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Methods of Investigation and Constructional Materials
Published in Janusz Turowski, Marek Turowski, Engineering Electrodynamics, 2017
Janusz Turowski, Marek Turowski
In turbine generators of older construction, rotor windings were made of soft electrolytic copper with the modulus of elasticity of 105 N/mm2, limit of elasticity of 42 N/mm2, and CTE of 17 × 10−6 K−1. At such small strengths of copper, any faster starting or stopping of large turbogenerators was accompanied by a permanent deformation of conductors in the slots, caused by reciprocal interaction of thermal expansion and the friction of the conductors on slots. It resulted in damages of winding, insulation, or clampings. Application of copper along with the addition of 0.07–0.1% of silver, with cold press treatment, increased its limit of elasticity to 150 N/mm2, which reduced the risk of such damages. Also, for windings of large transformers, sometimes a copper with silver additions is used, which, contrary to normal copper, does not lose its increased elasticity obtained by plastic treatment during exploitation. Due to similar reasons, for the rotor windings, sometimes a conducting aluminum alloy is used, for example, Cond-Al (Latek [1.35]) with a elasticity limit of 11 deca-newton (daN)/mm2 and a thermal coefficient of expansion of 13.1 × 10−6 1/K. In Table 1.3, selected important mechanical properties of copper are collected.
Annexures
Published in Ram Pravesh Bhagat, Agglomeration of Iron Ores, 2019
Typically, the crushing strength of pellets is measured by compressing at least 60-pellet samples one-after-another with size below 12.5 and above 9.5 mm diameter between parallel steel plates until the pellets break. The capacity of the load cell shall be at least 1,000 kg. The test values are reported in terms of: the mean crushing strength in daN (deca-Newton)/pellet, andthe percentage under 200 and 150 daN/pellet.
Introduction to Civil Engineering
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
Runways are generally named using numbers from 01 to 36. This number represents the magnetic azimuth of the runway’s heading measured in deca degrees. For example, a runway numbered as 09 points toward east (90°). While runway 18 points toward south (180°), runway 27 points west (270°). A runway pointing toward north (360°) is always designated as runway 36. It is never measured as 0° nor designated as runway 0. Denver International Airport’s 16R/34 L runway is designated as the longest commercial runway (16,000 ft) in North America.
A new advance in the potential exposure to “old” and “new” halogenated flame retardants in the atmospheric environments and biota: From occurrence to transformation products and metabolites
Published in Critical Reviews in Environmental Science and Technology, 2020
Shengtao Ma, Yingxin Yu, Yan Yang, Guiying Li, Taicheng An
Furthermore, debromination metabolism of BDE-209 was also demonstrated in human body. For example, significant accumulation of octa- and nona-BDE congeners was observed in occupational rubber workers after exposing to deca-BDE commercial mixture (Thuresson et al., 2005). The estimated half-life of BDE-209 was observed as 15 days, while the half-lives in workers for three nona- and four octa-BDE concenters were 18–39 and 37–91 days, respectively. For octa- to deca-BDEs, the half-lives were found to decrease with increasing the bromination degree, suggesting that BDE-209 may be more readily metabolized and/or eliminated from human body (Thuresson et al., 2006). Relatively high levels of octa- to nona-BDEs reported in serum (Bi et al., 2007) and breast milk (Tue et al., 2010) from e-waste dismantling workers can be attribute to the debromination of BDE-209. In addition, the metabolic debromination of highly brominated PBDEs occurred preferably through the loss of bromines at meta- and para-position relative to the diphenyl ether bond, resulting the formation of relatively higher concentrations of BDE-207, -197, -183, and -153 debromination products in human body (Ma et al., 2012).
Seasonal-spatial distributions, congener profile, and risk assessment of polychlorinated biphenyls (PCBS) in the surficial sediments from the coastal area of Bangladesh
Published in Soil and Sediment Contamination: An International Journal, 2019
Md. Habibullah-Al-Mamun, Md. Kawser Ahmed, Md. Saiful Islam, Masahiro Tokumura, Shigeki Masunaga
The homolog compositions (%) of PCB in the Bangladeshi coastal sediments are shown in Figure 3. Regardless of sites and seasons, the proportions of the homologs with different degree of chlorination were in the decreasing order of: medium (tetra- to hexa-CBs) > heavier (hepta- to deca-CBs) > lighter (mono- to tri-CBs), contributing 57–75%, 12–24%, and 10–15% to the ∑PCBs, respectively. In general, penta-CB was the most prevalent homolog in the sediment samples, accounting for 16–29% and 25–38% of ∑PCBs in winter and summer, respectively, followed by hexa-CB (12–21% and 12–24% of ∑PCBs in winter and summer, respectively) and tetra-CB (10–28% and 11–15% of ∑PCBs in winter and summer, respectively). Although the observed trends in PCB homologs composition were almost similar in the majority of the samples (Figure 3), the distribution patterns are, to some extent, different for some locations suggesting different or multiple emission sources of PCBs in the study area (Barakat et al., 2002). Overall, this pattern indicates the existence of local input sources and possibly ongoing release into the study area as well. From the Bay of Bengal coast of India, Rajendran et al. (2005) reported the dominance of tetra-, penta-, and hexa-CBs at some sites, while di-, tri-, and tetra-PCB homologs were more prevalent at other sites. The abundance of heavier homologs was also recorded in sediments from other coastal areas, such as penta- to octa-CBs from the Daliao River estuary (Men et al., 2014), tetra- to hepta-CBs from Alexandria Harbor, Egypt (Barakat et al., 2002), penta- and hexa-CBs from Sarno River and Estuary, Southern Italy (Montuori et al., 2016), and that was explained as the dominance of recent releases from the local inputs of PCBs in these study areas. However, the dominance of tri- and tetra-CBs due to the impact of historical PCB usage were reported in the surface sediments from Hyeongsan River of Korea (Koh et al., 2004) and Sea Lots, Port-of-Spain, Trinidad and Tobago (Mohammed et al., 2011). Although the homolog composition did not differ significantly between the two seasons (p > 0.05), collectively a shift to a smaller extent toward high-chlorinated homologs were noticeable in the case of summer samples (Figure 3).