25 posts • joined Sunday 13th March 2011 02:00 GMT
CTBTO detected radionuclides after the 2006 test, but not after the 2009 test, and lots of folks think the 2009 test was faked. There is not yet a report of radionuclide detection for the 2013 test, but we need to wait a few more days at least before we get a definite statement from CTBTO. My guess is this one was also a fake.
They were observed to have dug two tunnels. My guess is that one has a real A-bomb, while the other was filled with conventional explosive. The real test failed and they then blew the conventional bomb as a cover-up. This was not to fool the world, but rather to fool the upper echelon of NK, to avoid being executed for failure. It is not possible to fake the radionuclide signature, which is not just Xenon 133. It is, however, just possible that an underground test completely seals all of the cracks and that there is therefore no radionuclide signature at all.
World population is 7.066 Billion
At the rate of 1.75 billion/yr, we need 4 years to provide each human a phone. This includes every infant and every person in North Korea. Sure, some folks get a new phone every year, and some have more than one phone.
If half to population has phones and the average phone life is 2 years, that accounts for the entire market. Why do we expect any growth?
Re: USB 3.0
Yes. Each of the 4' shelves needs four disk power distribution systems (DPDS.) Each DPDS would be a 10-position power strip plugged into a USB-controlled plug. The four DPDSs plus the four USB hubs plus the computer plug into a 10-position power strip, so each shelf ends up with a single plug leading out.
The main bulk is in the DPDS power strips and their plugs. Since each disk has a power cord that unplugs from the disk unit, it's possible to build a custom DPDS by cutting the plugs off of these cords and screwing the wires directly to a terminal block inside an approved small electrical box. All of this fits between the two rows on disks on the1' wide shelf.
Re: USB 3.0
Update on power control: Its ugly, but a single-circuit USB-controlled unit costs $25 USD. So, 25 x $25 costs $625 USD, not the $2000 mentioned previously.
The costs mentioned in the original post were retail qty 1 on the web. I suspect you can get at least a 15% discount for this large order, so the total for each of the redundant 1PB systems is just over $50,000 USD.
Also, the architecture as stated is 7 systems, one per shelf, each capable of supporting 40 x 4TB, but actually supporting 36 to get an even balance. It might be prettier to use 8 shelves each supporting 32 x 4TB, just because it's binary. Adds slightly to the cost, but those $1200 computers are WAY overkill. In fact, since we are only powering up one set ot 10 at a time, we can actually get away with a single computer instead of 7 or 8 computers, which means we do not need the switch.
In case it's not obvious, this system is basically an automated version of a stack of unpowered disks on a shelf. Access time to a file will usually be about 10 seconds to allow the disks to spin up and stabilize.
you can buy a 4TB external USB3.0 drive for $210.00 USD. A 10-port hub costs $50 USD. A computer with USB 3.0 and a 10 Gig-e NIC costs $1200 USD. An 8-port 10Gig-e switch costs $1000.
one switch, 7 computers, 25 USB hubs, 250 drives: $1000+7x$1200+25x$50+210x$250=$63,150.
Now double it because we want a second one in a secure location for backup.
The external disks are 2" wide and < 5" deep, so 40 sit on a 4' shelf 1'deep, and we need 7 such shelves, about 8" high, and each has room for one computer and four hubs.
For power, we need a cheap way to turn the AC power on and off for the disks. Unfortunately, its not cheap so we turn them on and off in sets of 10. To access the data, turn on the correct set, copy the data, turn off the set. power control for 25 sets will cost perhaps another $2000.
Any parent could predict this
Children do exactly this, and need to be corrected. Watson called "BS,"probably correctly, but one must use the correct vocabulary subset depending on the audience and context. see:
You started by defining "the Internet" to ionclude its servers, and you are absolutely right. Buyt hte server component is siliocon and electronic, not photonic,. For servers, the figure of metis as recently as 2005 was ops/$. Now, the figure of merit is ops/Watt. Internet content providers (Google, Facebook, etc.) are no longer compute-constrainted, so now the cost of operatins is driven by the energy used. We can expect ops/Watt to continue to decrease even in the pure electronic domain due to increased integration at the chip level. Later, we will start to see power reduction in servers at the board level when chip-to-chip photonics replace chip-to-chip electrical signalling.
At the data center level, we will see much more power-efficient LANs. Up to now, LAN technology was driven by bps/$. But now, we can also look at bps/Watt. and dramatic improvements are possible.
One upshot of all of this is that the capability of a physical data center (ops per cubic meter) will continue to increase exponentially, even though our old metrics such as CPU cycles hve flattened.
