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Comment: Re:Such a bad summary (Score 1) 126

by steveha (#49327705) Attached to: Boeing Patents <em>Star Wars</em> Style Force Field Technology

I stand corrected. Mod parent up. Mod me down if you like.

US patent:

With each of the embodiments discussed, the system 10 is deployed to attenuate the energy of an advancing shockwave 24 form an explosion 22 by creating a second fluid medium 30 that differs from the first fluid medium 26, which may be ambient air, positioned so that it interacts with the shockwave. As shown in FIG. 10, as the shockwave contacts the interface 90 between the first fluid medium 26 and the second fluid medium 30, the difference in refractive index reflects a fraction of the incoming energy toward the explosion 22, as indicated by arrows A. This partial reflection occurs a second time as the shockwave passes through the second fluid medium 30 and contacts the interface 92 between the second medium and the ambient 26 as it exits the second medium. All gradients or discontinuities in the medium provide a reflection point for the incoming shockwave 24. For example, if the second medium 30 is non-uniform, reflection will occur at each of many places within the medium.

As shown in FIG. 11, shockwaves 24 obey Fermat's theory of least time and therefore an effective refractive index for the shockwave can be defined that is inversely proportional to the shock speed. The properties or composition of the second medium 30 are chosen such that the effective refractive index of the second medium 30 differs from the first medium 26 in at least one of temperature, molecular weight and composition. As the shockwave passes into or out of the second medium 30, the difference in effective refractive index refracts the wave, as shown by lines B, diverting it and defocusing it away from the protected asset 18. In the disclosed embodiments, the second medium 30 is created such that the shockwave travels faster in the second medium 30 than in the first medium 26, so the refractive index of the second medium is less than that of the first medium. Further, the second medium is created to have a convex shape and therefore acts as a divergent lens, so that the energy of the shockwave 24 spreads out, as shown by lines C, so its intensity drops as it approaches the protected asset 18.

In addition, the second medium 30 may absorb some shock energy as the shock travels through it. Factors contributing to the absorption of energy include energy retained in the molecules of the second medium itself (e.g., enhanced rotational energy, excited molecular bonds, excited electrons, molecular decomposition, and ionization) and shock energy converted to electromagnetic energy through blackbody emission from hot particles or photon emission from de-exciting various excited states.

A further mechanism for attenuating the energy density of the shockwave 24 is momentum exchange. If the second medium 30 is moving relative to the first medium 26, then it will exchange momentum with the shockwave 24. The result is a combination of reflection, slowing, and redirection of the shockwave. Any or all of the foregoing mechanisms may operate in a given embodiment. The composition, temperature, speed and location of the second medium 30 may be chosen or created to create any one or all of the aforementioned mechanisms.

So, it's not necessarily lasers that generate the plasma, and the protection comes mainly from the plasma having a different refractive index than the air through which the shock wave has propagated.

My comment that this serves as a "counter-wave" is in the patent but only as a "it might also do this" thing, not as the main thing.

Countering a shock wave with a generated one would be horribly complex.

I never thought they were trying to cancel out the explosion with another explosion whose sound waves have opposite phase to the first.

I tried to read TFA and figure out what the invention really did. You are right, going to the actual patent text was a better idea. That article did not do a good job of explaining the science.

Comment: Re:Star Wars? (Score 1) 126

by steveha (#49324043) Attached to: Boeing Patents <em>Star Wars</em> Style Force Field Technology

the shields really didn't appear to do a damn thing as far as I could tell. I remember the "double front" thing now that you mention it, but I'm not sure what those shields actually accomplished.

I think the in-universe explanation is that the shields were double front to protect against fire from the laser turrets on the Death Star, but when Vader and his TIE fighters hit the fighters from behind, the front shields didn't do any good.

