Slashdot is powered by your submissions, so send in your scoop


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 Internet speed test! ×

Comment create a 'defensive publication' (Score 5, Interesting) 163

From ...

Defensive publications, which are endorsed by the USPTO as an IP rights management tool, are documents that provide descriptions and artwork of a product, device or method so that it enters the public domain and becomes prior art. This powerful preemptive disclosure prevents other parties from obtaining a patent on the product, device or method. It enables the original inventor to ensure that they have access to their invention by preventing others from later making patent claims on it. It also means that they do not have to shoulder the cost of patent applications.

[emphasis mine]

Comment Re:But will it scale? (Score 1) 270

Okay I see your point more clearly now. The ribbon motion would need to have an acceleration greater than g at sea level. This is to ensure that the cabin can get off the ground at all. Otherwise the cabin free fall during release would negate any climbing done during the grab part of the cycle.

g at sea level is around 9.8 m/s^2. So the ribbon oscillation would need to have a displacement to match that (e.g. 10m at 1Hz).

Very stiff springs indeed!

The problem with a large displacement is the chance that the ribbon is too flexible at the level of tension it's under. Perhaps a smaller displacement is in order? 1m at 10Hz? .1m at 100Hz? 1cm at 1kHz?

Just how fast can the ribbon be vibrated longitudinally at it's required level of tension? That's a feature of the ribbon material and I don't have a clue how to even approximate it.

Another concern is just how fast can the cabin cycle between grab and release. Maybe this is why the broomstick example is demonstrating a method of cycling grab and release at high frequencies?

Comment Re:But will it scale? (Score 1) 270

I don't think that's how it works. The ribbon is suspended fully. It isn't in free fall. The two springs at the endpoint anchors control the acceleration of the entire ribbon as long as it's under tension. This is why it can be conceptualized as a ribbon laying horizontally on ice.

However, you're correct that the cabin is in free fall during release mode. The acceleration due to gravity will vary with altitude and the centripetal force applied by the sideways moving ribbon will apply an additional 'upward' force on the cabin near the top.

If the cabin can time the grab and release properly, perhaps with partial (slip) grabs, it can adjust the amount of force it 'steals' from the ribbon at different altitudes.

And quite near the top it will need to switch the grab and release timing completely to affect a deceleration for a soft 'landing' at the orbiting anchor.

Comment Re:But will it scale? (Score 1) 270

You seem to be forgetting the orbiting anchor. The entire suspension cable is *suspended* between two anchors, ground and orbit. It's reasonable to model this as long ribbon laying on frictionless ice, anchored securely at both ends.

Of course you are correct this is a 20 ton ribbon laying on the ice. Sure it takes a lot of energy to move it 1 meter. But what if the ends aren't secured to fixed anchor points.

Consider that the anchors could be springs with 1 meter play. The springs are under tension and the ribbon is still very much suspended but it's no longer fixed absolutely. Makes sense intuitively in the ribbon-laying-on-ice model. Well, same thing for the anchor-in-orbit model, too.

Now we only have to use force one time to move the ribbon the 1 meter distance. After that without friction it will oscillate back and forth forever (as long as the springs are 100% efficient).

Mind you this is a 20 ton ribbon. It seems reasonable that you could clamp some 'riders' to it and the oscillation won't be dampened very much. Not even when the riders move around.

Because the riders have a great opportunity to move around with little effort. The rider simply needs to time each grab and release. The ribbon is oscillating 1 meter back and forth (down it's length).

The rider can grab during motion in one direction and release during the opposite motion. The rider will inextricable travel the length of the ribbon.

The energy 'loss' caused by the rider can be added back at either end of the ribbon. In fact both ends can control the action of their respective springs for fine tuning. But the obvious power source is the ground anchor.

This is a very slow version of the broomstick example. Indeed I would expect the 'speed' of the system to decrease as the mass scales up. The analogy is sound however.

Comment demontrate control of the domain in question (Score 3, Insightful) 171

Why don't they use the method Google uses to verify control of a domain (and hence ownership)?

The CA should require a unique file (containing a serial number) to be posted to a specific location on the website. Failing that you should be able to receive mail to an arbitrary email address at the domain.

CAs who don't employ a technical measure (such as above) to verify domain ownership *prior* to issuing a cert would be taken out of the list of trusted CAs.

Slashdot Top Deals

Ocean: A body of water occupying about two-thirds of a world made for man -- who has no gills. -- Ambrose Bierce