367 miles / c = 0.00197 seconds = 1.97ms 379 miles / c = 0.002035 seconds = 2.035ms 391 miles / c = 0.002099 seconds = 2.099ms
That's one way though, between station and sat.
Because these are LEO sats though, they're moving fast and you're talking to different birds all the time. Regionally, this is should very fast, we're talking 5-10ms RTT.
Longer routes will likely be passed up to the 379-391mi sats and backhauled to the lower sats at the destination. How much latency that will induce is a good question, what's the path length, switching cost, and hop count? This will be one hell of an interesting networking problem to optimize. 3236 nodes moving at, what 56000-58000mph.
But the status quo of east to west latency terrestrially is somewhere in the neighborhood of 66-85ms. If they can beat that, this thing is going to win the Internet. It also enables the legions of robots and IOT devices that are coming online.
It's an open question if human beings can thrive on a planet like Mars with 38% of the gravity of Earth.
Venus has a bit over 90% of Earth's gravity.
Floating habitats in the Venus atmosphere can be situated at 1 Earth atmosphere of pressure. It's doubtful Mars will be able to have a 1atm atmosphere ever due to its low gravity.
And unless Venus is isothermal, it's theoretically possible to create a heat engine to cool some portion of it to any desired temperature.
I've heard of Exide but hadn't really been aware of some of those features, or hadn't yet run into the problems that would make those features interesting enough to remember. All I saw was a higher price tag but I can see the value now.:)
Yeah, I seem to be getting tripped up on the difference between gravimetric energy density and power density.
The abstract says an "energy density up to 20 Wh/kg, power density up to 20 kW/kg".
Do you have any suggestions on relating that power density quantity to other battery types?
I get 2-3kWh out of my 90lb 155Ah 12VDC AGM/SLA batteries sipping at a 60hr rate. But that battery is about 41kg, so what do they mean by 20 kW/kg? Shouldn't I get 41kg/battery * 20kW/kg = 1800kW/battery? Reducing that to 1.8MW doesn't seem realistic. What's the right way to think about this?
Hrm, yes. In the abstract, it says "energy density up to 20 Wh/kg, power density up to 20 kW/kg". (http://pubs.acs.org/doi/abs/10.1021/acsenergylett.6b00295)
I suppose I'm getting tripped up on the difference between "energy density" and "power density".
I use VmaxTanks SLR155 AGM/SLA 155Ah 12VDC batteries (https://www.vmaxtanks.com/SLR155-AGM-Solar-Battery-_p_66.html). These weigh 90lbs (40.9kg) and can store 2.1kWh of energy. (2.1kWh)/(40.9kg) = 51.3Wh/kg, which is about what you said.
So, you're right. 20Wh/kg FnCu < 51.3Wh/kg PbS. The difference in units between "energy density" and "power density" appears to be time.
How would you relate the gravimetric power density of 20kW/kg of the proposed battery cells to that VmaxTanks battery?
Or, what is the distinction between gravimetric energy density and power density?
I'm curious how these cells perform in cold weather conditions.
I use 12VDC lead-acid SLA batteries on a mountain top for a wireless repeater but those are like 0.05kw/kg and $280-300/ea. Getting heavy batteries up the mountain can be extremely challenging (think snowshoes uphill in 5-6ft of snow carrying a 100lb replacement battery). I'm also at the 49th parallel so winter peak solar is like 3 hours/day and you need a large buffer in case it is effectively zero hours of solar for days in a row while keeping your radios up 24/7.
Something like this would be great for me since it's something like 1500x more energy dense by weight... That is, if it can survive cold weather, or with a heater it is still an effective alternative.
There were the genderless J'naii in The Outcast (ST:TNG 05x17) who Riker pressured into sexual relations.
Captain Janeway in Voyager was widely believed to be a lesbian, despite her marriage.
Tasha Yar on TNG always talked about the rape gangs but held a position as chief security officer and was widely believed to be a lesbian or at least bi-sexual (and willing to get it on with fully-functional androids).
In ST:TNG 01x14 "Angel One", the Enterprise sends an away team to a female dominated planet. They take great pleasure in feminizing and dominating Riker and all of the men in that society are made to be feminine (by Earth standards).
This fits nicely with Blue Origin. It's one thing to get to space but you're going to need habitats and biospheres and other large scale structures once you get there. Bezos has talked about moving industrial activities off Earth along with mining asteroids.
