1) EVs do have kinetic energy recovery; it's called regenerative braking.
2) Gasoline vehicles that have them are known as hybrids.
3) All systems, including KERS, have purchase price, mass, and maintenance penalties, which is why they're not universally adopted.
4) The particular approach of flywheel-based kinetic energy storage has good W/kg but poor Wh/kg, W/l, and Wh/l. It has catastrophic failure mechanisms, limited storage time, and tends to offbalance vehicles. Flywheels have been becoming less popular with time in vehicles, not more - being overtaken by electric systems, which are increasingly compact and lightweight vs. their power output.
5) All kinetic energy recovery mechanisms suffer from losses. I haven't looked into the round-trip efficiency of flywheels, but round-trip efficiencies of conventional hybrids are often 40% or less, while for li-ion EVs they're often more like 60-70%. The problem is that you're storing and withdrawing power quickly, which reduces efficiencies, and all losses hit you twice - motor, drivetrain, controller, wiring and battery. Hybrids are hit worse than EVs because the packs are smaller (meaning higher-C charge/discharges) and the packs are generally NiMH, which is less efficient than li-ion.
6) Braking losses are only dominant in city driving. In combined driving they're significantly reduced and in highway driving they're almost an irrelevant fraction of the total. Aero losses dominate at high speeds while rolling losses dominate at low speeds.
7) The biggest energy benefit of a hybrid isn't recapturing braking losses, as most people assume. It's that it lets you operate with a much less powerful engine, without the vehicle feeling underpowered, thus helping the engine stay in its optimum power band (IC engines operate most efficiently when fairly near their maximum torque capability). Hybrid vehicle efficiencies don't drop that much when the hybrid system is broken (losing regenerative braking and stop/start), but they lose responsiveness.
8) Rolling losses, for the most part, come down to your tires; there's a balance between 1) grip, 2) rolling resistance, and 3) price. Choose two. (I could throw in other factors like noise, comfort, wearing, etc, but let's keep it simple)
9) Reducing aero losses comes down to reducing your cross sectional area and your drag coefficient. A reduced cross sectional area means that you can have a long car but not a wide or tall one. Reducing the drag coefficient means breaking with styling choices that people prefer in cars in favour of making it look more like an airplane (see the Aptera as an example of taking it to extremes).
Note that things that look aerodynamic often aren't; many "sleek"-looking race cars actually have high drag coefficients (on purpose - to add downforce). General principles for achieving a low drag coefficient include:
* A relatively blunt, steadily-curved front end. The popular American car style of a massive front end is right out - you want the length on the other end.
* Steady transition to a highly raked windshield (within the limits of strength, weight and visibility.. and construction, as multi-axis bending windscreens are more expensive than single-axis)
* A slowly tapered rear end, down to as small of an area as you can. Tapering can be on two axes (teardrop) or either axis alone (airfoil-shaped)
* If you can't achieve a slow taper at any point due to internal space constraints, truncate it sharpy, ideally with vortex generators; otherwise you'll get flow separation and drag a low pressure wake, which is Very Bad(TM).
* Adjust the vehicle angle to have zero net up or downforce.
* Reduce or eliminate the air intakes on the
Agree wholeheartedly... I love the amazing, "Gee, just 24 hours after the coup I happen to find a list in this drawer of nearly 3000 judges that must be dismissed..." coincidence;)
I've long said that Erdogan is Turkey's Putin, and he shows it ever more with every day. Thankfully he's not in a position to start "annexing" his neighbors...
Indeed, UVA is quite dangerous to human eyes - even though there are other wavelengths that are more dangerous. Metal halide lights for example kick out a great deal of UVA. To prevent eye damage they have to have a filter to block it. In cases where the filter has been damaged it can lead eye damage and even temporary blindness.
I think perhaps the person is confusing the fact that UVA doesn't damage DNA (except indirectly) with it not being damaging to the eye.
It seems that that absurdity in pcworld is the author's poor interpretation of this:
If materials were developed that operate in the infrared part of the spectrum, which would be invisible to people, and were even faster than the blue/green light system, the new approach could theoretically allow free-space optical data rates of more than 10 Gbps, Tiecke said.
