When my friend's car broke down on the mountain 15 minutes from both of our homes and I brought them a jacket and McDonalds while they wait for a tow, that was a rescue.
Pretty sure it's just a way to get more expansion from the same air charge.
It's a similar idea to the Atkinson cycle. You have dissimilar compression and expansion strokes. In normal engines, there's a limit to compression ratio because if it's too high, it causes knocking. But a bigger expansion ratio lets you extract more energy out of the combusted gas, which leads to higher efficiency.
The original Atkinson cycle idea was to use some complex linkage to get dissimilar compression and expansion strokes, but the way it's implemented in things like the Prius is to have a high compression engine, but mess with the intake valve timing such that you only use a small part of that compression during the intake phase so you effectively handicap your compression ratio to avoid knock, while still retaining the full stroke during the expansion phase.
>Knocking happens from pre-detonation, that's usually caused by heat from compression causing the fuel/air mix to ignite before it's triggered by spark.
No, it usually happens because the normal flamefront from the spark causes a rise in pressure that triggers compression-ignition in other parts of the cylinder. It's not solely from the compression, usually. That scenario is rare primarily because as you reduce the knock margin, you'd hit knock from what I said before you get to the state where it's so bad it ignites from compression alone.
Look at this picture; this is a typical waveform of cylinder pressure vs. crank angle. The spark happens 28 degrees before TDC, so basically the left edge of each of the graphs. As the flamefront consumes the air-fuel mixture inside the cylinder after the spark, the cylinder pressure gradually rises. During knock events, the cylinder pressure as risen by the normal combustion process gets to a point where it starts igniting the fuel elsewhere in the cylinder, away from the gradually expanding flamefront. This causes rapid combustion which causes the pressure to rise suddenly, which causes damage to the engine (if severe enough)
There are many pathways and schools internally for the different directorates.
Most programs are partnered with outside schools, with some giving you course credits for internal classified work and only requiring a few outside unclassified courses to fulfill needs. Many of these are MS degrees. I got one through one of these programs. Which come in handy with restrictions on promotions / positions based on ed reqs.
Is the statement just that if you use a random value for a nonce rather than some guaranteed never-used-once value, it's possible to get a collision faster than the "natural" block collision complexity (half block size or something like that)?
It's a birthday attack principle. With only 96bits after roughly a billion messages with the key and random IVs, you start reaching realistic probabilities that you will reuse an IV
not really related, but people say you shouldn't look directly at the sun.
I don't understand why having the sun in your field of view at all isn't dangerous then. wouldn't that cause the sun to burn a hole somewhere inside your eyeball that isn't the direct center?
The "Thundervolt" reference in that post is a project where they cut up a Wii PCB to leave just the DRAM and the processors on the PCB, and then they slap an external DCDC board on top of that cut up PCB to provide power to it, while also undervolting it since you reduce the IR losses.
At this point I'm a bit surprised that nobody has created a netlist of the board and simply reinstalled the relevant chips on it. There has to be more density that can be eked out for easier that way than carefully taking a Dremel to an existing board.
There are a few reasons for it:
- the cut board is compact enough for most/all hobby projects
- you can get Wiis for very cheap nowadays, perhaps cheaper than the parts themselves
- the original board makes heavy use of serpentine tracks. If they are not just to equalize track length, it’d be very hard to account for all delays in a redesign.
ofc I’m not a part of the community so their reasons might be complete different
No I think he literally means IR losses. ie voltage droop V=IR
Modern VRMs also reduce output voltage when the CPU draws more current. That way when the CPU later draws less current, the voltage doesn't inductively spike up and damage the CPU. Overclockers call this LLC (load line calibration), but don't google that because electrical engineers don't use that term and most articles and reddit threads explain this ass-backwards. Google "Active Voltage Positioning" instead to find correct documentation.
If your VRM is close to the chip, voltage droop will be ~0 and LLC can be ~0. This allows you to undervolt more and save power without instability. This is probably why most server CPUs have voltage conversion inside the chip (FIVR, Fully integrated voltage regulators)
Like it's not much, but come on.
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