszane drukiem wiersze neolingwistów warszawskich oraz papierowe wydania tomów Rozdzielczości Chleba. Wspomniani autorzy w swych manifestach diagnozowali radykalną zmianę paradygmatu twórczości na nowomedialną. Podkreślali potrzebę otwarcia się poetów na współprodukcję tekstów przez podłączone do internetu komputery, które podsuwają glitche, niechciane maile i reklamy. Głosili oni jednocześnie kres książki drukowanej kojarzonej w manifestach z postromantycznym modelem wiersza jako subiektywnego monologu. Analogowa poezja usterkowa mająca uwypuklić konflikt tych dwóch paradygmatów przybiera często formę postcyfrowych książek artystycznych, które ze względu na dominację graficznych efektów nad zrozumiałym dla człowieka tekstem stają się XXI-wieczną wersją ezoterycznego abstrakcjonizmu. Glitch poetry może też funkcjonować jako z pozoru tradycyjny czarny tekst wydrukowany na białej stronicy, łączący jednak zrozumiałe słowa i zdania z antyfonetycznymi usterkami cyfrowymi wyrażonymi znakami nieliterowymi.
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Millhouse, M., A. Melatos, G. Howitt, J. B. Carlin, L. Dunn, and G. Ashton. "An updated glitch rate law inferred from radio pulsars." Monthly Notices of the Royal Astronomical Society 511, no. 3 (January 29, 2022): 3304–19. http://dx.doi.org/10.1093/mnras/stac194.
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ABSTRACT Radio pulsar glitches probe far-from-equilibrium processes involving stress accumulation and relaxation in neutron star interiors. Previous studies of glitch rates have focused on individual pulsars with as many recorded glitches as possible. In this work, we analyse glitch rates using all available data including objects that have glitched never or once. We assume the glitch rate follows a homogeneous Poisson process, and therefore exclude pulsars that exhibit quasiperiodic glitching behaviour. Calculating relevant Bayes factors shows that a model in which the glitch rate λ scales as a power of the characteristic age τ is preferred over models that depend arbitrarily on powers of the spin frequency ν and/or its time derivative $\dot{\nu }$. For λ = A(τ/τref)−γ, where τref = 1 yr is a reference time, the posterior distributions are unimodal with $A=0.0066_{-0.002}^{+0.003}\ \rm {yr}^{-1}$ and $\gamma =0.27_{-0.03}^{+0.03}$. Importantly, the data exclude with 99 per cent confidence the possibility γ = 1 canvassed in the literature. When objects with zero-recorded glitches are included, the age-based rate law is still preferred and the posteriors change to give $A=0.0099_{-0.003}^{+0.004}\ \rm {yr}^{-1}$ and $\gamma =0.31_{-0.03}^{+0.03}$. The updated estimates still support increased glitch activity for younger pulsars, while demonstrating that the large number of objects with zero glitches contain important statistical information about the rate, provided that they are part of the same population as opposed to a disjoint population which never glitches for some unknown physical reason.
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Ho, Wynn C. G., Cristóbal M. Espinoza, Zaven Arzoumanian, Teruaki Enoto, Tsubasa Tamba, Danai Antonopoulou, Michał Bejger, Sebastien Guillot, Brynmor Haskell, and Paul S. Ray. "Return of the Big Glitcher: NICER timing and glitches of PSR J0537−6910." Monthly Notices of the Royal Astronomical Society 498, no. 4 (September 1, 2020): 4605–14. http://dx.doi.org/10.1093/mnras/staa2640.
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ABSTRACT PSR J0537−6910, also known as the Big Glitcher, is the most prolific glitching pulsar known, and its spin-induced pulsations are only detectable in X-ray. We present results from analysis of 2.7 yr of NICER timing observations, from 2017 August to 2020 April. We obtain a rotation phase-connected timing model for the entire time span, which overlaps with the third observing run of LIGO/Virgo, thus enabling the most sensitive gravitational wave searches of this potentially strong gravitational wave-emitting pulsar. We find that the short-term braking index between glitches decreases towards a value of 7 or lower at longer times since the preceding glitch. By combining NICER and RXTE data, we measure a long-term braking index n = −1.25 ± 0.01. Our analysis reveals eight new glitches, the first detected since 2011, near the end of RXTE, with a total NICER and RXTE glitch activity of $8.88\times 10^{-7}\, \mathrm{yr^{-1}}$. The new glitches follow the seemingly unique time-to-next-glitch–glitch-size correlation established previously using RXTE data, with a slope of $5\, \rm {d} \, \mu \mathrm{Hz}^{-1}$. For one glitch around which NICER observes 2 d on either side, we search for but do not see clear evidence of spectral nor pulse profile changes that may be associated with the glitch.
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Basu, A., B. Shaw, D. Antonopoulou, M. J. Keith, A. G. Lyne, M. B. Mickaliger, B. W. Stappers, P. Weltevrede, and C. A. Jordan. "The Jodrell bank glitch catalogue: 106 new rotational glitches in 70 pulsars." Monthly Notices of the Royal Astronomical Society 510, no. 3 (November 25, 2021): 4049–62. http://dx.doi.org/10.1093/mnras/stab3336.
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ABSTRACT Pulsar glitches are rapid spin-up events that occur in the rotation of neutron stars, providing a valuable probe into the physics of the interiors of these objects. Long-term monitoring of a large number of pulsars facilitates the detection of glitches and the robust measurements of their parameters. The Jodrell Bank pulsar timing programme regularly monitors more than 800 radio pulsars and has accrued, in some cases, over 50 yr of timing history on individual objects. In this paper, we present 106 new glitches in 70 radio pulsars as observed up to the end of 2018. For 70 per cent of these pulsars, the event we report is its only known glitch. For each new glitch, we provide measurements of its epoch, amplitude, and any detected changes to the spin-down rate of the star. Combining these new glitches with those listed in the Jodrell Bank glitch catalogue, we analyse a total sample of 543 glitches in 178 pulsars. We model the distribution of glitch amplitudes and spin-down rate changes using a mixture of two Gaussian components. We corroborate the known dependence of glitch rate and activity on pulsar spin-down rates and characteristic ages, and show that younger pulsars tend to exhibit larger glitches. Pulsars with spin-down rates between 10−14 and 10−10.5 Hz s−1 show a mean reversal of 1.8 per cent of their spin-down as a consequence of glitches. Our results are qualitatively consistent with the superfluid vortex unpinning models of pulsar glitches.
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Manchester, R. N. "Pulsar Glitches." Proceedings of the International Astronomical Union 13, S337 (September 2017): 197–202. http://dx.doi.org/10.1017/s1743921317009607.
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AbstractThe first known pulsar glitch was discovered in the Vela pulsar at both Parkes and Goldstone in March 1969. Since then the number of known glitches has grown enormously, with more than 520 glitches now known in more than 180 pulsars. Details of glitch parameters and post-glitch recoveries are described and some implications for the physics of neutron stars are discussed.
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Wang, Na, R. N. Manchester, R. Pace, M. Bailes, V. M. Kaspi, B. W. Stappers, and A. G. Lyne. "Glitches in Southern Pulsars." International Astronomical Union Colloquium 177 (2000): 109–10. http://dx.doi.org/10.1017/s0252921100059194.