This has always been fine with me. These are fighters, and it would be silly for the fighters to be invulnerable. They are small, and they have decent engines, decent weapons, and (at least X-Wings) even have a hyperdrive. It would be hard to believe they could have all that and also impenetrable shields. As with jet fighters in real life, their best defense is to blow up attackers before being attacked, or avoid the attack completely. If you can hit a modern jet with a missile you likely destroy that jet, and similarly if you can get a solid laser hit on a "snub fighter" you likely destroy it.

If you accept the LucasArts video game as canon, "double front" disables all shields to the rear, using the full output of the shield generators toward the front.

the shields on Hoth did what exactly?

The in-universe explanation was that the base was secure inside its shield bubble; the ships in orbit couldn't breach the shield. So the Imperial Walkers were landed somewhere outside the perimeter of the shield, then walked up until they could attack the shield generator.

I must admit I've never bought this. If you handwave a bit, maybe you can make it make sense: they Imperials know the rebels have multiple bases, and they want to capture people alive for interrogation to find other rebels; they could have swatted the base from orbit but it would leave a smoking crater, so they wanted to take the shield down and take prisoners. This seems inconsistent with the Empire that shot down escape pods in the first movie.

Also, I have really never bought the idea that the ground base was able to protect the transports by firing some sort of weapon at the ships in space, from the ground. But never mind.

I don't recall any shields in Star Wars. ;-)

One more: spacecraft hangars didn't have airlocks; just force fields, and the spacecraft could simply fly through the force field while atmosphere didn't leak out. I've never understood how exactly that's supposed to work.

And one more: a major plot point of Return of the Jedi was that the partially-completed new Death Star was protected by a shield generator on Endor. Until that shield was disabled, the rebels couldn't even attack the Death Star.

Comment: Such a bad summary (Score 5, Informative) 126

by steveha (#49323345) Attached to: Boeing Patents <em>Star Wars</em> Style Force Field Technology

Star Wars features force fields that can, for example, hold the air in a spacecraft hangar even while a spacecraft flies out.

Boeing has developed a technology where lasers fire a burst of energy to turn air into plasma, causing a shock wave. When sensors detect an incoming pressure wave (from an explosion or whatever) this system creates a counter-wave.

Even when I squint and wave my hands a lot, those two things don't look much alike.

The prior art on this is not Star Wars, but reactive tank armor.

Comment: Online streaming (Score 1) 59

I just checked, and Rhapsody has this music available for streaming. I'm a Rhapsody customer and I'm listening to this recording right now.

I presume that Spotify and Google Play probably have this by now also. It's public domain so they have no reason not to just add it. (But I haven't checked to confirm.)

Comment: Torrent? (Score 1) 59

I would like to download the music and listen to it. But while I'm not ready to send them any money yet, neither would I like to hit their servers and cost them bandwidth.

So I'd like to torrent this. I did search and haven't found a torrent yet.

Could someone who has already downloaded it please put up a torrent?

Comment: Re:Thinkpad T440s (Score 1) 385

by steveha (#49293693) Attached to: Ask Slashdot: Choosing a Laptop To Support Physics Research?

Or you know, you could configure the ThinkPad you are buying to have a quadcore and a 3K screen.

The T440s is the "Ultrabook" form factor; it tops out at dual-core, and 1920x1080 screen size.

The T440p is the "performance" form factor, and has quad-core available, but it's thicker and heavier.

I just checked the Lenovo web site, and the T440s is discontinued. They are now on the T450s and T450p. The T450p does have a quad-core i7 option and a 3K screen option. It can also be equipped with 16 GB of RAM (vs. max 12 GB for a T440s).

I'm only recommending the ThinkPad I have. I would rather have my T440s than a MacBook Pro, but I'm not sure how well I would like a T450p (thicker and heavier; weight listed as "starting at 5.5 pounds"). Also, the top-spec T450p, if ordered directly from Lenovo, would cost more than a 15" quad-core MacBook Pro.

I think in modern science, the heavy computation is likely being done on servers rather than on laptops, so it would make more sense to go thin and light on a laptop. I'm happy with the T440s so I recommended it.

Comment: Thinkpad T440s (Score 1) 385

by steveha (#49286643) Attached to: Ask Slashdot: Choosing a Laptop To Support Physics Research?

