高压共轨喷油器控制阀空化研究   总被引：1，自引：0，他引：1  

段炼  袁寿其  胡林峰  李德桃  夏兴兰  俞建达 《农业机械学报》2015,46(5):321-327

为了研究较高轨压条件对共轨喷油器控制阀的影响,对典型的共轨喷油器进行了可靠性试验,而且针对控制阀及其上游流道进行了非定常气液两相流动模拟计算和分析。计算所需的动网格边界条件由执行器衔铁杆位移测量试验获得。通过测量喷油器的动态回油流量,对计算模型进行了试验验证。可靠性试验结果表明控制阀的阀座锥面存在空化穴蚀损伤。模拟计算结果表明,当入口压力条件达到250 MPa级别后,在控制阀上游的导流孔内出现明显的空化现象;在150 MPa、200 MPa和250 MPa 3个级别的入口压力条件时气液两相质量交换率的比值为1∶1.187∶1.437。为匹配250 MPa及以上级别的轨压条件,控制阀上游流道结构须改进。  相似文献   

48个苜蓿品种对3种病害抗性的初步评价     

李彦忠  喻军强  李明 《草业学报》2021,30(9):62-75

在兰州大学榆中校区品种比较试验田,以发病率为指标,采用国际上通用的苜蓿病害抗病性评价的分级标准,比较了国内外48个苜蓿品种对褐斑病、霜霉病和锐顶镰刀菌根腐病的抗病性,并对其进行了综合评价。抗病性等级评价结果表明,不同苜蓿品种对褐斑病的抗性表现是UC-1465为高抗（HR）品种,UC-1887为抗病（R）品种,Siriver与Trifecta为中抗（MR）品种,Avrora、Hunter River、Saranac AR为低抗（LR）品种,其余41个品种均为感病（S）品种;对霜霉病的抗性表现是48个苜蓿品种均为高抗（HR）品种;对锐顶镰刀菌根腐病的抗性表现是48个苜蓿品种均为高抗（HR）品种。综合评价结果表明,Vertus、中兰1号和新牧1号对褐斑病、霜霉病和锐顶镰刀菌根腐病均具有较强的抗病性,为高抗品种;UC-1887、UC-1465和Saranac AR对褐斑病、霜霉病和锐顶镰刀菌根腐病的抗病性均较差,为感病品种。  相似文献   

动力机械振动监测方法探讨     

韦蕊蕊 《林业机械与木工设备》2007,35(8):50-51

振动监测是动力机械故障诊断的一个重要组成部分.本文通过分析动力机械中的往复式压缩机产生振动的原因,阐述其常见故障及诊断方法,指出采用振动监测的必要性,并介绍实际应用时振动监测系统的构成.  相似文献   

Apparent Digestibility of Various Cereal Grain By-products in Common Carp Diets     

O. Fagbenro 《Aquaculture International》1999,7(4):277-281

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Reduced differentiation of intestinal epithelial cells in wasting marmoset syndrome     

Kimie NIIMI  Eiki TAKAHASHI 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2021,83(5):784

Wasting marmoset syndrome (WMS) is a serious disease in captive common marmoset (Callithrix jacchus) colonies. Because of the high mortality rates, elucidation of the underlying mechanisms is essential. In this study, we compared the histopathology, the number of each epithelial cell in the jejunum and colon, and the expression patterns of some molecular markers between healthy and WMS-affected marmosets. Atrophy of villi in the jejunum and mononuclear cell infiltration in the lamina propria were observed in the intestinal tract of WMS-affected marmosets. Although the numbers of transient amplifying cells and tuft cells were increased, the number of goblet cells was obviously decreased in the jejunum and colon of WMS-affected marmosets compared to healthy marmosets. In addition, the number of enterocytes in the jejunum was decreased in WMS animals. There was no apparent difference in the numbers of stem cells, enteroendocrine cells, or Paneth cells. The expression of β-catenin and Tcf7l2 was increased in WMS, and the co-existence of β-catenin and Tcf7l2/Cyclin D1 was observed around the crypts in WMS-affected marmosets. These findings suggest that cell proliferation continues, but cell differentiation is halted in the intestinal tract due to the enhanced β-catenin/Tcf7l2/Cyclin D1signaling pathway in WMS, which results in malfunction of the villus and mucosa.  相似文献   