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AbstractParkes timing observations of 31 mostly young pulsars over nearly nine years are described. A total of 29 glitches were detected, of which 19 are previously unreported. Twelve glitches were seen in PSR J1341–6220, making this the most frequently glitching pulsar known, and the largest known glitch was detected in PSR J1614–5047. Distributions of glitch parameters were investigated.
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Fuentes, J. R., C. M. Espinoza, and A. Reisenegger. "Glitch time series and size distributions in eight prolific pulsars." Astronomy & Astrophysics 630 (October 2019): A115. http://dx.doi.org/10.1051/0004-6361/201935939.
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Context. Glitches are rare spin-up events that punctuate the smooth slow-down of the rotation of pulsars. For the Vela pulsar and PSR J0537−6910, their large glitch sizes and the times between consecutive events have clear preferred scales (Gaussian distributions), contrary to the handful of other pulsars with enough glitches for such a study. Moreover, PSR J0537−6910 is the only pulsar that shows a strong positive correlation between the size of each glitch and the waiting time until the following one. Aims. We attempt to understand this behaviour through a detailed study of the distributions and correlations of glitch properties for the eight pulsars with at least ten detected glitches. Methods. We modelled the distributions of glitch sizes and of the times between consecutive glitches for the eight pulsars with at least ten detected events. We also looked for possible correlations between these parameters and used Monte Carlo simulations to explore two hypotheses that could explain why the correlation so clearly seen in PSR J0537−6910 is absent in other pulsars. Results. We confirm the above results for Vela and PSR J0537−6910, and verify that the latter is the only pulsar with a strong correlation between glitch size and waiting time to the following glitch. For the remaining six pulsars, the waiting time distributions are best fitted by exponentials, and the size distributions are best fitted by either power laws, exponentials, or log-normal functions. Some pulsars in the sample yield significant Pearson and Spearman coefficients (rp and rs) for the aforementioned correlation, confirming previous results. Moreover, for all except the Crab pulsar, both coefficients are positive. For each coefficient taken separately, the probability of this happening is 1/16. Our simulations show that the weaker correlations in pulsars other than PSR J0537−6910 cannot be due to missing glitches that are too small to be detected. We also tested the hypothesis that each pulsar may have two kinds of glitches, namely large, correlated ones and small, uncorrelated ones. The best results are obtained for the Vela pulsar, which exhibits a correlation with rp = 0.68 (p-value = 0.003) if its two smallest glitches are removed. The other pulsars are harder to accommodate under this hypothesis, but their glitches are not consistent with a pure uncorrelated population either. We also find that all pulsars in our sample, except the Crab pulsar, are consistent with the previously found constant ratio between glitch activity and spin-down rate, ν̇g/|ν̇| = 0.010±0.001, even though some of them have not shown any large glitches. Conclusions. To explain these results, we speculate except in the case of the Crab pulsar, that all glitches draw their angular momentum from a common reservoir (presumably a neutron superfluid component containing ≈1% of the star’s moment of inertia). However, two different trigger mechanisms could be active, a more deterministic one for larger glitches and a more random one for smaller ones.
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Carlin, J. B., and A. Melatos. "Long-term statistics of pulsar glitches triggered by a Brownian stress accumulation process." Monthly Notices of the Royal Astronomical Society 494, no. 3 (April 8, 2020): 3383–91. http://dx.doi.org/10.1093/mnras/staa935.
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ABSTRACT A microphysics-agnostic meta-model of rotational glitches in rotation-powered pulsars is developed, wherein the globally averaged internal stress accumulates as a Brownian process between glitches, and a glitch is triggered once a critical threshold is surmounted. Precise, falsifiable predictions are made regarding long-term event statistics in individual pulsars. For example, the Spearman cross-correlation coefficient between the size of a glitch and the waiting time until the next glitch should exceed 0.25 in all pulsars. Among the six pulsars with the most recorded glitches, PSR J0537−6910 and PSR J0835−4510 are consistent with the predictions of the meta-model, while PSR J1740−3015 and PSR J0631+1036 are not. PSR J0534+2200 and PSR J1341−6220 are only consistent with the meta-model, if there exists an undetected population of small glitches with small waiting times, which we do not resolve. The results are compared with a state-dependent Poisson process, another microphysics-agnostic meta-model in the literature. The results are also applied briefly to recent pulse-to-pulse observations of PSRJ0835−4510, which appear to reveal evidence for a negative fluctuation in rotation frequency just prior to the 2016 glitch.
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Gügercinoğlu, Erbil, and M. Ali Alpar. "The largest Crab glitch and the vortex creep model." Monthly Notices of the Royal Astronomical Society 488, no. 2 (July 4, 2019): 2275–82. http://dx.doi.org/10.1093/mnras/stz1831.
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Abstract The Crab pulsar displayed its largest glitch on 2017 November. An extended initial spin-up phase of this largest glitch was resolved, for the first time with high cadence of observations both in radio and X-rays on a time-scale of 2 d. A combination of crustquake and vortex unpinning models is invoked to account for the extended spin-up, magnitude, and post-glitch relaxation characteristics of this glitch. We evaluate the extended spin-up followed by the familiar spin-down as due to the creep response to the initial induced inward motion of some vortex lines pinned to broken crustal plates moving inward towards the rotation axis, together with the common and familiar post-glitch creep response to the sudden outward motion of vortices unpinned at the glitch. Our analysis confirms that the number of unpinned vortices participating in glitches are similar in all Crab glitches, and within an order of magnitude in all glitches from all pulsars. This typical number of unpinned vortices is related to the broken plate size in quakes as triggers for vortex unpinning avalanches. The physical determinant of this universal broken plate size is in turn the critical strain angle in the neutron star crust. Occurrence of this largest Crab glitch after a relatively long inactive period is consistent with accumulation of the pinned vorticity to be tapped.
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Wang, N. "Pulsar glitches detected at Urumqi." Proceedings of the International Astronomical Union 5, H15 (November 2009): 228. http://dx.doi.org/10.1017/s174392131000894x.
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Gügercinoğlu, E., M. Y. Ge, J. P. Yuan, and S. Q. Zhou. "Glitches in four gamma-ray pulsars and inferences on the neutron star structure." Monthly Notices of the Royal Astronomical Society 511, no. 1 (January 28, 2022): 425–39. http://dx.doi.org/10.1093/mnras/stac026.
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ABSTRACT We present timing solutions from the Fermi-LAT observations of gamma-ray pulsars PSR J0835 − 4510 (Vela), PSR J1023−5746, PSR J2111+4606, and PSR J2229+6114. Data ranges for each pulsar extend over a decade. From data analysis, we have identified a total of 20 glitches, 11 of which are new discoveries. Among them, 15 glitches are large ones with Δν/ν ≳ 10−6. PSR J1023−5746 is the most active pulsar with glitch activity parameter being Ag = 14.5 × 10−7 yr−1 in the considered data span and should be a target for frequently glitching Vela-like pulsars in future observations. We have done fits within the framework of the vortex creep model for 16 glitches with Δν/ν ≳ 10−7. By theoretical analysis of these glitches, we are able to obtain important information on the structure of neutron star, including moments of inertia of the superfluid regions participated in glitches and coupling time-scales between various stellar components. The theoretical prediction for the time to the next glitch from the parameters of the previous one is found to be in qualitative agreement with the observed inter-glitch time-scales for the considered sample. Recoupling time-scales of the crustal superfluid are within the range of theoretical expectations and scale inversely with the spin-down rate of a pulsar. We also determined a braking index n = 2.63(30) for PSR J2229+6114 after glitch-induced contributions have been removed.