I suspect they will learn a thing or two about building these structures on Earth that will be applicable to the longer-term goals of the space-faring Bezos.
http://www.ubnt.com/ + RadioMobile + Renogy solar panels and charge controller + 155Ah VMaxTanks SLA/AGM battery (or two)
I was in your situation and did a 5 mile PTP backhaul with PowerBridge M5 400mm dishes and 900MHz for PTMP. I was actually worse off with only satellite internet availability that had terrible latency (700-1500ms+) and strict bandwidth caps (38GB/month, throttled at 85%) and no bandwidth accounting reporting. I actually had to gang together two WildBlue connections to get that and was paying just over $200/month.
Fixed terrestrial wireless is amazing and it will work for you if you put in the effort. Expect to spend $1500-2000 to get the radios, solar panels, batteries, STP cables, battery boxes, masts, etc.. I enjoy 50Mbps now.
Isn't the issue here the extremely long ROI for rural improvements? Is AT&T obligated to build out these areas that won't be profit centers for them? I'm guessing the state throwing money at them changes that equation.
Is AT&T the only provider who can do it? Did they even bid this out? I might have to RTFA here soon.:)
Seriously though, it appears to be an abstraction layer on top of the various public cloud APIs. So you could conceivably define an instance in OneOps and deploy that in Azure, Google Cloud, AWS, Helion, etc depending on your needs. I'm not sure how practical that will be in the real world though.
Slashdot Mirror
Best case latency:
367 miles / c = 0.00197 seconds = 1.97ms
379 miles / c = 0.002035 seconds = 2.035ms
391 miles / c = 0.002099 seconds = 2.099ms
That's one way though, between station and sat.
Because these are LEO sats though, they're moving fast and you're talking to different birds all the time. Regionally, this is should very fast, we're talking 5-10ms RTT.
Longer routes will likely be passed up to the 379-391mi sats and backhauled to the lower sats at the destination. How much latency that will induce is a good question, what's the path length, switching cost, and hop count? This will be one hell of an interesting networking problem to optimize. 3236 nodes moving at, what 56000-58000mph.
But the status quo of east to west latency terrestrially is somewhere in the neighborhood of 66-85ms. If they can beat that, this thing is going to win the Internet. It also enables the legions of robots and IOT devices that are coming online.
It's a brave new world.
This explains the insanity of Democrats, yes? They're all infected with this?
It's an open question if human beings can thrive on a planet like Mars with 38% of the gravity of Earth.
Venus has a bit over 90% of Earth's gravity.
Floating habitats in the Venus atmosphere can be situated at 1 Earth atmosphere of pressure. It's doubtful Mars will be able to have a 1atm atmosphere ever due to its low gravity.
And unless Venus is isothermal, it's theoretically possible to create a heat engine to cool some portion of it to any desired temperature.
Mars is interesting, no doubt, but it's not where we should be going.
Venus is Earth's twin.
Perl seems to be dying. Everybody loves bash again now, and python, go, node.js, etc..
A big miss by the Perl community was not getting AWS Lambda support or an AWS module for a long time. Boto ate Perl's lunch.
Sure, but what kind of differences are there between battery chemistries at say 32F or 0F at different states of charge?
I generally don't consider LiPos for cold-weather deployment, for instance. Though, maybe that's wrong to do.
That is actually pretty interesting, thanks.
I've heard of Exide but hadn't really been aware of some of those features, or hadn't yet run into the problems that would make those features interesting enough to remember. All I saw was a higher price tag but I can see the value now. :)
Yeah, I seem to be getting tripped up on the difference between gravimetric energy density and power density.
The abstract says an "energy density up to 20 Wh/kg, power density up to 20 kW/kg".
Do you have any suggestions on relating that power density quantity to other battery types?
I get 2-3kWh out of my 90lb 155Ah 12VDC AGM/SLA batteries sipping at a 60hr rate. But that battery is about 41kg, so what do they mean by 20 kW/kg?
Shouldn't I get 41kg/battery * 20kW/kg = 1800kW/battery? Reducing that to 1.8MW doesn't seem realistic. What's the right way to think about this?
Hrm, yes. In the abstract, it says "energy density up to 20 Wh/kg, power density up to 20 kW/kg". (http://pubs.acs.org/doi/abs/10.1021/acsenergylett.6b00295)
I suppose I'm getting tripped up on the difference between "energy density" and "power density".