In the days of sail, the RN did not use ships of the line against pirates. The RN used Frigates and smaller ships for that. Similarly, a big-deck carrier is completely inapproprate against modern pirates. Enterprise has a crew of 4600, and its task force has about that again, for a total of 9200. That's enough to crew 92 LCSs, and an LCS is just about ideal against pirates, since it can support fast patrol craft and helicopters. The problem is that neither the USN nor the RN really want to do anti-piracy becase it just isn't sexy and it does not provide seagoing commands for admirals. for LCS, see:
The US has 10 big-deck carriers plus 9 "little" carriers. The entire rest of the world has a total of zero big-deck carriers and nine "little" carriers. See:
The big carriers can support various high-performance aircraft. the little guys handle STOL or VTOL aircraft, which have all sorts of design compromises.
Today, in the data center we have 10Gbps over copper to each server. An individual server doing a non-trivial job might support a 10GB load. By Moore's law, an individual server may need to support a 100Gbps load in 2020. But we can do 100Gbps today, using WDM, on a single fiber, to each server. So today, CPU power is the constraint, not NIC bandwidth.
By 2020, a WM NIC should be able to handle 10x110 0Gbe or better, cheaply, on a single fiber. NIC BW will not be the conatraint. LAN BW will follow suit. WAN BW will (again) be the bottleneck.
Not 12 Lasers.
That is a "multi-core Fiber" (MCF.) It has 12 cores: effectively twelve spatially-separate optical channels, equivalent to 12 separate fibers in an (extremely) tight bundle. Each of thes cores supports a separate DWDM signal. Each of the many wavelengths within each of these twelve channels requires its own separate laser (or at least its own separate modulator.) The new innovation is the MCD with dramatically reduced cross-talk, and the optics that permit the 12 DWDM signals to be injected into the MCD and extracted from it. There appears to be no new innovation in the DWDM itself.
Truss as a tension/compression structure
The truss appears to use only rods. Rods provide both tension and compression. A well-designed truss can use rods for compression, and (much lighter) wires for tension. In this application, you can use carbon-composite rods for the compression members and truly light-weight fibers for the tension members. I suspect that the thinnest available Kevlar fibers will suffice for the tension members of the truss. So: a triangular truss would have three long composite rods, Nx3 very short rods, and 2Nx3 fibers. Or if you are brave Nx3 fibers. But this application does not need Symmetric triangular truss, because the forces in the three dimensions are not symmetric.
The trick here is to ensure that the rods and fibers have roughly the same coefficients of expansion (change in length with temperature.) Increased distiane between the rods will add weight but will reduce any warpage. Acceptable truss warpage, in turn, depend on how the truss orientation affects the mission parameters.
If all we need it a truss that points (approximately) "up", then at the extreme we need a single carbon rod. If we need more rigidity, then we need two or three rods. it is not clear why we need mor than two: gravity workss, after all.
Consider a two-dimensional truss of (say) one metre. Two 1-metre rods, separated at (say) 20-cm intervals with 100 mm rods. The rods are turn connected by digaonal Kevlar fibres at each junction. This two-dimensional structure is in turn stabilized at its midpoint by triangular outriggers in the third dimension, connected to each end of the truss with more kevlar fibres.
The design appears to include a rubber band from the titanium rod to the truss. Why? If you actually intend to use a real rubber band, you have a problem: it will become brittle at low temperature. Remember Challenger's O-rings.
e-beam lithography has lots of benefits, but it is extremely slow. This technique increases its speed by a factor of 10,000 by using parallel beams.
The article points out one advantage: you no longer need to create a mask, and the cost of the mask is drives the cost of the photolithographic process. Masks have become extremely challenging as feature sizes dropped below the wavelength of the light used for the photolithography: the mask is no longer a simple reproduction of the shape of the desire result. Rather, the mask (rather, the masks, since "double-patterning" is needed) have funny shapes that cause the light to interact with the surface based on the rules of optics,and not all desired results have corresponding masks.
But there is another consequence that is even more important: A mask is so expensive that you must produce a huge number of parts to amortize the mask cost. For E-beam, you can spefiy the exact result you want, and the beam can produce that exact result. But even more importantly, there is essentially no penalty for creating multiple different kinds of devices on the same wafer. This completely changes the economics for creating experimental devices and for small production runs of ASICS, and it allows the industry to re-open the idea of wafer-scale integration.
E-beam failed because is was too slow, and it lost ground to photolithography as the wafers got bigger and the feature sizes got smaller. But suddenly we have parallel e-beams, which conceptually increase the speed by number of parallel beams (currently 10,000.) But if 10,000 now, why not 1,000,000 in the future? We get to the point where a specialty fab could produce a single instance of an experimental custom device for not too much extra money, and suddenly we can create a small quantity of ASICs for $100 apiece.
Yes, 688 Mjoule
That's remarkably close. I computed 32 x 30 = 960 M joules of energy in the powder, and you computed 688 M joules in the shell based on MV^2. These are in fair agreement given that we were probably not working with exactly the same gun.
Not so much
A WWII battleship's 16" guns used approximately 300 Kg of propellant, at approximtely 3.2 Mjoule/Kg. So the gun imparted about 30 times the energy imparted by this railgun. We have a way to go yet, but not too bad for a $21 M device.
It's Plagiarism, because they did not attribute the source. That's unethical, but not illegal.