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Singha, Jaikhomba, Avishek Basu, M. A. Krishnakumar, Bhal Chandra Joshi, and P. Arumugam. "A real-time automated glitch detection pipeline at Ooty Radio Telescope." Monthly Notices of the Royal Astronomical Society 505, no. 4 (June 9, 2021): 5488–96. http://dx.doi.org/10.1093/mnras/stab1640.
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ABSTRACT Glitches are the observational manifestations of superfluidity inside neutron stars. The aim of this paper is to describe an automated glitch detection pipeline, which can alert the observers on possible real-time detection of rotational glitches in pulsars. Post alert, the pulsars can be monitored at a higher cadence to measure the post-glitch recovery phase. Two algorithms, namely median absolute deviation and polynomial regression, have been explored to detect glitches in real time. The pipeline has been optimized with the help of simulated timing residuals for both the algorithms. Based on the simulations, we conclude that the polynomial regression algorithm is significantly more effective for real time glitch detection. The pipeline has been tested on a few published glitches. This pipeline is presently implemented at the Ooty Radio Telescope. In the era of upcoming large telescopes like SKA, several hundreds of pulsars will be observed regularly and such a tool will be useful for both real-time detection as well as optimal utilization of observation time for such glitching pulsars.
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Buchner, Sarah. "Vela Glitch Monitoring from HartRAO." Proceedings of the International Astronomical Union 8, S291 (August 2012): 207. http://dx.doi.org/10.1017/s1743921312023654.
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AbstractThe Vela pulsar, like many other young pulsars, undergoes occasional sudden “spin-ups” in rotational frequency known as glitches. These glitches are characterised by a sudden (less than 30s) rise in the rotation frequency accompanied by a jump in the spin-down. This is generally followed by rapidly decaying transients in the spin-down and a gradual linear recovery. This recovery provides insight into the internal structure of the neutron star.The telescopes at HartRAO was been used to monitor the Vela pulsar almost daily from 1985 in order to monitor these glitches. The vast majority of these observations were made using the 26m antenna at 1.6 GHz and 2.3 Ghz. When the 26m antenna was offline due to a bearing failure for two years from 2008 the 15m MeerKAT prototype antenna was used to observe Vela.During the entire monitoring campaign 10 large glitches have been observed. The majority of the glitches show a similar recovery pattern. We discuss the characteristics of this common recovery. We compare the standard glitch recovery to that predicted by a hydrodynamic model of the neutron star interior.An exception to the standard glitch are the two glitches which occurred in 1994 separated by 32 days. This “double” glitch is unique amongst Vela glitches. The event is accompanied by typical transients in rotation frequency derivative but all of the long-term offset occurs at the first event and the rapidly-decaying transient is only seen with the second spin-up.
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Dunn, L., A. Melatos, S. Suvorova, W. Moran, R. J. Evans, S. Osłowski, M. E. Lower, M. Bailes, C. Flynn, and V. Gupta. "Systematic upper limits on the size of missing pulsar glitches in the first UTMOST open data release." Monthly Notices of the Royal Astronomical Society 512, no. 1 (March 2, 2022): 1469–82. http://dx.doi.org/10.1093/mnras/stac551.
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ABSTRACT A systematic, semi-automated search for pulsar glitches in the first UTMOST public data release is presented. The search is carried out using a hidden Markov model which incorporates both glitches and timing noise into the model of the assumed phase evolution of the pulsar. Glitches are detected through Bayesian model selection between models with and without glitches present with minimal human intervention. Nine glitches are detected among seven objects, all of which have been previously reported. No new glitches were detected. Injection studies are used to place 90 per cent frequentist upper limits on the size of undetected glitches in each of the 282 objects searched. The mean upper limit obtained is $\Delta f^{90{{\%}}}/f = 1.9 \times 10^{-8}$, with a range of $4.1 \times 10^{-11} \le \Delta f^{90{{\%}}}/f \le 2.7 \times 10^{-7}$, assuming step events with no post-glitch recoveries. It is demonstrated that including glitch recovery has a mild effect, in most cases increasing the upper limit by a factor of ≲5 conservatively assuming complete recovery on a time-scale of $100\ \mathrm{d}$.
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Wang, Wei-Hua, Heng Xu, Wei-Yang Wang, Shuang Du, Quan Cheng, Xiao-Ping Zheng, and Ren-Xin Xu. "Constraining mechanism associated with fast radio burst and glitch from SGR J1935." Monthly Notices of the Royal Astronomical Society 507, no. 2 (July 31, 2021): 2208–19. http://dx.doi.org/10.1093/mnras/stab2213.
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ABSTRACT The discovery of fast radio burst (FRB) 200428 from galactic SGR J1935+2154 makes it possible to measure rotational changes accompanied by FRBs and to test several FRB models which may be simultaneously associated with glitches. Inspired by this idea, we present order of magnitude calculations to the scenarios proposed. FRB models such as global starquakes, crust fractures, and collisions between pulsars and asteroids/comets are discussed. For each mechanism, the maximum glitch sizes are constrained by the isotropic energy release during the X-ray burst and/or the SGR J1935+2154-like radio burst rate. Brief calculations show that, the maximum glitch sizes for different mechanisms differ by order(s) of magnitude. If glitches are detected to be coincident with FRBs from galactic magnetars in the future, glitch behaviours (such as glitch size, rise time-scale, the recovery coefficient, and spin-down rate offset) are promising to serve as criterions to distinguish glitch mechanisms and in turn to constrain FRB models.
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Celora, T., V. Khomenko, M. Antonelli, and B. Haskell. "The effect of non-linear mutual friction on pulsar glitch sizes and rise times." Monthly Notices of the Royal Astronomical Society 496, no. 4 (July 6, 2020): 5564–74. http://dx.doi.org/10.1093/mnras/staa1930.
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ABSTRACT Observations of pulsar glitches have the potential to provide constraints on the dynamics of the high density interior of neutron stars. However, to do so, realistic glitch models must be constructed and compared to the data. We take a step towards this goal by testing non-linear models for the mutual friction force, which is responsible for the exchange of angular momentum between the neutron superfluid and the observable normal component in a glitch. In particular, we consider a non-linear dependence of the drag force on the relative velocity between superfluid vortices and the normal component, in which the contributions of both kelvin and phonon excitations are included. This non-linear model produces qualitatively new features, and is able to reproduce the observed bimodal distribution of glitch sizes in the pulsar population. The model also suggests that the differences in size distributions in individual pulsars may be due to the glitches being triggered in regions with different pinning strengths, as stronger pinning leads to higher vortex velocities and a qualitatively different mutual friction coupling with respect to the weak pinning case. Glitches in pulsars that appear to glitch quasi-periodically with similar sizes may thus be due to the same mechanisms as smaller events in pulsars that have no preferred glitch size, but simply originate in stronger pinning regions, possibly in the core of the star.
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Espinoza, C. M., D. Antonopoulou, R. Dodson, M. Stepanova, and A. Scherer. "Small glitches and other rotational irregularities of the Vela pulsar." Astronomy & Astrophysics 647 (March 2021): A25. http://dx.doi.org/10.1051/0004-6361/202039044.
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Context. Glitches are sudden increases in the rotation rate ν of neutron stars, which are thought to be driven by the neutron superfluid inside the star. The Vela pulsar presents a comparatively high rate of glitches, with 21 events reported since observations began in 1968. These are amongst the largest known glitches (17 of them have sizes Δν/ν ≥ 10−6) and exhibit very similar characteristics. This similarity, combined with the regularity with which large glitches occur, has turned Vela into an archetype of this type of glitching behaviour. The properties of its smallest glitches, on the other hand, are not clearly established. Aims. We explore the population of small-amplitude, rapid rotational changes in the Vela pulsar and determine the rate of occurrence and sizes of its smallest glitches. This will help advance our understanding of the actual distribution of glitch sizes and inter-glitch waiting times in this pulsar, which has implications for theoretical models of the glitch mechanism. Methods. High-cadence observations of the Vela pulsar were taken between 1981 and 2005 at the Mount Pleasant Radio Observatory. An automated systematic search was carried out that investigated whether a significant change of spin frequency ν and/or the spin-down rate ν̇ takes place at any given time. Results. We find two glitches that have not been reported before, with respective sizes Δν/ν of (5.55 ± 0.03) × 10−9 and (38 ± 4) × 10−9. The latter is followed by an exponential-like recovery with a characteristic timescale of 31 d. In addition to these two glitch events, our study reveals numerous events of all possible signatures (i.e. combinations of Δν and Δν̇ signs), all of them small with |Δν|/ν < 10−9, which contribute to the Vela timing noise. Conclusions. The Vela pulsar presents an under-abundance of small glitches compared to many other glitching pulsars, which appears genuine and not a result of observational biases. In addition to typical glitches, the smooth spin-down of the pulsar is also affected by an almost continuous activity that can be partially characterised by small step-like changes in ν, ν̇ or both. Simulations indicate that a continuous wandering of the rotational phase, following a red spectrum, could mimic such step-like changes in the timing residuals.
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Espinoza, Cristobal, Danai Antonopoulou, Alessandro Patruno, Ben Stappers, and Anna Watts. "Characterizing glitches and timing irregularities in pulsars and magnetars." Proceedings of the International Astronomical Union 8, S291 (August 2012): 381. http://dx.doi.org/10.1017/s1743921312024192.
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AbstractAs the quantity and quality of timing data improves, we have reached the point at which the difference between timing noise and small glitches is unclear. As a consequence, the number of events reported as glitches which show unusual properties, quite different to those of giant glitches, has increased. For example, there is now a substantial population of glitches that apparently involve a decrease in spin-down rate rather than an increase. Motivated by the theoretical implications of such a result, we are conducting a detailed review of how glitches are detected and characterised. We have focused on three main questions: the observational biases affecting glitch detection; the methods used to characterise error bars on changes in spin and spin derivatives; and the physical mechanisms that could potentially explain the different populations of timing irregularities, in the light of improved characterisation. While glitches are thought to be a consequence of the internal dynamics of the star, magnetospheric processes may be responsible for other irregularities, as timing noise and peculiar glitch recoveries. We report the first results from this study, using a small sample of radio pulsars that exhibit a wide variety of glitching behaviour.
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Urama, J. O., B. C. Joshi, and A. E. Chukwude. "On the glitch evolution of pulsars." Proceedings of the International Astronomical Union 8, S291 (August 2012): 533–35. http://dx.doi.org/10.1017/s1743921312024775.
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AbstractObservation of pulsar glitches remains a powerful tool for studying the interior of neutron stars. Many of the observed glitch properties are shown to result from the evolution of glitches in the different manifestations of neutron stars. Specifically, the type of glitches associated with the Crab and Vela pulsars are explained by this model. We are, also, able to adequately account for the absence, or very low rate, of glitches among the youngest and the very old pulsars.
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Morgan, Carleigh. "Calculated error." A Peer-Reviewed Journal About 8, no. 1 (August 15, 2019): 204–17. http://dx.doi.org/10.7146/aprja.v8i1.115426.
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This paper proposes a reconsideration of the aesthetic category of ‘glitch’ and advocates for a more careful theorisation around indexing — in the sense of both locating and naming — errors of a digital kind. Glitches are not as random as they seem: they are ordered and shaped by computational hardware and software, which impose a mathematical rubric on how glitches visually manifest and set ontological and technological constrains on glitch that limit how digital errors can and cannot be made to appear. Most crucially, this paper thinks about how one particular type of glitch — a compression artefact called a macroblock — can often appear as random, erratic, or unpredictable but is, in fact, materially constrained and visually conditioned according to the principles of computing and computer design. At its core, compression aesthetics can shed light on the operations of algorithms, the structures of digital technologies, and the priorities and patterns which occur as a function of algorithmic manipulation. The randomness, unpredictability, or messiness which glitch studies invokes around the glitch is in danger of overlooking the ways that the material architectures and algorithmic protocols structure the digital glitch by organising, constraining, and given form to its appearance.
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Yu, Meng. "Glitches detected in southern radio pulsars." Proceedings of the International Astronomical Union 8, S291 (August 2012): 571–73. http://dx.doi.org/10.1017/s174392131202491x.
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AbstractParkes pulse arrival-time data for 165 radio pulsars spanning from 1990 to 2011 have been searched for period glitches. Forty-six events out of the detected 107 glitches were found to be new contributions to the entire glitch population which currently contains approximately 400 events.
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Klimova, Nataliya, Oleksandr Yefanov, Irina Snigireva, and Anatoly Snigirev. "Determination of the Exact Orientation of Single-Crystal X-ray Optics from Its Glitch Spectrum and Modeling of Glitches for an Arbitrary Configuration." Crystals 11, no. 5 (May 2, 2021): 504. http://dx.doi.org/10.3390/cryst11050504.
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X-ray optics made of single-crystal materials are widely used at most of the X-ray sources due to the outstanding properties. The main drawback of such optics—the diffraction losses, also known as glitches of intensity in the energy spectrum of the transmitted/diffracted beam. To be able to handle this negative effect, one needs a reliable way to simulate the glitch spectrum in any configuration. Here, we demonstrate the way of precisely determining the crystallographic orientation and unit cell parameters of optical elements just from a small glitch spectrum with the consequent possibility of simulating glitches for any energy.
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Baykal, Altan, and Ali Alpar. "Expectancy of large pulsar glitches." International Astronomical Union Colloquium 160 (1996): 105–6. http://dx.doi.org/10.1017/s0252921100041154.
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AbstractWe study the expectancy of large glitches (ΔΩ/Ω > 10−7) from a sample of 472 pulsars other than the Vela pulsar. The pulsars in this sample have exhibited 20 large glitches. In the sample the total observation span is larger than 2000 pulsar years. We assume that all pulsars experience such glitches, with rates that depend on the pulsars’ rotation rate and spin-down rate, and on the glitch model. The superfluid vortex unpinning model gives good agreement with the observed distribution of glitches and with the parameter values deduced for the Vela pulsar glitches.
