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Comment Re:A really good idea, except for that one thing.. (Score 1) 343

by Skizzo (#29536875) Attached to: 250-Foot Hybrid Airship To Spy Over Afghanistan In
Sorry to burst your bubble, but blimps don't have much density (or metal) to them and will be practically invisible to RADAR. They also lack a thermal profile due to electric motors so they are invisible in the IR band too. Winds on the way to altitude are typically high, but it all varies seasonally, by position on the globe, jet stream, etc. Mostly, though, things are reasonably calm above 60k. Power is solar, with batts for night. Control power is an issue, as there isn't enough data to really derive good thrust/control-power requirements. Time to get to/from op altitude is really long. 10-17 hours is probably a good time range. You have to give the gas inside the envelope time to adjust, keeping the deltaTemp between the lifting gas and outside (called Superheat) within limits. Otherwise, you can get into runaway conditions where the ship will rise too fast out of control and burst, or descent out of control too fast and crush. All that time spent between takeoff and op altitude could see the ship blown way off course, requiring a long time to maneuver into position.
Programming

Submission + - Windows PowerShell in Action

Submitted by
jlcopeland
jlcopeland writes: "For two decades I've hated the command prompt in DOS and Windows. Inconsistencies abound and everything is a special case. The fallback on a Microsoft box has been running a Unix shell under Cygwin or installing Microsoft's own Services for Unix (or its predecessor, Softway's Interix), or by scripting in Perl, but those only get you so far. Having co-written nine years worth of trade rag columns using mostly Perl as the implementation language for the samples, and thinking of every problem that comes across my desk as an excuse to write a little bit of scripting code, I've got some well-formed views about scripting languages and what works and what doesn't. That means I've been eagerly watching the development of PowerShell since it was called Monad. It's got the advantage of being a unified command-line interface and scripting language for Windows, even if it does have a dorky name.

Bruce Payette's Windows PowerShell in Action is a great overview of PowerShell, aimed at an audience that's got some experience with other scripting languages. Bruce's book is a big improvement over Andy Oakley's earlier book, Monad, which I had been using: it's more complete and it's up-to-date for the first release of PowerShell. It's got great (and sometimes amusing) examples, and feels like the Perl Camel book in flow. When I was reading it in the gym or someplace else away from the keyboard, I kept wanting to run back to the office to try something out. There are also useful "why it works this way" digressions, which provide a lot of context. Since Bruce was on the original development team, wrote most of the commandlets, and was responsible for much of the language design, those digressions are more authoratitive than the directors' commentary tracks on most DVDs.

In outline, the nine chapters in the first part of the book build up as you'd expect: overview and concepts, to data types, to operators, to regular expressions, to syntax, to functions, to interpreting errors. It covers that ground better than many language books that now litter my shelves. The explanations are clear, and the examples are almost all exactly on point. It took me a second reading to realize that my complaints about the regular expression sub-chapter wasn't about the chapter itself, but about some of the implementation decisions — that's an argument about style more than substance, and an observation about me, not about Bruce's writing or PowerShell. The first part of the book is the "mandatory reading," if you will, to get the language down and begin exploring on your own.

The second part is where the real applications are covered. That's the part that you especially want to read sitting next to the keyboard. As you'd expect, the example code is available from the publisher's web site to start you off — look for "Example Code" under "Resources." There's a very good discussion of text processing and how-to-handle XML, complete with some not-obvious warnings about traps to avoid. I've been working very carefully through the really good chapter on using GUIs with PowerShell, "Getting Fancy — .NET and WinForms," and my own proof of concept for that has been rebuilding an old C++ data entry application into a much simpler PowerShell script. As a nice side effect, Bruce's book (and the WinForms chapter in particular) provide a gentle overview to some concepts in the .NET framework, which I hadn't had an opportunity to delve into. The appendix on using PowerShell as a management application will be especially useful to system managers — that was one of the original PoweShell target audiences, and the language achieved that goal very well. The appendix on the language's grammar is really useful, and I keep flipping back to it to check on things. It's helping to cement the language in my head.

After Oakley's Monad appeared, there was a long gap before the next PowerShell book appeared. Bruce's book looks to be the first of the post-release wave. If all it had going for it was the authoratative pedigree of the writer, it might be worth it, but it's also well-written, well-organized, and thorough, which I think makes it invaluable as both a learning tool and a reference.

[Requisite disclaimer: Bruce Payette and I have now worked together at two companies, and try to grab a cup of coffee and trade rumors about once a week. I was one of the technical reviewers of this book when it was in manuscript form. However, I approached PowerShell as a Unix and Perl bigot, and I've been surprised and pleased to see it answer nearly all of my objections.]"

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