There would be no need to ticket a driverless car.
Correct. It may need to be recalled for a safety recall, and the owner may be cited for inadequate or negligent maintenance or for tampering with the control system. The law of driverless cars will work more like industrial negligence law than current traffic law.
I think you can get that sort of ash from fly ash as well (pozzolanic), but it's been a couple of decades since I read a decent text on concrete.
Fly ash (which is a byproduct of coal-burning power plants with pollution control gear) has been widely used in US concrete since the 1970s. Currently, Texas reports a shortage because of cheaper natural gas replacing coal, while China, which is building and operating many new coal-fired power plants, is producing about twice as much as they can use.
Bad concrete is a generic problem in construction. It requires constant testing and hard-ass inspectors to keep concrete quality up.
Emerging technologies tend to get away with cutting corners drasticly anyway, so if you are right in ten years they'll be facing a huge bill to try to do it all again with the extra complication and expense of doing little bits at a time between trains or something.
The US Transcontinental Railroad had exactly the same problem. The original 1870 trackage, built in a frantic hurry, was of terrible quality. When Harriman took over the Union Pacific in 1898, he started some rebuilding, and around 1909, the whole line was rebuilt with heavier rail, better roadbed, and heavy steel bridges, allowing much bigger and heavier trains.
China has been doing that to its freight rail system. The high speed lines get all the press, along with the rather fragile line to Tibet, but the 100,000km of track in China is mostly used for freight.
Well, of course. China has 3x the population of the US.
First in steel production
First in auto production
First in electronics production
...
And the interior provinces aren't even fully industrialized yet. That will change rapidly as the expressway and high speed rail networks are built out.
C++ being "unsafe" in some areas is not something people are in denial about -- it is a purposeful tradeoff for providing unbeatable performance when you need it.
This is widely believed, but wrong. You don't have to go all the way to garbage collection to get memory safety. Most of the problems with buffer overflows stem from the language design concept that the language usually has no clue about how big an array is. If the compiler knows about array sizes, it can not only check them, it can optimize the checking. Bolt-ons via templates or macros can't do that efficiently.
C++ is a horrible language, and I say this as a professional C++ programmer.
C++ stands alone as the only major programming language with hiding but without memory safety. Strostrup is in denial about this, which prevents fixing the problem.
Templates don't help. Trying to make templates into a compile-time programming environment results in a language that makes Perl look readable. Just because templates are a Turing-complete term-rewriting system doesn't mean you want to use them that way. Papering over the safety issues with templates doesn't help; the mold always seeps through the wallpaper. Usually at system calls that demand raw pointers.
(Somewhere in the 1980s, low-level programming took a wrong turn. We had Pascal, the Modula family, and Ada. Things seemed to be getting better. Then Modula crashed and burned along with DEC, and Ada declined due to its bulk and overly expensive compilers. We all had to go back to C. That we're still stuck there is embarrassing. It's probably the worst major engineering standard since the British buffer-and-chain coupler from 1830 still in wide use.)
The volunteer process by which Japanese anime is subtitled within hours of release works a lot like this.
Re:Lego was not the ultimate do-it-yourself playth
on
Has Lego Sold Out?
·
· Score: 2
That title must go to Meccano [wikipedia.org].
Meccano is still available. Toys-R-Us carries it. I have a Meccano set I use for prototyping linkages. It's not unusual for first-round engineering prototypes to have some Meccano parts.
Foxconn, the biggest consumer electronics manufacturer in the world and China's largest private employer, is a contract manufacturer. They have no product lines of their own. This puts them in the lowest margin part of the product food chain. Although Foxconn makes the iPhone, the iPad, the Wii, and the XBox, the companies who own the brand make much more per unit than Foxconn does. At the other end, the semiconductor manufacturers who make the more complex parts also make higher margins.
Foxconn doesn't intend to stay in that subservient position forever. The Economist had an article on them a few weeks ago pointing this out. Acquiring a product line to call their own is a first step. They've chosen one which doesn't compete with their major customers. For now.
Five years out, Foxconn may be a major consumer brand. Foxconn phones, Foxconn tablets, Foxconn stores...
I could see going to work for Facebook before the IPO, but now? You've missed the chance to get rich. Working for Facebook seems to be crunch hell in giant bullpens with bad bosses.