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RAMPONE, SALVATORE, VINCENZO PIERRO, LUIGI TROIANO, and INNOCENZO M. PINTO. "NEURAL NETWORK AIDED GLITCH-BURST DISCRIMINATION AND GLITCH CLASSIFICATION." International Journal of Modern Physics C 24, no. 11 (October 14, 2013): 1350084. http://dx.doi.org/10.1142/s0129183113500848.
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We investigate the potential of neural-network based classifiers for discriminating gravitational wave bursts (GWBs) of a given canonical family (e.g. core-collapse supernova waveforms) from typical transient instrumental artifacts (glitches), in the data of a single detector. The further classification of glitches into typical sets is explored. In order to provide a proof of concept, we use the core-collapse supernova waveform catalog produced by H. Dimmelmeier and co-Workers, and the data base of glitches observed in laser interferometer gravitational wave observatory (LIGO) data maintained by P. Saulson and co-Workers to construct datasets of (windowed) transient waveforms (glitches and bursts) in additive (Gaussian and compound-Gaussian) noise with different signal-to-noise ratios (SNR). Principal component analysis (PCA) is next implemented for reducing data dimensionality, yielding results consistent with, and extending those in the literature. Then, a multilayer perceptron is trained by a backpropagation algorithm (MLP-BP) on a data subset, and used to classify the transients as glitch or burst. A Self-Organizing Map (SOM) architecture is finally used to classify the glitches. The glitch/burst discrimination and glitch classification abilities are gauged in terms of the related truth tables. Preliminary results suggest that the approach is effective and robust throughout the SNR range of practical interest. Perspective applications pertain both to distributed (network, multisensor) detection of GWBs, where some intelligence at the single node level can be introduced, and instrument diagnostics/optimization, where spurious transients can be identified, classified and hopefully traced back to their entry points.
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Tang, Zheng, Lirong Zheng, Shengqi Chu, Min Wu, Pengfei An, Long Zhang, and Tiandou Hu. "Optimal azimuthal orientation for Si(111) double-crystal monochromators to achieve the least amount of glitches in the hard X-ray region." Journal of Synchrotron Radiation 22, no. 5 (July 15, 2015): 1147–50. http://dx.doi.org/10.1107/s1600577515012345.
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Simulations of the periods, split regularities and mirror symmetries of the glitch pattern of a Si(111) crystal along with the azimuthal angles are presented. The glitch patterns of Si(111) double-crystal monochromators (DCMs) are found to be the superposition of the two sets of glitch patterns from the two crystals. The optimal azimuthal orientation φ1,2= [(2n+1)π]/6 (n= 0, ±1, ±2…) for Si(111) DCMs to achieve the least amount of glitches in the hard X-ray region has been suggested.
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Shang, Xinle, and Ang Li. "Revisiting the Post-glitch Relaxation of the 2000 Vela Glitch with the Neutron Star Equation of States in the Brueckner and Relativistic Brueckner Theories." Astrophysical Journal 923, no. 1 (December 1, 2021): 108. http://dx.doi.org/10.3847/1538-4357/ac2e94.
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Abstract We revisit the short-term post-glitch relaxation of the Vela 2000 glitch in the simple two-component model of the pulsar glitch by making use of the latest realistic equations of states from the microscopic Brueckner and the relativistic Brueckner theories for neutron stars, which can reconcile with the available astrophysical constraints. We show that to fit both the glitch size and the post-glitch jumps in frequency derivatives approximately 1 minute after the glitch, the mass of the Vela pulsar is necessarily small, and there may be demands for a stiff equation of state (which results in a typical stellar radius larger than ∼12.5 km) and a strong suppression of the pairing gap in the nuclear medium. We discuss the implications of this result on the understanding of pulsar glitches.
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SHIMIZU, Koichi, Daisuke SUZUKI, and Tomomi KASUYA. "Glitch PUF: Extracting Information from Usually Unwanted Glitches." IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences E95-A, no. 1 (2012): 223–33. http://dx.doi.org/10.1587/transfun.e95.a.223.
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Lyne, A. G. "A Massive Glitch in PSR 0355+54." Symposium - International Astronomical Union 125 (1987): 63. http://dx.doi.org/10.1017/s0074180900160498.
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Pulse timing observations at Jodrell Bank have shown that the relatively old pulsar PSR 0355+54 has suffered two glitches in the last 18 months, the second glitch being larger than any previously observed in any pulsar.
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Schnabel, Marc Aurel, and Blaire Haslop. "Glitch architecture." International Journal of Architectural Computing 16, no. 3 (September 2018): 183–98. http://dx.doi.org/10.1177/1478077118792376.
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Architectural designs are visualised on computer screens through arrays of pixels and vectors. These representations differ from the reality of buildings, which over time will unavoidably age and decay. How, then, do digital designs age over time? Do we interpret glitching as a sudden malfunction or fault in the computation of the design’s underlying data, or as digital decay resulting not from the wear and tear of tangible materials but from the decomposition of the binary code, or from system changes that cannot appropriately interpret the data? By exploring a series of experimental design practices for deployments and understandings that are the consequence of malfunctions during computational processing, glitches are reinterpreted. Advancing from two-dimensional glitch art techniques into three-dimensional interpretations, the research employs a methodology of systematic iterative processes to explore design emergence based on glitches. The study presents digital architectural form existing solely in the digital realm, as an architectural interpretation of computational glitches through both its design process and aesthetic outcome. Thus, this research intends to bring a level of authenticity to the field through three-dimensional interpretations of glitch in an architectural form.
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Sokolova, E. V., and A. G. Panin. "Search for glitches in gamma-ray pulsars with deep learning." Astronomy & Astrophysics 660 (April 2022): A43. http://dx.doi.org/10.1051/0004-6361/202038822.
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Pulsar glitches are generally assumed to be an apparent manifestation of the superfluid interior of neutron stars. Most of them have been discovered and extensively studied by continuous monitoring of radio emission. The Fermi-LAT space telescope has revolutionized the field by uncovering a large population of gamma-ray pulsars. In this paper we employ the observations of gamma-ray pulsars to search for new glitches. We developed a method capable of detecting step-like frequency changes associated with glitches in sparse gamma-ray data. The method is based on the calculation of the weighted H-test statistics and consequent glitch identification by a convolutional neural network. The method demonstrates the high accuracy of the Monte Carlo set and is applicable to searching for pulsar glitches in real gamma-ray data.
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Sato, Ryuta. "Generation Mechanism of Quadrant Glitches and Compensation for it in Feed Drive Systems of NC Machine Tools." International Journal of Automation Technology 6, no. 2 (March 5, 2012): 154–62. http://dx.doi.org/10.20965/ijat.2012.p0154.
