When I took control theory at university, in the last lecture, the lecturer took out a bike with rear wheel steering and challenged us to ride it in the hallway outside the lecture hall in the break. No one could get it to roll more than a couple of meters. The second half of the lecture was spent proving that a rear wheel steered bike is in fact (almost) impossible to control.
But it turns out that it doesn't matter whether you place the thrusters high or low, stability-wise. What matters is that the center of mass is in front of the center of the center of pressure.
Aren't they just as stable as regular rockets, but it's very inconvenient to put the thrusters on top?
It's called pendulum rocket fallacy and from what I can tell that's the case.
Yes, it was pretty much a reverse bike with the saddle on the frame and a handle bar just behind where the seat post should be, connected to the steering axle. The details is a little bit fuzzy since it was a couple of years ago but iirc it is actually possible bike backwards at slow speeds but require a lot more active balancing from the rider, and at some point it becomes impossible as the speed increases. Also it concerned the case where the bike is riding straight ahead, it is possible that it is easier to control if riding in a curve.
Looking for part-time or consulting position. I have a background in applied mathematics and I'm interested in working with optimization, machine learning, computer vision, data visualization and similar things.
1. Pretend it is the 1970s in East Berlin and someone follows you around, noting down every interaction you have with other humans and every bit of media you consume and collects this information in a file somewhere for future use. This is the horrifying and oppressive surveillance machine of a paranoid dictatorship.
2. Use a computer to the the exact thing automatically today. This is just the natural state of the world, nothing to do anything about it, move along.
There is a clear difference between 1970s East Berlin and now. Stasi spying propped up a system that provided a relatively low standard of living and a limited availability of consumer goods. Modern tracking of customers fuels a vibrant customer-good market that is a win-win for everyone.
I don't think it is ok for any entity to make notes of when you buy condoms and then spend the night at an adress you don't live on and infer whatever it infers from that and then sell this information to any other entity to do whatever it pleases with marketing or otherwise. Even if I make more money than the X% who still have a worse material standard today than the median East Berliner.
Except this technology is being used in China today to monitor the bulk of every purchase, every internet site visited and every message sent and received.
The Stasi hid cameras in handbags and behind buttons but regimes operating today do not need to operate in such corse ways.
If you're interested in algorithmic drawing, https://turtletoy.net is a nice little toy to play around in and it uses the same primitive operations as most plotters (pen up and down, move to coordinate). One popular plotter is AxiDraw which can be controlled in a multitude of ways including an Inkscape plugin and a REST-API.
This is made by a Swedish adver^H^H^H^H^H creative communications agency called ODD Company (https://oddcompany.se) who makes these kind viralbait product campaigns. Not sure if it is made for another client or just as a way to get som press for themselves but they mention Swedish payment solution provider Klarna a couple of times.
External debt is not the same as national debt and does not in it self say very much about the health of the public sector economy, since it includes private debt including accounts held in the country by foreigners for business reasons, tax evasion etc.
I am only intimately familiar with one EU country's banking transaction infrastructure, but there it is the case that when one (major) creditcard provider has a network outage the debit network is also down.
Sweden is about the same size as California but with about one third of its population (and about 2/3 of the population density of US), still it is in the top 10 internet access list in about every metric you can think of (together with for example Norway and Iceland, neither especially densely populated) so I don't think the density argument holds.
Stockholm and LA are excellent examples. In Stockholm, there is a municipally owned company that builds fiber. It received no government funding, and built the fiber over more than 15 years in a demand driven way (building first to businesses, then to places with highst demand). It leases access to ISPs, and there are no mechanisms to force it to subsidize lower income or disadvantaged people.
Contrast Los Angeles. There, Stokab’s business model would be illegal. Builiding out based on demand might mean that wealthier neighborhoods would get fiber a decade before poorer neighborhoods. Disproportionately, white residents would get fiber before hispanic residents. That would be politically untenable (and would be completely impossible to put the government’s imprimpteur behind such an effoet as with Stokab). For that reason, most US cities make Stokab’s business model illegal.
Los Angeles had a fiber proposal: https://www.wired.com/2013/11/la-fiber. It tried to get companies to build a fiber network. By contrast with Stockholm’s approach, neighborhood income and population density could not be a “factor” in the rollout. That means that any ISP would have to build to new neighborhoods that were not economically justifiable. The ISP moreover would have to provide a minimum level of free access to all residents. It would thus have to recover the cost of that from other residents, driving the price higher and decreasing the competitiveness of the product. Unsurprisingly, nobody took up Los Angeles on that proposal. Nobody would build it, it made no business sense.
In Stockholm, fiber was a simple business proposition, built with private capital. In California, it was a social justice initiative, unattractive to private capital. Which is not necessarily itself a problem, but if you want to do that you need to be willing to build it with public money.
Also, New Jersey is about as dense as many European countries that have great broadband and competition--yet New Jersey has crappy broadband. So, it's not due to USA's low population density.
6 years ago in Jersey City I had Fios, while across the river in Manhattan, it was very difficult to get. In my part of New Jersey in 2012, I had far better internet than I did in 2018 France — and much cheaper.
Sure, Swedish cities are a little less sprawly than American cities of the same size (I have no data on this but my general experience is that both apartments and houses a slightly larger in Sweden but a bigger part of the housing stock is in apartments), but I still don't think the geographical explanation holds especially in densely populated regions like the Bay Area.
I think it has more to do a lack of interest from US politicians.
The Bay Area isn’t densely populated. San Jose to San Francisco is mostly single family homes in suburban neighborhoods. Even the “dense” parts don’t hold a candle to East Coast cities.
