> What does a 1% increase in congestion mean for people in traffic?
Well, the article indicates the increase was 1% in amount of congestion, and 4.5% in duration. So, I suppose that means people in traffic are in traffic longer?
A fair amount of people will adjust their working hours to get a reasonable commute. They would prefer to work 8-5 (because that is what the day is setup to be - at least one friend (or their kid's school!) is on a fixed shift that cannot change, so matching shifts makes sense as it means the most time outside of work. However if that ideal time is too crowded they will adjust to a more reasonable compromise for their situation.
That is why rush hour exists. In Des Monies it is more like 15 minutes, in Minneapolis it is several hours. The idea is the same though: the time when the most people are trying to get someplace at the same time.
I understand the judgement calls one has to make as a moderator and I see how they are discussing the same topic.
The url for https://news.ycombinator.com/item?id=26887670 does not indicate that the University of Minnesota has been banned from contributing to the linux kernel. I judged that as a separate and unique part of the event.
Apologies if that isn't in alignment with how HN conversations are moderated.
Oh no worries! For future reference the main standard we apply is "is post X substantively the same story as post Y". In this case I'd say the answer is clearly yes, in the sense that the discussion it led to was more or less interchangeable with the other thread. But it's not always obvious in advance!
Edit: turns out the mod who downweighted the original thread, when the two were on the front page at the same time, thought that this one added significant new information and so the discussion should move here. In other words they saw things the same way you did. It's a reasonable interpretation :)
A Wankel has seals attached to the rotor that rub against the wall of the chamber. This engine only has three points on the chamber wall that touch the rotor, so the seals can be installed on the chamber wall and it is significant easier to cool and lubricate a fixed seal rather than a rotating seal.
As I understand it from friends who're in to rotary engines, the biggest problem is the spark plug hole. The seal - which is being forced outwards by rotation - will fall in to the hole slightly and then wear against the edges of the hole as it rotates past. This gradually increases blow-by and reduces efficiency until it no longer seals at all.
This design has a smooth surface against the seals at all times, and they can be lubricated directly.
That is not the primary source of wear problems on Mazda Wankels.
What you're describing is a challenge on peripheral port (race) engines where very large intake and exhaust ports must be bridged by the apex seals, and in the pursuit of performance their radius is often less than ideal making the transition onto and out of the port area more abrupt.
The spark plug hole however is relatively small and circular.
High-mileage Mazda Wankels typically require overhauling because the side seals become seized in a compressed state (their springs are meager segments of ~sinusoidal wire, and the motor burns oil by design causing excess carbon/coking clogging them up), resulting in excess blow-by and unintended oil burning. Once the side seals go, the combustion gases start reaching the oil control rings, baking their soft interior seals into brittle plastic and it's all downhill from there.
source: former rx-7 enthusiast with multiple diy engine rebuilds in his past.
Edit:
BTW something that's often misunderstood about Wankels is that the rotor turns lazily at 1/3rd the engine RPM. So despite it being a "high revving" engine, there isn't actually that much centrifugal force acting on the apex seals at conventional engine speeds. The pain point in this department is the stationary gears responsible for converting that 3X eccentric shaft speed into a mix of orbital and rotational motion at the rotors.
I'd still consider a 410 as a broken link. The article states
> Pretty much the only good reason for a document to disappear from the Web is that the company which owned the domain name went out of business or can no longer afford to keep the server running.
If you put the car's public key on the fob, the fob can validate that it is talking directly to the car over a secure connection and then the car can validate the fob's secret.
Please elaborate as to how the fob or car would detect the MITM:
1. You place device A near car and device B near fob.
2. Device A relays all Rf transmissions in the target frequency range(s) to device B, which rebroadcasts, and vice versa.
Public-key encryption / authentication only ensures that no-one in the middle is reading or editing your connection. It does not prevent someone from relaying your communication. (And a good thing too, else the entire encrypted web wouldn't work.)
Well, there may be one way. But it's not user friendly at all.
When the driver presses lock/unlock on the fob, the car first sends a signed message with a session secret. The fob checks the signature, takes the secret and creates a _single use_ auth token and signs it with the private key stored on the fob. That signed auth token is then sent from the fob to the car to lock/unlock the car.
To check if there was a MITM you would have to pull the door handle to see if your keypress was successful. If it was successful, you don't need to worry if the key was grabbed by a MITM, they can't use it even if they tried. If it was unsuccessful for some reason (e.g. the MITM knew it was single use auth token so they didn't pass the token onto the car in hopes you might not be paying attention and will press the button a second time) then there should be a manual override outside and inside the car that clears the valid auth tokens and allows you to lock/unlock/start the vehicle without sending any RF transmissions. A slot that you insert the key would work.
Signatures do nothing to prevent blind relaying. Transmitting through an amplifying relay in this attack looks identical to transmitting through free space, aside from the received power level and propagation delay.
The amplifier relays that signed signal to the fob. The fob receives it and its unlock signal is relayed back to the car.
No matter what tricky message protocol you come up with, it won't matter. The car and the fob can't detect the difference between being next to each other, and being next to a set of relays rebroadcasting their signals. Not by reading and transmitting radio signals at least.
You can't think about this like internet security. Normal encryption doesn't care how long the network cord is. Opening your car door does. This attack lengthens the cord between client and server without touching the data on the cord so that you are genuinely logged in from an encryption standpoint, but from a world standpoint you are sitting at your office desk unable to see your car.
