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81.
扭轮摩擦传动静力学分析 总被引:3,自引:1,他引:3
讨论了扭轮摩擦传动机构稳定运行的力学条件,扭轮所受驱动力和扭轮轴线之间的夹角.驱动力矩机构轴向栽荷与扭轮和传动轴间正压力的关系.通过分析得出了驱动力矩、扭轮所受的来自于传动轴圆周切向驱动力主要取决于扭轮与传动轴间的正压力,扭轮所受驱动力的方向和扭轮轴轴线的夹角随着扭轮与传动轴间正压力和传动轴的轴向栽荷的变化而变化的结论. 相似文献
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Based on the consultation and study for Xiangjiaba-Shanghai ±800 kV UHVDC(ultra high voltage direct current) project,this paper presents an optimal design for key technique solutions.In this paper,the DC system electrical scheme design,the DC filter design,the DC harmonic component suppression,the over voltage and insulation coordination,the requirements for converter station equipment,the main equipment technical parameters of equipment(including thyristor valve,converter transformer,smoothing reactor,DC breaker),the configuration of measuring device and DC control protection system,and the de-icing operation design are investigated.According to the UHVDC technology researched conclusions and the development of the project construction,the UHVDC system design for converter stations becomes an optimal combination.The optimized design solves numbers of technical problems of the world’s first UHVDC project,and it is applied to the project’s construction.Under the actual operating condition,the optimized design is proved to be correct and superior.These optimal design conclusions are impartment for developing UHVDC technique and equipment,and provide reference for future UHVDC projects. 相似文献
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86.
Eddie T. T. Tan Rafat Al Jassim Bruce R. D’Arcy 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2016,33(10):1587-1595
Camel meat production for human consumption and pet food manufacture accounts for a relatively small part of overall red meat production in Australia. Reliable statistical data for the Australian production and consumption of camel meat are not available; however, it is estimated that 300,000 feral camels roam within the desert of central Australia, with an annual usage of more than 3000 camels for human consumption, 2000 for pet food manufacture and a smaller number for live export. Despite a small Australian camel meat production level, the usage of camel meat for pet food has been restricted in recent years due to reports of serious liver disease and death in dogs consuming camel meat. This camel meat was found to contain residues of indospicine, a non-proteinogenic amino acid found in certain Indigofera spp., and associated with mild to severe liver disease in diverse animals after dietary exposure to this hepatotoxin. The extent of indospicine-contaminated Australian camel meat was previously unknown, and this study ascertains the prevalence of such residue in Australian camel meat. In this study, indospicine levels in ex situ (95 samples collected from an abattoir in Queensland) and in situ (197 samples collected from camels after field culling in central Australia) camel meat samples were quantitated using a validated ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The quantitation results showed 46.7% of the in situ- and 20.0% of the ex situ-collected camel meat samples were contaminated by indospicine (more than the limit of detection (LOD) of 0.05 mg kg–1 fresh weight). The overall indospicine concentration was higher (p < 0.05) in the in situ-collected samples. Indospicine levels detected in the present study are considered to be low; however, a degree of caution must still be exercised, since the tolerable daily intake for indospicine is currently not available for risk estimation. 相似文献
87.
Fermentation dynamics of Lactobacillus helveticus H9 revealed by ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry
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Zhihui Mi Lai‐yu Kwok Jiangang Xue Yuenan Wang Heping Zhang Yongfu Chen 《International Journal of Food Science & Technology》2018,53(6):1442-1451
Lactobacillus (L.) helveticus H9 is a probiotic strain that can produce antihypertensive peptides during milk fermentation. This study analysed the dynamics of skim milk fermentation by L. helveticus H9 by ultra‐performance liquid chromatography coupled to quadrupole time‐of‐flight mass spectrometry (UPLC/Q‐TOF MS). A total of 1992 metabolites were detected from all of the fermented samples in the LC‐MS analysis by multivariate statistical analysis. Metabolites with variable importance in projection (VIP) values ≥2 were considered differentially abundant among samples and were responsible for the unique taste and nutritional and functional qualities of fermented milk. Valine, threonine, l ‐methionine, tyrosine, asparagine and leucine were the predominant amino acids produced during fermentation, and their quantities changed remarkably during the fermentation process. Citric acid and uric acid were the major, and only detectable, organic acids. Some intermediate metabolites, such as N‐acryloylglycine and nicotinamide‐N‐oxide, were also detected. Moreover, certain oligopeptides such as Val‐Leu, Lys‐Gly, Ala‐Glu, Asp‐Ser, Leu‐Pro and Val‐Phe‐Ala were not detected until the middle and late fermentation periods. This study demonstrated dynamic metabolic changes, providing a strong foundation for deciphering the physiological and biochemical mechanisms of the fermentation process. 相似文献
88.
Weighted Self-Adaptive Threshold Wavelets for Interpolation Point Selection Used in Interconnect MOR
超高膨胀比涡轮噪声控制技术研究
赵辛午,黄洪雁
(哈尔滨工业大学 能源科学与工程学院,哈尔滨 150001)
中文说明:
气动噪声控制是提高鱼雷隐身性能的关键技术之一。本文讨论了局部进气的超高膨胀比涡轮气动噪声产生机理。相邻喷嘴与流道之间形成的三角形非出气区域引起的尾迹、圆周局部进气设计引起的不稳定性、喷嘴和转子之间区域形成的复杂激波系是这类涡轮气动噪声产生的三种主要来源。因此,本文提出了两种气动噪声控制方法,增加转静子之间的轴向间距,喷嘴下俯、双侧修型和尾缘吹气。数值模拟结果表明:在对原涡轮气动性能影响不大的情况下,优化后涡轮的气动噪声下降10 dB以上。
关键词:超高膨胀比涡轮、气动噪声、流动特性、优化
相似文献89.
目的 建立超高效液相色谱-四极杆飞行时间质谱法快速测定混合型饲料添加剂中培氟沙星、氯霉素、沙丁胺醇、盐酸克伦特罗、氧氟沙星、恩诺沙星、诺氟沙星、氟苯尼考、磺胺嘧啶、磺胺甲噁唑、磺胺间甲氧嘧啶、甲硝唑、多西环素、金刚烷胺共14种化学药物的分析方法。方法 样品经乙腈-水(8:2, V:V)提取, 上清液离心后上样, 以0.1%(V:V)甲酸甲醇溶液和0.1%(V:V)甲酸水溶液为流动相进行梯度洗脱(负离子模式流动相为乙腈-水), C18色谱柱(50 mm×2.1 mm, 1.7 μm)分离。分别采用正/负离子模式检测分析。结果 14种药物的质量数误差绝对值小于5 mDa, 在2.0~100.0 μg/L范围内线性关系良好, 相关系数大于0.99。4个浓度水平的平均回收率为70.6%~119.80%, 相对标准偏差1.0%~12.4%。结论 该方法操作简便、结果准确, 适用于混合型饲料添加剂中非法添加药物的快速筛查分析。 相似文献
90.
针对水泥混凝土桥面铺装破坏的现象,提出超薄罩面(3~4cm厚)修复技术,不仅能够对桥面铺装进行有效地修复,并且可以显著延长桥面铺装寿命。本技术引入PVA(聚乙烯醇纤维)陶粒纤维混凝土和PVA-ECC(超强韧性纤维混凝土),陶粒混凝土有效降低了桥梁恒载的增加,伸缩缝两侧铺筑PVA-ECC可以抵御此区域较强的车辆冲击荷载。此技术经济有效,工艺简单,是水泥混凝土桥面铺装加铺改建的理想选择。 相似文献