EmDrive (by alaric)

A British chappy claims to have built an reactionless engine, the EmDrive - I just read about it in New Scientist today, so threw up the Wikipedia page about it.

Any physicists around here who are able to do the maths and see if his claim (that a truncated-conical resonant cavity full of microwaves will experience an asymmetric photon pressure due to the group velocity of the waves changing as the local diameter of the tube varies, thanks to some relativistic effects) holds water?

And if it does, what becomes of conservation of momentum?

Accessing a Domino server from Java (by alaric)

For a project, I'm having to write some Java code to talk to a Domino server.

Finding any references on how to do this is a BIG pain, so for posterity, here is what I've found.

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Lead-free soldering (by alaric)

In the UK right now, just about every electronic component, PCB, or whatnot is being labelled RoHS Compliant.

In particular, this means that Maplin, the only local place I can just drive to to pick up electronic components and tools, is now only selling lead-free solder.

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The structure of network protocol suites (by alaric)

It's always struck me as odd that IP routes a packet to a transport-level protocol such as UDP, ICMP, or TCP and then lets that protocol handle routing it to an application process.

Since an application is likely to require a few different types of service for different parts of its operations, shouldn't the specification of the target application be more important than the transport mechanism?

Wouldn't it make sense to be able to send a UDP request to 'port 80' just as easily as you can send a TCP request, rather than requiring the web server to bind separate UDP and TCP listener sockets?

These chains of thought led me to design the MERCURY protocol.

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Protected methods (by alaric)

In Object-oriented programming, things defined in a class can have one of (usually) three access levels: public, private, or protected. Public things are accessible to all users of the class, private things are only accessible from other things defined within the same class - and protected things are accessible from within the class and its subclasses.

However, I have noticed that protected methods are often rather insufficiently documented.

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