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为了实现新能源高占比下的电力供需平衡,提升电力系统的灵活性显得十分重要。首先定性定量分析中国新能源电力系统在电源侧、电网侧和负荷侧对灵活性的不同需求。其次,归纳总结新能源电力系统灵活性的技术体系,介绍主要技术在中国已经开展的具体实践和效果。然后,根据国家能源转型目标,提出电力系统灵活性中长期目标和衡量灵活性进程的主要指标。最后,为了达成上述目标,从灵活性电源、灵活性电网、灵活性负荷和数字电网平台四个方面设计了发展路径。 相似文献
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盾构接收是盾构法施工的最后一道”关槛”,是盾构法施工的重点和难点之一,特别是当工作井周边存在不良地质或富水地层时,容易出现涌水、涌砂等险情,引起地面局部塌陷,严重的会影响地面交通及居民正常生活.文章通过对南京地铁三号线某区间钢套筒盾构接收施工工艺进行研究和分析,辨识该工艺存在的主要风险点并给出应对措施,对指导类似工程施工风险管控具有一定的借鉴意义. 相似文献
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提出一种利用低漏抗变压器和并联型低压有源电力滤波器实现对高电压等级补偿的新方法。针对现场工况情况,考虑到变压器的移相特性,采用一种新型数字锁相环技术对原有控制策略进行改进,实现了通过低压有源滤波器对高电压母线的谐波治理和无功补偿。在不改变低压有源滤波器内部结构的前提下,可以替代高压有源电力滤波器完成补偿任务,降低设备投资。低压有源滤波器电压等级较低,可以降低设备运维难度,并能提高运维人员的安全系数。通过PSCAD/EMTDC数字仿真和现场实物试验,验证了相关设计的有效性和可行性。 相似文献
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针对金属厚管料的下料问题,以自行研发的旋转疲劳弯曲精密下料机为平台,研究了精密下料过程中不同外载荷方式下304不锈钢管的断面质量情况。利用径向循环外载荷管料表面V型槽的应力集中效应,通过控制不同阶段施加给管料的弯曲疲劳外载荷频率值,实现了304不锈钢管的精密下料。通过对实验所加外载频率曲线的设计,进行304不锈钢管的精密下料实验,得出了下料过程中理想的外载频率曲线——即低频启动高频起裂和裂纹扩展最后再低频断料,用此加载方式获得了良好质量的管料断面,在理想外载频率曲线的基础上研究了不同壁厚管料的下料断面质量情况,并对其断面质量进行了测量和评价。实验结果表明,在文中所提下料工艺的基础上使用所提的外载频率曲线针对不同壁厚的304管料下料均能得到比较好的断面质量。 相似文献
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Probabilistic prediction of high cycle fatigue reliability of high strength steel butt‐welded joints
R. BEN SGHAIER CH. BOURAOUI R. FATHALLAH G. DEGALLAIX 《Fatigue & Fracture of Engineering Materials & Structures》2010,33(9):575-594
The aim of this paper is to develop a probabilistic approach of high cycle fatigue (HCF) behaviour prediction of welded joints taking into account the surface modifications induced by welding and the post‐welding shot peening treatment. In this work, the HCF Crossland criterion has been used and adopted to the case of welded and shot peened welded parts, by taking into account the surface modifications which are classified as follows: (i) the compressive residual stresses, (ii) the surface work‐hardening, (iii) the geometrical irregularities and (iv) the superficial defects. The random effects due to the dispersions of: (i) the HCF Crossland criterion material characteristics (ii) the applied loading and (iii) the surface modifications parameters are introduced in the proposed model. The HCF reliability has been computed by using the ‘strength load’ method with Monte Carlo simulation. The reliability computation results lead to obtain interesting and useful iso‐probabilistic Crossland diagrams (PCD) for different welding and shot peening surface conditions. To validate the proposed method, the approach has been applied to a butt‐welded joint made of S550MC high strength steel (HSS). Four types of specimens are investigated: (i) base metal (BM), (ii) machined and grooved (MG) condition, (iii) As welded (AW) condition and (iv) as welded and shot peened (AWSP) condition. The comparison between the computed reliabilities and the experimental investigations reveals good agreement leading to validate the proposed approach. The effects of the different welded and post‐weld shot peened specimen's surface properties are analysed and discussed using the design of experiments (DoE) techniques. 相似文献
10.
MOUNA BEN TAARIT KAMEL MSAADA KARIM HOSNI THOURAYA CHAHED BRAHIM MARZOUK 《Journal of Food Biochemistry》2010,34(1):142-151
The essential oil of aerial parts of Salvia verbenaca L., collected in three different locations in Tunisia, were obtained by hydrodistillation and analyzed by gas chromatography (GC) and GC–mass spectrometry. The oil yields of dried plants (w/w) were 0.09, 0.10 and 0.12% in Sabelet Ben Ammar, Sers and Somaa, respectively. Seventy-seven compounds were identified. The monoterpene hydrocarbons and oxygenated sesquiterpenes had the highest contributions. The major constituents in Sabelet Ben Ammar were viridiflorol (21.8%), camphene (17.6%), methyl eugenol (9.4%) and β-caryophyllene (7.1%), while those of essential oil collected from Somaa, were tricyclene (18.8%), nonane (10.3%), methyl eugenol (7.7%) and terpinolene (7.3%). In samples collected from Sers, essential oil consists mainly of (Z)-β-ocimene (29.5%), β-phellandrene (8.2%), β-thujone (7.9%) and α-pinene (5.5%).
In this study, it has been found that the oils of wild-growing Salvia verbenaca L. in Tunisia are rich in oxygenated sesquiterpenes and monoterpene hydrocarbons with great economical values. The plant family Labiatae contains several species with potential therapeutic activity due to their essential oils. Pharmacology, pharmaceutical botany, medical and clinical microbiology, phytopathology and food preservation are some fields in which essential oils can be applied. Many Salvia spp. are used as herbal tea and for food flavoring, as well as in cosmetics, perfumery and the pharmaceutical industry. It has shown that essential oil of S. verbenaca have strong antibacterial, antioxidant, antifungal, anti-inflammatory activities and peripheral analgesic properties. 相似文献
PRACTICAL APPLICATIONS
In this study, it has been found that the oils of wild-growing Salvia verbenaca L. in Tunisia are rich in oxygenated sesquiterpenes and monoterpene hydrocarbons with great economical values. The plant family Labiatae contains several species with potential therapeutic activity due to their essential oils. Pharmacology, pharmaceutical botany, medical and clinical microbiology, phytopathology and food preservation are some fields in which essential oils can be applied. Many Salvia spp. are used as herbal tea and for food flavoring, as well as in cosmetics, perfumery and the pharmaceutical industry. It has shown that essential oil of S. verbenaca have strong antibacterial, antioxidant, antifungal, anti-inflammatory activities and peripheral analgesic properties. 相似文献