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排序方式: 共有349条查询结果,搜索用时 15 毫秒
71.
配电网不停电作业受人员作业思维、技能素质、线路结构等因素影响较大,现有带电作业法(直接作业法和间接作业法)已不能适应供电可靠性提高的要求和社会公众对连续供电的期望,改进现有的带电作业法是大势所趋.提出基于无线遥控技术的配电网带电作业工具充分利用无线通信技术,融合了绝缘杆作业法、绝缘手套作业和综合作业法的优点,采用液压动... 相似文献
72.
筛分机的激振方式直接影响散体粘潮湿性物料的筛分效率。通过MATLAB中SimMechanics对一种多自由度激振筛分机进行了动力学响应分析,得出了该种型式筛分机的工作特点。并指出用SimMechanics进行机械动力系统运动仿真的优点。 相似文献
73.
74.
【目的】研究多水源高扬程供水工程在断电停泵时的水力过渡特性及其水锤防护措施。【方法】基于一维瞬变流理论和特征线法,对空气阀采用自由气体空穴理论,建立供水系统整体数学模型。针对无防护措施下的断电工况过渡过程计算结果,选择在水泵出口侧和扬水管地面段末端设置快关式逆止阀,在供水管道局部高点设置空气阀的联合水锤防护措施,并进行了空气阀参数的敏感性分析。【结果】在未采取水锤防护措施时,在水泵出口侧发生较大压降且供水管道沿线最低内水压力严重超标。在采取合适的水锤防护措施后,在断电工况下,水泵无反转且泵后最小压力不低于-5m,泵后扬水管最小压力不低于-5m,供水主管最大压力不超过160m,最小压力不低于-5m。【结论】空气阀可对水泵出口侧和供水管道的负压起到很好的控制效果。 相似文献
75.
汪学军 《安徽农业大学学报》2003,(3):51-54
随着全球公共养老保险而临的困境,各国政府纷纷对传统的养老保险进行改革。在改革过程中,企业年金发挥了越来越重要的作用。本文主要对企业年金制度在国内外的发展
展开讨论,并提出发展我国企业年金制度的初步设想。 相似文献
76.
This paper introduces a novel constant frequency switching PWM converter,as well as some improvements on the conventional bridge parallel resonant converters. By introducing mutual inductance and auxiliary into the original circuit topology ,a class of novel zero current switching multi-resonant converters regulated by PWM mode at a fixed switching frequency are presented,which overcomes some drawback of the original circuits.One illustrative example is analyzed and the experimental results are given, which confirms the advantages of this approach. 相似文献
77.
This study assessed the effect of probiotics on cecal microbiota, cecal short‐chain fatty acids (SCFAs), and the gene expression of cytokines in young specific‐pathogen‐free (SPF) chickens infected with S. enterica subsp. enterica. One‐day‐old SPF chickens (n = 105) were randomly assigned to one of the three treatment groups: control (Cont) group, Salmonella‐infected (Sal) group, and a Salmonella‐infected group treated with multi‐strain probiotics (ProSal group). All chickens except those in the Cont group were challenged orally with 1 × 108 cfu/ml of Salmonella 4 days after hatching. Chickens in the Sal group exhibited more abundance of Proteobacteria than those in the Cont and ProSal groups. At the genus level, chickens in ProSal group exhibited increased numbers of Lactobacillus and Oscillospira compared with those in the other groups. Chickens in the ProSal group exhibited a significant increase of cecal SCFAs compared with chickens in the Sal group. Chickens in the ProSal group exhibited increased gene expression of anti‐inflammatory cytokines, IL‐10 and TGF‐β4, and decreased expression of the proinflammatory cytokine, IFN‐γ, in the cecal tonsil compared with those in the Sal group. The results of this study indicated that the administration of probiotics can modulate microbiota, SCFAs, and immunomodulatory activity in SPF chickens. 相似文献
78.
Daniel J. Tolhurst Ky L. Mathews Alison B. Smith Brian R. Cullis 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2019,136(4):279-300
Genomic selection (GS) is a statistical and breeding methodology designed to improve genetic gain. It has proven to be successful in animal breeding; however, key points of difference have not been fully considered in the transfer of GS from animal to plant breeding. In plant breeding, individuals (varieties) are typically evaluated across a number of locations in multiple years (environments) in formally designed comparative experiments, called multi‐environment trials (METs). The design structure of individual trials can be complex and needs to be modelled appropriately. Another key feature of MET data sets is the presence of variety by environment interaction (VEI), that is the differential response of varieties to a change in environment. In this paper, a single‐step factor analytic linear mixed model is developed for plant breeding MET data sets that incorporates molecular marker data, appropriately accommodates non‐genetic sources of variation within trials and models VEI. A recently developed set of selection tools, which are natural derivatives of factor analytic models, are used to facilitate GS for a motivating data set from an Australian plant breeding company. The power and versatility of these tools is demonstrated for the variety by environment and marker by environment effects. 相似文献
79.
1WG-4.4A型多功能微耕机是适用于山区坡田地块耕作的农业机械。阐述该微耕机的结构特点、作业性能与主要技术参数,介绍该机具的多种作业功能,分析应用该机具的作业效果与经济效益,为其大面积推广提供理论与技术支持。 相似文献
80.
Changes in the Relationship Between Temperature During the Seed‐Filling Period and Soya Bean Seed Isoflavones Under Water‐Deficit Conditions
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Isoflavones have been shown to have health‐promoting activities in humans and are particularly abundant in soya bean. This study was conducted to determine how water deficit during seed fill affects the already known relationship between temperature and, alternately, solar radiation with soya bean seed isoflavone content. Isoflavone profile was analysed from seed samples of commercial cultivars grown in 76 environments in Argentina (29–38°S). Significant explanatory multiple linear regressions were detected for total isoflavones (TI), aglycones (AGL), glucosides (GLC), malonyl glucosides (MAL) and acetyl glucosides (ACE) regarding the following: temperature during seed fill (TmR5R7) and precipitation minus potential evapotranspiration during the reproductive period (pp‐PETR1R7), as well as for the combinations of these climatic variables. Cumulative solar radiation predicted isoflavone content but was less robust than TmR5R7 and pp‐PETR1R7. To our knowledge, this is the first report of changes in the relationship between TI, as well as AGL, GLC, MAL, and ACE and TmR5R7 as a function of drought in the field. When pp‐PETR1R7 was below 70 mm (indicating drought), TI, as well as AGL, GLC, MAL, and ACE decreased linearly with rising temperatures and with increasing water deficit (decreasing values of pp‐PETR1R7), with both climatic variables exhibiting additive effects on isoflavones. Our results also suggest that water deficit (estimated by pp‐PETR1R7) would be important for modelling the relationship between temperature and soya bean seed isoflavones in rainfed crops. 相似文献