And using yet-to-be developed components that work at wavelengths invisible to the human eye, the speed could be increased even more. If invisible to humans, the power could also be increased without danger of harming someone, further increasing speed and distance.
Yes, because as everybody knows, UV does no damage to the human eye...
Although, on the other side of the equation it's not as bad as it could be for several reasons:
1) The first stage does most of the "up", the second stage is almost entirely about the "across" portion. The first stage also does part of the "across", but its main purpose is to get the second stage out of the atmosphere to where it can operate efficiently.
2) The second stage comes back vastly ligher than it left.
3) Aero drag helps get rid of part of the forward velocity.
That said, it's still very difficult to get back, because getting to orbit is so demanding to begin with. You can't just reserve a quarter of your fuel for the return and still plan to get a useful payload to orbit. You have to return running on the dregs of the tanks.
Because the land landings mean turning around and reversing your momentum to get back to where you started.
Remember, going to orbit isn't so much about going up as it is about going across really, really fast. "Going up" is just to get high enough that you don't suffer from aero drag, it's a significant minority of the total energy requirements.
No, , it is not. The link you gave [janis.com] showed only a graph, no caption. The thickness may have been cited somewhere, but not anywhere on the page you linked.
Please learn the difference between a webpage and an image. I linked you to an image. You posted concerns about the thickness. I told you the thickness from the page. Not image.
In case for some bizarre reason you doubt the thickness, here you go, figure 9.
No. It is, however, accurate.
Then defend your claim. In the process of insisting that manufacturers and books and everyone else is lying about the subject, point out how either (1) plants simply loosely wrapped in plastic or plastic with holes in it won't rapidly equalize to the ambient temperature, or (2) why convection would still be relevant even if they're already at the ambient temperature.
The thickness was cited on the page, 2mm thickness. And "look, you're wrong" as a response to a rebuttal is the second least convincing answer possible, right after "LA LA LA I can't hear you!".
More pictures of keeping plants warm by suppressing convection
Things that are open and porous are blocking convection? And again, to reiterate: no matter what is over it, it will be the same temperature as the outside air, because the rate of heat loss through the plastic very quickly overwhelms the thermal inertia of the small amount of water and organic matter that makes up the plant. Something you keep refusing to address. If something is the same temperature as the outside air, what on earth is blocking convection supposed to do?
You do know that polymers are mostly transparent in the thermal infrared, right?
Unmodified cheapo thin polyethylene film usually blocks about 30% of thermal IR (rough ballpark of 10um), which is much better than "none". Unmodified polypropylene film blocks almost all thermal IR around that range. PVC as well, which is one of the main reasons that it's more popular for greenhouses in Japan than PE even though it costs more (as the linked book mentioned). Products specifically designed as anti-frost row covers and protectors often contain added IR absorbers.
Yes, polytunnels are often vented. Do you know why? Because if you don't vent them, they get too hot.
You clearly didn't even click on the link - it wasn't a poly tunnel. It was a floating row cover. And you completely ignore the fact that you're arguing that something that has is full of holes serves to block convection.
Exactly, businesses will have to pay what the market actually bears, not what the government mandates that they pay.
For a "neutral" conversion to UBI, you tack on extra taxes onto the service industries and the like that mainly suffer under minimum wage, roughly approximating the costs that they bear in paying minimum wages over what an unbiased market would bear. These taxes in turn pay for part of the UBI cost. Later tax reform bills can shuffle taxes around as desired, of course.
On top of the "on average" financially-neutral conversion, all businesses save on overhead as mandated worker benefits roll into UBI.
Are we spending 3 trillion a year on these social programs?
Are people getting 3 trillion a year in benefits?
Obviously if you compare a higher net benefit level then you're going to have to have a higher income to pay for it. Stop the presses here. Nobody says you have to compare a higher net benefit level when talking UBI.
And while we're at it, can we stop pretending that all forms of basic income that we call by different names in our current systems are paid for by the government? What exactly is minimum wage if not for UBI on poor workers that we mandate that companies pay? Yeah, you won't see that figure on any government balance sheet, but it's a very real cost to the economy nonetheless.
I don't know anything about Robert Greenstein. But I do know a straw man when I see one. So when someone writes:
There are over 300 million Americans today. Suppose UBI provided everyone with $10,000 a year. That would cost more than $3 trillion a year...
