轴流泵叶轮非线性环量数学模型建立与试验

以轴流泵叶轮出口速度梯度方程和轴面速度表达式为基础,建立了轴流泵叶轮非线性环量数学模型,并推导了叶片出口流动方程式.采用微型五孔球形探针,对南水北调工程用轴流泵模型(TJ04-ZL-06)最优工况下叶轮出口不同半径位置的环量和轴面速度分别进行了试验测量.试验结果表明,高效轴流泵叶轮出口环量呈现非线性分布,在叶片中部较为平直,在轮毂侧环量降低至中部的0.8倍左右,而轮缘侧增大至中部的1.2倍左右;同时叶轮出口轴面速度分布呈现抛物线流型,叶片中部速度最大.基于建立的非线性环量数学模型对叶轮出口轴面速度分布进行了计算,结果表明不同半径的轴面速度计算值与试验值误差均小于5％,验证了数学模型的可靠性.     

内蒙古膜下滴灌棉花叶面肥施用效果

以中棉所50和天元1号为材料,以喷施清水为对照,通过田间试验研究了从蕾期到铃期6次叶面喷施1%(质量分数,下同)尿素、0.5%磷酸二氢钾、1%尿素+0.5%磷酸二氢钾3种叶面肥对内蒙古膜下滴灌棉花产量与品质的影响。结果表明,喷施叶面肥处理均比对照增产,皮棉增产幅度为6.0%~10.6%,喷施1%尿素+0.5%磷酸二氢钾处理增产效果最佳。叶面肥处理对棉花纤维品质无显著影响,施用1%尿素+0.5%磷酸二氢钾叶面肥处理棉花纤维上半部平均长度、断裂比强度优于对照。     

Biochemical comparison of lectins among three different color strains of the red alga Kappaphycus?alvarezii

The red alga Kappaphycus alvarezii is economically important as an edible species and as a source of carrageenan, and has been extensively cultivated in many tropical countries. For this species, different color strains, which differ from each another in growth rate and carrageenan content, have been reported for decades. In this study, lectins from brown, red, and green strains of K. alvarezii cultivated in Vietnam were isolated and characterized for evaluation of their biochemical properties and contents. The results showed that each color strain contained in common the three lectins, named KAA-1, KAA-2, and KAA-3, which shared the hapten-inhibition profile of hemagglutination, 20 N-terminal amino acid sequence, and equivalent molecular mass within a range of 28,016 ± 1.2 to 28,021 ± 1.8 Da, but differed in their yields, with the highest yield of KAA-2. These properties of the three isolectins were also comparable among the three different color strains. However, the sum of the yields of the three isolectins decreased in the order: red (21.4 mg) to green (15.9 mg) to brown strains (15.1 mg), from 500 g fresh alga. Thus, this algal species can be a good source of useful lectins, irrespective of color strain.     

Effects of dietary protein to carbohydrate ratios on growth and body composition of juvenile yellow catfish, Pelteobagrus fulvidraco (Siluriformes, Bagridae, Pelteobagrus)

The present experiment was conducted to investigate the effects of dietary protein to carbohydrate ratios on growth and body composition of juvenile yellow catfish, Pelteobagrus fulvidraco . Nine diets were formulated to contain three protein levels (30%, 36% and 42%), each with three carbohydrate levels (24%, 30% and 36%). Each diet was randomly assigned to triplicate groups of 20 fish (initial mean body weight: 8.24±0.20 g) in indoor flow – through fibreglass tanks. The experiment continued for 8 weeks. Weight gain and specific growth rate were similar for the fish fed the 36% and 42% protein diets but higher than that fed the 30% protein diet. At the 36% protein level, carbohydrate contents varying from 24% to 36% ( P / E ratio of 24.0–28.2 mg protein kJ⁻¹) had no significant effects on growth performance and feed utilization ( P >0.05). Protein efficiency ratio tended to increase with dietary carbohydrate level at the same protein level. Dietary treatments significantly influenced body composition ( P <0.05), but not the condition factor, viscerosomatic index, hepatosomatic index and intraperitoneal fat ratio ( P >0.05). Based on these observations, 36% protein and 24–36% carbohydrate with the P / E ratio of 24.0–28.2 mg protein kJ⁻¹ seemed suitable for optimal growth and feed utilization, and carbohydrate could cause protein-sparing effect in diets for juvenile yellow catfish.     

