Russell: You must remember not all operate under Murphy. I know that I operate unde= r=20 Bates law. This makes it very hard to deal with. You see Bates law loosely=20 translated says Murphy was an optimist. Derward ----- Original Message -----=20 From: "RussellMc" To: "Microcontroller discussion list - Public." Sent: Monday, November 15, 2010 10:51 PM Subject: Re: [OT]:: Carnival Cruise ship? WASWhat the US has to do=20 tobeatChina at trade > >> the "hotel loads" shouldn't be able to take out the drive of the ship. > >> > > Did they? I thought it was the other way around; they lost the main > > engines, and the "hotel loads" died too... > > > > It would be interesting to read an engineering-oriented post-incident > > report. > I heard the crank case on generator #5 split and caught fire, which > burnt the generator room. > I presume some kind of firewall between the generators would suffice to > stop a reoccurrence. No. Murphy is not that easily bought :-). That would help reduce the probability of a similar appearing problem occurring again. Some kind of firewall would prevent some kind of fire causing a similar problem. Murphy has many kinds of fire and may have to resort to a different sort next time. Murphy also has many other sorts of disasters in his armoury and may even be forced to resort to a whole new class of disaster to get enough traction next time. One thing that helps Murphy a lot is that this sort of thing is a classic arms race with multiple players. There are the engineers, shareholders, public, OSHA or whoever, the laws of physics, and Murphy. The decision space is complex and Murphy has special powers - or appears to have. When the whole game play has been set in place Murphy is able to go over the whole scenario and twiddle all the parameters to find a suboptimum combination that will do most damage with minimum effort in a given case. This can seem very unfair if you are a shareholder, passenger, or engineer. OSHA are usually happy with this arrangement as it keeps them busy and in work. The classic arms race has the weapons makers ramping up the weaponry and the defendants ramping up the protection. Protection costs money and weight and space. Sharholders care. They want happy customers and happy OSHA but also bottom line profit, and people will also gamble with the 100 year storm, if they are allowed to, and often if they are not allowed to but can get away with it. A boat is of limited size and allows limited space to do things in. Murphy will find a way. Murphy is allowed to use eg 100 year storms, special resonances, unusual loading patterns, bulkhead doors that just happen to get left open, tell tales that fail to tell, tell tales that tell falsely once too often so that they are ignored or shut down at the fatally wrong time, front cargo doors that have been bent by a past vehicle impact and so don't seal properly against the unusually strong storm surge so that your rail deck floods and the rolling stock moves and your bulkhead overtops and ... :-( (not quite how the Zeebrugge ferry was lost but enough of that to be sobering). (Ferry losses are relatively common - the many such accounts make sobering reading). The Titanic's bulkheads stopped too low. Taller would have saved them easily. Flight 901 to Erebus needed 3 human errors in series spread over several years and THEN a lot of happenstance and a few people on drugs (perhaps) and unfortunate cloud cover and then some to claimm it's DC10. The Gimli glider was a far more complex situation thatn the populist reports tell - and the pilot did everything right - but the faulty fuel computer and people doing unauthorised things to safety circuits beat him. Rommel and Guderian should have made Dunkirk a different event than it was, had it not been for misimpressions in other people's minds. Murphy seems to sometimes take sides. Apollo 13 could easily have not happened, or have happened far worse, based on walking a thin and variable line amongst the various parameters. Firewalls may well be necessary, and if so, will be prescribed. But Murphy will just shrug his shoulders and pick up a different tool. All the above rambling may be translated into many other product areas with variable relative emphasis on sub-components. Knowing that things WILL go wrong, that Murphy cannot be beaten, but can be allowed for, is a good start to having things survive in the real world. . Russell McMahon --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .