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991.
992.
993.
发动机涡流室连接通道对空气流场影响的模拟研究 总被引:1,自引:0,他引:1
应用FLUENT软件,对S195型涡流室柴油机的压缩过程进行三维数值模拟,获得了涡流室内气体的速度与温度变化规律.通过对比分析研究了不同角度的连接通道对涡流室空气流场的影响. 相似文献
994.
采用传统电子陶瓷工艺制备了TiO_2-Co_3O_4-Cr_2O_3-Ni_2O_3-MnO掺杂的SnO_2-Sb_2O_3系压敏陶瓷材料.研究了MnO掺杂对SnO_2-Sb_2O_3系压敏陶瓷材料的致密化、小电流区非线性特性及脉冲电流耐受特性的影响.实验发现,少量的MnO掺杂可以改善材料的电压电流非线性特性和耐脉冲电流能力.但是当MnO的添加量多于0.06 mol%时,样品的非线性系数会减小,漏电流会升高.采用Mn(NO_3)_2水溶液作为MnO源能使Mn元素更均匀分布,比采用MnCO_3粉体获得的样品性能更好.当Mn(NO_3)_2添加量为0.06 mol%~0.1 mol%时,获得了电性能接近实际应用要求的产品,其非线性系数介于30~50,压敏电压V_(1mA)介于330~350 V/mm,并且能耐受峰值电流达1.5 kA/cm~2的8/20 μs波脉冲电流. 相似文献
995.
996.
Rajiv Sikand Arun M. Kumar Anil K. Sachdev Alan A. Luo Vipin Jain Anil K. Gupta 《Journal of Materials Processing Technology》2009,209(18-19):6010-6020
One of the prospective applications of wrought AM30 magnesium alloy is in the form of hollow circular extrusions. They can either be fabricated by employing a conventional conical die and mandrel that produce seamless extrudates, or by using a porthole die employing a welding chamber technique. The latter has become popular due to several advantages and has been adopted commercially for aluminium and magnesium alloy extrusions. In the present investigation, cast billets of AM30 magnesium alloy were extruded under similar conditions, using two different dies, i.e., a conventional conical die and a commercially used porthole die. The extruded circular tubes produced by the two methods were characterized for their microstructure as well as physical and mechanical properties. The tubes fabricated using porthole die showed significant refinement in microstructure with improved mechanical properties, outside the seam-joint portion, compared to the tubes fabricated using conical die. The extrusion loads using porthole die, were, however, higher compared to the conventional method. Processing issues, structure and properties of magnesium extrusions, produced by the two methods, are discussed in details in this paper. 相似文献
997.
ANDREA P. RODRIGUEZ HIDETSUGU TSUJIGIWA MEHMET GUNDUZ BEYHAN CENGIZ NORIYUKI NAGAI RYO TAMAMURA SILVIA S. BORKOSKY TOHRU TAKAGI MIHO INOUE HITOSHI NAGATSUKA 《Biocell》2009,33(1):39-47
Progenitor cells play an important biological role in tooth and bone formation, and previous analyses during bone and dentine induction have indicated that they may be a good alternative for tissue engineering. Thus, to clarify the influence of the microenvironment on protein and gene expression, MDPC23 cells (mouse dental papilla cell line) and KUSA/A1 cells (bone marrow stromal cell line) were used, both in vitro cell culture and in intra-abdominal diffusion chambers implanted in 4-week-old male immunodefficient mice (SCID mice). Our results indicate that KUSA/A1 cells differentiated into osteoblast-like cells and induced bone tissue inside the chamber, whereas, MDPC-23 showed odontoblast-like characteristics but with a low ability to induce dentin formation. This study shows that MDPC-23 cells are especial cells, which possess morphological and functional characteristics of odontoblast-like cells expressing dentin sialophosphoprotein in vivo. In contrast, dentin sialophosphoprotein gene and protein expression was not detected in both cell lines in vitro. The intra-abdominal diffusion chamber appears as an interesting experimental model for studying phenotypic expression of dental pulp cells in vivo. 相似文献
998.
999.
J. C. Akunna BEng MSc PhD CEng W. Shepherd BSc MSc 《Water and Environment Journal》2001,15(2):147-151
This paper describes a study which was carried out to evaluate the performance of two types of small sewage-treatment plant which are commonly available in the UK, i.e. a rotating biological contactor and a sequencing batch reactor. Both systems produced an effluent quality of less than 20 mg/l BOD and 30 mg/l SS; however, the sequencing batch reactor was more consistent in producing a better effluent (i.e. BOD<10 mg/l and SS<20 mg/l) than the rotating biological contactor. The sequencing batch reactor also demonstrated a greater tendency to remove nutrients, although the special design features which were used in this study were believed to have enhanced the rate of nutrient removal 相似文献