水泵水轮机泵工况轴向力特性分析与改善

水泵水轮机是抽水蓄能电站的核心部件,水泵水轮机的轴向力特性对其运行稳定性与安全性具有主要影响。作为一种典型的立式机组,为防止抬机事故的发生,机组转轮部分需要具有向下的轴向力,但在泵工况下,该轴向力容易过大,并可能引起机组下沉。采用计算流体动力学方法,研究分析抽水蓄能水泵水轮机泵工况不同流量与活动导叶开度下的轴向力特性。研究结果表明,在泵小流量、小导叶开度、高扬程的工况下,向下的轴向力较大;采用对称布置的均压管路连接转轮上冠腔体与尾水管,轴向力变为轻微向上,扬程与水力效率无显著变化,有效解决了机组泵工况向下轴向力较大的问题,机组运行的安全性与稳定性得到了显著提高。     

非班太尔对照品的定值研究

(目的)本文旨在联合使用质量平衡法与差示扫描量热法2种定值方法测定非班太尔对照品的含量。(方法)采用高效液相色谱法测定非班太尔的纯度,采用卡尔费休氏容量滴定法、炽灼残渣检查法、气相色谱法分别测定其水分、灰分和残留溶剂,由质量平衡法公式计算非班太尔对照品的含量;采用差示扫描量热法对非班太尔对照品含量加以佐证。(结果)质量平衡法和差示扫描量热法测定结果经科克伦判定互为等精度,取其算术平均值作为最终定值结果,即非班太尔对照品含量为99.66%。(结论)质量平衡法与差示扫描量热法对非班太尔对照品的定值结果基本一致,2种方法能够更好地保证非班太尔对照品赋值的准确性。     

Modelling the food web for assessment of the impact of stock supplementation in a reservoir ecosystem in India

Comparative estimates of trophic status and energy flow were carried out in a tropical reservoir ecosystem in India to assess the impact of fish stocking. Mass‐balanced models of the reservoir ecosystem were constructed for two periods – 1982–1983 and 2002–2003 – using ecopath software to determine the impacts on different groups before and after stocking. Mixed trophic impact (MTI) analyses indicated that phytoplankton and detritus have a positive impact on most groups. There was a decrease in nutrient flow through the system from pre‐stocking to post‐stocking (22.28%). The baseline was higher by 0.29% in the post‐stock phase indicating maturity. The ecosystem indices tested indicate that the reservoir was in a more resilient state post‐stocking than during the pre‐stocking phase. The ‘health’ of the ecosystem showed an improvement, which indicates a positive impact of stocking.     

季节性冻融区地下水位预测方法研究

为预测河套灌区冻融区全年地下水位变化过程,采用统计学方法,研究了冻融期地下水位与地表气温间的关系,建立了二者间的线性模型,结合非冻融期水量均衡模型,建立了改进型水量均衡模型,通过优化求解方法确定模型参数。结果表明,模型计算埋深与实测埋深拟合效果较好,提出的改进型水量均衡模型可较好地预测冻融区全年地下水位变化过程,解决了冻融期间地下水模拟难题,方法简单精确,具有很好的实用性。     

有机、无机磷肥配施对宁夏引黄灌区露地蔬菜磷素吸收利用与磷平衡的影响

2011—2013年,在宁夏引黄灌区利用田间定位试验研究了不同有机、无机磷肥配施对露地蔬菜的产量、磷素吸收利用、土壤无机磷残留和磷平衡的影响,并提出了合理的磷肥投入阈值。结果表明,过量增施磷肥对露地蔬菜的增产作用不显著。露地蔬菜经济产量与施磷量都符合二次曲线关系,花椰菜、紫甘蓝和大白菜最大产量施磷量分别为P2O5332.3、304.5、377.8 kg/hm2,最佳经济施磷量分别为P2O5282.9、271.2、365.3 kg/hm2。增施磷肥能促进露地蔬菜地上部磷素吸收累积,磷肥利用率随化学磷肥用量增加而降低。随着施磷水平的提高,0~20 cm土壤Olsen-P和Ca Cl2-P含量都呈增加趋势。土壤磷平衡与施磷量呈线性正相关关系,化肥磷施用量越高土壤磷素盈余越大。2011—2013年花椰菜、紫甘蓝和大白菜季合理的磷肥投入阈值范围分别为[141.0,332.3]、[107.1,304.5]和[104.9,377.8],施磷量、蔬菜产量及地上部吸磷量是影响该阈值范围的主要因素。     

