Topic: NXT Silver Bullion Gateway Gateway Updates and Information - page 4. (Read 12380 times)

awesome! i can never make heads or tales of fancy math stuff like that. it looks like french to me. i just have to work through the logic in my head

http://iweb.tntech.edu/murdock/books/bookv3.pdf

#7 under worked examples verifies that you're using the equations right

it doesn't need to be. the only point at which shrinking matters is past the point at which it has transitioned from liquid to solid. as long as its liquid it can flow freely through out the chamber of the mould. so the point at which it becomes solid is the upper bound for what i need to calculate.

For computing volumetric expension, you need to use the following formula:

dV/V=alpha_v*dT

alpha_v is the volum-expansion-coefficient that you find. The unit of the volumetric coefficient is the inverse of temperature K^-1 or C^-1. The unit Kelvin or Celcius can be interchange because a variation of 1K is equal to the variation of 1C.

dV: is the variation of volume, in the unit you choose (e.g. m^3)
V: is the volume of the solid (same unit as dV)
alpha_v : is the volumetric coefficient (unit K^-1 or C^-1)
dT: is the variation of temperature ( inverse unit of alpha_v)

So to compute the % volume variation:

you simply use alpha_v*dT*100.

Your case, alpha_V=58.3*10^-6
dT=933

then % volume variation = 58.3*10^-6*933*100=5,43%

You got the right answer.

Edit: well, that an approximate. Im not sure the formula is valid for very large dT. For large temperature gradient, you need to use integral formula as stated in wikipedia:
http://en.wikipedia.org/wiki/Thermal_expansion
Check volumetric expansion.

Its written as a linear expansion coefficient e.g. (m/m K) not (m^3/(m K)), a linear coefficient which is change in length per meter and degree of temperature, volumetric is 3x linear for a solid, but another reference I have says the volumetric expansion coefficient for silver is 54 *10^-6 (m^3/(m K)) AT 20C - So I think it may be a volumetric expansion coefficient just worng units....

BUT I don't think solid to liquid volume change can be calculated using a constant - so your 5% may be wrong because you have a 'state change'

EDIT:

density of solid silver at room temperature = 10.49gcm^-3
density of liquid silver at melting point= 9.320gcm^-3

perhaps this is a simpler - the ratio of the densities will give you a volume change between liquid silver and room temperature solid silver.

For the smart maths people out there

This chart says http://www.engineeringtoolbox.com/volum-expansion-coefficients-solids-d_1894.html the volumetric thermal expansion coefficient of silver is 58.3 (10-6 m/(m K)) i can only assume they mean m^3 since that is how you would measure volume.

So if i multiply 58.3*0.000001 i get 0.0000583

So silver expands at 0.0000583 meters cubed per meter cubed per kelvin.

Room temperature is about 300 kelvin. The melting point of silver is about 1233 kelvin. So that's a difference of 933 kelvin.

So then i just multiply 0.0000583*933 and get 0.0543939 meters cubed per meter cubed of change over 933 degrees.

Ive got to be honest that seems crazy. a 5.5% change in size as it cools? there is no way that can be right.

Well i cant tell you that because i don't know but i can tell you what i'm doing now and what i have left to do. at this moment i am trying to get the dimensions just right since there are some issues with the bars changing size while cooling and getting worn down a bit in finishing. i have to make the cavity of the mould over-sized so im trying to figure out by how much. then i have to build a model of the entire mould. next i have to find someone to convert it from skp to cad. next i have to find cnc machinist who can make the mould out of the cad file. then i have buy a furnace some silver shot and finally i have to actually make my first bar.

It looks very nice! When do you think you will produce the first bars?

Awesome! Need this!!! 

Final draft. What do you guys think? I'm pretty sure this is what the bars are going to look like.

well its gotten complicated. there is a problem with the lettering were if its recessed into the bar perpendicular to the surface of the bar than it may crack. So i have to do the lettering where the wall is at a 45 degree angle. Which means i have to do each and every angle for every letter by hand. so tedious it makes my stomach feel like it has bugs in it. I just have to get up the will to slog through it though. ill go work on it some more now.

*edit* i can copy and past individual letters after i make them so that saves some time

I keep silver bullion in a safe and if anyone redeems (a) silver bullion colored nxt token(s) at my public nxt address with a message attached specifying their address than i will ship them silver in an amount proportionate to the number of tokens redeemed.

Nice, looking forward to this!

Dont get it.. you store nxt in a physical wallet in some safe or something that will temporarely be worth nxt and can be exchanged for real nxt? Read the first post.. so maybe im far out

regards

Any news on this project, Anon?

+1  excited to see this develop

Interested!

I'm not a lawyer, but one way around that issue could be to call your tokens digital warehouse receipts. As far as I know, you don't need a license to issue a proof-of-ownership document to someone else (as long as you have the goods to back it up, of course.  ) It'd be like (say) a bike store issuing a receipt for a new bike in lieu of handing the bike over, which can be done for pre-sales of a model not out yet, or a claim check for a prime-rib roast from a grocery store that's "roast good." Again, I'm not a lawyer, but common sense says that a warehouse receipt in NXT form shouldn't cause you any legal snarl-ups...at least in the case of a non-transferrable receipt.

It might be a different animal if the receipt is transferrable...but it might not be. Back in the day when places like McDonald's sold paper gift certificates, they were bearer instruments and thus transferable. This angle dovetails perfectly with your plan to pour your own bars. x NXT = 1 Gift Certificate, Redeemable For One 10 Ounce Silver Bar At The Anon136 Foundry. There's loads of precedent to show that transferrable bearer gift certificates are legal.

The only difficulty I see comes with the fungibility of NXT. Where's the line between a transferrable warehouse receipt or gift certificate and a security? In Canada, there's a cozy old tradition courtesy of Canadian Tire corporation: "Canadian Tire money." Legally, they're "Cash Bonus" coupons "Redeemable in Merchandise only at Canadian Tire Stores" - i.e., gift certificates with no expiry date. They're bearer instruments, transferrable, and come in denominations as low as 5 Canadian cents. I have some in my wallet right now.

Were you Canadian, you could fend off the authorities by saying that your gateway issues "Cash Bonus Coupons for the silver bars I make, just like Canadian Tire money." A prosecutor would hear "well-known precedent" in the last clause and leave you be. But Canadian law, I'm sure, doesn't reach into your jurisdiction.

As I said, I'm not a lawyer. Pity we can't find a real one and get him or her hooked on NXT. It'd be better than inviting a family doctor to a house party 

My thoughts exactly)

Damn I missed this thread so far. This is awesome !