Uh-huh. You're delivering seat prices 1/4 of Concorde and halving passenger capacity. So that's about an order-of-magnitude cost reduction through the power of...magic, I guess?
Did not eat the 1/3lb hamburger at A&W. Knows math.
Readit Newsknappador commented on Concorde ‘B’ heritageconcorde.com/conc... · Posted by u/robin_reala
Disclosure: I'm at Boom, which is building a Mach-2.2 airliner. https://boomsupersonic.com/
I think it all depends on how much cost savings for how much speed. In today's dollars, a round-trip ticket on Concorde from New York to London was $20,000, or 4x today's business class price. For that, you got a tiny seat in a cramped cabin.
What we're targeting at Boom is an improvement over business class. We're making it profitable for airlines to operate the plane at today's business class fares. We're getting you there in half the time. And instead of a cramped two-and-two cabin arrangement, it's a one-and-one configuration (every seat is a window AND an aisle). The seats are similar to today's domestic first class seats, only designed for productivity.
So the choice a business traveler could soon face is: Would you like to get from New York to London in 7 hours in a lay-flat bed, or in 3h15m in a comfortable, productive environment? Price is the same either way. We think most people will pick the supersonic flight.
It should be noted also that the premium cabin market today is much larger than it was a few decades ago.
And finally, premium-cabin economics are only the first step. We think there's a roadmap to making supersonic flight cheaper than subsonic flight is today. It will take a few decades, but that is absolutely the path that Boom is on.
Who is building the engine?
knappador commented on Why Do Big Irons Still Exist? di.unipi.it/~nids/docs/wh... · Posted by u/diegolo
One reason big machines might make a comeback is the increasing capability putting off the super-linear cost growth into the realm of > 100GB in-memory or > 10TB on disk. CPU hasn't kept pace unless you consider GPGPU or Phi parts.
Super-linear disk cost back when disks were already atrociously slow compared to the rest of the machine have largely gone away with SSD's hitting huge capacities and tech like NVMe, solid state RAM modules, and Intel's upcoming Optane tech ensuring that more than ever, scaling horizontally can be put off way more than used to be possible.
If you look at scale-out vs scale-up for any applications that were disk limited, disk performance is now ridiculous - > 1GB/s and IOP's measured in 100's of thousands. I'm expecting a bit of a comeback for HA over HP. More than likely, your app can be served well by a single big machine that is well within the linear scaling regime, and you need several for durability and geo-availability.
knappador commented on How much battery storage does a solar PV system need? euanmearns.com/how-much-b... · Posted by u/martinald
Let's look at chemical storage with hydrocarbons in the mix, allowing some as-yet non-commercial (air-metal & combined cycle home generators) to make good food for speculation.
A consumer to operate a small gas turbine and store their energy in the form of hydrocarbons. If this is to be sensible, then 43MJ/kg would have to be enough, because that's what they're going to get with kerosene/jet fuel.
Now let's consider lithium. The problem with metal-air batteries has mostly been poisoning by unwanted gases. Let's assume for a moment that a membrane material is developed that only allows high purity oxygen through, but suffers low throughput. This is no problem for our off-grid solution because we're talking about large storage relative to power, similar to some flow battery applications. Using some method of specific ion or biological style solution, such a membrane is not implausible.
Lithium-air weighs in at 40MJ/kg specific energy. How much does it cost? Given that a metal-air battery uses lithium oxide, the lithium carbonate and lithium hydroxide prices are not quite valid guides, but the price of $7/kg is obtainable for the carbonate of "battery grade." If the pure oxide can be the material used in manufacture, then possibly the $7 value is in the ballpark.
Jet-A is $0.45 per kilogram. 1.41 $/gal / 3.78541 l/gal / 0.820 kg/l
Higher efficiency must be allowed because even with combined cycle at high latitudes where it's cold, we're looking at 90% round-trip for a battery vs ~75% for our Brayton cycle + home heating.
There are external costs to a large tank of kerosene and a pile of lithium carbonate. One requires a gas turbine and the other requires a battery & significant manufacturing. Excepting those two things, we're left with a roughly 7:1 factor of cost for the raw material, so a seven year payoff it is.
Lithium might not be the cheapest rechargeable precursor. It might be great for EV's (high power output is a requirement) and maybe something else will show up as the cheapest energy storage without requiring off-grid people to rely on ARES gravity trains.
Perovskites (new paper just suggested that hot-carrier phonons can be used to raise theoretical efficiency to 66%) throw yet another wrinkle into solar. Both energy storage and generation could become quite a bit cheaper.
All hypothetical, yes, but my napkin does tell me not to rule out off-grid, not that I'm sympathetic to off-grid, anti-social Ayn Rand acolytes =D Whatever matters for off-grid matters for a ton of settings, such as places where there is no grid still. It's tough to say definitively that a straight-renewable energy source won't become cost-competitive even in grid areas of high latitude within the decade.
Source on Jet A specific heat: http://www.exxonmobil.com/AviationGlobal/Files/WorldJetFuelS...
