Traffic-induced compaction in maize,cowpea and soya bean production on a tropical alfisol after ploughing and no-tillage: Soil physical properties

An experiment was conducted over three consecutive seasons during 1982 and 1983 with the objective of evaluating the effects of traffic-induced compaction on soil physical properties of an Alfisol for no-till and ploughed systems. Main treatments of the split plot design consisted of disc ploughing to a depth of 200 mm followed by harrowing compared with no-seedbed preparation. Compaction treatments of none, two and four passes of a 2-tonne roller were the sub-plots. The roller was 60 cm in diameter, 180 cm long, with a contact area of 0.1729 m² and was pulled by a 33.6 kW tractor. Compaction treatments were applied 2 to 3 days before seeding. Four passes increased the penetrometer resistance of the soil surface, and bulk density; and as a result there were significant reductions in total porosity, saturated hydralic conductivity, infiltration rate and the amount of water released between 0.1 and 100 kPa suctions. Two passes of the roller had small and non-significant effects on soil properties. The effects of vehicular traffic in terms of increasing soil compaction became progressively severe with repeated compaction in subsequent seasons. Compaction affected soil properties in the 0–100 mm depth layer only, and was more evident following ploughing than following no-tillage systems.     

华侨贮料面下贮粒施加工仓壁的环向水平压力研究

本文根据著名的詹森 (Janssan)理论和美国学者詹尼克 (A W Jenike)的基本观点 ,考虑筒仓内贮料由于某种原因 ,其料面倾斜 ,在此状态下 ,将仓内贮料分为两部分 ,斜面部分贮料作为外荷载考虑 ,而在斜面底水平面以下部分则按詹森理论分析水平压力与垂直压力 ;最后采用将斜面圆柱体部分贮料作为边界条件 ,导出在贮料面倾斜状态下 ,贮料施加于仓壁的环向水平压力表达式     

宽带偏振不灵敏张应变InGaAs半导体放大器光开关

研制了一种张应变准体InGaAs半导体放大器光开关.该结构具有显著的带填充效应,从而导致在80mA的注入电流下,器件的3dB光带宽大于85nm(1520～1609nm).该带宽几乎同时全部覆盖了C带(1525～1565nm)和L带(1570～1610nm).最为重要的是,在3dB光带范围内,光开关的偏振灵敏度小于0.7dB;光纤到光纤无损工作电流在70～90mA之间;消光比大于50dB.通过降低了载流子寿命,开关速度有所提高.在未来密集波分复用通信系统中,这种宽带偏振不灵敏半导体放大器光开关很有实用前景.     

Electrochemical processing of metallic nanowire arrays and nanocomposites

Electrochemical methods for surface modification and materials processing play an important role in many modern technologies. Electrochemical fabrication techniques are becoming increasingly attractive for the deposition of new materials and novel microstructures. We report on property enhancements observed for electrochemically deposited Co and Ni nanowire arrays and Ni/Al₂O₃ nanocomposite films.     

BB肥填充料的加工技术

BB肥具有颗粒大小均衡、施用方便、养分全面、肥效显著、配方灵活可随意配制等优点。本文根据丰富的实践经验．总结了四种BB肥填充料的经济加工方式，提出BB肥具有广阔的前景。     

浅谈大型仓储式超市建筑防火设计与消防管理

分析了大型仓储式超市建筑结构特点和火灾特点，对仓储式超级市场建筑防火设计审核中应该把握的关键点进行了探讨。并对设计和施工中存在的实际问题进行了论述．提出了相应的对策。     

Screw Configuration Effects on Corn Starch Expansion During Extrusion

Normal corn starch was extrusion cooked in a Brabender single-screw extruder. Three screws with no mixing, one mixing or two mixing elements were used to extrude the samples through a 3 mm cylindrical die nozzle at 140°C barrel temperature and 140 rpm screw speed. Dependent variables included overall and radial expansion ratios, bulk density and specific mechanical energy (SME). Extrudates were ground and re-extruded using the same three screws, and the same extrusion conditions. Significant differences (P < 0.05) in bulk density, SME and radial expansion ratio were found on re-extrusion. No changes occurred in overall expansion ratio (P < 0.05).     

YL—11型导爆管

文中介绍了YL-11型塑料导爆管的结构、性能和垂直法生产工艺,该产品能满足矿山大区微差爆破及其混装车的要求。     

化学气相沉积ZnS块材料的均匀性

本文以Ｈ２Ｓ与Ｚｎ为原料，通过化学气相沉积制备了ＺｎＳ块材料。分析了ＺｎＳ的沉积过程机理，研究了沉积参数如沉积温度，沉积区压力和Ｈ２Ｓ、Ｚｎ蒸汽、载气Ａｒ流量对ＺｎＳ厚度均匀性的影响规律，提出了改善ＺｎＳ厚度均匀性，抑制沉积表面球状物生长的途径。