NASA engineers

[steve_bnk]

If I am measuring a length with a micrometer I might make 5 measurements and average.

if I have a box of 100 chips, 90 red and 10 blue a sample of 5 is pretty useless.

When making electrical measurements the sample size is determined by the noise parameters. and the noise is not always Gaussian and stationary, parameters may vary with time.

http://en.wikipedia.org/wiki/Signal_averaging

There is no magic '5'.

Average, yes. Standard deviation, doesn't mean much.

It all depends on the situation. My first major project was setting up a manufacturing defect reduction and SPC program.

Once the manufacturing systemic errors were minimized a change in mean or SD in manufacturing failure rates would generally be traceable to something changing.


http://en.wikipedia.org/wiki/Control_chart

if I am making measurements and the sd seems large I’ll take a look and see if there is a reducible cause.

If you are sampling some parameter from a population of widgets, like the weight, the sd is the estimate of the population variation. 6 Sigma. The confidence level is error estimate of the population estimate.

The mean without a 6 sigma estimate is useless. You need both when making a statistical decision.

 

[Loren Pechtel]

Oh contraire.

A Measure of Dispersion: The Standard Deviation: ​

http://www.fgse.nova.edu/edl/secure/stats/lesson2.htm

The standard deviation is important because, regardless of the mean, it makes a great deal of difference whether the distribution is spread out over a broad range or bunched up closely around the mean. For example, suppose you have two classes whose mean reading scores are the same. With only that information, you would be inclined to teach the two classes in the same way. But suppose you discover that the standard deviation of one of the classes is 27 and the other is 10, as in the examples we just finished working with. That means that in the first class (the one where

27), you have many students throughout the entire range of performance.

There is another statistic every beginning psych student learns. That is Kurtosis. Sumarizing data isn't very meaningful if the data is spread abnormally. If the bulk of the data is clustered at two points,say the extremes of that being measured mean and median are meaningless since the data is scarce there the distribution measures are nearly as useless since they don't actually capture the two clusters at the extremes but rather signal a very broad span of distribution. Correlations with such data always come to the wrong conclusion. For instance drug comparisons may both be useful at certain dose levels or may be indicated at certain disease levels, but comparing them would be like comparing apples and oranges since one drug would have data clustered at one end of the regime spectrum while the other would be clustered at the other end. What would mean, median, or standard deviation tell them. Nothing.

One should not conduct experiments if one has no real idea of the underlying distributions.

I'll accept wide or narrow being useful information but with only 5 data points you won't even have much of an idea of that.

However, the initial discussion stemmed from a lack of error bars on the reported thrust produced--and some of us were saying that such error bars would be pretty much meaningless. I still think they are.

 

[barbos]

Unless one a NASA engineer one should not conduct experiments if one has no real idea of the underlying distributions.

Fixed for you.

 

[barbos]

I mentioned Italian cold fusion scammer Rossi and NASA.
Apparently new report came out
http://www.sifferkoll.se/sifferkoll/wp-content/uploads/2014/10/LuganoReportSubmit.pdf
Pretty unbelievable (in a bad way) stuff in it.
350 watt output reactor which requires (please seat) 360 watt (!!!) triac controller

These people literally pee on your boots and call it a rain.

 

[steve_bnk]

I mentioned Italian cold fusion scammer Rossi and NASA.
Apparently new report came out
http://www.sifferkoll.se/sifferkoll/wp-content/uploads/2014/10/LuganoReportSubmit.pdf
Pretty unbelievable (in a bad way) stuff in it.
350 watt output reactor which requires (please seat) 360 watt (!!!) triac controller

These people literally pee on your boots and call it a rain.

You must be dying for attention.

Having worked with power, heat transfer, and thermal radiation measurement I'd say resolving 10 watts out of 350 considering all the variables and the setup up is likely impossible.

The correct way to run the experiment would be calorimetry.

Immerse the setup in a vat of oil and measure the temperature rise.

http://en.wikipedia.org/wiki/Energy_Catalyzer

It does not claim to violate conservation. It claims to induce some form of nuclear process that generates heat, the analogy made to nuclear reactors.

