Search found 709 matches

by jmorgan3
Mon Aug 13, 2012 8:40 am UTC
Forum: Science
Topic: Important Scientific Papers
Replies: 17
Views: 6474

Re: Important Scientific Papers

If you want most influential and most cited, any paper outlining a now commonplace procedure Or, if you want a break from the heavy stuff, try a not-influential and too-much-cited paper outlining a procedure that's been around for hundreds if not thousands of years: http://care.diabetesjournals.org...
by jmorgan3
Tue Jun 19, 2012 6:47 pm UTC
Forum: Science
Topic: Remote fluid velocity sensor
Replies: 6
Views: 1963

Re: Remote fluid velocity sensor

Sounds like you want PIV . It requires seeding particles, and can be a bitch to get working properly. It needs to measure air and water outside in the field, so there's no possibility of preparing the medium in any way. Thank you for the link, though; looking around a little I was heartened by this...
by jmorgan3
Mon Jun 18, 2012 9:11 am UTC
Forum: Science
Topic: Remote fluid velocity sensor
Replies: 6
Views: 1963

Re: Remote fluid velocity sensor

Does anyone know if this exists or would be possible to build with any current means? An apparatus located at a certain place that can measure the velocity (vector) of the surrounding fluid at any arbitrary point (or a large grid of fixed points) around it, within a certain distance. It cannot just...
by jmorgan3
Fri Mar 23, 2012 7:20 am UTC
Forum: Science
Topic: Why do airplanes need wings?
Replies: 66
Views: 12084

Re: Why do airplanes need wings?

So, basically, if you want to increase the downwash, you increase the drag, and you increase the lift. Practically, you cannot do this forever. But even for small increases in downwash, either through airfoil shaping or geometric angle of attack changing, you increase both lift and drag. If you loo...
by jmorgan3
Fri Mar 23, 2012 7:08 am UTC
Forum: Science
Topic: Centrifugal Force in A.C. Clarke's "Rama"
Replies: 22
Views: 6450

Re: Centrifugal Force in A.C. Clarke's "Rama"

chenille wrote:Someone should probably check my math

Checked. Your math is correct.
by jmorgan3
Sun Mar 11, 2012 1:25 am UTC
Forum: Science
Topic: [SOLVED] Refraction of light
Replies: 14
Views: 4626

Re: Refraction of light

Feynman gives a quantum-mechanical reason in section 26-6 here: http://www.physics.uci.edu/~demos/pdf/o ... t_time.pdf
by jmorgan3
Thu Feb 23, 2012 4:06 am UTC
Forum: School
Topic: The AP test (History)
Replies: 2
Views: 2387

Re: The AP test (History)

So I'm a sophomore and planning to take the AP test for history at the end of the school year and I'm a little troubled. are there any things that i should study in depth over, or should i just generalize myself to knowing as much about everything as is possible. also, anyone got some tips that wou...
by jmorgan3
Thu Feb 09, 2012 2:23 am UTC
Forum: Science
Topic: Mars research - help required
Replies: 27
Views: 4346

Re: Mars research - help required

I have nothing to add to your project, but I think it's really interesting. I'd really appreciate it if you could let us know when you've published.
by jmorgan3
Sat Jan 21, 2012 4:45 am UTC
Forum: Science
Topic: Common Misconceptions within Physics and Astronomy
Replies: 98
Views: 17320

Re: Misconceptions within Physics and Astronomy

Misconceptions about airfoils, in order of increasing sophistication: ⋅ Airfoils produce lift by Bernoulli's equation because the air has to travel faster over the top of the wing to cover the larger distance in the same time ⋅ Airfoil lift has nothing to do with the Bernoulli eq...
by jmorgan3
Sun Jan 08, 2012 4:17 am UTC
Forum: Science
Topic: Resistance of both parallel and series
Replies: 17
Views: 3213

Re: Resistance of both parallel and series

yurell wrote:Tested that as part of a project at school. AAA batteries are virtually dead after an hour, with Duracell beating Energiser, and some cheap Chinese crap actually outlasting them both by a long margin


This might have been from high internal resistance rather than high energy content.
by jmorgan3
Sat Dec 31, 2011 8:28 am UTC
Forum: School
Topic: How much are you paying for books this semester?
Replies: 59
Views: 28829

Re: How much are you paying for books this semester?

