Smart RFID's harvest power from the radio signal, dumb RFID's just modulate the existing feild. Either way the distances involved are tiny - several centimeters, not meters.
If you RTFA, they didn't just use a regular WiFi access point. They modified the AP so that in addition to one channel carrying data, there were another two radios on non-overlapping channels transmitting noise. Great for powering your thermostat, but horrible for your neighbors.
The spectrum is already crowded with most homes transmitting one channel - imagine if everyone stated transmitting three. The noise floor would go up drastically and WiFi would be rendered near inoperable.
Linux "just running iptables" is perfectly secure.
In general you cant just hack firewall software directly. What you do is find a protocol that is allowed through the firewall and then exploit some vulnerability on that protocol. Examples would be default passwords or SQL injection in a web management interface, buffer overflows in a DNS response, weak encryption in a VPN etc.
You can get away with that using smaller "park flier" planes as they are less able to cause damage, but there is risk involved. If you hurt someone you will be personally liable and wont be insured.
By comparison any official club will register with international model aircraft organisations. They train their members in the rules of safe flying, and provide insurance if something goes wrong. A few years ago my local club was $180 per year, not cheap but not too bad considering they have to maintain grounds as well.
Crappy single phase AC motors have sucky low end torque because they dont have a second phase to produce and offset magnetic feild. They have to fake this second phase using capacitors, split coils, shaded poles etc, and those virtual second phases are quite weak.
Three phase AC motors have no such issue. They can produce high torque at low speeds, and can have quite consistent torque over a large range of speeds. This is perfect for a car as it gives you smooth acceleration.
A relatively cheap option for a controller is a 3 phase VFD (variable frequency drive) coupled to a three phase induction motor. Internally the VFD rectifies three phase mains to high voltage DC, so you just string up the batteries in series and it accepts the input power just fine.
Getting the regenerative braking to work is a bit harder though.
The static energy / current requirements seem plausible, but that may only be a small part of the picture. Any conductor moving in that feild - vehicles, people, ions from solar wind - will then generate an EMF and dissipate energy in the process.
Since it's storing local wireless keys on the device, I can only assume it has a wireless network interface and is intended to be connected for remote monitoring/administration.
Im not convinced. It's good that you've rated that pack at 50% depth of discharge (48V x 400Ah = 19kWh nominal, approx 10kWh @ 50% DoD), but typically lead acid packs will only get 1000 cycles at that rate. You typically have to go to a 30% DoD to get 10 years / 3000 cycles.
Lithium can do greater depth of discharge for far more cycles. The overall lifetime costs of lithium per kWh were already starting to beat lead acid, and the new Tesla pack is even better.
Stuff minutes. Make it hours or even a whole day. Anything less is speculation.
The stock market should be promoting real investment - i.e you do some research and have an educated opinion that a company will do well. You buy shares, wait for the returns and then sell when things have stabilised. That process takes time - months or years even.
The commonly used ABS plastic used in FDM machines is very durable, but the orientation of the print matters. You do have to design the prints so that the weak join between layers doesnt experience stress.
I do agree with the looking horrible part, but you can do funky things like acetone dips or acetone vapor to smooth and gloss them.
Not only that, the politicians start chasing the lowest common demoninator in order to get the votes of the ignorant masses. Stupid things like "stop the boats" probably wouldnt happen if we had voluntary voting.
That's got nothing to do with the LED and everything to do with the driver electronics. Unfortunately the packaging they are in limits the size of the driver circuitry significantly so i guess it's going to be more common with these filament bulbs.
That's a bit harsh and fails to see the significance.
From the article: "There are no analog circuits, no filters, no chokes, none of the traditional circuitry and components expected in a radio transmitter."
If it can be built as an peripheral chip, it can also be built onto the same silicon as a microprocessor.
Windows 3.11 machines were capable of SMB file sharing over a network. You should be able to use an old PCMCIA ethernet card and install the Microsoft TCP stack (it wasn't installed by default), then see other computers over a workgroup.
If that sounds too hard then serial transfer over null modem should be the easiest and I'm sure I did it many times myself back in the day. I cant remember what software I used to use, googling for Windows 3.11 serial file transfer shows lots of hits though.
Singapore is shocking for people walking two abreast and not splitting up when someone else approaches. My mate has taken to walking into them too, scares the crap out of them.
There's plenty of time when "lanes" on a footpath dissapear and you have to be more dynamic in your pathfinding. People looking at their smarphone arent doing this to the point that it's rude.
So, robots start replacing jobs because they can make widget X cheaper.
