水轮机组振动故障诊断和试验研究

振动故障严重影响水轮机组的正常运行和发电效益,要清除振动故障,必须认清振动的原因,找准振源。从机械、水力、电气等三个方面分析了引起水轮机组振动的主要原因及特征。介绍了转速、励磁和负荷试验在水轮机振动故障诊断中的应用,通过分析某电站现场振动试验中各部位振动及水压脉动的幅值随机组运行工况变化的规律,找出了引起该机组振动的原因和处理方法,具体说明了试验法在水轮机组振动故障诊断和处理中的应用。     

基于ELES模型的农民灌溉水价支付能力水平界定

从支付能力的角度定量研究农民对灌溉水价的承受能力,采用扩展线性支出系统(ELES)模型,通过实例计算分析了农户总体收支及水费支出、农民基本消费需求支出和支付能力水平的界定标准等,并分析了支付能力的主要影响因素.结果表明:研究区域内农民年人均纯收入774元和1 300元是支付能力水平的分界线,无支付能力、有一定支付能力和有支付能力的农户分别占6.1%、9.7%和84.2%;支付能力较低的农户均以农业生产为主要收入来源;不同支付能力组之间农民年人均水费支出与平均水费支出均无显著差异;耕地面积、农业收入和非农业收入对农民支付能力具有显著的影响.     

基于mtDNA COI的假眼小绿叶蝉系统发育研究

克隆测定了12个茶树假眼小绿叶蝉Empoasca vitis（Göthe）种群84个样本和5个叶蝉近缘种外群62个虫体的线粒体DNA COI基因序列片段,利用生物信息学软件分析其序列同源性、遗传结构及系统进化关系。发现我国茶树假眼小绿叶蝉种群间的遗传距离为0.5%~1.2%,远小于昆虫物种2%的界限,未呈现明显遗传分化,ML分子系统树也显示其种群个体呈平行分布。假眼小绿叶蝉与几种外群叶蝉的遗传距离在14.8%~24.5%之间,依次为葡萄小绿叶蝉<葡萄二星叶蝉<桃一点斑叶蝉,说明它与葡萄小绿叶蝉亲缘关系最近,与系统进化树的聚类结果一致。本研究首次通过mtCOI基因序列分析,揭示了假眼小绿叶蝉遗传结构及它与近缘种叶蝉的系统进化关系,为解释它在茶园的起源及适应机制提供了基础。     

幽深清远的诗意空间——论武汉宝通禅寺园林空间艺术

从研究中国传统寺庙园林空间特征入手,对武汉宝通禅寺园林的整体空间布局进行了分析,并对各层次空间在幽深清远的意境营造上进行了阐述。结合武汉宝通禅寺园林空间艺术上的开合收放以及意境营造上的关系,指出现代城市园林空间设计中存在只注重功能完整和形式统一而缺乏满足精神需求的不合理现象,提出希望通过研究充满诗画艺术魅力的寺庙园林空间,能为人们创造出一片诗意栖居的精神家园。     

Chemical and physical changes in milk protein concentrate (MPC80) powder during storage

The solubility and chemical changes due to the Maillard reaction were investigated in milk protein concentrate powder containing 80% protein (MPC80) during storage at temperatures and relative humidities in the ranges of 25-40 °C and 44-84%, respectively. The Maillard reaction was studied by measuring furosine (a product of lactosylated protein after digestion with acid) and free hydroxymethylfurfural (HMF) contents by HPLC and L*, a*, b* values with a color-meter. Furosine, free HMF, and browning in MPC80 increased during storage, whereas the solubility decreased. The correlation between the Maillard reaction and solubility loss was explored in modified MPC80 to which glucose was added to enhance the rate of the Maillard reaction. More furosine and brown pigments were observed in the glucose-containing MPC80 than in MPC80 with added lactose. The opposite trend occurred for solubility, suggesting that the Maillard reaction may be a cause of solubility loss in MPC powder.     