If she's spending her own money, it's hard to beat the value of a Thinkpad T440s. It's an "Ultrabook" so it's similar form factor to a MacBook Pro. Great screen, good battery life, good processor, and Linux works out of the box.

She will need to get a mini-DisplayPort to HDMI adapter, for giving presentations where there is an HDMI connection to use. The T440s has both mini-DisplayPort and VGA connectors built-in.

I have one running Linux Mint 17.1 64-bit MATE. I got the top-of-the-line one with the 1920x1080 display, which I recommend. I got mine from B&H Photo in New York; it was significantly cheaper than other web sites I checked.

I have mine set up on a docking station, which came with its own power supply. So its power supply stays in my laptop travel bag, ready to go. Just undock and you are good to go. This is one way in which this is actually better than a Mac.

The Mac will cost $700 extra, and come with a higher-resolution display, a quad-core processor, and more RAM. That may be a better deal for her if she plans to do a whole lot of work directly on the laptop, rather than using the laptop to access remote computers.

P.S. I recommend that she take a look at the IPython Notebook, if she hasn't already. Running SciPy under IPython will be great for her.

My favorite: XKCD-style plots in SciPy

Comment: Re:i don't get it..... (Score 1) 82

by steveha (#49279969) Attached to: 3D Audio Standard Released

Now that you explained your points I don't think I disagree with you about any of the technical stuff.

I interpreted "nothing is mixed in Neural Surround" as "Neural Surround does not mix anything" which wasn't your intent. I agree that there isn't much content in Neural Surround; that press release was from 2006, and I don't know if that radio station is still doing the 5.1 broadcasts or not.

I'm a feature film sound designer and mixer, DTS is completely out of theatrical and television -- the original theater format is owned by a different company now

Correct. DTS the company split into two, and the theatre-related one changed its name to Datasat.

"optimized" for Neo:X

I think that "optimized for Neo:X" might also mean that an audio mix with height channels might have been run through a downmixer to get a suitable 7.1 mix that can be upmixed properly to 11.1. I don't know if Expendables 2 has helicopters or planes flying overhead, but if so, the people who bought height speakers might as well get some sound out of them.

"Object-oriented" audio encoding formats solve the problem in the best way: if there is a helicopter overhead, there will be an audio object tagged "overhead" and the mix can be adapted to whatever speakers the user has. If the user has height speakers, they get used. That's what I want for my living room anyway.

Comment: Re:i don't get it..... (Score 1) 82

by steveha (#49279445) Attached to: 3D Audio Standard Released

[DTS Neural Upmix is] marketed as a spatializing upmixer that can also decode Neural Surround (which is a third format not necessarily related to Neo:X).

No, there is no "Neural Surround" format as such. Neural Downmix uses phase encodings and the output is just an audio stream (can be analog, saved as a wave file, saved as DTS Master Audio, saved as MP3, etc.).

Look at this PDF. There are two columns: one shows different disk formats and how many bits per second each one needs; the other column has one thing in it, Neural Surround. This is because Neural Surround isn't a format as such.

See also this press release. A radio station was broadcasting in 5.1 using Neural Surround... broadcasting in ordinary stereo FM as well as HD radio. Anyone could listen in stereo, but those with Neural Upmix in their stereo receivers could hear 5.1 sound.

But this feature is sorta incidental, as literally nothing is mixed in Neural Surround.

I'm sorry but you are completely mistaken on this point. Let's look at the DTS web site again:

DTS Neural Surround DownMix technology reduces multichannel surround sound to a stereo mix that accurately represents the original intent of the content creator.

The DTS Neural Surround DownMix uses patented âoeActive Correctionâ technology. By analyzing the audio, the phase and intensity are rewritten, creating a pristine Lt/Rt stereo mix.

This process eliminates problems that traditionally occur in matrix surround downmix systems, such as comb filtering and spatial distortion. DTS Neural Surround DownMix creates a natural sounding stereo mix that is spatially true to the original multichannel localization.