However, it's also a violation of copyright law. Wikipedia is copyrighted, and you are not permitted to copy the material except under the terms of its license. Those term are very liberal, but they do require attribution. Wikipedia could choose to sue the Vatican, and if they do, they will win.
Temperature in vacuum
In addition to worry about hotspots, you also need to remember that convective cooling does not work very well at reduced pressure. Fortunately, in this case the total heat is in bounded because the motor quits after a few seconds. I do hope you continued to monitor the temperature for at least a minute after the end of the burn, since it takes a few seconds at least for the heat to migrate from the inner wall of the chamber.
amount of ice
1km^^3 of ice is approximately 1 Gt, so 100 Gt of ice is about 100 km^^3 of ice. That's a 10x10 km area covered 1 km deep, or a 10 km x 10 km area covered 10 m deep, or a 100 km x 100 km area covered 10 cm deep.
For Americans, that's the District of Columbia covered in 4" of ice.
In 1987, three neutrino detectors in different countries each detected a burst of neutrinos at 7:38 UTC on the same day.About three hours later, multiple telescopes observed a new supernova at ah location now computed to be at a distance of 168,000 light years away. Theoretical analysis says that neutrinos are generated in a core collapse and are not delayed as they leave the core, while light is only emitted when the shockwave from the collapse reaches the surface of the collapsing star, about 3 hours later.
These observations are consistent win neutrinos moving at the speed of light. They are not consistent with neutrinos moving faster than the speed of light. A baseline of 168,000 light years is many orders of magnitude longer than the baseline from CERN to Gran Sasso.
The U.S. suppressed global warming in the same way in the 1970's. The problem is that the sulfur that created the aerosols that cause the cooling also causes acid rain. This is really bad for lakes and ponds (e.g., in the Northeast) that are not naturally buffered, so we started scrubbing the sulfur out to the stack gasses, which increased global warming.
Of course, if you live where the lakes and ponds ARE buffered (i.e., in a limestone area such as the southeast) then the extra sulfur is good for the crops.
Cache doesn't help RAID rebuild
Sorry, but a RAID rebuild must actually read the whole disk, so cache is useless during a rebuild.
However, with 2TB drives, you can just use RAID 1/0 and get excellent reliability. "rebuild" is simple enough to not affect operations. Cache brings the IO density of slow drives up to almost the speed of fast drives, so much so that a RAID 1/0 with (say) six 7200RPM disks (6TB usable) should be faster than any same-cost arrangement of 6TB 15KRPM disks.
10X on Fiber??
I doubt that a fiber with 100G links has 10x more capacity than one with 10G links. A fiber carries multiple channels using DWDM (dense wavelength division multiplexing.) Each link uses a slightly different "color" of light (i.e., a slightly different wavelength.) I single fiber can carry 160 different "colors" when each color is a 10G link. When the links are 100G the "colors" must be separated further, so the fiber cannot carry 160 100G links. I do not know how many 100G links a fiber can carry. I do k now that a fiber carries 80 40G links, so quadrupling the link speed doubles the fiber capacity.
Latency is silly issue. A huge IP packet (1000 bytes, 8000 bits) is transmitted in 8000ns (nanoseconds) at 1G, 800ns at 10 G, and 80ns at 100G. But the speed of light in fiber is 20cm/ns in fiber, so 8000ns is 1600 meters, 800ns is 160 meters, and 80ns is 16 meters. But the link is more than 500 kilometers, so the difference (160 meters -16 meters= 144meters) is inconsequential relative to the speed-of-light latency on the link.
Best used for ships and disasters
You don''t use satellite if you have an alternative, so the areas in which it makes sense are shrinking, But the demand in these areas is still increasing.
But once the satellite is launched, if fixed demand does decrease, it is very cheap to re-purpose it for maritime, where there is no alternative.
Another major use is during a disaster (e.g., Katrina) that wipes out the comms infrastructure. You can get a temporary cell tower/wifi hotspot, with a generator, running in about an hour after delivery, and you can deliver using a helicopter.
A third major use is as backup for terrestrial links. Several big retailers do this, each with thousands of stores. this leaves the store's inventory system up during a fiber cut or other local outage. At most a very few of the stores need to use the system at any one time.
"Daiichi means "first". "Daini" means "second.." Reactors 1,2, and 3 at daiichi" were commissioned starting in 1970, and reactor 1, the one that failed first, was scheduled to be decomissioned this month after 40 years of operation. It was first designed less than 20 years sfter the start of the atomic age. It failed because the diesel backup generators (used only to run the emergency pumps) failed after an hour of operation after the worst earthquake in a thousand years, and the failure mode (so far, at least) means only that this reactor which is at its end life anyway, will need to be scrapped. The containment vessel did not (and probably will not) fail, and at worst a few workers will get a small amount of extra radiation. The new problems are at reactors 2 and 3, which share the same (failed) generators.) 2 and 3 are only slightly newer and have only 2 and 3 years of life, os the loss is small.