tuga
Legal Alien
No, just cap number of children. Use contraceptives to prevent further pregancies. Unless this is not an emergency. In which case just keep calm and carry on...
Way to go Greta
- Thread starter ff1d1l
- Start date
No, just cap number of children. Use contraceptives to prevent further pregancies. Unless this is not an emergency. In which case just keep calm and carry on...
Tony L
Administrator
I agree entirely, though even a site the size of pfm generates far more content than I can hope to read in a day. I still believe that the idea of understanding and responding to one’s core demographic is the right way to moderate though, e.g. on Facebook pornography, white supremacy, beheading videos and other similarly grotesque content will put off way, way more people from using the platform than they attract, so moderating to the viewpoint of the majority/middle-ground where most punters exist is their best approach. I obviously run a forum within a very niche market of which I am very much a part of myself, so moderating is an infinitely easier thing conceptually here before one even considers the simply incomprehensible scale of Facebook, YouTube, Twitter etc. It is clear these entities all need to scale up their moderation recourses, though I acknowledge their wider demographic means they would host things I find unsavoury and would remove from here.
gintonic
50 shades of grey pussy cats
forcibly? or how do you police the policy?
It's all in the execution, and the original structural design. Your forks could, potentially, last a very long time, but it's unlikely. "Carbon fibre" on its own is simply a marketing buzzword, designed to engender a specific reaction and say specific things about the author, rather like "right-wing", "awareness", "mass" and "reality". "Single-use" has in this context been coined to cover things like cups and drinking straws, where multiple use would be systemically doable, but not practical because of the scale and cost of the washing-up required, more or less.
As I understand it, composite materials work like reinforced concrete. They consist of a structural matrix, with a core supporting medium (such as glass or carbon fibre) surrounded by resin, which hardens during manufacture as a result of a chemical reaction, not evaporation — Araldite rather than contact adhesive, if you will. The choice of the original form of the core material (eg: random strands—like felt, woven mat—like fabric, single strands—like fibre network cable) is fundamental to the intended purpose of the piece, as is the exact chemical makeup of the resin used, its resulting viscosity, and the method of curing (vacuum bags are often used with boats, so as to compress the resin to ensure that it surrounds intimately every strand of the core material during curing). Microspopic air bubbles will compromise it, but in theory, with perfect manufacture, and (crucially) a design which requires no drilling and no unsealed edges in order to incorporate the manufactured part into the rest of the product, you get something which should be ludicrously long-lived.
The big attraction of composite construction (which tends to mean carbon fibre reinforced plastic of some sort) is that the resulting item has remarkable stiffness relative to weight, so for things like boat hulls and bicycle forks, this is very attractive as it means that the constant repeated impacts to which are subjected (think of riding over a cattle grid) deflect them less so overall stiffness is theoretically increased. The downside of this is that the joint where the stiff part meets more conventional construction is now under greater stress, and the matrix of core material and resin is likely to start to break down here first. Same applies with holes drilled to fix other parts — holes break the matrix, and potentially provide an entry point for air and moisture which will encourage gradual breakdown; ie loss of intimacy and separation of the core material matrix from the surrounding hardened resin.
Because of this, composites are most effectively used when an entire item (such as a whole hull, or bicycle frame) is made at once, making it, structurally speaking, a single piece of material after manufacture. The core materials can be varied as appropriate in the parts of the item subject to different levels and types of stress, allowing the behaviour of the item under anticipated stresses to be engineered with some precision.
The problem with composites in terms of longevity is really the way they're used. The stiffness / weight ratio is so extraordinary that suddenly unprecedented levels of performance are possible, so things get built which embody the required strength with much reduced weight, and that's the raison d'etre and the temptation to which the designer is subject. I'm not aware of any field of endeavour which builds things using composites which are no heavier than if conventional materials were used, but just lasted indefinitely — but it's surely possible, albeit commercially suicidal. One big problem is that the 'super-unitary' nature of composite items means that any type of repair required as a result of accidental (ie; non-design envisaged) stress like crashing into something is just not practical, as the constructional matrix has been compromised, so the whole thing must be scrapped.
What wears out on a carbon (it's not just 'carbon' of course) boat are the joints between the hull shell, the bulkheads, the deck, and the mounting points for the rigging and spars. It shouldn't need a paint layer — this would just be extra weight, and you can add pigment to the resin anyway. To get the specified performance, all of these will have been specified for minimum weight, and they are where the stress appears. Fatigue happens when the repetition or degree of stress causes the resin to fail (crack, effectively) and from that point on, the intimacy between the core and the resin is compromised. The problem is not "carbon" per se, it's that the vessel was built for minimum weight no matter what. You can still build something less manic which will last longer, using similar construction — it's just that the one under discussion wasn't done this way, in exactly that same way as a "single-use" plastic cup isn't designed to be put in a dishwasher.
Bottom line: composite items are made and marketed for their performance, not for longevity. You may get longevity, but it's not guaranteed, and if you break it somehow, you'll need to replace rather than repair. There's nothing particularly 'green' about any of this, other than the related factor of lighter things needing less power to move them (hence the Boeing Dreamliner, which has been a flying learning curve) but it's not as simple as it's often presented, although it is rather fascinating. Far as I know, nobody's yet built a composite acoustic violin or guitar (drums, even), which could be interesting, although Kawai have I believe started making parts of acoustic piano key linkages from composites, as having less inherent weight in the mechanism allows greater manufacturing control of keybed feel.
gintonic
50 shades of grey pussy cats
could you elaborate
tuga
Legal Alien
I could, but I choose not to. I believe I've covered the requested point adequately. I even used my shift keys and attempted to punctuate in the spirit of effective communication, rather than dumbing it down to "Who else fancies the squealing lefty pedo-bait?"