Note the phrase "pristing Lt/Rt stereo mix" and the concerns about comb filtering in the output mix. There is mixing going on here.

DTS Neural Downmix produces a stereo output stream which may be saved in any format. You can feed the result to DTS Neural Upmix, even as an analog waveform, and it will upmix using the encoded signals. There is no disk format for "DTS Neural Surround" as such.

My understand is that the height channels are encoded sum-and-difference with the main L-R channels, and a special decoder reads reads additional channel data to subtract out the height channels from the mains.

I think it is possible that there is some additional metadata embedded in the DTS Master Audio bitstream, because old DTS decoders do understand metadata tags and will ignore them. But there is no bitstream change from plain DTS 7.1 to DTS 11.1, and you can play the 11.1 stream on an old DVD player and you will get 7.1 out. (Just like you could play Dolby Surround on a stereo and get stereo out, if you didn't have the Dolby Surround decoder to upmix from stereo to surround.)

If you are still convinced that DTS 11.1 has additional discrete channels, please find a reference and show me. If I'm wrong, I'm wrong, but I think the DTS web page I referenced in the previous post backs me up.

By "actual format" I mean its a communications channel where the sender and recipient agree on what goes into the channel and what is supposed to come out.

Then I would say that DTS 11.1 is an actual format exactly the way Dolby Surround was an actual format. Both rely on specific, agreed-upon phase encodings that are decoded to produce additional channels, and both are played back on older equipment just by playing them back. (Possibly DTS 11.1 uses metadata tags, which have no real equivalent in analog audio. But both just play back unchanged on older equipment; there are no extra channels to be dropped.)

Comment: Re:i don't get it..... (Score 1) 82

by steveha (#49278313) Attached to: 3D Audio Standard Released

There's a fundamental difference between an encoded mix and an upmixer. Dolby Surround is intended to be decoded from 2 tracks into LCRS, the filmmakers mixed the film in Dolby Stereo and were listening to the surrounds so they know what's in them. The phase encoding is part of the channel spec.

I'm with you so far.

An upmixer takes a stereo or 5.1 mix and applies effects to it to make it sound like it was mixed in a wider format, but there's nothing really being decoded, it's just synthesizing or guessing what should be in the additional channels using heuristics, all-pass filters, delays, crossover networks and other stuff that sounds cool or "provide a good experience" but, in fact, interfere with the filmmaker's intent.

The original Dolby surround and DTS Neural Upmix can both be applied to any stereo recording and some sort of upmix will occur, but both were designed to be used with a mix that was intended to be upmixed. DTS also sells DTS Neural Downmix which can take a 5.1 or 7.1 stream and output stereo with intentionally encoded signals that decode back to 5.1 or 7.1 sound.

When DTS Neural Upmix is working from a stereo signal that was made using DTS Neural Downmix, you get a really clean surround sound with no leakage. I used to listen to the multichannel recording of "Money" by Pink Floyd, and the cash register and coin sound effects very cleanly came from all the different directions like the original multichannel mix.

Again, you can't fit 8 kilos of flour into a 2-kilo sack, so 7.1 audio sent through downmix, then upmixed back to 7.1, can never perfectly reproduce the original multichannel recording. But I was impressed by just how well it did.

Despite the name "Neural Upmix", it is designed to work with phase-encoded signals intentionally mixed using Neural Downmix.

Neural Upmix is an upmixer, DTS Neo:X is an actual format that decodes an 11.1. Neo:X home receivers also employ upmixing, mainly because no films are mixed in 11.1 Neo:X, it's a surround audiophile format, and it needs to do an upmix in order to justify people spending money on it.

My understanding is that DTS 11.1 audio uses intentionally encoded signals for the height channels, but the on-disk format is DTS Master Audio 7.1 (no additional discrete channels).

Just as the original Dolby surround could be listened to in stereo if you didn't have surround speakers, the 11.1 mix can be listened to in 7.1 if you don't have height speakers; in both cases, the downmix process is supposed to not add anything objectionable.