Zero. I'm expected to work off lecture notes in all my classes.
by jmorgan3
Thu Dec 29, 2011 7:38 am UTC
Forum: School
Topic: What 'tier' of schools should I be looking at?
Replies: 2
Views: 2393

Re: What 'tier' of schools should I be looking at?

If you had good research experience, you probably would have a shot at a "top-tier" school like MIT. Without research experience, it's very hard to say, because I don't know anyone who applied to grad schools with no research experience. If I had to guess, I'd say to make your "reach&...
by jmorgan3
Mon Dec 12, 2011 10:08 am UTC
Forum: Science
Topic: Detecting a voyager-like object
Replies: 11
Views: 2261

Re: Detecting a voyager-like object

A very robust light source can be created by just collecting a bunch of hydrogen atoms together. Make it roughly the right amount, and it burns for billions of years without maintenance. It will even withstand most disturbances that are likely the be encountered over such a time period. Isn't there...
by jmorgan3
Sun Dec 11, 2011 6:20 am UTC
Forum: Science
Topic: airbreathing engines and brayton cycle
Replies: 12
Views: 2032

Re: airbreathing engines and brayton cycle

I don't need a very accurate model, just a order of magnitude one, to see if the technology is realistic Well, to a first order, you just count combustion as heat addition, so replacing 1GW of burning fuel with 1GW of lasers doesn't change anything too important thermodynamically. \eta = 1 - \frac{...
by jmorgan3
Tue Dec 06, 2011 1:00 am UTC
Forum: School
Topic: Tough Grad School Application Situation
Replies: 10
Views: 3251

Re: Tough Grad School Application Situation

Did any of the technical classes you took have a project component? That's a good way to demonstrate aptitude and interest, and a professor might remember you. If you are willing to put off grad school for another year, you could probably get some undergrad research experience or some EE design proj...
by jmorgan3
Wed Nov 30, 2011 7:23 am UTC
Forum: Science
Topic: Physics for beginners?
Replies: 8
Views: 2192

Re: Physics for beginners?

If you're okay with physics without math, there's a Berkeley course called Physics for Future Presidents that you might want to check out. The professor is a physicist, so I assume the physics he teaches is correct, but I know he makes several mistakes in the jet/rocket lecture.
by jmorgan3
Mon Nov 28, 2011 11:14 pm UTC
Forum: Science
Topic: Control system implementation
Replies: 11
Views: 2348

Re: Control system implementation

That sounds really slow. You could probably get away with just position control on a stepper motor, updating every few seconds. No need to design a control system.
by jmorgan3
Wed Nov 23, 2011 4:58 am UTC
Forum: School
Topic: Reactions to your Major
Replies: 344
Views: 56564

Re: Reactions to your Major

Rumpelstiltskin wrote:Everytime I say I study journalism people think I wanna be on TV.
Nothing further from the truth T_T

So you want to write for a website?
by jmorgan3
Fri Nov 18, 2011 6:34 am UTC
Forum: School
Topic: Failing basic arithmethics issue+coping with such failure
Replies: 22
Views: 7116

Re: Failing basic arithmethics issue+coping with such failur

Dopefish wrote:It seems that basic arithmetic errors become far more common the further you go in math. (I'm pretty sure theres a PHDcomic to that effect too.)

Indeed.
by jmorgan3
Fri Nov 18, 2011 6:30 am UTC
Forum: School
Topic: Sinks in German classrooms?
Replies: 23
Views: 4833

Sinks in German classrooms?

