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Bryophyte-like Fossil （Parafunaria sinensis） from Early-Middle Cambrian Kaili Formation in Guizhou Province, China

Acta Botanica Sinica 2004年第2期46卷 180-185页

作者： YANGRui-Dong MAOJia-Rer ZHANGWei-Hua JIANGLi-Jun GAOHui guizhouuniversityoftechnology Guiyang550003China

Abundant well-preserved animal and macroalgal fossils were discovered in the Early-MiddleCambrian Kaili Formation of Taijiang County, Guizhou Province, China, which constitute the Kaili Biota,named as one of the three important Burgess Shale-type faunas. The bryophyte-like fossil (Parafunariasinensis Yang gen. et sp. nov) was discovered in the horizon of occurrence of Macroalgal fossils. The fossilof P. sinensis possesses typical characters of bryophyte, such as whorled leaves, capsule and seta, andcomplex rhizoid or foot. We infer that the bryophyte-like fossil could be the ancestor of bryophyte. Thediscovery provides a new lead for further study on the origin and evolution of bryophyte or land plant.

关键词：类似藓类植物凯里组中寒武世贵州化石生物群

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Dynamics of Gradient Bioceramic Composite Coating on Surface of Titanium Alloy by Wide-Band Laser Cladding

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Journal of Iron and Steel Research(International) 2004年第6期11卷 57-62页

作者： LIUQi-bin ZOULong-jiang ZHUWei-dong LIHai-tao DONGChuang DalianUniversityofTechnology Dalian116024China guizhouuniversityoftechnology Guiyang550003China

The gradient bioceramic coating was prepared on the surface of titanium alloy using wide-band laser cladding.The dynamics of gradient bioceramic composite coating containing hydroxyapatite(HA)prepared with mixture of CaHPO4·2H2O and CaCO3 under the condition of wide-band laser was studied theoretically.The corresponding mathematical model and its numerical solution were presented.The examination experiment showed that HA bioceramic composite coatings can be obtained by appropriately choosing wide-band laser cladding parameters.The microstructure and surface morphology of HA bioceramic coating were observed by SEM and X-ray diffraction.The experimental results showed that the bioceramic coating is composed of HA,β-TCP,CaO,CaTiO3 and TiO2.The surface of bioceramic coating takes coral-shaped structure or short-rod piled structure,which helps osteoblast grow into bioceramic and improves the biocompatibility.

关键词： wide-band laser cladding bioceramic composite coating dynamics

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Equal Channel Angular Deformation (ECAD) of As-Cast AM60 Magnesium Alloy

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Journal of Materials Science & Technology 2003年第6期19卷 513-515页

作者： PengLUO XiaolinWU KenongXIA SchoolofMechanicalEngineeringandAutomation GuizhouUniversityofTechnologyGuiyang550003China DepartmentofMechanicalandManufacturingEngineering UniversityofMelbourneVIC3010Australia

As-cast AM60 magnesium alloy ingot with grains coarser than those of as-extruded AZ series is more liable to produce cracks under ECAD with severe shear strain. A feasible scheme of equal channel angular deformation (ECAD) for as-cast AM60 magnesium alloy ingot was proposed in this paper. The tests were conducted on Instron machine with hydraulic back-force machine. Through analysing load us displacement curves, the effects of ECAD processing conditions on deformability and microstructure of as-cast magnesium AM60 billets were discussed. During testing, the back-force employment was helpful to keep ECAD processing more stable. And with back-force, it was observed that the number of ECAD passes in different routes could tremendously affect the deformability and microstructure of magnesium specimens. It was concluded that ECAD processing is entirely feasible for as-cast magnesium AM60 alloy under severe shear strain, and back-force employment, multi-passes deformation and lubrication of graphite paper are the factors primarily beneficial to improvement of deformability and refinement of grained structure. This work provides a way to produce magnesium alloy with fine-grained structure directly from casting ingot by ECAD technique.

关键词： ECAD AM60 magnesium alloy Deformability Metallography

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Neuro-Knowledge-Based Expert System (NKBES) for Optimal Scheming of Die Casting Process

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Journal of Materials Science & Technology 2004年第5期20卷 622-626页

作者： QiaodanHU PengLUO YiYANG LiliangCHEN SchoolofMaterialsScienceandEngineering HuazhongUniversityofScienceandTechnologyWuhan430074China SchoolofMechanicalEngineeringandAutomation GuizhouUniversityofTechnologyGuiyang550003China SchoolofManufacturingScienceandEngineering SichuanUniversityChengdu610065China

We develop a neuro-knowledge-based expert system (NKBES) frame in this work. The system mainly concerns with decision of gating system and die casting machine based on a neuro-inference engine launched under the MATLAB software environment. For enhancement of reasoning agility, an error back-propagation neural network was applied. A rapidly convergent adaptive learning rate (ALR) and a momentum-based error back-propagation algorithm was used to conduct neuro-reasoning. The working effect of the system was compared to a conventional expert system that is based on a two-way (forward and backward) chaining inference mechanism. As the reference, the present paper provided the neural networks sum-squared error (S5E) and ALR vs iterative epoch curves of process planning case mentioned above. The study suggests that the neuro-modeling optimization application to die casting process design has good feasibility, and based on that a novel and effective intelligent expert system can be launched at low cost.

关键词： Die casting Neuro-knowledge-based expert system Process planning

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