A Time Evolution Study of the Superhumps of the Dwarf Nova 1RXS J232953.9+062814 by Wavelet Transform

The time evolution behaviour of the superhumps of the dwarf nova1RXS J232953.9+ 062814 is investigated with the wavelet analysis method. On the basis of two nights CCD photometry performed during its first superoutburst as well as other published brightness data, we reveal the superhump's time-dependence as a function of periods and time. Our light curves, which phased in the rapid decay ending portion of the superoutburst and in the dawn of a following normal outburst, are important to help trace the superhump evolution for the star. Both the superhump period and the orbital period of the binary system are detected in the present data. We obtain P _sh=0.0458±0.0002d and P _orb=0.0450±0.0002d. They agree with those existing values. The two periods exchanged their roles during the superhump evolution. The general profile of brightness fading over the outbursts roughly followed an exponential decay law or a form of a five-order polynomial. This revised version was published online in July 2006 with corrections to the Cover Date.     

TRIFFID observations of the cores of the three globular clusters M15, M92 and NGC 6712

We present the results of TRIFFID simultaneous V - and B -band observations of the cores of the globular clusters M15, M92 and NGC 6712. A variability search of their dense centres was made feasible through performing post-exposure image sharpening on the images, increasing the image resolution by a factor of ∼2. The isis implementation of the image subtraction technique developed by Alard & Lupton was then used to detect flux variations in our image sets. We have obtained periods for all observable variables (in our field of view) in NGC 6712 and we have found two new RR Lyrae variables (an RRab and an RRc). We have confirmed three variables in our field of view of the M92. For M15, we detect 48 variables in our field of view, 23 of which are new discoveries. We obtain periods and amplitudes for all variables and classify new ones based on the light-curve shape, the most significant period and the mean magnitude in the V band. Among the detected RR Lyrae we find 19 RRc, 12 RRab and two RRd types. In the subsequent analysis we find a marked increase in RRc over RRab variables in the core. In a refined procedure to search for fainter objects we find no dwarf novae in our field of view of M15. Simulations performed on the data set to quantify our sensitivity to such objects indicate that an upper limit of 10 dwarf novae (at 92 per cent probability) exist in our field of view. The implications this result has on globular clusters are discussed.     

昆仑山口大地震与地形变异常的讨论

针对昆仑山口大地震，总结了多种地形变（大地测量）手段所显示的异常变化及其时空分布，结果显示：8．1级大震前存在空间尺度大，时间尺度的地形变前兆异常，简要介绍了相关的异常图像，给出了初步解释，并对未来震情的发展进行了探讨，认为近期内强震活动向华北迁移的可能性不大。     

北秦岭晋宁期中酸性侵入岩带地球化学特征与构造环境

北秦岭侵入岩带中的中酸性侵入岩主要形成于晋宁旋回的中晚期阶段。主要岩石类型包括辉石闪长岩、闪长岩、石英闪长岩、英云闪长岩、花岗闪长岩、斜长花岗岩、花岗岩和钾长花岗岩。岩石化学、稀土元素和微量元素地球化学研究证明,这些岩石主要形成于B型俯冲和碰撞造山的构造环境中,而钾长花岗岩形成于后造山的伸展阶段。据此,该侵入岩带揭示了北秦岭褶皱带在晋宁旋回中晚期阶段的演化过程。     

A qualitative and quantitative evaluation of experimental model catchment evolution

Due to the geological time scales required for observation of catchment evolution, surrogates or analogues of field data are necessary to understand long‐term processes. To investigate long‐term catchment behaviour, two experimental model catchments that developed without rigid boundaries under controlled conditions are examined and a qualitative and quantitative analysis of their evolution is presented. Qualitatively, the experimental catchments have the visual appearance of field scale data. Observation demonstrates that changes in catchment shape and network form are conservative. Quantitative analysis suggests that the catchments reach an equilibrium form while a reduction in the channel network occurs. While the catchments are laboratory scale models, the results provide insights into field scale behaviour. Copyright © 2003 John Wiley & Sons, Ltd.     

Size and shape evolution of pores in a viscoplastic matrix under compression

The frequent use of soils and earth materials for hydraulic capping and for geo‐environmental waste containment motivated our interest in detailed modelling of changes in size and shape of macro‐pores to establish links between soil mechanical behaviour and concurrent changes in hydraulic and transport properties. The objective of this study was to use finite element analysis (FEA) to test and extend previous analytical solutions proposed by the authors describing deformation of a single macro‐pore embedded in linear viscoplastic soil material subjected to anisotropic remote stress. The FEA enables to consider more complex pore geometries and provides a detailed picture of matrix yield behaviour to explain shortcomings of approximate analytical solutions. Finite element and analytical calculations agreed very well for linear viscous as well as for viscoplastic materials, only limited for the case of isotropic remote stress due to the simplifications of the analytical model related to patterns and onset of matrix‐yielding behaviour. FEA calculations were compared with experimental data obtained from a compaction experiment in which pore deformation within a uniform modelling clay sample was monitored using CAT scanning. FEA predictions based on independently measured material properties and initial pore geometry provided an excellent match with experimentally determined evolution of pore size and shape hence lending credence to the potential use of FEA for more complex pore geometries and eventually connect macro‐pore deformation with hydraulic properties. Copyright © 2006 John Wiley & Sons, Ltd.     

Real-time difference imaging analysis of MOA Galactic bulge observations during 2000

We describe observations carried out by the MOA group of the Galactic bulge during 2000 that were designed to detect efficiently gravitational microlensing of faint stars in which the magnification is high and/or of short duration. These events are particularly useful for studies of extrasolar planets and faint stars. Approximately 17 deg² were monitored at a sampling rate of up to six times per night. The images were analysed in real time using a difference imaging technique. 20 microlensing candidates were detected, of which eight were alerted to the microlensing community whilst in progress. Approximately half of the candidates had high magnifications (≳10), at least one had very high magnification (≳50), and one exhibited a clear parallax effect. The details of these events are reported here, together with details of the on-line difference imaging technique. Some nova-like events were also observed and these are described, together with one asteroid.