... and makes that a backbone of their argument, then it better represent what proponents of UBI actually want. Since when is UBI about "Let's change nothing else about the system except for adding a $10k per person per year payout on top of everything else"? UBI is supposed to replace all of our current, haphazard, inefficient patchwork welfare systems:
* Government pensions / social security
* Extra medical support
* Welfare
* Food support
* Assisted housing
* Unemployment insurance
* Minimum wages (just basic income in a disguise, hoisted on the back of companies)
And on and on. And all of the overhead associated with all of those programs - both overhead on governments and corporations. We, as societies in many different countries, have already more or less come to the conclusion that we don't want people starving in the streets. So we have these patchworks of programs designed to roughly approximate the effects of UBI in this regard. And they're a waste and have gaps for people to fall through. Let's call a spade a spade, accept what we're already trying to accomplish and call it for what it is, and then replace it with a much simpler version.
After that point we can argue over how much money defines a basic standard of life that we don't want anyone to have to live below, wherein conservatives will argue for a lower figure and liberals for a higher one.
I said that greenhouses work by suppressing convection, and you reply by showing an image of using plastic to suppress convection. Thanks.
And you ignore my comment about how the thermal inertia of the tree is irrelevant in comparison to the heat loss rate. Do I need to show you the mass? The tree will in minutes equalize to the temperature of the outside air. The only difference the plastic provides is blocking radiative exchange.
If you'd rather, maybe you'd prefer, say, this picture ? Or this, or this, or this? How well do you think this blocks convection? It has holes in it. Floating row covers are designed specifically to extend growing seasons by blocking radiant exchange without hindering plant respiration. What do you want, books covering the subject?
I'll reiterate: most frost occurs at temperatures above freezing
It's not about the salmon, they don't get up to the highlands. It's about general environmental production. We have what was up until Kárahnjúkar the largest untouched wilderness in Europe. It's still a national treasure.
Basically, by your principle of how greenhouses work, this common citrus practice would be meaningless. Which it demonstrably isn't.
To head you off.... no, the thermal inertia of the water within the tree is completely insignificant compared to the rate of conductive heat loss through the plastic. It's purely about IR, to prevent frost burn on nights where the air temperatures are above freezing but the sky temperature is low and radiative cooling leads to surface frosts.
A physical greenhouse-- the kind made with glass-- works by the principle of the glass admitting light, but suppressing loss of heat via convection.
I'm currently building my second greenhouse (about 200 m^2), how many have you built? Greenhouses work by both principles. That's why people sell panels with extra IR-absorbing coatings - it saves you money on heating. Absorption and re-radiation of IR is absolutely critical at night, particularly on clear nights, where the effective sky temperature is so low.
You can string up a sheet of plastic over your plants without sealing the air in at all, and the plants beneath it will still be warmer at night than plants nearby without the plastic over them. Indeed, most frosts are radiation frosts, where the air is above freezing but surfaces cool to below freezing due to ratiation.
"Wrong type of mountain"? What sort of claim is that? What, are they home to magical water-trolls that will drink all of the water that comes in contact with them?
lol they don't have high enough areas to store water for hydro, never mind the water.
Lol back to you. There are ~800m mountains near Port Augusta (conveniently shaped into long thin Vs), right near a limitless supply of water (Spencer Gulf and Lake Torrens
Yeah, but people here are only lukewarm on the idea of the power line, as it means making a bunch more power generation here, and in most cases they're going to want to do that with dams. And people are already mad enough about the progressive damming up of our highlands. Yes, we technically have vast amounts more hydroelectric power that remains untapped. But most people would much prefer to leave it that way.
Geothermal, while a lot of people don't want more of that either, at least gets more support than dams. But the power companies prefer dams because it saves a króna or two per kWh. There's also the issue of transmission lines, whatever power type is produced. Most people wouldn't be opposed to underground lines, but the power companies always try to push through above-ground lines. Part of the thing about our nature here is that there's no trees to block your view, and that out in the highlands there's no signs of human development for vast distances; above-ground lines through the highlands are like a scar on the landscape.