Source on Lithum Air theoretical specific energy: https://en.wikipedia.org/wiki/Lithium%E2%80%93air_battery
Jet A price: http://www.indexmundi.com/commodities/?commodity=jet-fuel
Lithium Carbonate Price (ev grade): http://www.globalstrategicmetalsnl.com/_content/documents/40...
knappador commented on Cutting Back Sugar Improves Obese Children's Health in Just 10 Days well.blogs.nytimes.com/20... · Posted by u/imjk
Lustig just doesn't give up. He has already been crushed by Alan Aragon five years ago.
http://www.alanaragonblog.com/2010/02/19/a-retrospective-of-...
Credentials would tend to support the practicing endocrinologist. Also, the data Lustig really had to go get was the causal inference where increasing fructose had a delayed response of increased metabolic syndrome. That study has been done now.
knappador commented on How is the work quality at Blizzard as a developer? · Posted by u/johnlevenstein
Well according to my 6 year old information from WoW, they used C++ for their servers and have a bit of a NIH streak.
So I am guessing it's probably still a C++ heavy shop like many gamedev places.
I've heard a lot of enthusiastic talk of entity-component architecture from those interested in game-dev. The way of modelling seems very appropriate and well-suited to C++. Things like holding each entity in a component class's static member array and calling the static method to, for instance, update the health component of every health-having entity is just too elegant not to appreciate. Immediately the problem is mapping each component across threads and just trivial to make parallel/concurrent.
To start though you need multiple inheritance likely to get this to work idiomatically. C would also do fine, as would Java, except the Java would look like C because of the lack of multiple inheritance/mix-in, while the C code could result in some type insanity -- although components can be implemented as simple structs in structs for entities, except the whole construction/destruction phase of life.
As an outsider looking in, C++ seems filthily well-suited to game development.
knappador commented on Engineers Build Ugly Products techcrunch.com/2015/10/25... · Posted by u/confiscate
It's incredibly counterproductive to make statements like in the title. If you need your product to be better in terms of how it looks and feels, you get a UX Engineer and expect them to be able to do data analysis, modify analytics on their own, and apply what's learned from that analysis in dimensions beyond the X and Y in Photoshop.
Reducing a task graph is exactly the role that I'd expect a UX Engineer to be perfect at, and yet the article is titled "Engineers Build Ugly Products" while going on to state exactly the expected benefit of having a UX Engineer deeply involved with the product team -- reduced tasks, focused functionality.
Where this kind of thinking blows back on real decisions is when someone says, "Look, I know how you engineers think..." suffixed by some opinion completely drawn from the realm of speculation. Subscribe to such thinking if you want to arbitrarily override the work of your best modelers.
The absolute worst kinds of push-back are fueled by identity politics statements like these bait into. You wake up in a conversation about prioritizing core value and someone pushes on wanting to change the color of the drapes and calls the entire engineering team anti-design like we don't get anything outside of text-highlighting in our code editors. It's infuriating.
knappador commented on A small British firm shows that software bugs aren't inevitable (2005) spectrum.ieee.org/computi... · Posted by u/cjg
Maybe he probably proved the mathematical algorithm was correct. The problem is we have to implement algorithms using machines, which aren't perfect. They do a great job most of the time, but they exist in a physical environment which has restrictions and outside influences.
We can only work with the tools and techniques we've discovered so far. Later, we find situations or results that show our tools or techniques aren't correct or aren't good enough and we improve them to cover the new situations.
Safe points, jit, and VM all introduce extra layers of complexity. I bet it's definitely harder in the context of the JVM muddying up the picture.
knappador commented on A small British firm shows that software bugs aren't inevitable (2005) spectrum.ieee.org/computi... · Posted by u/cjg
Small imperative functions are just as easy to make bug free, I don't buy it.
Also true. Still, purity (just part of referential transparency) should be highlighted as something that helps not just with the function you're writing , but also functions that need to call that function.
knappador commented on A small British firm shows that software bugs aren't inevitable (2005) spectrum.ieee.org/computi... · Posted by u/cjg
A referentially transparent, small function, has always been easy to write bug-free assuming the OS doesn't lose a page-table entry, a network interrupt isn't exploitable, and cosmic rays don't flip bits. The issue has never been that we can't write something that's correct.
Getting that correctness to propagate because of the strictness of all the tools involved and accuracy of their construction is the issue, which leaves us with needing to either automate proofs with Coq or prove things in more general ways that lead to undecidable problems etc. Still, the fact that one function can be written bug-free and known to be bug-free does indicate that it's not an inevitability of probability playing out as code grows.
We have null-pointer exceptions and no maybe type. The API's that emit nulls sometimes make me expect sewage to leak from light sockets. It's possible to do better. We just don't, and none of us love it. Rust and Kotlin are at least very exciting. I'd like to understand some Coq more in the context of x86. What routines are strictly necessary to even do Coq? A response based on some statement about how the Y-combinator enables X where X leads to Y would not surprise me.