Facebook seems to have peaked in terms of users and traffic.Now it's all about "monetizing the user base", i.e. shoving as many ads as possible at the users and selling tracking data.
The jammer could just jam every frequency at once.
That's called a "denial jammer". Historically, denial jammers aren't very effective other than at very short ranges. It takes huge amounts of power to jam a whole band so solidly that no narrow-band redundant signal can get through. Denial jammers are very easy to find in peacetime and targets for homing anti-radiation missiles in wartime.
maybe link the jumping to cryptographic keys, you have to know the private key in order to be listening to the right spot on the band at the right time. That way the jamming would have to know the keys in order to predict where it has to jam...
That's how classical frequency-hopping systems work.
One of the interesting possibilities of doing this with a software-defined radio is to have the receiver listen to the whole band and recognize the signal of interest without knowing in advance what the transmitter will do. This avoids the shared key problem and the cryptosync problem. The transmitter's hopping pattern can be random, instead of psuedorandom, so the jammer can't predict it even in theory.
OK, so this guy has a dumb battery, motors, wheels platform, with no sensors. On this, he put a web server with WiFi, which he then controls from a cell phone. So all that this does is run two small DC motors under manual remote control.
This is lame even by amateur robotics standards today. There's enough compute power there for a full vision system. Running Apache and node.js is not useful. It might be worthwhile to get familiar with the technology, but you don't publicize it.
The rules aren't available on the site yet, but I assume they're interested in resistance to jamming. From a theoretical perspective, as long as the receiver isn't saturated, there should be some data rate at which transmission is possible. This follows from Shannon. Noise can be overcome with redundancy, at the cost of data rate.
You can usually do better than that by moving around the spectrum to quieter areas. That's what frequency-hopping systems do. Jammers can be agile too, but unless the jammer is in a direct line between sender and receiver, the jammer is always at a time disadvantage due to speed of light lag. Very fast frequency hopping can overcome agile jammers.
What DARPA wants, I suspect, are systems that package up all this into a system that takes care of any noise problems automatically and will get a message through if it is physically possible. DoD has had systems for that for decades, but the technology tended to assume that the opposition didn't know the details of how it worked. It may be possible to have jam-resistant systems that work even if the opposition knows the technology.
Note that the proposed law gives the power to censor to the Israeli justice minister. Yaakov Neeman, the current justice minister, is kind of weird. News articles:
There's a sizable ultra-orthodox faction in Israel which wants a political system where rabbis run things. Neeman is from that faction. Israel already has rabbinical courts, but they're currently restricted to ruling on religious issues and divorces. Neeman has said he wants to expand the authority of rabbinical courts, which in Israel are dominated by ultra-othodox rabbis.
Ultra-orthodox groups are very anti-Internet. This goes way beyond censoring pornography. There are special censored ISPs that only allow a list of 400 approved sites, most of which are religious.
So that's where this may be going, or at least where one faction would like to go. (Israel politics is currently deadlocked worse than US politics. There are many parties, none with a majority, and shifting coalitions. Different factions control different ministries as part of the deals made to put coalitions together. Just because the Justice Minister wants something doesn't mean the Government does.)
That one in particular has been for sale for a very long time, and they have revamped the site at least twice to try to draw more interest.
I know. Yet it's one of the more useful sites. It has an airstrip, and it's reasonably close to major Eastern US cities. If there's an emergency, you have a reasonable chance of getting there. There's a useful house above ground, and a comfortable bunker. Even after a nuclear war, you only need to spend about two weeks in a fallout shelter before you can go outside. And there are lots of contingencies for which merely being in a solid house in an isolated area is enough.
The Nebraska facility is almost certainly a former Bell System facility. It has a classic AT&T microwave tower and high bays for switching equipment. AT&T used to have underground centers across the country for survivable communications. Here's one that is for sale.
There are a surprising number of bunkers for sale in the US. I see some on the market that were being offered a decade ago. The costs of refurbishing and operating a big military facility in the middle of nowhere are high, and few people bother. Some have done so, and then realized they don't really want to live there.
