I’m building a simple, opinionated tool to create and manage roadmaps the right way (IE not features on a Gantt chart). Think of the opinions that the basecamp guys bake into their products, but targeted at roadmapping.
Going to use it with my own internal product team for a while, but could easily see it being a good standalone product.
Ask HN: What interesting problems are you working on?
521–530 of 709 posts
Re: Ask HN: What interesting problems are you working on?
#522How to find an accurate numerical approximation to e, the base of the natural logarithm? Last weekend stumbled onto a shockingly easy and effective way! Google query "base of the natural logarithm e" reports e = 2.718281828459 that is, 13 digits. The calculator with Windows 10 reports e = 2.7182818284590452353602874713527 that is 32 decimal digits. Last weekend found e = 2.71828182845904523536028747135266250 that is,…
That's Calculus 1.
Re: Ask HN: What interesting problems are you working on?
#523Earlier quoted context omitted.
I've actually been thinking about the issue of energy storage a lot recently -- I've read a ton about how lithium-ion battery production is exploding (usually not literally), but it seems unreasonable to store enormous amounts of renewable energy in a device that itself has to be replaced after a certain number of cycles. The device used for pumped energy storage -- a tank (to simplify greatly) -- basically never nee…
> it seems unreasonable to store enormous amounts of renewable energy in a device that itself has to be replaced after a certain number of cycles. The device used for pumped energy storage -- a tank (to simplify greatly) -- basically never needs to be replaced. It's a fair point but I think that you oversimplify the pumped hydro case. Pumped hydro also has quite some electronic components (turbines/motors), electroni…
That's a good point. I think it seems likely that given the relatively larger storage capacity per unit[0] with pumped hydro vs. batteries, that the overall maintenance costs -- including the environmental costs of materials needed -- would be lower, but you're absolutely right that we'd have to do the math to know for sure.
[0]When I say "per unit," I just mean that a huge battery is made up of many cells that will need to be replaced individually, whereas large pumped hydro facilities are still only a small number of total reservoirs.
Re: Ask HN: What interesting problems are you working on?
#524Earlier quoted context omitted.
I've actually been thinking about the issue of energy storage a lot recently -- I've read a ton about how lithium-ion battery production is exploding (usually not literally), but it seems unreasonable to store enormous amounts of renewable energy in a device that itself has to be replaced after a certain number of cycles. The device used for pumped energy storage -- a tank (to simplify greatly) -- basically never nee…
I think the point you just made about the rate of replacement of lithium-ion batteries is very pertinent to solar panels(to the point that many consider solar a scam)
I've never heard that said before, but I'm interested to hear more. Do you have any sources on that? My understanding was that solar panels last quite a long time.
Re: Ask HN: What interesting problems are you working on?
#525Paysapp, a worldwide payment system that allows you to send money as simple as texting a message like "pay 100 to George", available right now in Whatsapp, Telegram, Keybase, Matrix, Discord, Slack and Twitter, just add the Paysapp bot to your chats and type 'help' to start. We're at a very early stage and looking for investors.
Which countries is it available for? Are you compliant with all the complex and sometimes tiresome regulations on cross border transfers?
Worldwide, all 200 countries wherever there is internet.
Regarding regulations we are studying two possible scenarios, comply with all or simply Uberize the model and let people sell money for a fee. For the former we need tons of money, attorneys and on/off ramps with the banking world. For the latter we only would be the messaging transport and people would buy and sell money informally, that's the long tail of the unbanked and informal merchants.
Re: Ask HN: What interesting problems are you working on?
#526How to find an accurate numerical approximation to e, the base of the natural logarithm? Last weekend stumbled onto a shockingly easy and effective way! Google query "base of the natural logarithm e" reports e = 2.718281828459 that is, 13 digits. The calculator with Windows 10 reports e = 2.7182818284590452353602874713527 that is 32 decimal digits. Last weekend found e = 2.71828182845904523536028747135266250 that is,…
That's Calculus 1.