As unemployment increases, less poeple will have the money required to buy widet X. The manufacturers will have to lower prices in order to get sales, and their cost reductions through robots will evaporate. Meanwhile everything just got cheaper.
At some point we'll reach equilibrium again, where the cost benefit of adding a robot will be balanced by the lack of sales due to poeple not having an income. It might be painfull for a while until we get there, but it will happen.
These low power PC's are opening up new opportunities for UPS's, namely that they all run off low voltage DC (nominally 12V) and open up the possability of a 12V UPS. It saves on the inverter required in the UPS, and increases the overall efficiency.
For a device like this with a variable input voltage you can run it directly from a 12V SLA battery, and then keep the battery topped up with a decent mains charger rated to higher power than the PC. You can generally do the same thing with access points and 12V network switches, and any 5V devices can be run from a $5 step down DC-DC converter.
The only problem I've had with this method is 3.5inch USB Hard Drives, as they usually require a well regulated 12V supply. For those I bought a fancier buck-boost DC-DC converter, they were a little pricier and harder for find than, but still quite reasonable.
In the end you may have 30W worth of devices hanging from the SLA batteries, then just buy a multistage charger rated to the next higher power - eg 30W = approx 2.5A @ 12V, so get a 3 or 4amp charger. You can expand to as many parallel as you like, all it does is slow down the recharge time.
One of the best ways to seed the oceans is with the addition of iron based minerals. Plants in the food chain need this to grow, but it's very scarce in the ocean. Historically there was a natural seeding process as iron laden dust was blown off the coastlines, but human development has reduced that source.
In Australia we get a Strata Title deed, with common shared assets managed by a strata management company.
For simple blocks subdivided into a few houses, the homeowners can form their own strata company with little to no costs. For apartments buildings they generally employ a third part to manage it, and residents will then pay monthly strata management fees.
I used to build & configure production reporting systems for industry, and the increase in complexity on the math was freaking painful when you had to take in to account daylight savings. Instead of assuming 24 hours in a day, you would always have to calculate "day end minus day start".
These methods would handle leap seconds just as well, but the cost to performance is massive for such a rare event.
Slashdot Mirror
Smart RFID's harvest power from the radio signal, dumb RFID's just modulate the existing feild. Either way the distances involved are tiny - several centimeters, not meters.
If you RTFA, they didn't just use a regular WiFi access point. They modified the AP so that in addition to one channel carrying data, there were another two radios on non-overlapping channels transmitting noise. Great for powering your thermostat, but horrible for your neighbors.
The spectrum is already crowded with most homes transmitting one channel - imagine if everyone stated transmitting three. The noise floor would go up drastically and WiFi would be rendered near inoperable.
Linux "just running iptables" is perfectly secure.
In general you cant just hack firewall software directly. What you do is find a protocol that is allowed through the firewall and then exploit some vulnerability on that protocol. Examples would be default passwords or SQL injection in a web management interface, buffer overflows in a DNS response, weak encryption in a VPN etc.
If you think requiring vaccination to attend free public school makes you a slave, you might want to rethink your priorities a little....
You can get away with that using smaller "park flier" planes as they are less able to cause damage, but there is risk involved. If you hurt someone you will be personally liable and wont be insured.
By comparison any official club will register with international model aircraft organisations. They train their members in the rules of safe flying, and provide insurance if something goes wrong. A few years ago my local club was $180 per year, not cheap but not too bad considering they have to maintain grounds as well.
Crappy single phase AC motors have sucky low end torque because they dont have a second phase to produce and offset magnetic feild. They have to fake this second phase using capacitors, split coils, shaded poles etc, and those virtual second phases are quite weak.
Three phase AC motors have no such issue. They can produce high torque at low speeds, and can have quite consistent torque over a large range of speeds. This is perfect for a car as it gives you smooth acceleration.
A relatively cheap option for a controller is a 3 phase VFD (variable frequency drive) coupled to a three phase induction motor. Internally the VFD rectifies three phase mains to high voltage DC, so you just string up the batteries in series and it accepts the input power just fine.
Getting the regenerative braking to work is a bit harder though.
The static energy / current requirements seem plausible, but that may only be a small part of the picture. Any conductor moving in that feild - vehicles, people, ions from solar wind - will then generate an EMF and dissipate energy in the process.
Since it's storing local wireless keys on the device, I can only assume it has a wireless network interface and is intended to be connected for remote monitoring/administration.
