基于VXI总线的超宽带线性调频信号源的设计

主要介绍了VXI总线C尺寸超宽带线性调频信号源的设计方法，重点描述了利用现场可编程逻辑器件FPAG和DSP设计VXI总线接口电路，以及数字波形存储直读技术在线性调频信号源中的应用。     

PHOSPHORUS AND PHOSPHATE LEVELS IN THE ALEURONE CELLS OF CEREAL GRAINS

The aleurone cells of barley, wheat, rice, rye, oats and triticale contained, comparatively, higher percentages of phosphorus than the aleurone cells of sorghum, maize or millet. The aleurone tissues of barley, wheat and rice had more phosphate than corresponding tissues of sorghum and maize. Phosphate was not detected in the aleurone tissue of maize but was found in trace amounts in the aleurone tissue of sorghum.     

漏斗贮料压力计算公式

本文从平衡条件和常系数假定出发，建立贮料压力微分方程，导出了正倒锥漏斗、倒锥漏斗贮料压力计算公式。文中说明，圆柱仓筒贮料压力微分方程为上述方程的特殊情形。本文成果可供筒仓工程设计使用，还可供确定斗口给料机贮料荷载参考。     

长颗粒(柱状晶)Si3N4陶瓷的研究及进展

Si3N4陶瓷材料由于具有很好的高温性能及高的力学性能，而被广泛地用于结构陶瓷，如切削刀具等。然而，因为其对缺陷很敏感，故易受灾难性的失效。人们发展了多种Si3N4增韧陶瓷，其中自增韧由于一些优异的性能越来越受到人们的重视。在此文中，着重介绍了影响Si3N4陶瓷长颗粒(柱状晶)晶粒生成的因素，并介绍了国内外对长颗粒Si3N4晶的控制研究。     

Mycological and physical parameters for selecting suitable packaging material for pre- and post-irradiation storage of cereal grains in Ghana

Owing to the rough warehouse handling of storage sacks in tropical areas in Africa, a suitable storage sack should not support de novo growth of fungal spores because this would reduce the tensile strength of the packaging material and act as a springboard for infecting grain contents. This paper reports the effect of activity of saprophytic fungi on the tensile strength of jute and woven polypropylene sacks. New woven polypropylene sacks carried lower levels of fungal spores (1.3×10¹ cfu/72 cm²) than jute sacks (3.0×10³ cfu/72 cm²). The natural mould penetration and growth was examined on sections (4×5 cm) of both jute and woven polypropylene after previous incubation at relative humidities of 55, 60, 65, 70, 75, 80, 90 and 95% for 10 weeks by placing them on Sabouraud's Agar. There was a significant difference (P = 0.05 level of significance) between the higher penetration of mould growth on jute sacks and that obtained on woven polypropylene sacks. Saprophytic fungi (Aspergillus candidus, A. flavus, A. fumigatus, A. niger, A. japonicus, A. parasiticus, A. ustus, Fusarium oxysporium, F. moniliforme, Penicillium verucosum var. cyclopium, Rhizopus oryzae and Trichoderma viride) isolated from jute sacks reduced tensile strength, measured by an Instron Model 1026, by 50–75% after 10 weeks at 90% R.H. Same fungal species on woven polypropylene sacks did not alter the tensile strength. Woven polypropylene sacks did not absorb moisture whilst the moisture content of jute sacks increased by 5.3–6.0% in 10 weeks at 90% R.H. with concomitant increase in mould and yeast counts by 1–2 log cycles. Evidence is presented to show that there was a positive correlation between the final mycoflora on jute sacks and loss in tensile strength. No correlation, however, was found between the total aerobic bacteria on jute sacks and the concomitant reduction in tensile strength. Fungi therefore play a major role in the reduction of tensile strength of jute sacks. Sterilization by gamma irradiation (8.0 kGy) of jute and woven polypropylene sacks did not affect their intrinsic tensile strength. Woven polypropylene sacks therefore have many microbiological and physical advantages over the traditional jute sacks to merit their use for grain storage in tropical areas like Ghana.     

