Archived threads in /sci/ - Science & Math - 2177. page

>>7640247
For practical purposes, truly "micro"-nuclear reactors are impossible.

In order for a nuclear fission reactor to work, you have to be able to sustain a chain reaction. That means that every fission event needs to trigger, on average, at least one other fission event. Because the ability of materials to absorb neutrons is limited - neutron radiation is fairly penetrating, especially at the high energies emitted by fission events - this means you need a big enough chunk of uranium or plutonium that the emitted neutrons from one fission event will have a good enough chance of hitting and splitting another atom.

This creates a fundamental minimum limit on the amount of fissile material needed, known as the "critical mass." ("criticality" being the critical point where the nuclear chain reaction is self-sustaining, each fission event causing exactly one other on average.)

This can be improved with components like moderators and neutron reflectors, but ultimately you need a fairly large nuclear system to sustain a workable reactor.

Also, there's the problem of how to extract power - converting nuclear energy directly into electrical is nearly impossible, and so all existing reactors use thermal systems. These are also bulky.

However, if you aren't insisting on it being a *reactor*, you could use other nuclear energy processes like alphavoltaics or betavoltaics, harnessing the high-energy charged particles caused by nuclear alpha or beta decay to generate current directly. They're very inefficient, however.

>>7640275
The smallest reactors I've ever seen actually designed were for potential spaceflight applications; the smallest was the HOMER-15, a reactor producing 15 kW of thermal output (and 3 kW of electrical) that weighed just 214 kg and was 41 cm in diameter and 2.4 m tall.

A reactor designed for Earth usage could be made smaller, since you can use convection and conduction of heat to cool the reactor more efficiently, instead of having to radiate everything. However, you're not getting it too much smaller than that. Certainly not to credit-card size!

I wonder how small you could build a Farnsworth Fusor, but you're not gonna get any energy from that.

"What the fuck did you just fucking say about me, you little bitch? I’ll have you know I graduated top of my class in the Navy Seals, and I’ve been involved in numerous secret raids on Al-Quaeda, and I have over 300 confirmed kills. I am trained in gorilla warfare and I’m the top sniper in the entire US armed forces. You are nothing to me but just another target. I will wipe you the fuck out with precision the likes of which has never been seen before on this Earth, mark my fucking words. You think you can get away with saying that shit to me over the Internet? Think again, fucker. As we speak I am contacting my secret network of spies across the USA and your IP is being traced right now so you better prepare for the storm, maggot. The storm that wipes out the pathetic little thing you call your life. You’re fucking dead, kid. I can be anywhere, anytime, and I can kill you in over seven hundred ways, and that’s just with my bare hands. Not only am I extensively trained in unarmed combat, but I have access to the entire arsenal of the United States Marine Corps and I will use it to its full extent to wipe your miserable ass off the face of the continent, you little shit. If only you could have known what unholy retribution your little “clever” comment was about to bring down upon you, maybe you would have held your fucking tongue. But you couldn’t, you didn’t, and now you’re paying the price, you goddamn idiot. I will shit fury all over you and you will drown in it. You’re fucking dead, kiddo."
There, OP

>>7640249
Close but no cigar

>>7640244
Vigenère style, use correlation index shit to find language. Then try to guess key size with smart padding for a starter.

>>7640095
You realize no one INVENTED the goddamn axle, right? Long, cylindrical objects occur everywhere in nature. An axle is useless without a wheel. Someone had to actually INVENT the goddamn wheel, that took some actual ingenuity.

>>7640108
I just want you to know that everything you are saying right now is factually wrong.

>>7640108
also, thats not the axle. The axle is the entire assembly, including the hooks on the bottom that attach it to the cylinder.

>>7640020
You should get him some dark matter.

>>7640020
>just graduated from college
Booze. He's a recently graduated student. Get him a normal gift like all people his age. You shouldn't buy gifts like books, hobbyshit or novelty items unless you know that person really really well. Get consumables for people who aren't your girlfriend/close friend.

...unless you can afford to buy him a cyclotron or something. Then get him that.

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>>7640020
That's a tough question, anon, but I can tell you about something he'll definitely NOT like: popsci books. Non-science people will tend to think we'll love those while nothing could be further from the truth.

pic related, received it years ago, still haven't opened it

listen to loud music breh

>>7640005
It's all in your head anon, just man up and stop listening to it.

set a radio to play whitenoise. it will mask the ringing.

is that tan^-1 literally the reciproce of tan or the arctan

Okay mate it's pretty simple
you use the derivative formula for inverse tan and the chain rule

>>7639964
Are you asking why the derivative of arctan(f(x)) is
[math]
\frac{f'(x)}{1+(f(x))^2}
[/math]
or what?

>>7639960
How long until your startup space station company gets off the ground?

>>7639960
why would anyone need that ?

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>>7640396
>gets off the ground
8/10 made me giggle senpai

>>7639885
Buy Quantum Mechanics by Cohen-Tannoudji.
Work through it until you understand it.
You are now a linear algebra master.

>>7639885
But seriously, I don't know what to tell you besides work through problems, watch lectures online, etc. There are plenty of youtube lectures and sometimes a second perspective is what helps someone learn. Linear algebra is immensely useful and applicable, so it's worth learning well if you plan to continue in STEM.

>>7639885
Holy shit, how?
eigenvalues?
You are fucked if you are struggling with simple matrices and row reduction
You should practice, look at cheat sheets/notes with examples

>>7639875
>What is the point of mathematics?
it's a useful tool
>What drives it forward?
autism
>Why do people do it without a usage (in reality) for it?
autism

>>7639875
Why do people climb Mount Everest? Why do people get good at anything that doesn't have a practical application? It tickles their senses in a way they can't get otherwise.

>>7639896
I agree partly. Many problems that math asks weren't there in the first place. Someone had to think of them first. And while your sense can "be tickled" by solving problems i dont think that making up problems does so.

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>>7639727
>Bacteria
>Cell

I believe you are the victim of trolling OP, lay off the drugs

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>>7639727
>injecting insulin producing bacteria into the body with no way to regulate the insulin output
10/10 idea
what could possibly go wrong
brb gonna patent it before someone else does

I can see the problems but its nowhere near 'are you high' tier.

You should be physically superior to pure gold

>>7639679
magnet

>>7639682
What?

the surface area of the night sky

Idk m8
Can you really calculate the surface area when the cone of vision is constantly changing?

>>7639647
Then calculate surface areas of the different cones of vision and put them on a table. It would be interesting to know the max and min.

Why do you study CS if you don't like math?

CS is basically applied math.

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>>7639624

> feels good finding an algorithm before I even start coding
So you normally just type random lines and hope it works?

>expecting us to debug your code without posting said code

>>7639558
sorry, completly forgot:

clc;
x = -3.1415:0.1:3.1415; %limits for x coordinates
a = sin(x) %defining a
b = x %defining b
c = x - ((x.^2)/2) %defining c
d = x - ((x.^2)/2) + ((x.^4)/24) %defining d
plot (x,a, 'r')
hold on;
plot (x,b, 'b')
hold on;
plot (x,c, 'g')
hold on;
plot (x,d, 'y')
hold off;
legend ('y=sin(x)', 'y=x', 'x-x^2/2', 'x-x^2/2 + x^4/24')

>>7639587
how are you calling the file?

>>7639445
Sure, if you had a big enough balloon. But you' still have to get it up to orbital speed, which would take the same amount of fuel.

>>7639449
*you'd

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>>7639445
We could use a hybrid airship as a reusable launch shuttle....

Put the platform between two airships as a pad
or four airships

o

0 X 0

o

X = Launch pad