基于冲刷试验的贵州耕地土壤抗冲性研究

对5种不同坡度(5°～25°)的翻耕地以及有苔藓覆盖的荒坡地(20°)进行不同流量下(0.042～0.250L/s)的放水冲刷试验,以探讨贵州耕地坡面水动力性质、土壤抗冲性及地表生物(苔藓)对坡面侵蚀产沙的影响。结果表明,贵州地区坡耕地坡面流速与冲刷流量呈较好的幂函数关系,而与坡面坡度无关。坡面土壤分离速率与坡度及冲刷流量均呈显著正相关,并可用水动力学参数水流剪切力来估算贵州坡耕地土壤分离速率。与黄土高原相比,在同一坡度、同一冲刷流量下贵州坡耕地坡面产沙速率低于黄土高原坡耕地,表明贵州黄壤抗冲性高于黄土。苔藓覆盖可显著减小坡面侵蚀速率,在同一冲刷流量下,具有苔藓覆盖的荒坡地坡面产沙速率低于翻耕地达3个数量级。     

基于STM32温室环境测控系统的研究

在传统温室自动化监控系统的基础上,针对目前温室大棚面积不断增大、温室内传感器种类及数量不断增多,且不易连栋管理的现状,设计了基于ARM CORTEX-M3核的以STM32单片机为核心的智能温室控制系统。系统采用CAN总线技术对连栋大棚的主要环境因子,如温度、湿度及光照度等进行智能控制,通过串行通信实现上位机控制,增强了温室大棚的智能化和实用性。     

Species composition of arbuscular mycorrhizal fungi in two mountain meadows with differing management types and levels of plant biodiversity

Species composition of arbuscular mycorrhizal fungi (AMF) was analysed in two differently managed mountain grasslands in Thuringia (Germany). Arbuscular mycorrhizal fungi were studied in the roots of 18 dominant plant species from a total of 56 (32%). Additionally, spores of AMF were isolated from soil samples. Arbuscular mycorrhizal fungi species composition was analysed based on 96 sequences of the internal transcribed spacer of the nuclear ribosomal DNA, 72 originated from mycorrhizal roots, and 24 originated from AMF spores. Phylogenetic analyses revealed a total of 19 AMF species representing all genera of the Glomeromycota except Scutellospora and Pacispora. Despite a different farming intensity, resulting in remarkable differences concerning their plant species diversity (27 against 43 plant species), the diversity of AMF was found to be similar with 11 species on the intensively farmed meadow and ten species on the extensively farmed one. Nevertheless, species composition between both sites was clearly different. It thus seems likely that the AMF species composition, but not necessarily the species number, is related to above ground plant biodiversity in the system under study.     

Antibacterial and antioxidant activities of essential oils isolated from Thymbra capitata L. (Cav.) andOriganum vulgare L

Antilisterial activities of Thymbra capitata and Origanum vulgare essential oils were tested against 41 strains of Listeria monocytogenes. The oil of T. capitata was mainly constituted by one component, carvacrol (79%), whereas for O. vulgare three components constituted 70% of the oil, namely, thymol (33%), gamma-terpinene (26%), and p-cymene (11%). T. capitata essential oil had a significantly higher antilisterial activity in comparison to O. vulgare oil and chloramphenicol. No significant differences in L. monocytogenes susceptibilities to the essential oils tested were registered. The minimum inhibitory concentration values of T. capitata essential oil and of carvacrol were quite similar, ranging between 0.05 and 0.2 microL/mL. Antioxidant activity was also tested, the essential oil of T. capitata showing significantly higher antioxidant activity than that of O. vulgare. Use of T. capitata and O. vulgare essential oils can constitute a powerful tool in the control of L. monocytogenes in food and other industries.     

混氢改善汽油机低怠速性能研究

在一台加装了电控氢气喷射系统的四缸汽油机上,试验研究了混氢对发动机低怠速性能的影响。在怠速转速不变、维持进气混合气处于当量比的条件下,在0～6%的范围内逐渐增加氢气在总进气中的体积分数,测试了发动机转速分别为800、700、600 r/min时的低怠速性能。试验结果表明,纯汽油机怠速为800 r/min时,发动机稳定运行的燃料能量流量Ef为30.8 MJ/h,而当混氢分数增加至6.0%、怠速转速降至600 r/min时,Ef降低至18.6 MJ/h;随进气混氢体积分数的提高,发动机低怠速时的燃烧持续期缩短,HC、CO及NOx排放量降低,循环变动也减小。可见,进气掺氢可有效改善发动机的低怠速性能。