天津西青区王稳庄蓖麻产业化项目财务实证分析

以王稳庄蓖麻产业化项目为实证，采用文字和表格相结合方式，较全面系统地对王稳庄蓖麻产业化项目进行了财务实证分析。     

IMPACT OF SULFUR FERTILIZATION ON DIFFERENT FORMS AND BALANCE OF SOIL SULFUR AND THE NUTRITION OF WHEAT IN WHEAT-SOYBEAN CROPPING SEQUENCE IN TARAI SOIL

A field experiment was conducted at farmer's field in Mollisols of Tarai soils in Uttarakhand (India), to assess the direct and residual effect of sulfur fertilization in wheat-soybean cropping sequence. Four levels of sulfur (S; 0, 15, 30, and 45 kg ha^?1) were applied to main crop (wheat) along with recommended dose of nitrogen (N), phosphorous (P), and potassium (K). The direct and residual effect of sulfur at highest level showed 27 and 6 percent increase in grain yield of wheat and soybean over control, respectively. The increase in grain yield of wheat was significant at each sulfur level. The direct as well as residual effect of sulfur showed significant increase in sulfur concentration and its uptake by grain and straw except increase in sulfur concentration and uptake by soybean straw. In wheat-soybean cropping sequence, the agronomic efficiency and apparent sulfur recovery decreased with increase in levels of sulfur, but the percent response increased with increasing sulfur application. Different forms of sulfur such as total sulfur, organic sulfur, calcium chloride extractable sulfur, potassium dihydrogen phosphate extractable sulfur, and non-sulfate sulfur in post-harvest soil increased according to sulfur level applied but it decreased under control and also after residual crops. The buildup of sulfur in surface soils was greater than in the deeper soils. Application of sulfur showed the positive sulfur balance and it increased with increase in sulfur level, while it was negative under control. A major portion (46–62%) of applied sulfur contributed to increase in sulfur content of root zone soil followed by unaccounted component (25–40%) and small portion (11–18%) was absorbed by wheat plant as uptake.     

基于热平衡法检测植物茎流传感器的标定

植物茎杆的茎流量是植物重要的生理信息之一,该文主要是对基于热平衡法的植物茎流传感器进行标定试验的研究,通过标定试验,测试了茎流检测装置的性能。试验结果表明,计算出传感器输出值与茎流量有很高的决定系数R2=0.96～0.97,分辨率为1×10-3 g/min,精度为±3%。因此参照标定试验,可以较准确地获取植株茎流速率,进而可以反映出植物的蒸腾及需水状态信息,并据此可以为植物生长环境的调控、节水灌溉等提供有效的监测工具。     

温度对中国对虾能量分配和元素组成的影响

于１９９５年８月～１０月,在２０℃、２５℃和３０℃下,以日本刺沙蚕为饵料,测定中国对虾的能量分配和元素组成（ＣＮＨ）。结果表明,水温３０℃时呼吸能显著增大（Ｐ＜０．０５）,占摄食能的７７．８％。三个温度下平均能量分配比例为：排泄能２．２７％,粪便能３．４６％,蜕壳能４．１９％,生长能２２．２７％,呼吸能６７．７３％。呼吸能的变化对生长能影响显著。元素组成以２０℃含量最高,虾体能值也最大。Ｃ／Ｎ值变化表明,随温度升高,脂肪作为中国对虾能量代谢的能源物质比例增大。     

基于NSGA-Ⅲ算法与TOPSIS决策下的区域水资源多目标优化配置

为缓解水资源供需紧张,指导区域用水管理,以社会、经济、生态综合发展为目标,供水量与需水量双向约束构建区域水资源优化配置模型.结合该模型特点,引入NSGA-Ⅲ算法对模型进行求解,以寻求Pareto前沿面与最优解集.同时,利用TOPSIS决策理论对众多Pareto可行解进行综合评价,选择权衡解作为最佳折衷方案.将该模型应用于南阳市鸭河口灌区进行验证,对灌区来水频率P=75%时下近期水平年与远期水平年进行水资源优化配置,并进行二次水资源供需平衡分析.结果表明,相对于基本方案,折衷方案在近期水平年余水量增长至11 497.60万m3,可节约水资源3 272.38万m3;远期水平年由缺水4 279.28万m3变为余水3 950.30万m3,可节约水资源8 229.58万m3,节水效果明显,符合鸭河口灌区整体规划与用水需求.