I don't know what you mean by "DTS 11.1 is an actual format"... if you mean that it has 12 discrete channels, I believe you are mistaken on this point.

Here's how DTS describes the 11.1 system:

An important goal of the DTS multi-tiered plan is to enable content creators to produce 3D audio and provide it to consumers without changing the delivery chain. With the DTS Neo:X capability for near discrete Height/Wide output, studios can produce directional cues intended only for these speakers, with no audible leakage into other channels. Studios can also produce soundtracks optimized for DTS Neo:X that offer a compatible listening environment in âoestandardâ multi-channel playback configurations.

From the "How it works" tab on this page:

"without changing the delivery chain": no new audio format, disks play fine on older DTS decoders

"no audible leakage": there's no problem with leakage if you have discrete channels; if we are even talking about leakage, we are talking about an upmix.

I don't believe Imade any mistakes in my original post.

Comment: Re:i don't get it..... (Score 3, Interesting) 82

by steveha (#49277503) Attached to: 3D Audio Standard Released

binaural = stereo

Actually in the audio world, "binaural" is used to specifically mean a recording intended for being played directly into the ears.

I was once present for a binaural recording session. The guy doing the recording had brought a fake human head, and the two microphones for the recoding were positioned in the two ears. The idea was to reproduce as fully as possible what you would have heard if you had been sitting in that spot in the room, with your head in that position.

You can listen to a binaural recording on speakers of course, but for the best experience you should use headphones.

For the absolute best experience, the recording should use a fake head that is exactly like your head. Not many people are ever going to experience that.

Audio can do funny things as it travels around your head. For the absolute best 3D experience with headphones, you want to measure what happens to audio around your head; this is called your "Head-Related Transfer Function" or "HRTF". Instead of recording the audio with a fake head shaped just like yours, companies can just record a good 5.1 or 7.1 recording, and then you can mix that down to a binaural stereo mix that is perfect for your head if you have your HRTF. According to the article the AES is standardizing a file format for HRTF data, so that the software you get will be more likely to be able to work with your HRTF data if you have it measured.

The ultimate in VR audio will be headphones with motion tracking, and real-time mixing that uses your HRTF and changes the mix as you turn your head. If something is supposed to be coming from your left, and you turn your head to the left, that sound should get louder; then if you turn your head away from it, it should get quieter. If this is done right it should be incredible. People have been working on this for years and I'm sure someone somewhere has done it right, but I haven't seen any commonly available products to do it yet.

But with VR goggles you should totally have VR audio like I described above. It would be really immersive.

3d audio = surround sound (5.1/7.1/8.1/etc)

Pretty much, 3D audio is intended to include speakers above the plane of the 5.1 or 7.1 speaker setup; the industry calls these "height speakers". DTS 11.1 audio, for example, has a standard 7.1 setup, and then 4 height speakers: two in the front and two in the back.

The current ultimate in 3D audio is a 22.2 setup, where the ceiling has a 3x3 array of speakers, there are speakers at mid height, and there are speakers at ground level. However, IMHO there is zero chance that 22.2 will catch on as an audio standard.

Before the 5.1 and 7.1 digital standards, there was Dolby Surround that was encoded within a stereo soundtrack. A simple audio mixer could "upmix" from stereo to surround. DTS Neural Upmix can make a very clean 7.1 from a stereo signal, and it works from an analog signal (it's not something tricky inside a digital encoded format). You can't get 8 kilograms of flour into a 2-kilo bag, and Neural Upmix 7.1 can't completely reproduce the same mix as you can play through 8 discrete channels, but it can provide a good experience.

DTS 11.1, as I understand it, uses technology similar to DTS Neural Upmix to encode the 4 "height" channels within the other 7.1 channels. Turning 7.1 into 11.1 should be a lot easier than turning 2.0 into 7.1 so it should provide a good experience.

