Cyclical Changes in the Timing Residuals from the Pulsar B0919+06

We report the detection of a large glitch in the pulsar B0919+06 (J0922+0638). The glitch occurred in 2009 November 5 (MJD 55140) and was characterized by a fractional increase in the rotation frequency of Deltanu/nu=1.3x10^{-6}. A large glitch happens in the pulsar whose rotation has unstable character. We present the results of the analysis of the rotation behavior of this pulsar over the 30-year time span from 1979 to 2009. These results show that the pulsar's rotation frequency underwent continuous, slow oscillations which look like glitch-like events. During the 1991-2009 interval, the pulsar experienced a continuous sequence of 12 slow glitches with a fractional increase in the rotation frequency Deltanu/nu=1.5x10^{-9}. All the slow glitches observed have a similar signature related to a slow increase in the rotation frequency during 200 days and the subsequent relaxation back to the pre-glitch value during 400 days. We show that a continuous sequence of such slow glitches is characterized by practically identical amplitudes equal to Deltanu=3.5x10^{-9} Hz and identical time intervals between glitches of about 600 days and is well described by a periodic sawtooth-like function. The detection of two different phenomena, such as a large glitch and a sequence of slow glitches, indicates the presence of two types of discontinuities in the rotation frequency of the pulsar B0919+06. These discontinuities can be classified as normal and slow glitches.Comment: 24 pages, 5 figures. Submitted to Ap

Nature of cyclical changes in the timing residuals from the pulsar B1642-03

We report an analysis of timing data for the pulsar B1642-03 (J1645-0317) gathered over the 40-year time span between 1969 and 2008. During this interval, the pulsar experienced eight glitch-like events with a fractional increase in the rotation frequency Deltanu/nu=(0.9-2.6)x10^{-9}. We have revealed two important relations in the properties of these peculiar glitches. The first result shows that there is a strong linear correlation between the amplitude of the glitch and the time interval to the next glitch. The second result shows that the amplitude of the glitches is modulated by a periodic large-scale sawtooth-like function. As a result of this modulation, the glitch amplitude varies discretely from glitch to glitch with a step of 1.5x10^{-9} Hz in the range (2.4-6.9)x10^{-9} Hz. The post-glitch time interval also varies discretely with a step of about 600 days in the range 900-2700 days. An analysis of the data showed that three modulation schemes with modulation periods of 43 years, 53 years and 60 years are possible. The best model is the 60-year modulation scheme including 12 glitches. We make a conclusion that the nature of the observed cyclical changes in the timing residuals from PSR B1642-03 is a continuous generation of peculiar glitches whose amplitudes are modulated by a periodic large-scale sawtooth-like function. As the modulation function is periodical, the picture of cyclical timing residuals will be exactly repeated in each modulation period or every 60 years.Comment: 26 pages, 9 figures. Accepted for publication in the Astrophysical Journa

Observations of three slow glitches in the spin rate of the pulsar B1822-09

Three slow glitches in the rotation rate of the pulsar B1822-09 were revealed over the 1995-2004 interval. The slow glitches observed are characterized by a gradual increase in the rotation frequency with a long timescale of several months, accompanied by a rapid decrease in the magnitude of the frequency first derivative by 1-2 per cent of the initial value and subsequent exponential increase back to its initial value on the same timescale. The cumulative fractional increase in the pulsar rotation rate for the three glitches amounts to Delta_nu/nu ~ 7 10^{-8}.Comment: 11 pages, 3 figures. Accepted for publication in MNRA

29 Glitches Detected at Urumqi Observatory

Glitches detected in pulsar timing observations at the Nanshan radio telescope of Urumqi Observatory between 2002 July and 2008 December are presented. In total, 29 glitches were detected in 19 young pulsars, with this being the first detection of a glitch in 12 of these pulsars. Fractional glitch amplitudes range from a few parts in 10^{-11} to 3.9 x 10^{-6}. Three "slow" glitches are identified in PSRs J0631+1036, B1822-09 and B1907+10. Post-glitch recoveries differ greatly from pulsar to pulsar and for different glitches in the same pulsar. Most large glitches show some evidence for exponential post-glitch recovery on timescales of 100 -- 1000 days, but in some cases, e.g., PSR B1758-23, there is little or no recovery. Beside exponential recoveries, permanent increases in slowdown rate are seen for the two large glitches in PSRs B1800-21 and B1823-13. These and several other pulsars also show a linear increase in nudot following the partial exponential recovery, which is similar to the Vela pulsar post-glitch behaviour. Analysis of the whole sample of known glitches show that fractional glitch amplitudes are correlated with characteristic age with a peak at about 10^5 years, but there is a spread of two or three orders of magnitude at all ages. Glitch activity is positively correlated with spin-down rate, again with a wide spread of values.Comment: 17 pages, 29 figures, 4 tables; accepted by MNRA

Heat-resistant concrete based on alumina cement from substandard raw material

Results are provided for development of refractory concrete based on modified alumina cement using chemical industry waste. A quantitative ratio for mixed filler fractions, the effect of production factors on concrete strength, the dependence of its strength properties on form of filler, and solidification conditions are established. It is shown that with respect to physical mechanical and engineering properties the concretes developed is no worse than those existing in the market.With respect to all engineering properties this form of refractory product may be recommended as lining for high-temperature units

Heat-resistant concrete based on alumina cement from substandard raw material

Results are provided for development of refractory concrete based on modified alumina cement using chemical industry waste. A quantitative ratio for mixed filler fractions, the effect of production factors on concrete strength, the dependence of its strength properties on form of filler, and solidification conditions are established. It is shown that with respect to physical mechanical and engineering properties the concretes developed is no worse than those existing in the market.With respect to all engineering properties this form of refractory product may be recommended as lining for high-temperature units