...also exploits polarization to a high degree. In fact, many developmental optical communication systems exploit polarization purity for higher base digital transmission, and even if polarization modulation slows things down for some schemes, the resulting bandwidth can overcome the obstacles by an order of magnitude or more over the reduced rate of the mux/demux. The issues with these schemes is more about cost. But most of these programs are directed at n-fold increases in existing optical fiber network bandwidth. Their time will come.
Oh dear, that one. Promises promises.
It always works out great on paper....
It costs roughly $10k to fly my 182 for 100 hours a year. Hangar, maintenance, fuel, overhaul reserve, insurance, etc. It is a matter of priorities.People all over the income brackets spend more on their 4WD trucks than I spent to either own or operate my 182. I'd take flying any day.
You can load up a 182 with 4 persons, their stuff, and nearly 5 hours of fuel, and cruise around 130 knots. You can spend hours looking at ads for 182's under $60k.
Lots of very, very nice 172's out there for less than $50k. Some for less than $20k.
1. That's all a person needs, or wants most of the time, to fly. Old radios. Round gauges. The rest has had zero impact on safety. Safety comes from between the ears, not from behind the panel.
2. Costs. Yes, but it is only slightly more expensive in constant dollars than 30 years ago. The real issue is that we all make less in constant dollars.
3. Regs are ridiculous at times. Again, flying is expensive. I have a dual GPS IFR panel. Not a single radio in the panel costs more than 3500. You can spend all you want. Or you can spend less...for used.
4. ADS-B is nice. But that's all. It only enhances safety...but it has not shown itself to actually improve it significantly enough to measure. Remember- if you avoid making the decision to fly into instrument conditions when you are not rated for them, and are careful enough to not run out of gas, you've just eliminated the causes for 95% of all accidents. Mechanical issues make up most of the rest. Things like mid-airs are so far down the list, you might as well worry about lightning. The latest tech has not proven itself to have any impact on general aviation safety- even in the aircraft so equipped. With one notable exception: the new ELT's (406 MHz).
5. Regs squelch anythign new coming into aviation. And the personalities one finds in aviation are often deeply conservative, curmudgeonly, and sort of unpleasant anyways.
6. Yes, it seems to be a badge of honor for the FAA to stay locked in the past...sort of like medical residencies ("We had to pull 36 hour shifts as residents, so new med students should too."). It is silly. After 30 years of flying, when they actually had teletypes and sub 100 baud faxes, it is silly to have to do a decode of weather.
Well, they say there is a pilot shortage out there too. Which is a lie. The airlines simply have a shortage of pilots willing to donate $100k of personally financed funds in training and experience to work for a near minimum wage job.
Bottom line: why spend 100k-150k on your own training/opportunity costs, all to make $15k to $20k a year for a few years, maybe get a copilot position after that for 35k, maybe a pilot situation after 5 years of experience (which will take 6-8 years in reality, due to furloughs), and watch as retirement and other benefits rapidly disappear as you approach mid-career?
Folks who are mid career have it great compared to what folks getting into it can look forward to, and their predecessors had it oodles better then.
Flying for fun and occasional business is expensive. But it is also not much more expensive than it was 30 years ago (perhaps 20% more in constant dollars). The cold hard truth is that people don't make as much in constant dollars now, and that expense went out the window for the vast majority of the middle class long ago.
In constant dollars, the initial cost of buying a plane is quite a bit lower than it was 30 years ago (mostly because the fleet ages year for year because hardly any airplanes are made any more). The cost of maintenance has gone up due to age, even as shop costs for aviation have gone down. Parts have gone up. Fuel (at around $5.50 a gallon) is roughly 20% more expensive in constant dollars. Flight training is roughly 35% more expensive in constant dollars (due to trends in increasing the average time a person is asked to train before soloing and taking exams).
On the other hand, there is a vast world of unique experiences out there one simply cannot have unless one flies themselves around. There are fewer people who can prioritize/afford it in the middle class. In a world where median engineering or technical fields would pay $175k a year in constant dollars since the mid-60's, when reality is more like 85-100k, there will be adjustments.
In the mean time, I'm happily trading extra years of working life for being able to fly to mountain wilderness airstrips to camp and fish in solitude, desert airstrips to explore remote canyons, ski areas to take advantage of powder days without turning into an expensive, multi-day trip, and see my parents as they grow old more often (for less than flying a commercial flight). It costs...yes...and I am fortunate to be able to have one hobby I love that I can sacrifice for. I wouldn't trade these things as a younger person for an early retirement any day.
...and asymmetric, then the only legitimate targets for an adversary become the public citizens that fund the efforts.
If no military response can ever be effective, it is the only thing left. We call it terrorism now, but it will be business as usual in the near future. Drones bombing your weddings?
Bomb their weddings. And schools and anything else.
The only limits to empire are consequences. When an empire can inflict with no fear of retribution to overtly military assets, other targets of retribution will be placed at risk.
It looks pretty darn well sealed to me. It's just a thermopile design. Phase change simply means a carefully designed system can get away without pumping a lot of fluid around.
The stuff is expensive. A gallon or so can set you back several hundred dollars...and not new stuff either....that's a reclaimed cost.
Nucleate boiling is what keeps the lights on if you depend on coal or gas for your electricity. It precedes the zone where your Leidenfrost effect is relevant, and actually increases the heat transfer coefficient by factors.