We really need to tap into wind here, in the capital region (say, between Keflavík and Reykjavík). Power has been so cheap that nobody's bothered - we only got our first industrial-scale wind turbines just a couple years ago, and only on a test basis. But we're one of the windiest places on Earth. We also have big tides and waves, and have nothing to harvest from them either, nor anything to harvest from the vast amoounts of lower-temperature geothermal that we produce (we just dilute it with cold water to bring it down to distribution temperature). I think if managed properly we could export power just fine to the UK, without ruining our environment, and still sell it at a price that would be competitive. But I, like most people here, neither trust our government nor power companies to choose the least-destructive path to generate said power.
Slashdot Mirror
1) EVs do have kinetic energy recovery; it's called regenerative braking.
2) Gasoline vehicles that have them are known as hybrids.
3) All systems, including KERS, have purchase price, mass, and maintenance penalties, which is why they're not universally adopted.
4) The particular approach of flywheel-based kinetic energy storage has good W/kg but poor Wh/kg, W/l, and Wh/l. It has catastrophic failure mechanisms, limited storage time, and tends to offbalance vehicles. Flywheels have been becoming less popular with time in vehicles, not more - being overtaken by electric systems, which are increasingly compact and lightweight vs. their power output.
5) All kinetic energy recovery mechanisms suffer from losses. I haven't looked into the round-trip efficiency of flywheels, but round-trip efficiencies of conventional hybrids are often 40% or less, while for li-ion EVs they're often more like 60-70%. The problem is that you're storing and withdrawing power quickly, which reduces efficiencies, and all losses hit you twice - motor, drivetrain, controller, wiring and battery. Hybrids are hit worse than EVs because the packs are smaller (meaning higher-C charge/discharges) and the packs are generally NiMH, which is less efficient than li-ion.
6) Braking losses are only dominant in city driving. In combined driving they're significantly reduced and in highway driving they're almost an irrelevant fraction of the total. Aero losses dominate at high speeds while rolling losses dominate at low speeds.
7) The biggest energy benefit of a hybrid isn't recapturing braking losses, as most people assume. It's that it lets you operate with a much less powerful engine, without the vehicle feeling underpowered, thus helping the engine stay in its optimum power band (IC engines operate most efficiently when fairly near their maximum torque capability). Hybrid vehicle efficiencies don't drop that much when the hybrid system is broken (losing regenerative braking and stop/start), but they lose responsiveness.
8) Rolling losses, for the most part, come down to your tires; there's a balance between 1) grip, 2) rolling resistance, and 3) price. Choose two. (I could throw in other factors like noise, comfort, wearing, etc, but let's keep it simple)
9) Reducing aero losses comes down to reducing your cross sectional area and your drag coefficient. A reduced cross sectional area means that you can have a long car but not a wide or tall one. Reducing the drag coefficient means breaking with styling choices that people prefer in cars in favour of making it look more like an airplane (see the Aptera as an example of taking it to extremes).
Note that things that look aerodynamic often aren't; many "sleek"-looking race cars actually have high drag coefficients (on purpose - to add downforce). General principles for achieving a low drag coefficient include:
* A relatively blunt, steadily-curved front end. The popular American car style of a massive front end is right out - you want the length on the other end.
* Steady transition to a highly raked windshield (within the limits of strength, weight and visibility.. and construction, as multi-axis bending windscreens are more expensive than single-axis)
* A slowly tapered rear end, down to as small of an area as you can. Tapering can be on two axes (teardrop) or either axis alone (airfoil-shaped)
* If you can't achieve a slow taper at any point due to internal space constraints, truncate it sharpy, ideally with vortex generators; otherwise you'll get flow separation and drag a low pressure wake, which is Very Bad(TM).
* Adjust the vehicle angle to have zero net up or downforce.
* Reduce or eliminate the air intakes on the
Agree wholeheartedly... I love the amazing, "Gee, just 24 hours after the coup I happen to find a list in this drawer of nearly 3000 judges that must be dismissed..." coincidence ;)
I've long said that Erdogan is Turkey's Putin, and he shows it ever more with every day. Thankfully he's not in a position to start "annexing" his neighbors...
Indeed, UVA is quite dangerous to human eyes - even though there are other wavelengths that are more dangerous. Metal halide lights for example kick out a great deal of UVA. To prevent eye damage they have to have a filter to block it. In cases where the filter has been damaged it can lead eye damage and even temporary blindness.