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Circular motion tests are commonly used to evaluate the accuracy of the motion of feed drive systems. However, large quadrant glitches are often observed in circular trajectories as the motion changes across thexandyquadrants. It is well known that this phenomenon is caused by friction forces acting on the feed drive mechanism. This paper investigates the generation process of quadrant glitches and proposes a quadrant glitch compensator based on the investigation. As a result of the experiments and simulations, it is clarified that the axis velocity does not stay at zero during direction changes and that the proposed generation mechanism model for quadrant glitches accurately describes actual behavior. It is also confirmed that the proposed friction compensator can eliminate quadrant glitches effectively even if the radius and feed rate change.
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Dunn, L., M. E. Lower, and A. Melatos. "Effects of periodicity in observation scheduling on parameter estimation of pulsar glitches." Monthly Notices of the Royal Astronomical Society 504, no. 3 (April 19, 2021): 3399–411. http://dx.doi.org/10.1093/mnras/stab1097.
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ABSTRACT In certain pulsar timing experiments, where observations are scheduled approximately periodically (e.g. daily), timing models with significantly different frequencies (including but not limited to glitch models with different frequency increments) return near-equivalent timing residuals. The average scheduling aperiodicity divided by the phase error due to time-of-arrival uncertainties is a useful indicator when the degeneracy is important. Synthetic data are used to explore the effect of this degeneracy systematically. It is found that phase-coherent tempo2 or temponest-based approaches are biased sometimes towards reporting small glitch sizes regardless of the true glitch size. Local estimates of the spin frequency alleviate this bias. A hidden Markov model is free from bias towards small glitches and announces explicitly the existence of multiple glitch solutions but sometimes fails to recover the correct glitch size. Two glitches in the UTMOST public data release are reassessed, one in PSR J1709−4429 at MJD 58178 and the other in PSR J1452−6036 at MJD 58600. The estimated fractional frequency jump in PSR J1709−4429 is revised upward from Δf/f = (54.6 ± 1.0) × 10−9 to (2432.2 ± 0.1) × 10−9 with the aid of additional data from the Parkes radio telescope. We find that the available UTMOST data for PSR J1452−6036 are consistent with Δf/f = 270 × 10−9 + N/(fT) with N = 0, 1, and 2, where $T \approx 1\, \text{sidereal day}$ is the observation scheduling period. Data from the Parkes radio telescope can be included, and the N = 0 case is selected unambiguously with a combined data set.
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Cunha, M. S., P. P. Avelino, J. Christensen-Dalsgaard, D. Stello, M. Vrard, C. Jiang, and B. Mosser. "Analytical modelling of period spacings across the HR diagram." Monthly Notices of the Royal Astronomical Society 490, no. 1 (September 16, 2019): 909–26. http://dx.doi.org/10.1093/mnras/stz2582.
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ABSTRACT The characterization of stellar cores may be accomplished through the modelling of asteroseismic data from stars exhibiting either gravity-mode or mixed-mode pulsations, potentially shedding light on the physical processes responsible for the production, mixing, and segregation of chemical elements. In this work, we validate against model data an analytical expression for the period spacing that will facilitate the inference of the properties of stellar cores, including the detection and characterization of buoyancy glitches (strong chemical gradients). This asymptotically based analytical expression is tested both in models with and without buoyancy glitches. It does not assume that glitches are small and, consequently, predicts non-sinusoidal glitch-induced period-spacing variations, as often seen in model and real data. We show that the glitch position and width inferred from the fitting of the analytical expression to model data consisting of pure gravity modes are in close agreement (typically better than 7 ${{\ \rm per\ cent}}$ relative difference) with the properties measured directly from the stellar models. In the case of fitting mixed-mode model data, the same expression is shown to reproduce well the numerical results, when the glitch properties are known a priori. In addition, the fits performed to mixed-mode model data reveal a frequency dependence of the coupling coefficient, q, for a moderate-luminosity red-giant-branch model star. Finally, we find that fitting the analytical expression to the mixed-mode period spacings may provide a way to infer the frequencies of the pure acoustic dipole modes that would exist if no coupling took place between acoustic and gravity waves.
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Abbott, R., T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, A. Adams, C. Adams, et al. "Constraints from LIGO O3 Data on Gravitational-wave Emission Due to R-modes in the Glitching Pulsar PSR J0537–6910." Astrophysical Journal 922, no. 1 (November 1, 2021): 71. http://dx.doi.org/10.3847/1538-4357/ac0d52.
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Abstract We present a search for continuous gravitational-wave emission due to r-modes in the pulsar PSR J0537–6910 using data from the LIGO–Virgo Collaboration observing run O3. PSR J0537–6910 is a young energetic X-ray pulsar and is the most frequent glitcher known. The inter-glitch braking index of the pulsar suggests that gravitational-wave emission due to r-mode oscillations may play an important role in the spin evolution of this pulsar. Theoretical models confirm this possibility and predict emission at a level that can be probed by ground-based detectors. In order to explore this scenario, we search for r-mode emission in the epochs between glitches by using a contemporaneous timing ephemeris obtained from NICER data. We do not detect any signals in the theoretically expected band of 86–97 Hz, and report upper limits on the amplitude of the gravitational waves. Our results improve on previous amplitude upper limits from r-modes in J0537-6910 by a factor of up to 3 and place stringent constraints on theoretical models for r-mode-driven spin-down in PSR J0537–6910, especially for higher frequencies at which our results reach below the spin-down limit defined by energy conservation.
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Fuentes, J. R., C. M. Espinoza, and A. Reisenegger. "The glitch activity of rotation-powered pulsars." Proceedings of the International Astronomical Union 13, S337 (September 2017): 217–20. http://dx.doi.org/10.1017/s1743921317009644.
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AbstractA statistical study of the glitch population and the behavior of the glitch activity across the known population of neutron stars is presented. A constant ratio between the glitch activity and the spin-down rate $\dot{\nu }_{\rm {g}}$/|$\dot{\nu }$| = 0.010 ± 0.001 is consistent with the behavior of all rotation-powered pulsars and magnetars. This relation is dominated by large glitches (Δν ≳ 10 μ Hz), which occur at a rate directly proportional to |$\dot{\nu }$|. The only exception are the rotation-powered pulsars with the highest values of |$\dot{\nu }$|, such as the Crab pulsar and PSR B0540–69, which exhibit a much smaller glitch activity, intrinsically different from each other and from the rest of the population. This contribution is based on the work done by Fuentes et al. (2017) “The glitch activity of neutron stars”, accepted for publication in A&A.
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Oda, Mitsunari, Takashi Torihara, Eiji Kondo, and Noriyoshi Kumazawa. "Feasibility Study of a Hybrid Spindle System with Ball and Active Magnetic Bearings for Quadrant Glitch Compensation During End Milling." International Journal of Automation Technology 13, no. 3 (May 5, 2019): 432–39. http://dx.doi.org/10.20965/ijat.2019.p0432.
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Quadrant glitches are caused by friction and motion loss on the feed axis of machine tools. A previously developed method of compensating for quadrant glitches using the feed axis in which the friction model and time series data are not consistent with the actual friction behavior has some problems, making it difficult to construct a feedback system with a high response problems such as a feed axis with a large lost motion. The ultimate goal of this study is to develop an innovative method of compensating for the quadrant glitches caused by the motion of the feed axis of the machine tool using a newly proposed hybrid spindle system with an active magnetic bearing at the end near the end mill and a ball bearing at the other end in combination with a proportional-integral-derivative controller. This study aims to verify the effectiveness of the proposed quadrant glitch compensation method through experiments on the motion of the end mill using a model experimental device for the hybrid spindle system. Through experiments, a quadrant glitch with a peak of 7 μm without compensation is decreased to 1 μm by applying the proposed method using the hybrid spindle system. The undercut error is also decreased by applying the proposed method.