I use VmaxTanks SLR155 AGM/SLA 155Ah 12VDC batteries (https://www.vmaxtanks.com/SLR155-AGM-Solar-Battery-_p_66.html).
These weigh 90lbs (40.9kg) and can store 2.1kWh of energy. (2.1kWh)/(40.9kg) = 51.3Wh/kg, which is about what you said.
So, you're right. 20Wh/kg FnCu < 51.3Wh/kg PbS. The difference in units between "energy density" and "power density" appears to be time.
How would you relate the gravimetric power density of 20kW/kg of the proposed battery cells to that VmaxTanks battery?
Or, what is the distinction between gravimetric energy density and power density?
I'm curious how these cells perform in cold weather conditions.
I use 12VDC lead-acid SLA batteries on a mountain top for a wireless repeater but those are like 0.05kw/kg and $280-300/ea. Getting heavy batteries up the mountain can be extremely challenging (think snowshoes uphill in 5-6ft of snow carrying a 100lb replacement battery). I'm also at the 49th parallel so winter peak solar is like 3 hours/day and you need a large buffer in case it is effectively zero hours of solar for days in a row while keeping your radios up 24/7.
Something like this would be great for me since it's something like 1500x more energy dense by weight... That is, if it can survive cold weather, or with a heater it is still an effective alternative.
Good argument, you're right.
I bet Kumar is laughing his ass off that Harold has to suck a dick.
There were the genderless J'naii in The Outcast (ST:TNG 05x17) who Riker pressured into sexual relations.
Captain Janeway in Voyager was widely believed to be a lesbian, despite her marriage.
Tasha Yar on TNG always talked about the rape gangs but held a position as chief security officer and was widely believed to be a lesbian or at least bi-sexual (and willing to get it on with fully-functional androids).
In ST:TNG 01x14 "Angel One", the Enterprise sends an away team to a female dominated planet. They take great pleasure in feminizing and dominating Riker and all of the men in that society are made to be feminine (by Earth standards).
This fits nicely with Blue Origin. It's one thing to get to space but you're going to need habitats and biospheres and other large scale structures once you get there. Bezos has talked about moving industrial activities off Earth along with mining asteroids.
I suspect they will learn a thing or two about building these structures on Earth that will be applicable to the longer-term goals of the space-faring Bezos.
Somebody has been watching too much Burlesque...
Exactly.
http://www.ubnt.com/ + RadioMobile + Renogy solar panels and charge controller + 155Ah VMaxTanks SLA/AGM battery (or two)
I was in your situation and did a 5 mile PTP backhaul with PowerBridge M5 400mm dishes and 900MHz for PTMP. I was actually worse off with only satellite internet availability that had terrible latency (700-1500ms+) and strict bandwidth caps (38GB/month, throttled at 85%) and no bandwidth accounting reporting. I actually had to gang together two WildBlue connections to get that and was paying just over $200/month.
Fixed terrestrial wireless is amazing and it will work for you if you put in the effort. Expect to spend $1500-2000 to get the radios, solar panels, batteries, STP cables, battery boxes, masts, etc.. I enjoy 50Mbps now.
Isn't the issue here the extremely long ROI for rural improvements? Is AT&T obligated to build out these areas that won't be profit centers for them? I'm guessing the state throwing money at them changes that equation.
Is AT&T the only provider who can do it? Did they even bid this out? I might have to RTFA here soon. :)
Your math is right based on the summary but the article says:
"With a stable system and a turnover frequency of 360,000 moles of hydrogen per hour per mole of catalyst, the potential here is real."
http://www.n5dux.com/ham/files...
Why will living forever never be possible?
Seriously though, it appears to be an abstraction layer on top of the various public cloud APIs. So you could conceivably define an instance in OneOps and deploy that in Azure, Google Cloud, AWS, Helion, etc depending on your needs. I'm not sure how practical that will be in the real world though.
Well first, build a datacenter...
Obligatory: http://www.terrybisson.com/pag...
Wireless communications may become more interesting in the future thanks to this pioneering research: http://www.nature.com/articles...
See also the theoretical paper: http://journals.aps.org/prl/ab... (http://arxiv.org/pdf/math-ph/0703059.pdf)
It's not clear what the implications are for signal loss or if this is more of an illusion akin to beam steering.