The real problem is sex offenders with religious power and organized support for cover-ups. The Catholic church has had a huge problem with this for decades. Now it's coming out that the New York
ultra-Orthodox Jewish community has a similar problem. They're having big rallies for a sex abuser. Not for the victim, for the abuser. The 12 year old
abused girl "wore supposedly indecent clothing, read People magazine and questioned God's authority in a religious school class", which in that community is considered justification for sexually molesting her.
And New York State is worried about video game chat.
There was at one time a mechanical interlock device for guns which used a magnetized ring worn by the user. Without a strong magnet on the grip, the gun would not unlock and fire. It wasn't that popular, but did work. Some gun users with kids at home liked it.
Gun safety systems have improved, and there should be minimum standards in that area. Col. Dave Hackworth (WWII, Korea, Vietnam, highly decorated, quit the Army after Vietnam over war policy and became a noted critic) was involved in evaluating replacements for the M1911A1 pistol. He mentions that Army records showed that weapon had killed more US soldiers through accidents than enemy soldiers. (Bear in mind the military approach to pistols - pistols are carried by people who don't plan to use them. When you're looking for trouble, you carry a rifle or heavier.)
With the M1911A1, you can remove the magazine, but if there's a round in the chamber, still fire the weapon. Most modern semi-auto pistols are interlocked against that, which tends to reduce "I didn't know it was loaded" accidents. The unloading process is more complicated than one might expect, and involves disengaging the safety and pulling the trigger.
That class of problem can be solved by design. It may take legislation, just as it did to get auto transmission quadrants to all be PRNDL. In the 1950s, General Motors used a different sequence than Ford and Chrysler, leading to "I didn't know it was in reverse" accidents.
Yeah, you can have omnidirectional antenna coverage for both uplink and downlink.... This is the preferred method if you can close your link and data budgets because it makes the system vastly simpler and inherently fail safe.... A secondary directional downlink may be reasonable if you have very high data requirements (e.g. streaming video or ultra high definition imagery)
Most commercial and military satellites have a low-bandwidth omnidirectional uplink and downlink for control. USAF satellites used to have (and may still have) almost a complete separation between the "bus" and "payload" sides, with the "bus" side on omni antennas. At the ground end, the USAF had big steerable dishes at about six tracking stations around the world. The spacecraft was piloted through those. Command and control of most USAF satellites were run from the Blue Cube in Sunnyvale until that operation was moved to Falcon and Vandenberg AFBs.
Once the spacecraft was in the desired orbit and oriented, directional antennas were used by the payload to communicate with the payload user's control center. With directional antennas, smaller ground-side dishes could be used.
The big steerable dishes were a scarce resource needed for multiple satellites, so tying them up for payload data like imagery was avoided.
Back in the early 1980s, one of the amateur radio satellites was incorrectly commanded to transmit on its own control receive frequency. This blocked the receiver from receiving further commands. To recover the satellite, the Stanford Dish was used. That 46 meter steerable radio telescope had, left over from old USAF work, a 3MW transmitter.
The combination of a huge dish and a high powered transmitter allowed focusing enough power on the satellite to get through to the receiver and tell the satellite to change its transmit frequency. It took two tries (the first time the codes sent were wrong) but on the second try it worked.
Sorry, but the Makerbot and other FDM printers are a dead end.... FDM has come a long way in the last 2 years, but, at the end of the day, it's still dropping a noodle onto other noodles, with a very limited choice of materials which have varying qualities of unusability.
I tend to agree. Trying to weld a hot thing to a cold thing never works well. The process is touchy and unreliable. I've suggested using a laser aimed at the weld point, or just ahead of it, to heat the other side of the joint, and an IR thermometer to monitor the welds. I've been to Makerbot meetups, and everybody seems to be fussing with frame and table drive designs. Those are not the problem. The business end of the extruder/welder is where work is needed.
Some days I think that half the output of the RepRap/MakerBot crowd consists of the same demo files, mostly the Yoda and Darth Vader heads. The stereolithography users make real parts.
UV hardened resins are where it's at, but predatory patent trolls have locked that up in patent hell for the next few decades.
Maybe on both items. Stereolithography machines do a good job, but you're limited to materials that polymerize when hit by UV. The patent problems should be resolved soon. The basic patent was filed in 1984 and has expired. 3D Systems and Envisiontech settled last week. The infringement complaint against Formlabs involves a rather minor improvement which Formlabs can probably work around.