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Eya, I. O., J. O. Urama, and A. E. Chukwude. "ENTRAINMENT FACTOR OF INDIVIDUAL GLITCH FRACTIONAL MOMENT OF INERTIA." Revista Mexicana de Astronomía y Astrofísica 55, no. 1 (May 31, 2019): 3–9. http://dx.doi.org/10.22201/ia.01851101p.2019.55.01.01.
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The superfluid in the inner crust of a neutron star is assumed to be the reservoir of momentum released in a pulsar glitch. Recently, due to crustal entrainment, it appears debatable whether the magnitude of the inner crust is sufficient to contain the superfluid responsible for large glitches. This paper calculates the fractional moment of inertia (FMI)(i.e. the ratio of the inner crust superfluid moment of inertia to that of the coupled components) associated with individual glitches. It is shown that the effective moment of inertia associated with the transferred momentum is that of the entrained neutrons. The FMI for glitches in three pulsars, which exhibit the signature of exhausting their momentum reservoir, were calculated and scaled with the entrainment factor. Some of the glitches require an inner crust superfluid with moment of inertia larger than the current suggested values of 7-10% of the stellar moment of inertia.
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Flanagan, Claire S. "Twelve years of Glitches in the Vela Pulsar." International Astronomical Union Colloquium 160 (1996): 103–4. http://dx.doi.org/10.1017/s0252921100041142.
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The Vela pulsar (PSR B0833–45) has been observed from Hartebeesthoek RAO since 1984, as part of an ongoing monitoring project. During this time, the pulsar has undergone five sudden and relatively large spin-ups (“glitches”). Good observational coverage was obtained for the four most recent of these events.The post-glitch behaviour of(t) is modelled by:
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Ho, Wynn C. G., Cristóbal M. Espinoza, Danai Antonopoulou, and Nils Andersson. "Pinning down the superfluid and measuring masses using pulsar glitches." Science Advances 1, no. 9 (October 2015): e1500578. http://dx.doi.org/10.1126/sciadv.1500578.
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Pulsars are known for their superb timing precision, although glitches can interrupt the regular timing behavior when the stars are young. These glitches are thought to be caused by interactions between normal and superfluid matter in the crust of the star. However, glitching pulsars such as Vela have been shown to require a superfluid reservoir that greatly exceeds that available in the crust. We examine a model in which glitches tap the superfluid in the core. We test a variety of theoretical superfluid models against the most recent glitch data and find that only one model can successfully explain up to 45 years of observational data. We develop a new technique for combining radio and x-ray data to measure pulsar masses, thereby demonstrating how current and future telescopes can probe fundamental physics such as superfluidity near nuclear saturation.
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CHUNG, KI-SEOK, TAEWHAN KIM, and C. L. LIU. "A COMPLETE MODEL FOR GLITCH ANALYSIS IN LOGIC CIRCUITS." Journal of Circuits, Systems and Computers 11, no. 02 (April 2002): 137–53. http://dx.doi.org/10.1142/s0218126602000367.
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One of the major factors, which contribute to the power consumption in CMOS combinational logic circuits, is the switching activities in the circuits. Many of such switching activities are due to spurious pulses, called glitches. Recently, a new model of glitch analysis, called G-vector has been proposed. The power of the model is that, unlike the existing ones, which model only the propagation of glitches to count the number of glitches in the circuits, it allows to model the generation, propagation and elimination of glitches to be able to not only count the number of glitches but also locate the glitches. In this paper, we complete the concept of G-vector by providing a set of efficient solutions to the three important practical issues: (1) extending to signals over multiple clock cycles, which exactly accounts for a sequence of input signals over multiple clock cycles. (2) extending to a nonzero delay model, which accounts for both nonzero and nonuniform delay of each gate in the circuit and (3) extending to a logic decomposition utilizing the model, which reveals a possibility of utilizing the model in synthesizing logic circuit with less glitches. Integrating the solutions all together enables G-vector to be practically very efficient. A set of experimental results is provided to show the effectiveness of the proposed solutions.
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Udall, R. P., and D. Davis. "Bayesian modeling of scattered light in the LIGO interferometers." Applied Physics Letters 122, no. 9 (February 27, 2023): 094103. http://dx.doi.org/10.1063/5.0136896.
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Excess noise from scattered light poses a persistent challenge in the analysis of data from gravitational wave detectors such as Laser Interferometer Gravitational-wave Observatory. We integrate a physically motivated model for the behavior of these “glitches” into a standard Bayesian analysis pipeline used in gravitational wave science. This allows for the inference of the free parameters in this model, and subtraction of these models to produce glitch-free versions of the data. We show that this inference is an effective discriminator of the presence of the features of these glitches, even when those features may not be discernible in standard visualizations of the data.
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Rafan, N. A., Z. Jamaludin, T. Tjahjowidodo, L. S. Chey, and T. H. Chiew. "Theoretical Analysis of Friction Compensation Using Sliding Mode Control." Applied Mechanics and Materials 229-231 (November 2012): 2385–88. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.2385.
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Friction is an undesired nonlinear phenomenon that reduces position and tracking accuracy in machine tools application. This paper focuses on development of control technique to compensate friction force at motion reversal of a drive system that generates quadrant glitch phenomenon thus improving tracking accuracy. Sliding Mode Control (SMC) is designed to compensate friction. The Generalized Maxwell-Slip (GMS) friction model is applied for numerical analysis. The performance of the controller is analysed based on the reduction in the quadrant glitches magnitude. The performance of the SMC controller is compared with the classical PID controller. Results show that SMC controller yields the smallest quadrant glitch magnitudes.
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Bridges, Frank, Xun Wang, and J. B. Boyce. "Minimizing “glitches” in XAFS data: A model for glitch formation." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 307, no. 2-3 (October 1991): 316–24. http://dx.doi.org/10.1016/0168-9002(91)90199-z.
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Haskell, B., D. Antonopoulou, and C. Barenghi. "Turbulent, pinned superfluids in neutron stars and pulsar glitch recoveries." Monthly Notices of the Royal Astronomical Society 499, no. 1 (September 4, 2020): 161–70. http://dx.doi.org/10.1093/mnras/staa2678.
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ABSTRACT Pulsar glitches offer an insight into the dynamics of superfluids in the high-density interior of a neutron star. To model these phenomena, however, one needs to have an understanding of the dynamics of a turbulent array of superfluid vortices moving through a pinning lattice. In this paper, we develop a theoretical approach to describe vortex-mediated mutual friction in a pinned, turbulent and rotating superfluid. Our model is then applied to the study of the post-glitch rotational evolution in the Vela pulsar and in PSR J0537-6910. We show that in both cases a turbulent model fits the evolution of the spin frequency derivative better than a laminar one. We also predict that the second derivative of the frequency after a glitch should be correlated with the waiting time since the previous glitch, which we find to be consistent with observational data for these pulsars. The main conclusion of this paper is that in the post-glitch rotational evolution of these two pulsars we are most likely observing the response to the glitch of a pinned turbulent region of the star (possibly the crust) and not the laminar response of a regular straight vortex array.