Just a quick question for any Teutonic xkcdians: do German (university) classrooms commonly have sinks? If so, what are they used for? I ask because, in class today, my German professor (he's from Germany; he doesn't teach German) bemoaned the lack of sinks in American classrooms and I'm not sure why.
by jmorgan3
Sun Nov 13, 2011 9:46 am UTC
Forum: Science
Topic: Kelvin vs. Celsius
Replies: 60
Views: 12445

Re: Kelvin vs. Celsius

The celsius scale is quite natural, I think, because the freezing and boiling of water are two very common and very important natural phenomena. Noone ever cares about the difference between -1F and +1F. But the difference between -1°C and +1°C, that is the difference between being well fed in the ...
by jmorgan3
Fri Nov 04, 2011 1:37 am UTC
Forum: School
Topic: Extra time for tests
Replies: 28
Views: 7334

Re: Extra time for tests

I have a related question. I took a test the other day which had a time limit, but you could start the test at pretty much any point in the day. You signed in at the start and signed out at the end. Apparently, another student made an honest mistake and took an extra 30 minutes on the test. How woul...
by jmorgan3
Fri Oct 28, 2011 12:34 pm UTC
Forum: Science
Topic: "The only instance where mass and weight are different."
Replies: 42
Views: 7480

Re: "The only instance where mass and weight are different."

Tass wrote:
thoughtfully wrote:and Euler is pronounced oiler :)


Of course. How else would you pronounce it?

Out of curiosity, how do you pronounce "Euclid"?
by jmorgan3
Tue Oct 18, 2011 7:30 pm UTC
Forum: School
Topic: Technical skills for Engineering
Replies: 14
Views: 3328

Re: Technical skills for Engineering

Signing off as a PE does make you responsible for the project, but someone has to do it. If they have to hire someone else to be responsible for everything you do, they'll probably pay you less.
by jmorgan3
Tue Oct 18, 2011 8:42 am UTC
Forum: School
Topic: Technical skills for Engineering
Replies: 14
Views: 3328

Re: Technical skills for Engineering

To throw my own 2c in, a fair number of the engineering majors I knew at community college took one or more welding courses on the principle that it's a nice backup skill to have. To ask about another angle here, what sort of technical credentials are good "next steps" after a bachelor's ...
by jmorgan3
Sat Oct 08, 2011 4:28 am UTC
Forum: Science
Topic: Question about JETPACKS! (and physics)
Replies: 30
Views: 3648

Re: Question about JETPACKS! (and physics)

And I guess there's no very sensible way to use air as your fuel source even if you have craploads of electricity? You don't need a fuel source, you need reaction mass. The most straightforward way to do this would be a propeller. More outlandish would be a turbojet or ramjet with the combustor rep...
by jmorgan3
Sat Oct 08, 2011 12:43 am UTC
Forum: Science
Topic: Question about JETPACKS! (and physics)
Replies: 30
Views: 3648

Re: Question about JETPACKS! (and physics)

You could have her use an arcjet rocket . Basically, you use electric heating to flash the water to steam, and direct the steam backwards to generate thrust. Alternately, use a high-voltage arc to ionize the water, and use a strong electric field to accelerate the ions backwards. Note that either of...
by jmorgan3
Mon Oct 03, 2011 3:39 am UTC
Forum: Science
Topic: Jack Horner wants to make dinosaurs out of chickens
Replies: 35
Views: 5769

Re: Jack Horner wants to make dinosaurs out of chickens

Jack Horner is positing that activating a whole bunch of chicken genes will create a dinosaur. So, what I'm referring to is No, he's positing that modifying a chicken will create a dinosaur. Activating deactivated genes (and I wager, silencing active genes) are just one of the tools he plans on usi...
by jmorgan3
Mon Oct 03, 2011 2:23 am UTC
Forum: Science
Topic: Jack Horner wants to make dinosaurs out of chickens
Replies: 35
Views: 5769

Re: Jack Horner wants to make dinosaurs out of chickens

Making a dinosaur from a chicken in the way Horner proposes , also conveniently located in the title of this thread. So what are these 'million things that haven't gone right'? I never wrote the text in your quote, and it is not an accurate paraphrase. For Horner's task to be possible, a million th...
by jmorgan3
Mon Oct 03, 2011 12:59 am UTC
Forum: Science
Topic: Jack Horner wants to make dinosaurs out of chickens
Replies: 35
Views: 5769