Im not convinced. It's good that you've rated that pack at 50% depth of discharge (48V x 400Ah = 19kWh nominal, approx 10kWh @ 50% DoD), but typically lead acid packs will only get 1000 cycles at that rate. You typically have to go to a 30% DoD to get 10 years / 3000 cycles.
Lithium can do greater depth of discharge for far more cycles. The overall lifetime costs of lithium per kWh were already starting to beat lead acid, and the new Tesla pack is even better.
Stuff minutes. Make it hours or even a whole day. Anything less is speculation.
The stock market should be promoting real investment - i.e you do some research and have an educated opinion that a company will do well. You buy shares, wait for the returns and then sell when things have stabilised. That process takes time - months or years even.
Yeah I thought the same thing?????
The commonly used ABS plastic used in FDM machines is very durable, but the orientation of the print matters. You do have to design the prints so that the weak join between layers doesnt experience stress.
I do agree with the looking horrible part, but you can do funky things like acetone dips or acetone vapor to smooth and gloss them.
Not only that, the politicians start chasing the lowest common demoninator in order to get the votes of the ignorant masses. Stupid things like "stop the boats" probably wouldnt happen if we had voluntary voting.
That's got nothing to do with the LED and everything to do with the driver electronics. Unfortunately the packaging they are in limits the size of the driver circuitry significantly so i guess it's going to be more common with these filament bulbs.
That's a bit harsh and fails to see the significance.
From the article: "There are no analog circuits, no filters, no chokes, none of the traditional circuitry and components expected in a radio transmitter."
If it can be built as an peripheral chip, it can also be built onto the same silicon as a microprocessor.
Windows 3.11 machines were capable of SMB file sharing over a network. You should be able to use an old PCMCIA ethernet card and install the Microsoft TCP stack (it wasn't installed by default), then see other computers over a workgroup.
If that sounds too hard then serial transfer over null modem should be the easiest and I'm sure I did it many times myself back in the day. I cant remember what software I used to use, googling for Windows 3.11 serial file transfer shows lots of hits though.
Singapore is shocking for people walking two abreast and not splitting up when someone else approaches. My mate has taken to walking into them too, scares the crap out of them.
There's plenty of time when "lanes" on a footpath dissapear and you have to be more dynamic in your pathfinding. People looking at their smarphone arent doing this to the point that it's rude.
It reads like it was generated by algorthmic patenting - http://yro.slashdot.org/story/...
So, robots start replacing jobs because they can make widget X cheaper.
As unemployment increases, less poeple will have the money required to buy widet X. The manufacturers will have to lower prices in order to get sales, and their cost reductions through robots will evaporate. Meanwhile everything just got cheaper.
At some point we'll reach equilibrium again, where the cost benefit of adding a robot will be balanced by the lack of sales due to poeple not having an income. It might be painfull for a while until we get there, but it will happen.
These low power PC's are opening up new opportunities for UPS's, namely that they all run off low voltage DC (nominally 12V) and open up the possability of a 12V UPS. It saves on the inverter required in the UPS, and increases the overall efficiency.
For a device like this with a variable input voltage you can run it directly from a 12V SLA battery, and then keep the battery topped up with a decent mains charger rated to higher power than the PC. You can generally do the same thing with access points and 12V network switches, and any 5V devices can be run from a $5 step down DC-DC converter.
The only problem I've had with this method is 3.5inch USB Hard Drives, as they usually require a well regulated 12V supply. For those I bought a fancier buck-boost DC-DC converter, they were a little pricier and harder for find than, but still quite reasonable.
In the end you may have 30W worth of devices hanging from the SLA batteries, then just buy a multistage charger rated to the next higher power - eg 30W = approx 2.5A @ 12V, so get a 3 or 4amp charger. You can expand to as many parallel as you like, all it does is slow down the recharge time.
I've seen studies on that before.
One of the best ways to seed the oceans is with the addition of iron based minerals. Plants in the food chain need this to grow, but it's very scarce in the ocean. Historically there was a natural seeding process as iron laden dust was blown off the coastlines, but human development has reduced that source.
In Australia we get a Strata Title deed, with common shared assets managed by a strata management company.
For simple blocks subdivided into a few houses, the homeowners can form their own strata company with little to no costs. For apartments buildings they generally employ a third part to manage it, and residents will then pay monthly strata management fees.
I used to build & configure production reporting systems for industry, and the increase in complexity on the math was freaking painful when you had to take in to account daylight savings. Instead of assuming 24 hours in a day, you would always have to calculate "day end minus day start".
These methods would handle leap seconds just as well, but the cost to performance is massive for such a rare event.