FDM is the "aluminized paper dot matrix printer using arcs to produce ozone and dark spots" of this generation's printers.
I once suggested using those printers as a log medium for a voting machine project. They're cheap and reliable. The output is permanent and hard to tamper with. Unlike thermal printers, the paper does not turn brown and become unreadable when stored in a warm warehouse. Unlike inkjets, you can't run out of ink. But you can't get those printers any more.
So there is a trope in the engineering world that the safest reactors are the ones that are confined to paper studies, or, to put it more timely, to PowerPoint slides.
"An academic reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose. (7) Very little development will be required. It will use off-the-shelf components. (8) The reactor is in the study phase. It is not being built now."
"On the other hand a practical reactor can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It requires an immense amount of development on apparently trivial items. (4) It is very expensive. (5) It takes a long time to build because of its engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated."
Looking at the history of reactors, almost everything other than water-cooled reactors has been an operational failure. Pebble-bed reactors have pebble jams. Helium-cooled reactors leak. Sodium-cooled reactors have fires. Boiling water reactors are basically simple devices, and even they have problems. Complexity in the radioactive side of a reactor system has not worked well in practice. The environment is hostile and the required lifetime without maintenance is decades long.
The article indicates that Adm. Rickover didn't like molten salt / sodium cooled reactors because the "Navy knew how to handle water". In reality, Rickover's nuclear program tried both approaches. The Nautilus (SSN-571) used a boiling water reactor, and the Seawolf (SSN-575) used a sodium cooled reactor. Both were built, both went to sea, and both performed reasonably well. But the sodium-cooled reactor turned out to be harder to maintain than the boiling water reactor, and couldn't be run at full capacity because of some design problems. so after a year, Seawolf was returned to the yards and converted to a boiling water reactor.
That was very typical of the military approach of the period - fully develop several alternatives, operate them, then dump the losers. The history of 1950s jet fighters is a striking example.
Slashdot Mirror
There would be no need to ticket a driverless car.
Correct. It may need to be recalled for a safety recall, and the owner may be cited for inadequate or negligent maintenance or for tampering with the control system. The law of driverless cars will work more like industrial negligence law than current traffic law.
I think you can get that sort of ash from fly ash as well (pozzolanic), but it's been a couple of decades since I read a decent text on concrete.
Fly ash (which is a byproduct of coal-burning power plants with pollution control gear) has been widely used in US concrete since the 1970s. Currently, Texas reports a shortage because of cheaper natural gas replacing coal, while China, which is building and operating many new coal-fired power plants, is producing about twice as much as they can use.
Bad concrete is a generic problem in construction. It requires constant testing and hard-ass inspectors to keep concrete quality up.
Emerging technologies tend to get away with cutting corners drasticly anyway, so if you are right in ten years they'll be facing a huge bill to try to do it all again with the extra complication and expense of doing little bits at a time between trains or something.
The US Transcontinental Railroad had exactly the same problem. The original 1870 trackage, built in a frantic hurry, was of terrible quality. When Harriman took over the Union Pacific in 1898, he started some rebuilding, and around 1909, the whole line was rebuilt with heavier rail, better roadbed, and heavy steel bridges, allowing much bigger and heavier trains.
China has been doing that to its freight rail system. The high speed lines get all the press, along with the rather fragile line to Tibet, but the 100,000km of track in China is mostly used for freight.
Any incoming e-anything goes to the spam bin. If it has any executable content, the odds are it's hostile code.
Bah! Humbug!
Well, of course. China has 3x the population of the US.
And the interior provinces aren't even fully industrialized yet. That will change rapidly as the expressway and high speed rail networks are built out.
C++ being "unsafe" in some areas is not something people are in denial about -- it is a purposeful tradeoff for providing unbeatable performance when you need it.
This is widely believed, but wrong. You don't have to go all the way to garbage collection to get memory safety. Most of the problems with buffer overflows stem from the language design concept that the language usually has no clue about how big an array is. If the compiler knows about array sizes, it can not only check them, it can optimize the checking. Bolt-ons via templates or macros can't do that efficiently.
C++ is a horrible language, and I say this as a professional C++ programmer.
