Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?

Comment Re: I don't care if my superiours are techies or n (Score 2) 152

I think a manager needs to understand enough of the technology to make good decisions, and to know if their employees are technically competent.

I manage a small RF group. We recently had to decide on doing and I/Q or DDC based system for a high channel count receiver. I feel that I need to know enough about both of those to understand the trade-offs. Since this is an unusual application; a sensor system, not a data system, its important to know if the most commonly used solution for most applications applies here. The trade-off is not simple, there are differences in firmware complexity, calibration systems, hardware costs and flexibility.

Comment Estimates are useful if used correctly (Score 3, Interesting) 299

Estimates are useless as a measure of how well an engineer is performing. How far he is ahead or behind schedule only indicates the extent to which he was able to get away with padding his estimate in the first place.

That said, estimates ARE very valuable when you have a complex set of interlocking projects and resources that can be tasked in different places. This is especially true if external pressure require that a project be done on an exact date.

To take an extreme example, if the launch window for Europa is at a known date, the spacecraft firmware must be fully tested and installed by that date. Working backwards that says when the first version must be ready. The estimate helps decide what resources should be applied, and later it lets you know if you are so far behind that you need to change the launch date to the next window (over a year away). That affects budget etc.

At SLAC we have complex projects that require the work of lots of people to all come together. This results in very rigid schedules - There is typically a 2 month window for major upgrades, if you miss it, you wait a year. If someone working for me doesn't like doing estimates, I basically say "we need a guess. I can guess or you can, but since you are doing the work, your guess will be better than mine".

Comment Re:what if they don't find any ? (Score 2) 72

GR requires them to exist. I don't know if there are other gravity theories that are consistent with all other observations that do not.

We do see spin-down of binary neutron stars that is consistent with gravitational wave radiation, so its pretty darn clear that they do exist - we just don't have direct detection.

In the future LISA ( http://lisa.nasa.gov/ ) and other more advanced instruments may be able to to gravity wave astronomy. Ultimately we could imagine detecting gravitational radiation from the very early universe - long before any other signals are available.

Comment Re:The age old question (Score 3, Interesting) 72

Tricky as it is to create a gravitational detector, a gravitational radiator the emits significant power is a lot tougher. I seem to remember that thermonuclear bombs and asymmetric explosions generate a trivial amount of gravitational wave energy.

LIGO is looking for supernova scale sources - probably not a good idea to build one in our solar system.

Comment Re:Where was the decision made (Score 1) 471

Intent will be a big issue here.
If the code "happens" to provide better emissions during the driving test it may not look so bad. If the code clearly cheats (looks for a lack of steering input, or no passengers, or detects a certain sequence of settings, then it will look like deliberate fraud.

Comment Where was the decision made (Score 1) 471

I wonder who at the company was aware of this. It could have been anything from a high level decision. to an overly clever firmware developer who thought he had a really clever idea.

Of course the company is responsible for their products, but it might be the difference between negligence and fraud .

Comment Re:For future reference, (Score 1) 221

(not disagreeing with your conclusions) Depends on how you define efficiency. For an ideal jet engine the power to produce a given thrust goes up with airspeed, but since you are moving faster, the energy per distance remains the same. (distance * Weight / (L/D) = energy_use. ) ,.

For a real engine though the efficiency does go down. Conventional ram jets don't work well at high speed because slowing down the inlet air to subsonic heats it too much, and involves aerodynamic losses.

Supersonic Combustion Ram Jets can work - there you never slow down the air so there isn't much loss in efficiency. (see the X-51 for example). Still, its difficult for many reasons. You do need to slow the air some - and the aerodynamic efficiency of the inlet decreases for much the same reason the wings get less efficient at high speeds. Its tricky to mix the hydrogen in at high speeds - you need lots closely spaced injectors, and that can add drag. The flame speed in hydrogen is subsonic, so you need some way to keep it from blowing out the back of the engine - constant ignition, or detonation wave combustion (mostly a concept for >mach12), or some other trick.

Noting violates basic physics but this is a LONG way from being practical for a passenger aircraft.

Comment Re:For future reference, (Score 3, Informative) 221

Agreed. Its also very difficult to make efficient scramjets which makes the problem even worse. The best scram jets so far have barely been able to maintain steady flight at a single mach number and in a short range test vehicle.

I think there is a good chance that you want to jump from supersonic all the way to mostly ballistic sub-orbital. It also completely avoids the noise footprints except (and its a BIG except) at the launch and landing points.

As several people have also said, I'll take hyper-sonic travel seriously only after we have supersonic commercial flight again. Existing airliner speeds haven't changed significantly in 60 years. (!!!). (the same time it took to go from the Wright brothers to near mach-1 travel).

Comment Why only cyber weapons (Score 2) 220

I see no reason to limit companies to cyber weapons. Once they have located an attacker, having privately owned armed drones would be very handy. if the attacker is a nation state, even more aggressive measures could be used. I can see aircraft carriers, and maybe even ballistic missile subs with corporate logos.

Comment Re:Yes (Score 1) 492

I was unable to validate the license for my office account without installing a local outlook account. Win 10 popped up a login app, but it always hung. Spent an hour and final gave up and installed an outlook account/

Yes I could have probably eventually figured it out, but I have other things to do with my life.

Comment Re:There's no reason to go to the moon again (Score 1) 248

Unfortunately I agree.

Sadly 1 is pretty unlikely, Its difficult to imagine anything of enough value that only exists in space

2 could happen, but as a society we are moving away from high energy density technology like nuclear because there are better options on earth. Rockets already make pretty efficient use of chemical energy. Other schemes like space elevators seem really improbable. (I hope I'm wrong).

So 3 seems the most likely.Eventually maybe some space-faring race will discover and catalog the ruins we left behind.

A right is not what someone gives you; it's what no one can take from you. -- Ramsey Clark