Hard Minjingu Phosphate Rock: an Alternative P Source for Maize Production on Acid Soils in Tanzania

The phosphate rock (PR) deposit at Minjingu in northern Tanzania consists of two forms, locally called hard Minjingu phosphate rock, MPR (4.8 × 10⁶ Mg with 10.6% P) and soft MPR (3.3 × 10⁶ Mg with 13.3% P). Extensive chemical and instrumental analyses have shown that the two MPRs differ mainly in consistency, while their reactivities are comparable. Soft MPR in direct application has been extensively evaluated with good results under greenhouse and field conditions whereas hard MPR has only been tested in a greenhouse experiment. The agronomic value of directly applied hard MPR on maize growth was therefore tested under field conditions on four acidic soils low in available Ca and P at Magadu (Ultisol), Mlingano (Oxisol), Nkundi (Ultisol) and Sasanda (Andisol). The treatments tested were hard MPR, soft MPR, triple superphosphate (TSP) and a control. Each P source was applied at a rate of 80 kg ha⁻¹ P at Magadu, Mlingano and Nkundi but 160 kg ha⁻¹ P at Sasanda. Other nutrient deficiencies were corrected in each soil with appropriate fertilizers that were applied in all three years of experimentation. The soils gave significant positive responses to application of the three P sources but TSP application resulted in significantly higher P concentrations in leaves and grain yields than MPR addition in the first year. However, in the second and third years the performance of MPRs approached that of TSP and the relative agronomic effectiveness (RAE) of MPRs increased from 50 – 70% in the first year to 80 – 95% in year three. Moreover, crop performances on hard MPR-treated plots and soft MPR-treated plots were not significantly different. This important result suggests that hard MPR can replace soft MPR and even TSP on acidic soils low in available Ca and P. However, more testing is needed to ensure confident delineation of soils that respond to direct application of hard MPR from non-responding soils. The rather poor performance of MPR for the first year must also be improved.     

氮化无压烧结氮化硅材料制备及评价

此项研究使用了两种不同的有机溶剂，按三种不同工的配方加工出了17炉氮化无压烧结（NPS）粉材料。结果表明，溶剂和加工过程直接影响着NPS粉末的性能，测试结果表明，P95C在NPS粉末系统中是一种最适合于再生产的氮化硅粉末，在1780C下，P95C粉末烧结3h可加工出完全致密的结构材料，且在抛光后的表面上无较大缺陷。     

变截面管沿壁薄膜压力计算

本文对自调匀整器中的气体压力传感器的压力分布进行了研究,利用二维 N—S 方程计算出沿壁薄膜内压力分布的表达式。从而,为气体压力传感器的传压孔位置的确定提供可行的方法。     

城市热岛与建筑热工设计

本文在简要介绍城市热岛概念、特征及形成机理的基础上,探讨了城市热岛现象对城市区域的建筑保温设计、建筑防热设计和建筑防潮设计的影响,给出了消除城市热岛不利影响的途径和设计方法。     

Pd合金／Si接触过渡层的结构组分研究

淀积合金薄膜的 Si 片退火时,通过固相反应在界面处生成接触过渡层,其组分与结构均不同于一般条件下生成的硅化物.本文介绍了 Pd 合金/Si接触过渡层的形成工艺,对接触过渡层的结构组分进行了分析与讨论.基于“相分层”效应,可用掺氮或掺氧的方法提高阻挡层的质量.     

苎麻织物增强不饱和聚酯树脂复合材料成型工艺及其阻燃性能

为了探究苎麻织物增强不饱和聚酯(UP)树脂复合材料的模压成型工艺以及提升其阻燃性能,通过差示扫描量热对树脂固化工艺进行研究,通过对苎麻织物克重、模压压力以及织物铺层层数进行探究,得出复合材料的最佳制备工艺;利用植酸(PA)对苎麻织物进行阻燃改性,研究PA含量对复合材料阻燃及其力学性能的影响.结果表明,UP的最佳固化工艺...     

Dual‐Layer Hollow Fibers for Sulfur Removal from Fuels

Emission of sulfur compounds to the atmosphere is universally recognized as one key target to be reduced. For membrane pervaporation which is considered as a potential purification process of fuels, dual‐layer polyurethane (PU)/polyethersulfone hollow‐fiber membranes were prepared. A novel fabrication technique is proposed using a quadruple spinneret to produce the fiber with such morphology by simultaneous spinning of two polymer solutions in the presence of two corresponding precipitation media. Activated carbon was added into the PU solution to improve the transport properties of the selective layer. Resulting hollow‐fiber membranes showed very good adhesion between the selective layer and its support, in addition to an effective removal of a sulfur compound such as 2‐methyl thiophene from a typical model fuel, an indication of good prospects for both the fabrication technique and for sulfur removal by pervaporation of fuels.     

Structural Control of NiO–YSZ/LSCF–YSZ Dual‐Layer Hollow Fiber Membrane for Potential Syngas Production

The objective of this study was to fabricate dual‐layer hollow fiber as a microreactor for potential syngas production via phase inversion‐based co‐extrusion/cosintering process. As the main challenge of phase inversion is the difficulty to obtain defect‐free fiber, this work focuses on the effect of the fabrication parameters, that is, nonsolvent content, sintering temperature and outer‐layer extrusion rate, on the macrostructure of the produced hollow fiber. SEM images confirm that the addition of nonsolvent has successfully minimized the finger‐like formation. At high sintering temperature, more dense hollow fiber was formed while outer‐layer extrusion rate affects the outer layer thickness.     

利用模糊综合评判法评价水井分层注水效果

对水井分层注水进行评价,可直观体现出注水井分层注水前后的效果,为此针对各因素对水井井组影响的不确定性,建立了一套适用于井组评价的定量化方法。在对井组进行注水效果评价之前,对现有各井做出评价,并利用模糊综合评判的方法计算出井组综合评价系数来评判各个井组的性质。结合普17断块的实际地质和开发状况,根据计算得出的综合评价系数E2,找出E2值与注水效果的递增关系,通过综合系数E2值评价出各井组注水效果的优劣,既可以评价井组分层注水是否合理。     

编织碳纤维复合材料雷击损伤特性研究

采用实验方法研究了编织碳纤维/环氧树脂复合材料层合板在干燥环境下受到不同强度等级模拟雷电冲击后的电击破坏特性,并进行了系统分析与机理解释。研究显示,雷电冲击对复合材料造成了三种典型破坏形式,并随着电击强度的增加及铺层角度的改变呈现出不同形态的变化。微观扫描分析发现,电击会对树脂与纤维界面造成严重破坏。