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请回答自耗电极安装的基本要求和注意事项。

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正确答案:

自耗电极安装的基本要求有二,其一是必须牢固(焊接时要焊牢),以保证熔炼过程中不脱落、不松动。因脱落会造成强迫停炉或击穿结晶器;松动易在把持器和电极间隙处起弧烧坏把持器或者把辅助电极焊死在把持器上,同样造成停炉或电极摆动击穿结晶器而造成事故。其二是电极必须装正,与结晶器轴线重合。否则电极偏离中心,在间隙小一方易产生边弧烧坏结晶器。

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Selling Digital Music without Copy-protection Makes Sense A. It was uncharacteristically low-key for the industry’s greatest showman. But the essay published this week by Steve Jobs, the boss of Apple, on his firm’s website under the unassuming title “Thoughts on Music” has nonetheless provoked a vigorous debate about the future of digital music, which Apple dominates with its iPod music-player and iTunes music-store. At issue is “digital rights management” (DRM)—the technology guarding downloaded music against theft. Since there is no common standard for DRM, it also has the side-effect that songs purchased for one type of music-player may not work on another. Apple’s DRM system, called FairPlay, is the most widespread. So it came as a surprise when Mr. Jobs called for DRM for digital music to be abolished. B. This is a change of tack for Apple. It has come under fire from European regulators who claim that its refusal to license FairPlay to other firms has “locked in” customers. Since music from the iTunes store cannot be played on non-iPod music-players (at least not without a lot of fiddling), any iTunes buyer will be deterred from switching to a device made by a rival firm, such as Sony or Microsoft. When French lawmakers drafted a bill last year compelling Apple to open up FairPlay to rivals, the company warned of “state-sponsored piracy”. Only DRM, it implied, could keep the pirates at bay. C. This week Mr. Jobs gave another explanation for his former defence of DRM: the record companies made him do it. They would make their music available to the iTunes store only if Apple agreed to protect it using DRM. They can still withdraw their catalogues if the DRM system is compromised. Apple cannot license FairPlay to others, says Mr Jobs, because it would depend on them to produce security fixes promptly. 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