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1.
In this paper the researchers collected 28 times of maximum light including 4 times of those observed at the Xinglong station,
the National Astronomical Observation of China between May 27, 2004 and June 1, 2004 and 1 time of maximum light from a 60
cm telescope on May 4, 1984. It found that the O-C point distribution was more completely compared than in any papers published
before. The period is decreasing at the rate of about (1.4±0.1)×10−8 per year, which should not be caused by stellar evolution. It might be only part of a binary orbital light-time variation
or other unknown reason. The time scale is longer than Pocs and Szeidl’s suggestion; the star needs more observations before
we can be certain of the exact light-time variation. 相似文献
2.
Jian-Ning Fu Chao Zhang Kanokwan Marak Chayan Boonyarak Pongsak Khokhuntod Shi-Yang Jiang 《中国天文和天体物理学报》2008,8(2):237-244
New time-series photometric observations of BL Cam in the V band and white light were made during 2005 to 2007 at the Xinglong Station of China. The frequency analysis confirms two closely separated frequencies, 25.181 d-1 and 25.571 d-1, but the frequency of 31-32 d-1 reported in the literature was not detected in the new data. New times of maximum light were determined from both our light curves and those available on Internet, allowing a more comprehensive study of the O - C diagram, together with the times of maximum light in the literature. A new interpretation, including the period increasing before 1988 and decreasing since 1992 of BL Cam and the light-time effect in a binary system, looks plausible. 相似文献
3.
The rocks of the Delhi Supergroup, which occur around Barr-Sendra and Phulad-Deogarh regions in Central Rajasthan, show three
phases of deformational episodes: (i) phase D1—tight-to-long limbed isoclinal fold (F1); phase D2—open, asymmetric fold (F
2) controlling the map pattern of the formational boundaries; and (iii) phase D3—major warps (F3). Interference between nearly coaxial F1 and F2 on northerly axes produced hook-shaped and crescent patterns whereas superimposition of easterly trending F3 on F2 produced dome-and-basin patterns. The thermal peak was achieved during the second phase of deformation when the rocks were
constructively metamorphozed and granites (850−750 m.y.), late synkinematic with respect to second phase of deformation, were
emplaced. The sequence of deformation and the structural pattern of the rocks of the Delhi Supergroup in Central Rajasthan
strikingly resemble those in northeastern Rajasthan. Structurally the characteristics of the Delhi Supergroup as verified
in the entire region from NE to Central Rajasthan are: (a) the same sequence of development of folds, F1, F2 and F3, interspersed with nearly identical phases of recrystallization, (b) hook-shaped interference pattern due to near-coaxial
refolding of F1 by F2, and (c) variation in axial plunge of F2 resulting in culminations and depressions. Lastly, phases of the recrystallization history indicates little time gap between
F1 and F2, and a considerable gap between F2 and F3. 相似文献
4.
S. Narayanan N. Raghunathan U. B. Nayak A. K. Lahiri 《International Journal of Mineral Processing》1983,10(4):309-317
The effect of surface-active agents in improving the grinding efficiency for haematite, expressed as a measure of reduction ratio, has been studied. Drying of the feed before grinding has been found to improve the grinding efficiency. The effect of surfactant additions on hardness, microhardness, crushing strength and wet grinding of haematite has shown that dispersants are better than flocculants, and each dispersant has a critical concentration at which the grinding efficiency is maximum. 相似文献
5.
Sudipta Lahiri 《Journal of the Indian Society of Remote Sensing》1996,24(4):265-272
Spatial characteristies of drainage geometry of Brahmaputra river and its tributaries were studied based on visual interpretation of 1RS IB imagery (on 1:250,000 scale) and topographical maps of different periods. Observed features of drainage lines alongwith possible mechanism of their formation in terms of neotectouie adjustment are discussed It is inferred that selected stretches of Brahmaputra river viz. between Dibrugarh and Jorhat and between Guwahati and Goafpara may represent channels with active boundaries that have restrieted/controlled the width of sinuous lines of discharge of the river within the valley. Local tilting of ground, lying to the south-east of Brahmaputra river, between Noa Dihing and Burhi Dihing rivers, may explain some of the observed features of these drainage lines Movement along some lineaments in recent past has occurred. This inference is based on the evidence of adjustment of several drainage lines viz, Dihing. Burhi Dihing. Dikrang. and Mora Bhareh rivers and displacement of rocks of younger age. 相似文献
6.
Motivated by some previous works of Rudra et al. we set to explore the background dynamics when dark energy in the form of New Variable Modified Chaplygin gas is coupled to dark matter with a suitable interaction in the universe described by brane cosmology. The main idea is to find out the efficiency of New variable modified Chaplygin gas to play the role of DE. As a result we resort to the technique of comparison with standard dark energy models. Here the RSII brane model have been considered as the gravity theory. An interacting model is considered in order to search for a possible solution of the cosmic coincidence problem. A dynamical system analysis is performed because of the high complexity of the system. The statefinder parameters are also calculated to classify the dark energy model. Graphs and phase diagrams are drawn to study the variations of these parameters and get an insight into the effectiveness of the dark energy model. It is also seen that the background dynamics of New Variable Modified Chaplygin gas is consistent with the late cosmic acceleration. After performing an extensive mathematical analysis, we are able to constrain the parameters of new variable modified Chaplygin gas as m<n to produce the best possible results. Future singularities are studied and it is found that the model has a tendency to result in such singularities unlike the case of generalized cosmic Chaplygin gas. Our investigation leads us to the fact that New Variable Modified Chaplygin gas is not as effective as other Chaplygin gas models to play the role of dark energy. 相似文献
7.