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Zareei, Mo H., Dale A. Carnegie, and Ajay Kapur. "Physical Glitch Music: A Brutalist Noise Ensemble." Leonardo Music Journal 25 (December 2015): 63–67. http://dx.doi.org/10.1162/lmj_a_00937.
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This article introduces an ensemble of mechatronic sound-sculptures designed and developed to realize glitch music outside of computers; the sculptures instead create glitches mechanically, physically and visibly. A brief description of the three different instrument types forming the ensemble is followed by a discussion of how the sound-sculptures employ a Brutalist “anti-beauty” approach in terms of both design and ideology.
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Gügercinoğlu, Erbil, and M. Ali Alpar. "The 2016 Vela glitch: a key to neutron star internal structure and dynamics." Monthly Notices of the Royal Astronomical Society 496, no. 2 (June 23, 2020): 2506–15. http://dx.doi.org/10.1093/mnras/staa1672.
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ABSTRACT High-resolution, pulse-to-pulse observation of the 2016 Vela glitch and its relaxation provided an opportunity to probe the neutron star internal structure and dynamics with unprecedented detail. We use the observations of this glitch to infer superfluid characteristics in the framework of the vortex creep model. The glitch rise time constraint of 12.6 s put stringent limits on the angular momentum exchange between the crustal superfluid and the observed crust. Together with the observed excess acceleration in the rotation rate as compared to the post-glitch equilibrium value, this discriminates crustal superfluid-crust lattice and core superfluid-crustal normal matter coupling time-scales. An evident decrease in the crustal rotation rate immediately before the glitch is consistent with the formation of a new vortex trap zone that initiates the large-scale vortex unpinning avalanche. Formation of vortex trap by a crust breaking quake induces short-lived magnetospheric changes. The long-term post-glitch spin-down rate evolution reveals the moments of inertia and recoupling time-scales of the superfluid layers participating in the glitch and leads to an estimation of the time to the next glitch that agrees with the time interval between the 2016 and 2019 glitches. Our results are consistent with theoretical estimates of effective neutron and proton masses in the superfluid. We also constrain the vortex line-flux tube pinning energy per intersection as 2 MeV.
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Matthews, Linda, and Gavin Perin. "Exploiting ambiguity: The diffraction artefact and the architectural surface." International Journal of Architectural Computing 17, no. 1 (March 2019): 103–15. http://dx.doi.org/10.1177/1478077118804153.
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In the contemporary ‘envisioned’ environment, Internet webcams, low- and high-altitude unmanned aerial vehicles and satellites are the new vantage points from which to construct the image of the city. Armed with hi-resolution digital optical technologies, these vantage points effectively constitute a ubiquitous visioning apparatus serving either the politics of promotion or surveillance. Given the political dimensions of this apparatus, it is important to note that this digital imaging of public urban space refers to the human visual system model. In order to mimic human vision, a set of algorithm patterns are used to direct numerous ‘soft’ and ‘hard’ technologies. Mimicry thus has a cost because this insistence on the human visual system model necessitates multiple transformative moments in the production and transmission pipeline. If each transformative moment opens a potential vulnerability within the visioning apparatus, then every glitch testifies to the artificiality of the image. Moreover, every glitch potentially interrupts the political narratives be communicated in contemporary image production and transmission. Paradoxically, the current use of scripting to create glitch-like images has reimagined glitches as a discrete aesthetic category. This article counters this aestheticisation by asserting glitching as a disruption in communication. The argument will rely on scaled tests produced by one of the authors who show how duplicating the digital algorithmic patterns used within the digital imaging pipeline on any exterior building surface glitches the visual data captured within that image. Referencing image-based techniques drawn from the Baroque and contemporary modes of camouflage, it will be argued that the visual aberrations created by these algorithm-based patterned facades can modify strategically the ‘emission signature’ of selected parts of the urban fabric. In this way, the glitch becomes a way to intercede in the digital portrayal of city.
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WANG, N., J. P. YUAN, Z. Y. LIU, J. B. WANG, and C. ZHU. "RECENT PROGRESS ON PULSAR OBSERVATIONS AT NANSHAN." International Journal of Modern Physics: Conference Series 23 (January 2013): 152–56. http://dx.doi.org/10.1142/s2010194513011215.
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Recent results of pulsar observations at Nanshan are present in this paper. In total 47 glitches were detected in the young pulsars, including a giant glitch in PSR B2334+61. We also investigated the scintillation parameters with the quasi-continuous observations of PSR B0329+54 spanning twenty days. Mainly using the same dataset, consecutive mode-switching events were analyzed in pulse profiles of PSR B0329+54.
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Parthasarathy, A., S. Johnston, R. M. Shannon, L. Lentati, M. Bailes, S. Dai, M. Kerr, et al. "Timing of young radio pulsars – II. Braking indices and their interpretation." Monthly Notices of the Royal Astronomical Society 494, no. 2 (April 9, 2020): 2012–26. http://dx.doi.org/10.1093/mnras/staa882.
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ABSTRACT In Paper I of this series, we detected a significant value of the braking index (n) for 19 young, high-$\dot{E}$ radio pulsars using ∼10 yr of timing observations from the 64-m Parkes radio telescope. Here, we investigate this result in more detail using a Bayesian pulsar timing framework to model timing noise and to perform selection to distinguish between models containing exponential glitch recovery and braking index signatures. We show that consistent values of n are maintained with the addition of substantial archival data, even in the presence of glitches. We provide strong arguments that our measurements are unlikely due to exponential recovery signals from unseen glitches even though glitches play a key role in the evolution of a pulsar’s spin frequency. We conclude that, at least over decadal time-scales, the value of n can be significantly larger than the canonical 3 and discuss the implications for the evolution of pulsars.
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Montoli, Alessandro, Marco Antonelli, Brynmor Haskell, and Pierre Pizzochero. "Statistical Estimates of the Pulsar Glitch Activity." Universe 7, no. 1 (January 5, 2021): 8. http://dx.doi.org/10.3390/universe7010008.
Full textAbstract:
A common way to calculate the glitch activity of a pulsar is an ordinary linear regression of the observed cumulative glitch history. This method however is likely to underestimate the errors on the activity, as it implicitly assumes a (long-term) linear dependence between glitch sizes and waiting times, as well as equal variance, i.e., homoscedasticity, in the fit residuals, both assumptions that are not well justified from pulsar data. In this paper, we review the extrapolation of the glitch activity parameter and explore two alternatives: the relaxation of the homoscedasticity hypothesis in the linear fit and the use of the bootstrap technique. We find a larger uncertainty in the activity with respect to that obtained by ordinary linear regression, especially for those objects in which it can be significantly affected by a single glitch. We discuss how this affects the theoretical upper bound on the moment of inertia associated with the region of a neutron star containing the superfluid reservoir of angular momentum released in a stationary sequence of glitches. We find that this upper bound is less tight if one considers the uncertainty on the activity estimated with the bootstrap method and allows for models in which the superfluid reservoir is entirely in the crust.