矿井煤岩体变形失稳问题的研究

本文对矿井中几种变形失稳现象:煤体冲击地压、矿震、顶底板冲击地压及煤与瓦斯突出,分别建立了煤岩体压缩、剪切、拉伸、固液耦合失稳模型及失稳判别准则,初步构画了矿井煤岩体失稳问题的框架.     

回转分离器内气固两相流的理论分析

详细地推导了回转分离器内颗粒的运动方程,对分离器内颗粒的运动轨迹.特别是在考虑颗粒形状对阻力影响的情况下作了一定程度的计算,将计算结果与球形颗粒运动轨迹进行了比较,并作了适当的分析.此外,还较为详细地介绍了此类问题的数值求解方法.     

下切式节能旋耕刀刃口线设计研究

本文比较了犁耕和旋耕的功耗特点,指出了降低旋耕刀切土功耗的技术途径,并以放射螺线作为刃口线在俯视图中的投影曲线,建立了刃口曲线微分方程式,还讨论了刃口线设计参数取值。所设计的正切刃口曲线将作为曲导线用于构造下切式节能旋耕刀正切刃面。     

精细小件化学热处理滚筒炉的研制

研制了适于精细小零件大批量化学热处理的滚筒炉,有效地解决了薄片状小零件在其它类型炉中散料处理时,由于零件相互堆叠、不能更位而导致加热和与活性气氛接触不均匀所带来的质量问题。为照相机、仪表、标准件等行业提供了一种新型工艺装备。     

调制式旋转导向系统导向力"等力合成模型"的建立与分析

导向力的形成机理是研制旋转导向工具的核心。在深入研究国外旋转导向工具的基础上,参考导弹制导原理,提出了调制式旋转导向工具新的导向方式,建立了导向力"等力合成模型",并对其影响规律进行了分析。结果表明,这种导向方式与PowerDriveSRD导向系统相比,有其独特的优点。控制面不稳定程度对合导向力的影响并不很大,在控制面摆动度达14°时,合导向力仅下降1%。这为调制式旋转导向工具稳定平台的研制提供了宽松的约束条件。     

Peat record reflecting Holocene climatic change in the Zoigê Plateau and AMS radiocarbon dating

Through the use of reliable AMS dating of high resolution (15–30 years) peat and the establishment of monsoon climate proxies sequence, we have been able to recognize several cold, dry events in the Tibetan Plateau during the Holocene. The more obvious ones occurred around 12800, 11300, 10200, 9580, 8900, 6400, 4400, 3700, 2800 and 1500 cal. aBP. These events correlate well with both ice rafting events recorded in high latitude North Atlantic Ocean sediment cores and cooling events in the low latitude SST. Spectral analysis indicates high frequency climate variation on centennial-millennial time scale during the Holocene. This further reflects Holocene climate instability and the existence of centennial-millenium scale rhythm in mid latitude areas as well.     

The mutator phenotype theory can explain the complex morphology and behaviour of cancers

Almost all solid malignancies exhibit complex cytological and architectural abnormalities, which vary from cell to cell and area to area within the same tumour, and between tumours of the same type. The degrees of these abnormalities do not correlate perfectly with the biological behaviour (especially growth rate and metastatic potential) among the various tumour types. These features of tumours have long been considered to invalidate simple mutational or 'abnormal gene expression' (epigenetic) theories of carcinogenesis. The 'mutator phenotype/clonal selection' hypothesis is based on the now well-established phenomenon of genetic instability of cancer cells, and proposes that this instability is an essential requirement for the development of tumours, and not an irrelevant side-effect of some other process. This paper argues that this hypothesis can provide a satisfactory explanation for the diverse histological and biological features of solid malignancies. Further, because virtually all solid tumours are histologically abnormal, genetic instability is likely to be essential for the malignant process. The concepts of mutator phenotype and clonal selection are therefore supported. Received 8 April 2002; accepted 25 April 2002     

浅谈公路黄土边坡坡面防护

在前人进行边坡优化设计的基础上充分考虑了坡面的不稳定因素,对边坡的坡角和坡高等进行设计,并总结了黄土地区边坡坡面的防治措施。     

高阶FD-WENO格式用于Richtmyer-Meshkov不稳定性数值模拟

用双曲守恒律组的高阶加权本质上无振荡有限差分格式(FD-WENO)求解在众多领域有着重要应用的高马赫数二维流体界面Richtmyer-Meshkov不稳定性问题及激波与气泡相互作用问题,获得了较为理想的数值结果。表明高阶FD-WENO格式的确特别适合于求解这类既具有激波有具有复杂流动结构的流体动力学问题,它比通常的二阶Godunov格式(如PPM等)更为优越。