4 650 kW热媒炉存在的问题及解决方法     

谷鸣 《油气储运》2000,19(10):49-51

提出了中洛（中原油田－洛田）输油管道濮阳首站两台4650kW热媒炉存在的主要问题，通过对炉内保温层脱落，炉前燃烧装置卢火筒保温层碎裂，热媒泵及热媒氧化等存在问题的分析，提出了相应的解决措施。  相似文献   

数字普惠金融对农民农村共同富裕的影响及机制研究          下载免费PDF全文

罗振军 《安徽农业大学学报》2023,32(6):62-71

以农民农村共同富裕为研究对象，就数字普惠金融对农民农村共同富裕的影响及作用机制进行实证分析，结果表明，数字普惠金融发展对农民农村共同富裕有着显著的正向推动作用，且不同区域的影响有所差异；区域经济发展、家庭收入水平、收入分配结构是数字普惠金融推动农民农村共同富裕实现的中介变量，对促进农民农村共同富裕起着重要的调节作用。由此，应进一步加强数字基础设施建设、加强数字技术与金融发展融合力度、充分发挥数字普惠金融对农民农村共同富裕的作用功效，为推进农民农村共同富裕提供政策方向。  相似文献   

同基础无偏心多塔基底隔震结构隔震效果分析     

袁正国  周宪伟 《森林工程》2006,22(6):51-53

本文通过对无偏心的单塔基底隔震结构和同基础多塔基底隔震结构进行数值分析，计算在地震作用下的反应。结果表明，对于上部结构无偏心的结构，采用单塔基底隔震结构与同基础多塔基底隔震结构的形式，隔震效果基本相同，没有明显的差别。  相似文献   

Influence of turbidity and fluctuating water levels on the abundance and depth distribution of small, benthic fish in New Zealand alpine lakes   总被引：2，自引：0，他引：2  

D. Rowe  E. Graynoth  G. James  M. Taylor  L. Hawke 《Ecology of Freshwater Fish》2003,12(3):216-227

Abstract –  Minnow trapping was used to determine the distribution and abundance of two small, benthic species of fish, common bullies ( Gobiomorphus cotidianus ) and koaro ( Galaxias brevipinnis ), in five oligotrophic lakes varying in both turbidity and the extent of water-level variation. Koaro were 5–20 times more abundant in the large turbid lakes than in the clear ones, indicating that turbidity may reduce the extent of salmonid predation on koaro. However, the scarcity of koaro in the clear lakes was related mainly to the prevalence of brown trout ( Salmo trutta ) compared with rainbow trout ( Oncorhynchus mykiss ) as the former were more piscivorous and had a stronger inverse relationship with koaro. Common bullies were more abundant at sites 20 m or more away from the shoreline, and at depths of 9–12 m irrespective of season, year and turbidity level. However, the overall abundance of bullies was reduced by 70–90% in the turbid lakes. As bullies are relatively insensitive to the direct effects of increased turbidity, indirect effects such as reductions in macrophytes from reduced water clarity or smothering of benthic habitats by settled solids are thought to influence their abundance in the lakes affected by glacial turbidity. There was no relationship between the extent of water-level fluctuation and the abundance of koaro or common bullies in the lakes, but the depth distribution of bullies was shallowest in the lake with the least water-level fluctuation and was deepest in the lake with the greatest water-level fluctuation.  相似文献   

译学理论与实践之文化转向的思考     

郭勇  李延林  张沉香 《中南林业科技大学学报(自然科学版)》2004,24(3):77-79

传统的译学理论与实践注重的是源语与宿语在语言层面的转换且以源语为中心.自从20世纪80、90年代西方译学研究发生"文化转向"以来,翻译界已展现出一幅全新的画面,翻译本身已成为一种文化现象."文化转向"背景下的翻译观以及应和时代需要的"通变原则"对指导译者在两种异质文化框架内进行再创造非常重要.  相似文献