Yes, to quote, as I wrote,
> notes to get a nephew of 9
I'm writing the notes for my 9 year old niece. So, the notes are for a boy of 9. And it's calculus, for a boy of 9. Of course it's "calculus 1".
I thought I mentioned it was for a boy of 9.
So, I omitted (1) a real valued function of a real variable with a compact domain has a Riemann integral if and only it is continuous on a set of measure zero, (2) for such function, if it is differentiable, then it has no jump discontinuities, (3) there is such a function that is differentiable but whose Riemann integral does not exist.
But, still, it is amazing how easy it is to get 36 decimal digits of e, and 500 if want.
I've been through calculus, advanced calculus, advanced calculus for applications, differential equations, local series solutions to the Navier-Stokes equations, exterior algebra, real analysis, measure theory, and more, have taught calculus in college, applied it in US national security and business, and published in it, and still I'd never seen a clear treatment of how easy it is to get so many digits of e from Taylor series.
The results I found are amazing, and my good and long experience indicates that only a tiny fraction of calculus students appreciate that.
And as we know,
e = lim_{i \rightarrow \infty} (1 + 1/i)^i
and it turns out that that iteration is painfully slow, and from my experience this fact is also amazing and poorly known.
It was amazing stuff and a productive weekend.
Re: Ask HN: What interesting problems are you working on?
#527Earlier quoted context omitted.
I've been wanting to disrupt orthodontistry for quite a long time. With the state of 3d scanners, 3d printers, 3d software modeling, why hasn't the market price of orthodontist treatments dropped to cost-of-materials yet? As soon as at least one satisfactory / integrated open-source stack exists I think it's only a matter of time before it does...
I don't know if this is what you mean but in Japan many dentists have machines to make tooth crowns. Not sure how common that is in the west. I went to a dentist in SF, they did something and then I had to come back in 2 weeks after they made the crown. Been to several dentists in Japan where they could make the crown while you wait 20-30 mins
They do happen in the west as well. It is faster/cheaper to print crowns/etc, but I don't believe it's generally on par with an expert Dental Technician yet.
Re: Ask HN: What interesting problems are you working on?
#528Earlier quoted context omitted.
How large is a typical system - how much land you need to excavate?
If we attach our installation to an existing reservoir, we'll take up nearly zero land above ground. If we build a new self-contained upper reservoir it will be about 0.5 miles on each side and 40 feet deep. It can be built with material excavated from the lower reservoir. This may seem large, but it's for a huge amount of storage 20GWh - enough to balance the load of a large city. And keep in mind that it's about th…
This would correspond to a height difference of about 1 km between upper and lower reservoir right?
Re: Ask HN: What interesting problems are you working on?
#529Earlier quoted context omitted.
This is anecdotal, but I remember reading an article about a dentist who was convicted of doing expensive and completely unnecessary surgeries on many of his patients, to the tune of hundreds of thousands of dollars per patient in some cases. I can't find the article, unfortunately.
I believe Atlantic had such an article recently. Good starting read is "How dentists rip us off" from Readers Digest. However, it's a bell curve. There are extremely moral and extremely immoral people. Some of them are dentists.
> There are extremely moral and extremely immoral people. Some of them are dentists.
Absolutely true. However, it seems that other areas of medecine have better systems in place to prevent abuse, and dentristry would do well to follow suit.
Re: Ask HN: What interesting problems are you working on?
#530Earlier quoted context omitted.
Agreed, the differences between municipalities makes this really hard to scale. If data providers like the ones you mention don't exist, the two ideas that immediately come to mind are a) becoming that data provider (obviously), or b) building a platform for municipalities to store their land ownership data on. Both sound like interesting problems, and it would be awesome if municipal-level land data was available at…
How do you become that data provider? You need some scalable way to get all that data, right?
I'm not sure how to do it scalably, other than by becoming the host for that data, which is why I included my second option. It seems much easier (and much more profitable) than figuring out how to access the data in its existing format.