老挝固体钾盐矿选矿设计的优化与创新—以开元500 kt/a氯化钾项目为例

选矿厂设计是矿山建设中极其重要的关键环节。做好选矿厂设计工作,对于节省项目建设投资,确保工厂如期达产达标,并取得良好的经济效益,具有决定性的作用。本文结合老挝开元500 kt/a氯化钾项目选矿厂生产过程中的技术改造与创新,对该类型选矿厂设计进行经验总结,并指明设计中仍需优化与创新的环节。选矿厂设计中工艺流程的选择应具有较强的生产兼容性,且工艺流程主要环节之间有灵活的可切换性,以适应井下开采过程中性质多变的原矿。工艺配置,设备选型和厂房设计既要兼顾原矿和产品性质,也要充分考虑当地的气候条件和自然环境。厂房和工艺设备的防腐,自动化技术的开发应用和工艺流程样品的自动采集与分析是未来仍需优化和创新的重要环节。本研究可为今后同类选矿厂的设计提供有益的参考。     

GPS归心盘的一种新设计

分析了GPS测点的现状,论述了进行GPS归心盘优化设计的必要性及新设计GPS归心盘的主要特点,简要叙述了GPS归心盘在重庆市GPS建设中的应用情况及良好效果,为今后的高精度GPS建设提供了一种方法经验。     

中国金矿床T／S（T／V）分布及其意义

对中国大陆境内１３８个已勘探岩金矿床的Ｔ／Ｓ（Ｔ／Ｖ）数据进行了统计,结果表明,Ｔ／Ｓ（Ｔ／Ｖ）分布是一个多重分开明。成矿作用强度具有层次性和一定尺度内的无标度性,这一事实构成了建立矿床分级预测模型的基础。此外,Ｔ／Ｓ（Ｔ／Ｖ）的统计研究提供了划分矿床级别的另一可行途径。     

Colliding winds in V1016 Cygni

We present MERLIN observations of the symbiotic nova V1016 Cygni made at 6 cm between 1992 and 1997 and at 18 cm in 1993 and 1997. In the 6-cm images we find complex structure which has not been previously seen, in particular three bright components. These components do not appear to be expanding as would be expected from the remains of a hot wind resulting from the nova outburst. The change in positions of two of the features exhibits tentative east–west movement. The brightness temperature of the peak with the highest flux density remains above 50 000 K in all epochs, thereby confirming the presence of shocked material in the system. At 18 cm there is no evidence of any non-thermal emission as might be expected from comparison with a sister star, HM Sge.     

The continuing saga of Sakurai's object (V4334 Sgr): dust production and helium line emission

We report further UKIRT spectroscopic observations of Sakurai's object (V4334 Sgr) made in 1999 April/May in the 1–4.75 μm range, and find that the emission is dominated by amorphous carbon at T _d~600 K. The estimated maximum grain size is 0.6 μm, and the mass lower limit is 1.7±0.2×10⁻⁸ M_⊙ to 8.9±0.6×10⁻⁷ M_⊙ for distances of 1.1–8 kpc. For 3.8 kpc the mass is 2.0±0.1×10⁻⁷ M_⊙.
We also report strong He  i emission at 1.083 μm, in contrast to the strong absorption in this line in 1998. We conclude that the excitation is collisional, and is probably caused by a wind, consistent with the P Cygni profile observed by Eyres et al. in 1998.     

软岩工程地质力学研究进展

在中国煤矿软岩工程地质力学的研究中 ,作者指出了国际岩石力学学会关于软岩定义的缺陷 ,提出了新的软岩定义和分类 ,并论述了软岩的变形力学机制、软化状态方程、软岩巷道支护理论、支护荷载的确定以及软岩工程地质力学设计方法。可以认为 ,中国软岩工程地质力学已经形成了较为完整的理论框架体系.     

The multi-temperature X-ray spectrum of the intermediate polar V1223 Sagittarii

We describe fits to the Ginga LAC and ASCA GIS and SIS X-ray spectra of the intermediate polar V1223 Sgr using a multi-temperature emission model and including reflection from the white dwarf surface. Shock temperatures of and were obtained for the Ginga LAC, ASCA GIS and SIS instruments, respectively, giving a mean value of The data reveal significant amounts of reflection as well as a heavy metal underabundance by a factor of 2.
Multiple absorption components are required to successfully model the observed X-ray spectra at low energies, suggesting the presence of complex intrinsic absorption. All data sets reveal a low-energy spectral hardening at the minimum in the spin cycle caused by an increase in the amount of absorption at this phase. The requirement of such complex absorption is becoming increasingly common in the good quality X-ray spectra from magnetic cataclysmic variables.     

High-resolution spectroscopy of V854 Cen in decline – absorption and emission lines of C2 molecules

High-resolution optical spectra of the R Coronae Borealis (RCB) star V854 Centauri in the early stages of a decline show, in addition to the features reported for other RCBs in decline, narrow absorption lines from the C₂ Phillips system. The low rotational temperature, T _rot=1150 K, of the C₂ ground electronic state suggests the cold gas is associated with the developing shroud of carbon dust. These absorption lines were not seen at a fainter magnitude on the rise from minimum light, nor at maximum light. This is the first detection of cold gas around an RCB star.     

The evolution of a rapidly accreting helium white dwarf to become a low-luminosity helium star

We have examined the evolution of merged low-mass double white dwarfs which become low-luminosity (or high-gravity) extreme helium stars. We have approximated the merging process by the rapid accretion of matter, consisting mostly of helium, on to a helium white dwarf. After a certain mass is accumulated, a helium shell flash occurs, the radius and luminosity increase and the star becomes a yellow giant. Mass accretion is stopped artificially when the total mass reaches a pre-determined value. As the helium-burning shell moves inwards with repeating shell flashes, the effective temperature gradually increases as the star evolves towards the helium main sequence. When the mass interior to the helium‐burning shell is approximately 0.25 M_⊙, the star enters a regime where it is pulsationally unstable. We have obtained radial pulsation periods for these models.
These models have properties very similar to those of the pulsating helium star V652 Her. We have compared the rate of period change of the theoretical models with that observed in V652 Her, as well as with its position on the Hertzsprung–Russell diagram. We conclude that the merger between two helium white dwarfs can produce a star with properties remarkably similar to those observed in at least one extreme helium star, and is a viable model for their evolutionary origin. Such helium stars will evolve to become hot subdwarfs close to the helium main sequence. We also discuss the number of low-luminosity helium stars in the Galaxy expected for our evolution scenario.