NASA comment. It is not cold fusion.

http://nickelenergy.wordpress.com/2...nasa-langley-acknowledges-andrea-rossi-e-cat/

'...Dennis Bushnell: The most interesting, and promising, at this point, in the farther term, but maybe not so far, is low-energy nuclear reactions. This has come out of [22] years of people producing energy but not knowing what it is — and we think we have a theory on it. It’s producing beta decay and heat without radiation. The research on this is very promising and it alone, if it comes to pass, would literally solve both [the] climate and energy [problems.]...

Back in 2005, 2006, [Allen] Widom [and Lewis] Larsen came out with a theory that said, no it’s not “cold fusion,” it’s weak interactions using the Standard Model of quantum mechanics, only the weak interaction part. It says that if you set up one of the cells, and you don’t have to use deuterium, hydrogen works fine, nickel works fine and you don’t need palladium....'

You never know until it fully tested.

 

[barbos]

steve_bnk, you misunderstood.
I was bitching about 360 watt triac controller, which is nonsense because it can't be more than 100 miliwatt.
But apparently these swedish professors included losses in triac itself into the number.
Anyhow, I have been following this scam since its beginning. And all these names (Bushnell, Widom-Larsen) are familiar to me.
All these people are idiots, and Bushnell works at NASA.

 

[steve_bnk]

steve_bnk, you misunderstood.
I was bitching about 360 watt triac controller, which is nonsense because it can't be more than 100 miliwatt.
But apparently these swedish professors included losses in triac itself into the number.
Anyhow, I have been following this scam since its beginning. And all these names (Bushnell, Widom-Larsen) are familiar to me.
All these people are idiots, and Bushnell works at NASA.

Don't have a clue what you mean about the triacs. At several hundred watts the triac losses would be greater than 100mw.

RMS current times approx 2 diode drops, about 1.4 volts on voltage. Plus switching losses.

You miss my point, nothing ventured nothing gained.

 

[steve_bnk]

If I am measuring a length with a micrometer I might make 5 measurements and average.

if I have a box of 100 chips, 90 red and 10 blue a sample of 5 is pretty useless.

When making electrical measurements the sample size is determined by the noise parameters. and the noise is not always Gaussian and stationary, parameters may vary with time.

http://en.wikipedia.org/wiki/Signal_averaging

There is no magic '5'.

Average, yes. Standard deviation, doesn't mean much.

The SD is actually an RMS, Root Mean Squared value. Same as in engineering.

The problem is you can have zero mean which tells you nothing. A sine wave with no dc componet has zero mean value and 1.414*peak RMS.

Averaging gives you the mean, but says nothing abut variability. SD as an estmate o variability is important. You need both mean and SD.

In the case of Gaussian noise, the SD is the RMS value of the signal. +- 3 SD is the probability of the noise being at a given amplitude at a time t.

 

[barbos]

steve_bnk, you misunderstood.
I was bitching about 360 watt triac controller, which is nonsense because it can't be more than 100 miliwatt.
But apparently these swedish professors included losses in triac itself into the number.
Anyhow, I have been following this scam since its beginning. And all these names (Bushnell, Widom-Larsen) are familiar to me.
All these people are idiots, and Bushnell works at NASA.

Don't have a clue what you mean about the triacs. At several hundred watts the triac losses would be greater than 100mw.

RMS current times approx 2 diode drops, about 1.4 volts on voltage. Plus switching losses.

You miss my point, nothing ventured nothing gained.

I did not miss your point. You missed mine ... twice.
Anyway, that last report is a repeat of previous ones with none of the problems addressed plus new ones were added.

 

[somebody2]

Dumbass here, I was reading about this possible new discovery, EMdrive. Searching on Frdb, I was sent here.

I read that it breaks a law of physics. Something about motion? Idk. So I thought is that possible?... Then I read that China and NASA were replicating the experiments at different successes. I don't remember the source. I am way out of my element here, but is this thing plausible? If so, what a wonderful time to be alive. couldn't it theoretically save the planet? No more gasoline or coal?

I am real sorry if you've covered this.

 

[barbos]

Dumbass here, I was reading about this possible new discovery, EMdrive. Searching on Frdb, I was sent here.