3
35451
Guest
Yo Yo Ma likes carbon cellos.
http://cardiffviolins.co.uk/luis-and-clark-instruments/
AnD OT to Greta, but interesting comparison of wood vs CF fiddle.
Oh, brilliant! News to me — much thanks for that. It'll be interesting for future generations to see happens to the structure after several hundred years of playing, as the stresses imposed on it will be similar, albeit on a different scale (ho).
gintonic
50 shades of grey pussy cats
no you haven't.
vuk
\o/ choose anarchy
should this and the post you replied to not be in the zuckerface thread?
Joe P
Memory Alpha incarnate | mod; Shatner number = 2
Reposted to help get the thread back on track.
Yes, atmospheric CO2 concentrations do fluctuate naturally over millennia — we can thank legions of climate scientists for doing the hard field and lab work to be able to say this unequivocally — but what's happening now is not natural.
And here are the real-time atmospheric CO2 measurements taken since 1958: https://www.esrl.noaa.gov/gmd/ccgg/trends/mlo.html
Joe
Yes, atmospheric CO2 concentrations do fluctuate naturally over millennia — we can thank legions of climate scientists for doing the hard field and lab work to be able to say this unequivocally — but what's happening now is not natural.
And here are the real-time atmospheric CO2 measurements taken since 1958: https://www.esrl.noaa.gov/gmd/ccgg/trends/mlo.html
Joe
Marky-Mark
pfm Member
No similarity to this one at all.
Joe P
Memory Alpha incarnate | mod; Shatner number = 2
Vuk,
Removing atmospheric CO2 by pumping some other gas in the air? Nope, that’s news to me. I’m not sure how that would work anyway, since adding other gases wouldn’t remove CO2 unless they condense it and cause it to precipitate out of the sky.
But there is a tried and true chemical reaction that removes CO2 from the atmosphere, generates oxygen in the process and provides food and ultimately habitat for critters —
6 CO2 + 6 H2O + light energy → C6H12O6 (sugar) + 6 O2
Photosyntha something, I think.
Joe
Removing atmospheric CO2 by pumping some other gas in the air? Nope, that’s news to me. I’m not sure how that would work anyway, since adding other gases wouldn’t remove CO2 unless they condense it and cause it to precipitate out of the sky.
But there is a tried and true chemical reaction that removes CO2 from the atmosphere, generates oxygen in the process and provides food and ultimately habitat for critters —
6 CO2 + 6 H2O + light energy → C6H12O6 (sugar) + 6 O2
Photosyntha something, I think.
Joe
awkwardbydesign
Officially Awesome
Stop it, you!
Marky-Mark
pfm Member
Greta might want to swing by a Banking convention on her next cruise ...
https://www.banktrack.org/article/banking_on_climate_change_fossil_fuel_finance_report_card_2019#_
https://www.banktrack.org/article/banking_on_climate_change_fossil_fuel_finance_report_card_2019#_
Joe P
Memory Alpha incarnate | mod; Shatner number = 2
Vuk,
If someone has figured a way to remove CO2 from the atmosphere, that person would be tripping over bars of gold-pressed latinum.
Here's a sobering pile of figures — the number of years it has taken us to increase the concentration of CO2 in the atmosphere by 10 parts per million (ppm) —
from 320 ppm → 330 ppm: 12 years
from 330 ppm → 340 ppm: 8 years
from 340 ppm → 350 ppm: 6 years
from 350 ppm → 360 ppm: 7 years
from 360 ppm → 370 ppm: 6 years
from 370 ppm → 380 ppm: 5 years
from 380 ppm → 390 ppm: 5 years
from 390 ppm → 400 ppm: 5 years
from 400 ppm → 410 ppm: 4 years
No only is the amount of CO2 in the atmosphere increasing, but the rate of increase is also increasing. Each and every molecule of CO2 in the atmosphere does this —
— and the more CO2 the hotter it gets.
Joe
If someone has figured a way to remove CO2 from the atmosphere, that person would be tripping over bars of gold-pressed latinum.
Here's a sobering pile of figures — the number of years it has taken us to increase the concentration of CO2 in the atmosphere by 10 parts per million (ppm) —
from 320 ppm → 330 ppm: 12 years
from 330 ppm → 340 ppm: 8 years
from 340 ppm → 350 ppm: 6 years
from 350 ppm → 360 ppm: 7 years
from 360 ppm → 370 ppm: 6 years
from 370 ppm → 380 ppm: 5 years
from 380 ppm → 390 ppm: 5 years
from 390 ppm → 400 ppm: 5 years
from 400 ppm → 410 ppm: 4 years
No only is the amount of CO2 in the atmosphere increasing, but the rate of increase is also increasing. Each and every molecule of CO2 in the atmosphere does this —
— and the more CO2 the hotter it gets.
Joe
awkwardbydesign
Officially Awesome
Is that right? I thought CO2 trapped heat, rather than passed it.
— and the more CO2 the hotter it gets.
Joe
Joe P
Memory Alpha incarnate | mod; Shatner number = 2
awkward,
Carbon dioxide absorbs infrared radiation bouncing back from the surface of the planet, then re-emits back towards Earth's surface, further warming it.
The process has been known since 1896, when Svante Arrhenius published the first paper on the contribution of carbon dioxide to the greenhouse effect: https://www.rsc.org/images/Arrhenius1896_tcm18-173546.pdf
Joe
Carbon dioxide absorbs infrared radiation bouncing back from the surface of the planet, then re-emits back towards Earth's surface, further warming it.
The process has been known since 1896, when Svante Arrhenius published the first paper on the contribution of carbon dioxide to the greenhouse effect: https://www.rsc.org/images/Arrhenius1896_tcm18-173546.pdf
Joe