Chayan Boonyarak Jian-Ning Fu Pongsak Khokhuntod Shi-Yang Jiang 《Astrophysics and Space Science》2011,333(1):125-131
A 16-inch Schmidt-Cassegrain telescope on the campus of Naresuan University of Thailand and several similar-size telescopes
in China equipped with CCD cameras were used to observe 14 high amplitude delta Scuti stars: GP And, CY Aqr, BS Aqr, YZ Boo,
AD CMi, VZ Cnc, EH Lib, DY Her, V927 Her, KZ Hya, BE Lyn, V1162 Ori, DY Peg, and CW Ser, between the years 1999 and 2010.
Data were also collected from scientific journals and sources on the Internet for these variable stars. Times of light maximum
of these delta Scuti stars were then either determined from the observations or obtained from the literature to analyze the
pulsation period variations. For the 14 delta Scuti stars we concluded that 7 stars (BS Aqr, CY Aqr, AD CMi, EH Lib, KZ Hya,
BE Lyn and DY Peg) are binary or multiple systems. 10 delta Scuti stars are found with periods increasing with rates between
5.86×10−9 and 2.34×10−6 per year and the other 4 stars (BS Aqr, DY Her, BE Lyn and DY Peg) show periods decreasing with rates of about 10−9 to 10−8 per year. 相似文献
8.
Ai-Ying Zhou Shi-Yang Jiang B. Chayan Bai-Tian Du 《Astrophysics and Space Science》2002,281(4):699-714
The new time-resolved CCD photometry of XX Cyg was presented. We investigate the time-dependent behaviour of the light variations
by reanalyzing the data in the literature. XX Cyg was demonstrated beyond any doubt again to be a monoperiodic pulsator. Its
light curves can be well reproduced by the sinusoids with the fundamental frequency f
0 = 7.41481 ± 0.00001 cycle d-1(P
0 = 0d
. 1348652 ± 0.0000001) and its first nine harmonics. Fourier, wavelet and O–C analyses based on all the available data reveals
the amplitude and period variations during the years 1974 to 2000.The general trend of the amplitude changes is decreasing
at a rate of one percent milli-magnitudes per year. The parabolic analysis on the updated 101 times of maximum light suggests
a slowly continuous increasing at a rate of 1.3 × 10-3 days per million years in the period.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Chayan Ranjit Shuvendu Chakraborty Ujjal Debnath 《Astrophysics and Space Science》2013,346(1):291-299
In this work, we have considered the flat FRW model of the universe in (n+2)-dimensions filled with the dark matter and the magnetic field. We present the Hubble parameter in terms of the observable parameters Ω m0 and H 0 with the redshift z and the other parameters like B 0, ω, μ 0, δ, n, w m . The natures of magnetic field B, deceleration parameter q and $\operatorname{Om}$ diagnostic have also been analyzed for accelerating expansion of the universe. From Stern data set (12 points), we have obtained the bounds of the arbitrary parameters by minimizing the χ 2 test. The best-fit values of the parameters are obtained by 66 %, 90 % and 99 % confidence levels. Now to find the bounds of the parameters (B 0,ω) and to draw the statistical confidence contour, we fixed four parameters μ 0, δ, n, w m . Here the parameter n determines the higher dimensions and we perform comparative study between three cases: 4D (n=2), 5D (n=3) and 6D (n=4) respectively. Next due to joint analysis with BAO observation, we have also obtained the bounds of the parameters (B 0,ω) by fixing other parameters μ 0, δ, n, w m for 4D, 5D and 6D. The best fit of distance modulus for our theoretical model and the Supernova Type Ia Union2 sample are drawn for different dimensions. 相似文献
10.
Saturated wetland soils are typically depleted in oxygen due to rapid consumption by biological processes. Fine-grained sediments limit the vertical flux of oxygenated surface water. In forested wetlands potential exists for advective transport along preferential flow pathways created by decomposing roots or tree remains, resulting in isolated zones of oxygenated pore water. This potential is enhanced in wetlands that are perched above the regional water table, where increases in surface-water depth create significant downward hydraulic gradients. Along the Mississippi River floodplain, many wetlands are now perched as a result of groundwater mining. This study was conducted at Sky Lake, MS, through a growing season, with high temporal-resolution monitoring of redox potential as a proxy for the delivery of oxygenated surface water at 30 and 60 cm depths at six locations. Results showed reducing conditions at all locations under moderate inundation, but redox potential rose significantly at a subset of locations when surface-water exceeded one meter in depth. Rising redox potential is argued to represent localised advective transport of oxygen in excess of the rate of biological consumption. Wetland plants growing in perennially saturated soils may benefit from periodic increases in water depth and subsequent increase in the flux of oxygen along preferential flow paths. 相似文献