Tuning a closed system to exploit this is an exercise (fluid chemistry, pressure, temperature), but it is also ubiquitous. As for cavitation, it's a red herring in the nucleate boiling zone- the size of the bubbles is so small, and hence the driving frequency is so high, there is a) less mechanical coupling for the vibration, and b) the energy of cavitation is so low as to not be an issue.
...and Fukushima is a perfect example.
In the months following the incident, the press was hyping the accident to ethereal levels.
In the years following the incident, the US nuclear industry groups busily developed counter propaganda, using official measurements and downplaying risks ("1% greater chance of dying from cancer for 77 people") and the like. Carefully written op-ed and science pieces appeared all over the press from the Smart Serious People in the room, to soothe a worried public, that their superior assessment of the situation proved the concerns of pollution would become cautionary tales of hysteria.
The Japanese government deliberately withheld information until after the election, and now the pollution levels emanating form the plant render many the carefully written, I-told-you-it-was-hysteria explanations, riddled in Smug by the Serious Persons seem pretty silly, if not entertaining, to read.
If anything can be drawn from all this, it is, "It ain't over till it's over..."
People are afraid of people with stupid plastic extruding machines? What about all the folks with CNC mills and lathes in their garages, including those who have had them for decades (yours truly included)?
Americans are gullible, frightened creatures. Many of the folks I know with CNC or other metalworking equipment either have made, are making,or want to make firearms. While I do worry about the obsession with open ended tubes that allow expanding gas to propel a small lump of metal out the end, it doesn't make them terrierists.
People can make powerful bombs from items at their local Ace hardware store, or they can paint their home with the same stuff. People can use their 3d printers to make cute buttons for sale on Etsy, or they can make stupid, pointless guns. I've seen folks with incredible custom metal artwork or commercial side work coming out of their home metal shops, and have also seen many, many AR-15 rifles made entirely in the same places. Again, its not my thing, but all they can do is make it illegal...they can't get rid of it. And why should they?
The thing that is missed here is that 3D printing is simply one way to make these or a range of other items. It simply makes it easier for a noob. A guy with a CNC mill can churn out actual parts out of mechanically sound materials (engineering plastics & metals for example). This is actually a fairly large cottage industry already, both illicit and legal. These things are not hard.
The ONLY reason we don't see a lot of this is: motivation. More people who can casually make a few mouse clicks with a 3D printer to make parts out of brittle material without and law-breaking motivation will do so. People seem to be attracted to law-breaking for various reasons, nefarious and otherwise- just for the sake of it. But a lot of weapons are being produced right now on hobby equipment, both legal and illegal. The parts someone makes might be just as easily used as a door stop as a lethal device...and it is always a subjective law enforcement act to decide which case it is. This has not worked so well in the past.
The vanishingly small majority is doing it for nefarious purposes, and *NOTHING* stops them from obtaining/making these parts with a variety of methods. Is the computer model the criminal possession? The finished article?
The laws that outlaw writing down or linking to or simulating how illegal acts are committed are abhorrent and end up being counter productive on the one hand, and suppress free speech on the other. Outlawing a description of the Bayer process, for example, because it can be used to purify a range of illicit drugs even as it is the basis for a vast array of industrial processes (this happened, BTW). Outlawing certain books or placing on a federal watch list anyone that purchases/borrows/reads certain books that most suburban 14 year old boys of a certain age have probably read (happened, BTW).
This is the latest round of irrationality. I'm no great fan of guns, and American culture is significantly diminished by the presence of gun violence. But people literally believe that by passing laws and invoking prohibitions that they can make a dent in the violence problems, and because of this, they can ignore more complex issues that are actually causative- the drug war, for example, and a culture of war that has been widening for decades in America.
Some folks will make stuff with 3d printing out of boredom. Others out of a desire to break the law (like owning a switchblade in junior high school). No law stands in the way of an individual with nefarious intent, and 3d printing is but one tool they might use to achieve a goal. Nothing can stop them, really. They can't even really slow them down.
Manned hypersonic flight is a long ways off.
An 'unstart' on a hypersonic vehicle would decelerate ridiculously fast, potentially crushing the occupants (10's of G's). This is one reason why the US scramjet experiments have faced difficulties. The break even pressure ratio in the combustor is very difficult to achieve. If you aren't at a break even pressure ratio, you can't produce enough thrust to overcome drag; this means the vehicle begins slowing down (fast), making it even harder to achieve a break even combustor pressure ratio, etc. This failure happens in a matter of milliseconds: a sudden loss of thrust while travelling at speeds that generate fantastic amounts of drag, meaning fantastic deceleration follows.
For the Mercury capsules, for example, if the main engines were to suddenly stop at maximum pressure velocity, the entire structure would decelerate at nearly 15G's. If the capsule alone were to be released at that point, the loads would increase to cause the occupant to be unambiguously crushed from deceleration due to getting rid of the momentum of the rest of the rocket. The Mercury rockets included an escape tower that not only got the capsule away from a malfunctioning rocket, but provided thrust to allow the capsule to decelerate at survivable levels.
Unstarts with supersonic test planes and production planes have resulted in some injuries from the sudden loss of thrust at high speed.
"Also, making the skies BRIGHTER (as per TFS and TFA) means increasing photon flux density. "
No, it doesn't. It also happens to mention this in the main article.
Diffuse light is slightly less efficiently collected in real plants.