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Rälsens expansion (Bana)

av Per Ljungberg, Tuesday, March 24, 2009, 08:12 (5824 dagar sedan) @ Lars Borneland

Naturlagarna kan vi inte ändra på så skenorna vill fortfarande ändra sin längd beroende på temperaturen. Man har en s.k. neutralpunkt vid ca +15 grader där det inte finns några krafter i rälsen. Vid högre temperatur blir det tryckkrafter och vid lägre temperaturer blir det dragkrafter i rälsen. Genom spårbäddens utformning kan dessa krafter tas upp utan att spårläget ändras. Ungefär som när man trycker ihop eller drar ut ett radergummi. Så ett rälsbrott vid låg temperatur kan innebära att det blir ett stort gap mellan rälsändarna vid brottstället.
PLj

Hela tråden:

 

Time: 236
SELECT COUNT(*) FROM mlf2_entries LEFT JOIN mlf2_akismet_rating ON mlf2_akismet_rating.eid = mlf2_entries.id LEFT JOIN mlf2_b8_rating ON mlf2_b8_rating.eid = mlf2_entries.id WHERE pid = 0 AND (mlf2_akismet_rating.spam = 0 AND mlf2_b8_rating.spam = 0) AND category IN (0, 4, 5, 6, 7, 8, 9, 25, 14, 23, 19, 22, 24, 10, 21, 11, 12, 13, 15, 16, 26, 18, 20, 27)

Time: 1140
SELECT COUNT(*) FROM mlf2_entries LEFT JOIN mlf2_akismet_rating ON mlf2_akismet_rating.eid = mlf2_entries.id LEFT JOIN mlf2_b8_rating ON mlf2_b8_rating.eid = mlf2_entries.id WHERE (mlf2_akismet_rating.spam = 1 OR mlf2_b8_rating.spam = 1)
Time: 1244
SELECT COUNT(*) FROM mlf2_entries LEFT JOIN mlf2_akismet_rating ON mlf2_akismet_rating.eid = mlf2_entries.id LEFT JOIN mlf2_b8_rating ON mlf2_b8_rating.eid = mlf2_entries.id WHERE category IN (0, 4, 5, 6, 7, 8, 9, 25, 14, 23, 19, 22, 24, 10, 21, 11, 12, 13, 15, 16, 26, 18, 20, 27) AND (mlf2_akismet_rating.spam = 0 AND mlf2_b8_rating.spam = 0)

Total time: 2629