C++ stands alone as the only major programming language with hiding but without memory safety. Strostrup is in denial about this, which prevents fixing the problem.
Templates don't help. Trying to make templates into a compile-time programming environment results in a language that makes Perl look readable. Just because templates are a Turing-complete term-rewriting system doesn't mean you want to use them that way. Papering over the safety issues with templates doesn't help; the mold always seeps through the wallpaper. Usually at system calls that demand raw pointers.
(Somewhere in the 1980s, low-level programming took a wrong turn. We had Pascal, the Modula family, and Ada. Things seemed to be getting better. Then Modula crashed and burned along with DEC, and Ada declined due to its bulk and overly expensive compilers. We all had to go back to C. That we're still stuck there is embarrassing. It's probably the worst major engineering standard since the British buffer-and-chain coupler from 1830 still in wide use.)
The volunteer process by which Japanese anime is subtitled within hours of release works a lot like this.
That title must go to Meccano [wikipedia.org].
Meccano is still available. Toys-R-Us carries it. I have a Meccano set I use for prototyping linkages. It's not unusual for first-round engineering prototypes to have some Meccano parts.
Foxconn, the biggest consumer electronics manufacturer in the world and China's largest private employer, is a contract manufacturer. They have no product lines of their own. This puts them in the lowest margin part of the product food chain. Although Foxconn makes the iPhone, the iPad, the Wii, and the XBox, the companies who own the brand make much more per unit than Foxconn does. At the other end, the semiconductor manufacturers who make the more complex parts also make higher margins.
Foxconn doesn't intend to stay in that subservient position forever. The Economist had an article on them a few weeks ago pointing this out. Acquiring a product line to call their own is a first step. They've chosen one which doesn't compete with their major customers. For now.
Five years out, Foxconn may be a major consumer brand. Foxconn phones, Foxconn tablets, Foxconn stores...
I could see going to work for Facebook before the IPO, but now? You've missed the chance to get rich. Working for Facebook seems to be crunch hell in giant bullpens with bad bosses.
Facebook seems to have peaked in terms of users and traffic.Now it's all about "monetizing the user base", i.e. shoving as many ads as possible at the users and selling tracking data.
The jammer could just jam every frequency at once.
That's called a "denial jammer". Historically, denial jammers aren't very effective other than at very short ranges. It takes huge amounts of power to jam a whole band so solidly that no narrow-band redundant signal can get through. Denial jammers are very easy to find in peacetime and targets for homing anti-radiation missiles in wartime.
maybe link the jumping to cryptographic keys, you have to know the private key in order to be listening to the right spot on the band at the right time. That way the jamming would have to know the keys in order to predict where it has to jam...
That's how classical frequency-hopping systems work.
One of the interesting possibilities of doing this with a software-defined radio is to have the receiver listen to the whole band and recognize the signal of interest without knowing in advance what the transmitter will do. This avoids the shared key problem and the cryptosync problem. The transmitter's hopping pattern can be random, instead of psuedorandom, so the jammer can't predict it even in theory.
OK, so this guy has a dumb battery, motors, wheels platform, with no sensors. On this, he put a web server with WiFi, which he then controls from a cell phone. So all that this does is run two small DC motors under manual remote control.
This is lame even by amateur robotics standards today. There's enough compute power there for a full vision system. Running Apache and node.js is not useful. It might be worthwhile to get familiar with the technology, but you don't publicize it.
The rules aren't available on the site yet, but I assume they're interested in resistance to jamming. From a theoretical perspective, as long as the receiver isn't saturated, there should be some data rate at which transmission is possible. This follows from Shannon. Noise can be overcome with redundancy, at the cost of data rate.
You can usually do better than that by moving around the spectrum to quieter areas. That's what frequency-hopping systems do. Jammers can be agile too, but unless the jammer is in a direct line between sender and receiver, the jammer is always at a time disadvantage due to speed of light lag. Very fast frequency hopping can overcome agile jammers.
What DARPA wants, I suspect, are systems that package up all this into a system that takes care of any noise problems automatically and will get a message through if it is physically possible. DoD has had systems for that for decades, but the technology tended to assume that the opposition didn't know the details of how it worked. It may be possible to have jam-resistant systems that work even if the opposition knows the technology.