I think perhaps the person is confusing the fact that UVA doesn't damage DNA (except indirectly) with it not being damaging to the eye.
It seems that that absurdity in pcworld is the author's poor interpretation of this:
Yes, because as everybody knows, UV does no damage to the human eye...
Slashdot: News for Americans. Stuff that matters to Americans.
Not everyone operates on a medical system like the weird one in the US....
Although, on the other side of the equation it's not as bad as it could be for several reasons:
1) The first stage does most of the "up", the second stage is almost entirely about the "across" portion. The first stage also does part of the "across", but its main purpose is to get the second stage out of the atmosphere to where it can operate efficiently.
2) The second stage comes back vastly ligher than it left.
3) Aero drag helps get rid of part of the forward velocity.
That said, it's still very difficult to get back, because getting to orbit is so demanding to begin with. You can't just reserve a quarter of your fuel for the return and still plan to get a useful payload to orbit. You have to return running on the dregs of the tanks.
Because the land landings mean turning around and reversing your momentum to get back to where you started.
Remember, going to orbit isn't so much about going up as it is about going across really, really fast. "Going up" is just to get high enough that you don't suffer from aero drag, it's a significant minority of the total energy requirements.
Please learn the difference between a webpage and an image. I linked you to an image. You posted concerns about the thickness. I told you the thickness from the page. Not image.
In case for some bizarre reason you doubt the thickness, here you go, figure 9.
Then defend your claim. In the process of insisting that manufacturers and books and everyone else is lying about the subject, point out how either (1) plants simply loosely wrapped in plastic or plastic with holes in it won't rapidly equalize to the ambient temperature, or (2) why convection would still be relevant even if they're already at the ambient temperature.
The thickness was cited on the page, 2mm thickness. And "look, you're wrong" as a response to a rebuttal is the second least convincing answer possible, right after "LA LA LA I can't hear you!".
Things that are open and porous are blocking convection? And again, to reiterate: no matter what is over it, it will be the same temperature as the outside air, because the rate of heat loss through the plastic very quickly overwhelms the thermal inertia of the small amount of water and organic matter that makes up the plant. Something you keep refusing to address. If something is the same temperature as the outside air, what on earth is blocking convection supposed to do?
Unmodified cheapo thin polyethylene film usually blocks about 30% of thermal IR (rough ballpark of 10um), which is much better than "none". Unmodified polypropylene film blocks almost all thermal IR around that range. PVC as well, which is one of the main reasons that it's more popular for greenhouses in Japan than PE even though it costs more (as the linked book mentioned). Products specifically designed as anti-frost row covers and protectors often contain added IR absorbers.
You clearly didn't even click on the link - it wasn't a poly tunnel. It was a floating row cover. And you completely ignore the fact that you're arguing that something that has is full of holes serves to block convection.
Exactly, businesses will have to pay what the market actually bears, not what the government mandates that they pay.
For a "neutral" conversion to UBI, you tack on extra taxes onto the service industries and the like that mainly suffer under minimum wage, roughly approximating the costs that they bear in paying minimum wages over what an unbiased market would bear. These taxes in turn pay for part of the UBI cost. Later tax reform bills can shuffle taxes around as desired, of course.
On top of the "on average" financially-neutral conversion, all businesses save on overhead as mandated worker benefits roll into UBI.
Are people getting 3 trillion a year in benefits?
Obviously if you compare a higher net benefit level then you're going to have to have a higher income to pay for it. Stop the presses here. Nobody says you have to compare a higher net benefit level when talking UBI.
And while we're at it, can we stop pretending that all forms of basic income that we call by different names in our current systems are paid for by the government? What exactly is minimum wage if not for UBI on poor workers that we mandate that companies pay? Yeah, you won't see that figure on any government balance sheet, but it's a very real cost to the economy nonetheless.
I don't know anything about Robert Greenstein. But I do know a straw man when I see one. So when someone writes:
* Government pensions / social security
* Extra medical support
* Welfare
* Food support
* Assisted housing
* Unemployment insurance
* Minimum wages (just basic income in a disguise, hoisted on the back of companies)
And on and on. And all of the overhead associated with all of those programs - both overhead on governments and corporations. We, as societies in many different countries, have already more or less come to the conclusion that we don't want people starving in the streets. So we have these patchworks of programs designed to roughly approximate the effects of UBI in this regard. And they're a waste and have gaps for people to fall through. Let's call a spade a spade, accept what we're already trying to accomplish and call it for what it is, and then replace it with a much simpler version.