祁连山水源林生态系统结构与功能的研究

在祁连山水源涵养林区,围绕水源林生态系统结构与功能的动态变化,开展了森林小气候、森林水文生态效应的研究。结果表明,祁连山水源涵养林不仅具有拦蓄降水、缩小温差、保持较高土壤湿度等作用,而且具有十分显著的消洪补枯、涵养水源、保持水土的水文生态作用。森林覆被率６５％的流域比３２％的流域年枯水径流量增加２８８７ｍｍ,年洪水径流量减少９８８７ｍｍ;森林土壤贮水２９８１２～３９１９３ｍｍ,草地仅１８２０９ｍｍ;林地很少产生地表径流,草地年土壤流失量１７９３９ｋｇ·ｈｍ－２;高寒山区多年冻土与季冻土致使试验区河川径流系数高达０７３,蒸散较小为１５６５４ｍｍ;多年监测资料显示祁连山林分质量下降,冰川退缩,河川径流逐年减少,生态环境明显恶化,建议各级政府部门高度重视祁连山生态保护问题。     

The effects of vitamin E on non-specific immune response of the juvenile soft-shelled turtle <Emphasis Type="Italic">Pelodiscus sinensis</Emphasis>

ABSTRACT:   This study was conducted to determine the effect of dietary vitamin E supplements on non-specific immune responses in juvenile soft-shelled turtles. Turtles were fed diets supplemented with vitamin E at 0 (control), 50, 250, 500, 1000 and 5000 mg/kg, respectively, for 4 weeks. Results showed that blood cell phagocytosis and serum bactericidal activity were significantly improved in turtles from two diets (250 and 500 mg/kg vitamin E supplementation), while had no significant improvement in turtles from the three remaining diets (50, 1000 and 5000 mg/kg vitamin E supplementation) when compared to turtles from the control group. Serum bacteriolytic activity in turtles from diets with 50, 250, 500 and 1000 mg/kg vitamin E supplementation were higher than activity levels quantified for the control group, but no significant difference was observed between the 5000 mg/kg vitamin E supplementation diet and the control diet. The results suggest that vitamin E has an upper and lower threshold for improving non-specific immune function in soft-shelled turtles, and the optimal supplementation may be between 250 and 500 mg/kg.     

近红外多组分分析中异常样本识别方法

近红外光谱分析中,异常样本的存在严重影响定标模型的预测性能和适配性。基于 X / Y 联合的ODXY异常样本识别和剔除方法,提出并证明了一种专用于多组分分析的MODXY异常样本识别方法。实验采用80组玉米近红外光谱数据,利用不同异常样本识别方法剔除异常样本后建立玉米含水率、含油率、蛋白质含量和淀粉含量4种组分的偏最小二乘预测模型,采用预测均方差和决定系数作为评价指标比较所建模型的性能,检验MODXY方法在多组分分析中的异常样本识别能力。实验结果表明：在近红外多组分分析中,MODXY方法在大多数情况下具有更好的异常样本识别能力;MODXY方法和ODXY方法均有一定的适用范围,它们更适合于相应组分化学值的相对标准偏差较大的情况。     

治黄之本在于水土保持

该论证了在漫长的地质时期，黄土高原的土壤侵蚀强度变化幅度很大，有时异常强烈，有时则很轻微。根据子午岭地区土壤侵蚀由强变弱的实例，以及许多水土保持综合治理先进典型，说明黄土高原的土壤侵蚀完合可以治理。只有水土保持才是根治黄河水害，促进当地农业持续发展的根本保证。     

基于MED-EEMD的滚动轴承微弱故障特征提取

针对滚动轴承在强噪声环境下故障信号微弱、故障特征难以提取等问题,提出了基于最小熵反褶积(minimum entropy deconvolution,MED)和总体平均经验模态分解(ensemble empirical mode decomposition,EEMD)两者相结合的方法来提取滚动轴承微弱故障特征。通过对仿真信号和风电齿轮箱的振动信号分析,结果表明:为了弥补在强背景噪声下EEMD对微弱信号特征提取的局限性,该文选取MED作为EEMD的前置滤波器,最后对敏感的本征模态函数进行循环自相关函数解调分析,得出了风电齿轮箱的故障来自于高速轴的微小弯曲和高速轴输出端#10轴承外圈点蚀。同时与EEMD进行对比分析,表明了这种方法对微弱故障特征提取有较好的适用性。该文为多故障共存并处于强背景噪声下的微弱特征提取提供了参考。