I expect the industry to go to "object oriented" audio. This means that audio will have metadata tags saying what direction the audio is coming from, and then a real-time mixer upmixes from the digital format with the metadata tags to whatever mix you need (i.e. if you have 11.1 speakers you get an 11.1 mix, if you actually have 22.2 speakers you get that, if you have 7.1 you get that, etc.) I believe Dolby Atmos works this way, and I believe DTS will be coming out with something similar.

Few people even want a standard with 24 discrete channels of audio. It just makes more sense to encode the audio you need in a digital format and then mix it on the fly. In a 22.2 audio mix, if there is no sound coming from overhead, you have 9 channels being used just to play silence; with object-oriented you would simply not have any encoded signal tagged to be coming from overhead.

Comment: Re:price? (Score 1) 328

Despite my mentioning the Cree 4FLOW, I still recommend buying Cree's more-expensive but better-made bulbs. The 4FLOW costs less, but it has a much shorter warranty and isn't nearly as well made.

The 4FLOW would be perfect for a light inside a closet that's rarely turned on, but then if it's rarely turned on you might as well leave the incandescent bulb in there until it burns out.

Comment: Re:price? (Score 2) 328

I had a similar experience with fluorescents. I replaced most of the ordinary light fixtures in my home with special fixtures with a circular fluorescent bulb (not "compact fluorescent"). I liked the quality of the light and I figured I'd be saving electricity.

Then the fixtures started burning out. Sometimes it would just be the bulb, but usually it was the whole fixture. At first I replaced the fixture with another (at $20 per fixture), but eventually I decide it was stupid and I started replacing the fluorescent fixtures with ordinary fixtures that take standard bulbs. At the time I installed compact fluorescents. And of course the compact fluorescents, which would be easy to replace if they die, never die. (I don't care, I'm replacing them with LEDs anyway.)

As for avoiding burning your house down, I suggest you do as I do: buy Cree products. I get the top of the Cree line, the "TrueWhite" bulbs, but they have new "4FLOW" bulbs that cost less and run very cool.

The cheapest LED bulbs will be like the cheapest anything electronic: made at some random factory in China with possibly bad quality control and even possibly bad safety. Sounds like you had the bad luck to get a bad bulb. Sometimes it's worth it to pay a bit more for a name brand.

Comment: Re:price? (Score 3, Informative) 328

by steveha (#49246581) Attached to: New Crop of LED Filament Bulbs Look Almost Exactly Like Incandescents

waiting for a good price point

I don't know how much these cost where you live, but where I live I can get LED bulbs at Home Depot from $6 to $20 depending on quality and brightness. They have an expected lifetime of 20+ years, and I don't have to change the light in that time. To me, this is a no-brainer and I've been buying LEDs for my whole house.

In fairness, I know that the power company where I live is subsidizing the bulbs, and absent the subsidy they would cost more. But it seems likely that you might be able to buy subsidized bulbs where you live too.

Also, I just checked the EarthLED web site, and without asking me where I live, the site showed me a deal: $100 for a 20-pack of LED bulbs. I've never heard of the brand ("Euri") but surely you could pay $5 per bulb for something that will last so long?

I like the Cree TrueWhite bulbs and I pay extra for them. LED bulbs tend to be a bit too yellow, so Cree developed a "notch filter" that takes out some of the yellow from the light, correcting the color. But now the light is a bit dimmer since some was taken out; so Cree puts a few extra LED modules into the bulb. Result: same amount of light, better color, consumes a little more power but not too much more.

I have also replaced all the 48-inch fluorescent fixtures in my home with Cree Linear LS4 fixtures at 3500K color temperature. Wow, it's so much nicer light and completely silent. Totally worth it.

If you are using incandescent bulbs, and you replace your most-commonly-used ones with LED bulbs, you will save enough money on electricity to pay for the new bulbs within a reasonable time. If you already have compact fluorescent bulbs, and you don't mind their light, then LEDs aren't guaranteed to pay for themselves right away and it might make sense to keep waiting. Otherwise, go for it.

Don't be irreplaceable, if you can't be replaced, you can't be promoted.