Note that the proposed law gives the power to censor to the Israeli justice minister. Yaakov Neeman, the current justice minister, is kind of weird. News articles:
There's a sizable ultra-orthodox faction in Israel which wants a political system where rabbis run things. Neeman is from that faction. Israel already has rabbinical courts, but they're currently restricted to ruling on religious issues and divorces. Neeman has said he wants to expand the authority of rabbinical courts, which in Israel are dominated by ultra-othodox rabbis.
Ultra-orthodox groups are very anti-Internet. This goes way beyond censoring pornography. There are special censored ISPs that only allow a list of 400 approved sites, most of which are religious.
So that's where this may be going, or at least where one faction would like to go. (Israel politics is currently deadlocked worse than US politics. There are many parties, none with a majority, and shifting coalitions. Different factions control different ministries as part of the deals made to put coalitions together. Just because the Justice Minister wants something doesn't mean the Government does.)
That one in particular has been for sale for a very long time, and they have revamped the site at least twice to try to draw more interest.
I know. Yet it's one of the more useful sites. It has an airstrip, and it's reasonably close to major Eastern US cities. If there's an emergency, you have a reasonable chance of getting there. There's a useful house above ground, and a comfortable bunker. Even after a nuclear war, you only need to spend about two weeks in a fallout shelter before you can go outside. And there are lots of contingencies for which merely being in a solid house in an isolated area is enough.
I want to set my own price. Facebook can take their usual 30% cut.
The Nebraska facility is almost certainly a former Bell System facility. It has a classic AT&T microwave tower and high bays for switching equipment. AT&T used to have underground centers across the country for survivable communications. Here's one that is for sale.
There are a surprising number of bunkers for sale in the US. I see some on the market that were being offered a decade ago. The costs of refurbishing and operating a big military facility in the middle of nowhere are high, and few people bother. Some have done so, and then realized they don't really want to live there.
"Manufacturing" means producing disks and boxes, or setting up download servers. That's a routine operation.
The real problem is sex offenders with religious power and organized support for cover-ups. The Catholic church has had a huge problem with this for decades. Now it's coming out that the New York ultra-Orthodox Jewish community has a similar problem. They're having big rallies for a sex abuser. Not for the victim, for the abuser. The 12 year old abused girl "wore supposedly indecent clothing, read People magazine and questioned God's authority in a religious school class", which in that community is considered justification for sexually molesting her.
And New York State is worried about video game chat.
There was at one time a mechanical interlock device for guns which used a magnetized ring worn by the user. Without a strong magnet on the grip, the gun would not unlock and fire. It wasn't that popular, but did work. Some gun users with kids at home liked it.
Gun safety systems have improved, and there should be minimum standards in that area. Col. Dave Hackworth (WWII, Korea, Vietnam, highly decorated, quit the Army after Vietnam over war policy and became a noted critic) was involved in evaluating replacements for the M1911A1 pistol. He mentions that Army records showed that weapon had killed more US soldiers through accidents than enemy soldiers. (Bear in mind the military approach to pistols - pistols are carried by people who don't plan to use them. When you're looking for trouble, you carry a rifle or heavier.)
With the M1911A1, you can remove the magazine, but if there's a round in the chamber, still fire the weapon. Most modern semi-auto pistols are interlocked against that, which tends to reduce "I didn't know it was loaded" accidents. The unloading process is more complicated than one might expect, and involves disengaging the safety and pulling the trigger.
That class of problem can be solved by design. It may take legislation, just as it did to get auto transmission quadrants to all be PRNDL. In the 1950s, General Motors used a different sequence than Ford and Chrysler, leading to "I didn't know it was in reverse" accidents.
Yeah, you can have omnidirectional antenna coverage for both uplink and downlink. ... This is the preferred method if you can close your link and data budgets because it makes the system vastly simpler and inherently fail safe. ... A secondary directional downlink may be reasonable if you have very high data requirements (e.g. streaming video or ultra high definition imagery)
Most commercial and military satellites have a low-bandwidth omnidirectional uplink and downlink for control. USAF satellites used to have (and may still have) almost a complete separation between the "bus" and "payload" sides, with the "bus" side on omni antennas. At the ground end, the USAF had big steerable dishes at about six tracking stations around the world. The spacecraft was piloted through those. Command and control of most USAF satellites were run from the Blue Cube in Sunnyvale until that operation was moved to Falcon and Vandenberg AFBs.