Stored energy analysis of Zn—5Al eutectic alloy in superplastic deformation

The stored energy and the energy release during SPD(superplastic deformation)of a Zn-5Al alloy were studied.The alloy after rolling process gains more stored energy,and the as-rolled speciment can obtain maximum elongation and minimum flow stress without hot loding treatment before SPD.Experimental results show that stroed energy release process is along with SPD process and is also an impetus to SPD.The as -rolled Zn-5Al alloy has 48J/mol stored energy which was measured with DSC(differential scanning calorimeter)and conforms well to the calcuated value.The as-rolled Zn-5Al alloy after SPD with an elongation of 2500% releases 112J/mol stored energy,Analysis shows that the strain rate is in direct ratio to the rate of stred energy release.     

Storage effects on nutritional quality of commonly consumed cereals

Storage effects on nutritional quality of commonly consumed cereal grains are studied. Freshly harvested wheat, maize and rice grains were stored at 10, 25 and 45 °C for six months. A significant decrease in pH and an increase in titratable acidity was observed during storage of these three cereal grains at 25 and 45 °C. A gradual decline in moisture, total available lysine and thiamine contents was observed during storage. Total available lysine contents decreased by 6.50% and 18.5% in wheat, 14.3% and 20.7% in maize and 23.7% and 34.2% in rice during six months of storage at 25 and 45 °C, respectively. Six month’s storage of rice, maize and wheat grains at 25 and 45 °C resulted in reduction of thiamine contents by 16.7% and 29.2%, 17.2% and 24.1% and 21.4% and 29.5%, respectively. About 36.4–44.4% decrease in total soluble sugars at 45 °C and 9.30–31.8% increase in total soluble sugars were observed at 10 and 25 °C during six months storage of these cereal grains. Protein and starch digestibilities of cereal grains also deceased during six months of storage at 25 and 45 °C. No significant change in nutritional quality was observed during storage of cereal grains at 10 °C.     

Effect of Annealing on the Surface Microstructure of Y-Ba-Cu-O Superconducting Ceramics

Precusors to the YBa₂Cu₃O_7-δ material were prepared by both the oxalate precipitation method and conventional ceramic processing. Second-phase grains were observed to develop on the exposed fracture surface during annealing at 500° to 600°C in an ambient atmosphere. The second-phase grains were identified to be BaCO₃ using EDX and XRD. The liquid phase, which was formed because of local chemical inhomogeneity in the Y-Ba-Cu-O system, contributed to the formation of second-phase grains as a source of Ba.     

不锈钢上激光熔敷涂层结构特征与质量研究

采用5kW连续CO2激光器对经等离子喷涂的NiCoCrAlY结合层和ZrO2陶瓷层进行二次重熔处理，并利用金相显微镜、扫描电镜、电子探针和显微硬度计对激光熔敷涂层进行了显微结构、元素分布以及显微硬度观察与测试，结果表明：多道搭接工艺能降低熔敷涂层气孔率，ZrO2陶瓷层稀释度低，与基体结合完好，并观察到NiCoCrAlY合金层中存在明显的对流图案，加入了TiO2-Al-Ti添加剂的ZrO2陶瓷层激光重熔后得到了无裂纹的定向生长柱状晶，并且呈现一次枝晶平均间距为2．3μm的表层和平均间距为3．8μm的次表层结构。     

二氧化碳与磷化氢混合熏蒸防治储烟害虫试验

目前,储烟害虫防治普遍采用磷化铝片剂常规熏蒸法,磷化铝施用量为6～9g/m3,安全上存在一定的隐患。为了减少磷化铝用药量,于2003年应用微电脑控制的仓外混合熏蒸机,施用钢瓶装液化二氧化碳和56%磷化铝片剂,进行了二氧化碳与磷化氢混合熏蒸杀虫试验,以8g/m3磷化铝常规熏蒸法为对照。试验结果表明,磷化铝施用量为2.3g/m3、二氧化碳施用量为12g/m3,混合熏蒸结果达到100%杀死害虫。与对照相比,杀虫效果相同,混合熏蒸法具有磷化铝施用量较小、较为安全和有利于减少污染等优点。