I read that it breaks a law of physics. Something about motion? Idk. So I thought is that possible?... Then I read that China and NASA were replicating the experiments at different successes. I don't remember the source. I am way out of my element here, but is this thing plausible? If so, what a wonderful time to be alive. couldn't it theoretically save the planet? No more gasoline or coal?

I am real sorry if you've covered this.

No, EMdrive is not only impossible, it's idiotic too.

 

[GenesisNemesis]

I forgot OP linked to a site called "libertarian news". That's funny.

 

[DrZoidberg]

http://www.libertariannews.org/wp-c...ustProductionFromanRFTestDevice-BradyEtAl.pdf

Taxpayer's money are spent on this bullshit, Unbelievable!!!
NASA is just a bunch of retarded engineers who would not even pass "experiments&measurements" 101.
Forget about math and physics 101.

NASA is the coolest thing humanity ever has been able to produce. Well... almost. Second place to the USSR space agency. But second place ain´t bad either. Either way, they´ve accomplished feats all humans before us could only dream of. Any price would be worth it.

 

[barbos]

I forgot OP linked to a site called "libertarian news". That's funny.

LOL, I just noticed that too.

 

[barbos]

NASA is the coolest thing humanity ever has been able to produce. Well... almost. Second place to the USSR space agency.

You are being sarcastic, right?

 

[Ford]

NASA is the coolest thing humanity ever has been able to produce. Well... almost. Second place to the USSR space agency.

You are being sarcastic, right?

Soviet space program was very good at sending comrades into space.


Return safely? Eh...but what an adventure for mother Russia!

 

[barbos]

Oh my personal troll is here

 

[Ford]

Oh my personal troll is here

If Ukraine sent up space probe, Russians would shoot it down!




Then blame Ukraine....

 

[DrZoidberg]

You are being sarcastic, right?

Soviet space program was very good at sending comrades into space.


Return safely? Eh...but what an adventure for mother Russia!

USSR won the space race in every way they attempted. They were the first at everything they tried. The only thing the Russians didn´t attempt, simply because they thought it was a colossal waste of money, was to send a human to the Moon and back. But they did the rest first.

Pretending that USA won the space race is stupid. They lost, in a really really big way. Here´s the long list of all the second places USA managed to get:

http://en.wikipedia.org/wiki/List_of_spaceflight_records

"The Russians sent a dog? We´ll send a monkey. At least we´ll be first with that specific type of mammal".

Scientifically we learned almost nothing from Apollo 11, 16 and 17 that we couldn´t have learned staying home and working in a lab. Don´t get me wrong, it was cool that we did it. But going to the Moon was more about propaganda than science. I´m not saying that the Russians were above propaganda. Certainly not. But as far as scientific value is concerned the Russians spent their space funding more wisely than NASA did. That´s just fact. Which is doubly impressive considering what a hopelessly corrupt shit hole of a country that is. It also may have something to do with the US president putting his big nose into what NASA should be working with. Khrushchev, bless his little heart, at least had the common sense to understand what it was he didn´t understand.

As far as safety concerns, both USA and Russia primarily sent dare devil fighter pilots right up until the Challenger disaster. That accident made both sides realise the propaganda loss potential deaths are. From that time on they both shifted from sending adrenalin junky adventurers to calm and methodical scientists. So, historically there´s no difference at all when it comes to willingness to take risks.

 

[dystopian]

USSR won the space race in every way they attempted. They were the first at everything they tried. The only thing the Russians didn´t attempt, simply because they thought it was a colossal waste of money, was to send a human to the Moon and back. But they did the rest first.

This really isn't true. The US accomplished many things first. Among them the first Solar powered satellite, the first communications satellite, first weather satellite, first solar probe, first object recovered from orbit, first navigation satellite, first geosynchronous orbit, first geostationary orbit, first pilot-controlled spacecraft, first orbital photograph of earth, first reusable spacecraft, first orbital rendezvous, first orbital docking, first mars flyby, first spacecraft to orbit another planet (mars), first spacecraft on solar escape trajectory, first spacecraft to enter asteroid belt and leave the inner solar system, first jupiter flyby, first mercury flyby, and the first gravity slingshot maneuvre.

Many of these were also attempted by the soviets. It requires some very selective vision to think the soviets were first at everything they tried. Although I will agree that nobody 'won' the spacerace.