Ar+CH4混合气体中电子漂移速率的双栅法测量

提出了一种快速、准确测量电子在气体中漂移速率的新方法。通过分析电子在双栅电离室中两个栅极上产生的感应信号波形来确定电子漂移的起止时刻,从而得出电子在一定约化场强下的漂移速率。采用数据采集卡（waveformdigitizer）对电离室的极板信号进行记录。测量了电子在8种混合比例的Ar+CH₄气体中漂移速率随约化场强的变化曲线。通过分析实验数据,得到任意混合比例的Ar+CH₄气体中电子漂移速率的计算公式。     

固体核径迹火花自动计数器效率标定

对固体径迹火花自动计数器探测效率的影响因素进行了分析,重新确定了最佳径迹蚀刻条件以及放电参数。利用小型平板裂变电离室在多种模型下对固体径迹火花自动计数器探测效率进行了重新标定,得到了不同实验条件下固体径迹火花自动计数器效率。     

发动机涡流室连接通道对空气流场影响的模拟研究

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.     

锰离子掺杂对SnO_2~-Sb_2O_3系压敏材料电性能的影响

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.     

固体火箭发动机燃烧室壳体纤维缠绕模具设计

介绍一种固体火箭发动机燃烧室壳体纤维缠绕芯模的设计。这项工作的目的在于提供一种可重复使用的纤维缠绕芯模。它采用的方法是钢模分瓣法。这种芯模的关键技术是芯模的组装和脱模。这项工作的意义在于提高纤维缠绕固体火箭发动机燃烧室壳体的比强度,节约生产成本,提高工作效率。     

AM30 porthole die extrusions—A comparison with circular seamless extruded tubes

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.     

Influence of the microenvironment on gene and protein expression of odontogenic-like and osteogenic-like cells

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.     

在铝箔轧制中对Schneider过滤器的管理

Schneider过滤器在轧制油的管理和控制中是相当重要的。介绍Schneider过滤器在实际生产中的作用和管理工作要注意的问题。     

Comparison of RBC and SBR Systems for the Treatment of Sewage from Small Communities

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     

综合改炉与节约能源

从炉膛炉拱布置和余热的利用等方面介绍了锅炉综合改造的有效途径以及科学的管理办法