Once the spacecraft was in the desired orbit and oriented, directional antennas were used by the payload to communicate with the payload user's control center. With directional antennas, smaller ground-side dishes could be used. The big steerable dishes were a scarce resource needed for multiple satellites, so tying them up for payload data like imagery was avoided.
Back in the early 1980s, one of the amateur radio satellites was incorrectly commanded to transmit on its own control receive frequency. This blocked the receiver from receiving further commands. To recover the satellite, the Stanford Dish was used. That 46 meter steerable radio telescope had, left over from old USAF work, a 3MW transmitter. The combination of a huge dish and a high powered transmitter allowed focusing enough power on the satellite to get through to the receiver and tell the satellite to change its transmit frequency. It took two tries (the first time the codes sent were wrong) but on the second try it worked.
Sorry, but the Makerbot and other FDM printers are a dead end. ... FDM has come a long way in the last 2 years, but, at the end of the day, it's still dropping a noodle onto other noodles, with a very limited choice of materials which have varying qualities of unusability.
I tend to agree. Trying to weld a hot thing to a cold thing never works well. The process is touchy and unreliable. I've suggested using a laser aimed at the weld point, or just ahead of it, to heat the other side of the joint, and an IR thermometer to monitor the welds. I've been to Makerbot meetups, and everybody seems to be fussing with frame and table drive designs. Those are not the problem. The business end of the extruder/welder is where work is needed.
Some days I think that half the output of the RepRap/MakerBot crowd consists of the same demo files, mostly the Yoda and Darth Vader heads. The stereolithography users make real parts.
UV hardened resins are where it's at, but predatory patent trolls have locked that up in patent hell for the next few decades.
Maybe on both items. Stereolithography machines do a good job, but you're limited to materials that polymerize when hit by UV. The patent problems should be resolved soon. The basic patent was filed in 1984 and has expired. 3D Systems and Envisiontech settled last week. The infringement complaint against Formlabs involves a rather minor improvement which Formlabs can probably work around.
FDM is the "aluminized paper dot matrix printer using arcs to produce ozone and dark spots" of this generation's printers.
I once suggested using those printers as a log medium for a voting machine project. They're cheap and reliable. The output is permanent and hard to tamper with. Unlike thermal printers, the paper does not turn brown and become unreadable when stored in a warm warehouse. Unlike inkjets, you can't run out of ink. But you can't get those printers any more.
So there is a trope in the engineering world that the safest reactors are the ones that are confined to paper studies, or, to put it more timely, to PowerPoint slides.
Yes. Here's the original source of that, from Hyman Rickover, 1953:
"An academic reactor or reactor plant almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose. (7) Very little development will be required. It will use off-the-shelf components. (8) The reactor is in the study phase. It is not being built now."
"On the other hand a practical reactor can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It requires an immense amount of development on apparently trivial items. (4) It is very expensive. (5) It takes a long time to build because of its engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated."
Looking at the history of reactors, almost everything other than water-cooled reactors has been an operational failure. Pebble-bed reactors have pebble jams. Helium-cooled reactors leak. Sodium-cooled reactors have fires. Boiling water reactors are basically simple devices, and even they have problems. Complexity in the radioactive side of a reactor system has not worked well in practice. The environment is hostile and the required lifetime without maintenance is decades long.
The article indicates that Adm. Rickover didn't like molten salt / sodium cooled reactors because the "Navy knew how to handle water". In reality, Rickover's nuclear program tried both approaches. The Nautilus (SSN-571) used a boiling water reactor, and the Seawolf (SSN-575) used a sodium cooled reactor. Both were built, both went to sea, and both performed reasonably well. But the sodium-cooled reactor turned out to be harder to maintain than the boiling water reactor, and couldn't be run at full capacity because of some design problems. so after a year, Seawolf was returned to the yards and converted to a boiling water reactor.
That was very typical of the military approach of the period - fully develop several alternatives, operate them, then dump the losers. The history of 1950s jet fighters is a striking example.