Re: Jack Horner wants to make dinosaurs out of chickens

Care to respond to the remaining majority of my post, where I point out that for Horner to succeed, a million little things have to have gone exactly right, and that we know that at least one of those things has not gone exactly right?
by jmorgan3
Mon Oct 03, 2011 12:35 am UTC
Forum: Science
Topic: Jack Horner wants to make dinosaurs out of chickens
Replies: 35
Views: 5769

Re: Jack Horner wants to make dinosaurs out of chickens

What is curious to me is that the article has stated that a single gene has been identified which when activated, causes tooth growth in the beaks of birds, is present and activated in reptiles, and is present but inactivated in birds. Scientists have experimentally activated the gene in birds and ...
by jmorgan3
Sun Oct 02, 2011 6:57 pm UTC
Forum: Science
Topic: How Does A Bike Work?
Replies: 20
Views: 4249

Re: How Does A Bike Work?

A net angular momentum of zero should still resist the change a dainbramage pointed out. No, it won't. Imagine one of those bicycle-wheel-on-handles things that are used for physics class demonstrations. They resist torques because they move at angle perpendicular to applied torque (and also perpen...
by jmorgan3
Fri Sep 30, 2011 2:33 am UTC
Forum: Mathematics
Topic: Interesting Quadratic Models
Replies: 7
Views: 1457

Re: Interesting Quadratic Models

Aerodynamic drag is quadratic in velocity.
by jmorgan3
Mon Sep 26, 2011 11:58 pm UTC
Forum: Science
Topic: what might this HW question be asking?
Replies: 2
Views: 1666

Re: what might this HW question be asking?

What is the charge-averaged value of r^2 (i.e. x^2+y^2+z^2 for an origin-centered sphere) for the entire sphere?

EDIT: And how do you take averages over a continuous set?
by jmorgan3
Mon Sep 26, 2011 4:24 am UTC
Forum: Science
Topic: stationary hovering
Replies: 12
Views: 1920

Re: stationary hovering

gorcee wrote:
jmorgan3 wrote:
lesto wrote:how much to return perfectly on the origin?
I see no feasible way to do this without absolute position feedback.
Adaptive state estimation. Even a Kalman filter should suffice

With only the angular parameters? Wouldn't you need a very good linear accelerometer or a very good model for the system?
by jmorgan3
Mon Sep 26, 2011 1:46 am UTC
Forum: Science
Topic: stationary hovering
Replies: 12
Views: 1920

Re: stationary hovering

how much to return perfectly on the origin? I see no feasible way to do this without absolute position feedback. As for the rest of the question, how advanced is your background in dynamics and in controls? If you have taken a class or two, you should be able to make a model of 1-D lateral motion g...
by jmorgan3
Sun Sep 25, 2011 3:51 am UTC
Forum: Science
Topic: Re: A question about orbits... [Solved]
Replies: 8
Views: 1678

Re: A question about orbits...

In an otherwise-empty space (only two objects), there is no lower mass limit. Orbit around an object of any given mass and at any given radius is possible with a low enough orbital velocity.
by jmorgan3
Mon Sep 12, 2011 4:59 am UTC
Forum: School
Topic: Reactions to your Major
Replies: 344
Views: 56564

Re: Reactions to your Major

To continue the appliances analogy, I have strong opinions about what functionality I want in a blender for my own personal use, but I apply those strong opinions by being discriminating about the blender I use. I might go so far as to tell someone responsible for engineering the blender's parts ab...
by jmorgan3
Thu Sep 08, 2011 6:14 am UTC
Forum: Science
Topic: The Faucet Question
Replies: 14
Views: 2485

Re: The Faucet Question

Ship generating a wavey pattern behind its bow wave. I am not sure why ships sometimes cause this wavey pattern, while supersonic aircraft only generate a "bow wave" without a wavey pattern behind it. I think it's because gravity and surface tension waves in liquids are dispersive, while ...
by jmorgan3
Fri Sep 02, 2011 5:25 am UTC
Forum: Mathematics
Topic: Multiplication or the summation operator (sigma)
Replies: 28
Views: 4053

Re: Multiplication or the summation operator (sigma)

gmalivuk wrote:
Macbi wrote:Otter?
Good point.

We're not talking about points until next week.

Go to advanced search