After that point we can argue over how much money defines a basic standard of life that we don't want anyone to have to live below, wherein conservatives will argue for a lower figure and liberals for a higher one.
** that should have read "maths", not "mass" :P
And you ignore my comment about how the thermal inertia of the tree is irrelevant in comparison to the heat loss rate. Do I need to show you the mass? The tree will in minutes equalize to the temperature of the outside air. The only difference the plastic provides is blocking radiative exchange.
If you'd rather, maybe you'd prefer, say, this picture ? Or this, or this, or this? How well do you think this blocks convection? It has holes in it. Floating row covers are designed specifically to extend growing seasons by blocking radiant exchange without hindering plant respiration. What do you want, books covering the subject?
I'll reiterate: most frost occurs at temperatures above freezing
It's not about the salmon, they don't get up to the highlands. It's about general environmental production. We have what was up until Kárahnjúkar the largest untouched wilderness in Europe. It's still a national treasure.
Basically, by your principle of how greenhouses work, this common citrus practice would be meaningless. Which it demonstrably isn't.
To head you off.... no, the thermal inertia of the water within the tree is completely insignificant compared to the rate of conductive heat loss through the plastic. It's purely about IR, to prevent frost burn on nights where the air temperatures are above freezing but the sky temperature is low and radiative cooling leads to surface frosts.
I'm currently building my second greenhouse (about 200 m^2), how many have you built? Greenhouses work by both principles. That's why people sell panels with extra IR-absorbing coatings - it saves you money on heating. Absorption and re-radiation of IR is absolutely critical at night, particularly on clear nights, where the effective sky temperature is so low.
You can string up a sheet of plastic over your plants without sealing the air in at all, and the plants beneath it will still be warmer at night than plants nearby without the plastic over them. Indeed, most frosts are radiation frosts, where the air is above freezing but surfaces cool to below freezing due to ratiation.
"Wrong type of mountain"? What sort of claim is that? What, are they home to magical water-trolls that will drink all of the water that comes in contact with them?
And you better inform the good people of Yokinawa that their seawater pumped hydro station is impossible.
I'm sorry, continue your rant about "eco-idiots".
Apparently someone isn't aware that saltwater is also water.
Lol back to you. There are ~800m mountains near Port Augusta (conveniently shaped into long thin Vs), right near a limitless supply of water (Spencer Gulf and Lake Torrens
And hydro isn't the only way to store power.
Bingo.
Visible light in. IR blocked on the way out.
Are you of the belief that CO2 doesn't do this, despite the fact that it very easily demonstrably does?
Yeah, but people here are only lukewarm on the idea of the power line, as it means making a bunch more power generation here, and in most cases they're going to want to do that with dams. And people are already mad enough about the progressive damming up of our highlands. Yes, we technically have vast amounts more hydroelectric power that remains untapped. But most people would much prefer to leave it that way.
Geothermal, while a lot of people don't want more of that either, at least gets more support than dams. But the power companies prefer dams because it saves a króna or two per kWh. There's also the issue of transmission lines, whatever power type is produced. Most people wouldn't be opposed to underground lines, but the power companies always try to push through above-ground lines. Part of the thing about our nature here is that there's no trees to block your view, and that out in the highlands there's no signs of human development for vast distances; above-ground lines through the highlands are like a scar on the landscape.
We really need to tap into wind here, in the capital region (say, between Keflavík and Reykjavík). Power has been so cheap that nobody's bothered - we only got our first industrial-scale wind turbines just a couple years ago, and only on a test basis. But we're one of the windiest places on Earth. We also have big tides and waves, and have nothing to harvest from them either, nor anything to harvest from the vast amoounts of lower-temperature geothermal that we produce (we just dilute it with cold water to bring it down to distribution temperature). I think if managed properly we could export power just fine to the UK, without ruining our environment, and still sell it at a price that would be competitive. But I, like most people here, neither trust our government nor power companies to choose the least-destructive path to generate said power.
I'm curious, do you have a followup on this topic, a link on the subject?