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Graphene: Fast, Strong, Cheap, and Impossible To Use

MattskEE Re:wimpy talk (186 comments)

Graphene in addition to the engineering challenges does have some very fundamental scientific challenges as well.

The most important challenge is its lack of a bandgap meaning that graphene transistors cannot be turned off. That drawback means that while it may have a ~500GHz cutoff frequency on par with silicon and below the InP records it will not modulate current in an energy-efficient way, and while it can create some forms of logic the lack of a bandgap limits its power amplifying frequency to a measly 50GHz, well below the competing technologies. Contrast that with Northrop Grumman's recent 1000GHz amplifier, which is admittedly not a great amplifier since it is run very near its cutoff frequency it has 1dB or less gain per stage, but it works which is still quite impressive.

So far the various methods that can give graphene a bandgap also take away the extremely fast electron transport properties that made graphene so interesting for electronics in the first place. Some of us working on competing technologies wonder why hundreds of millions of dollars have been spent on graphene transistor development without solving the fundamental bandgap problem - of course we just want that money directed to our own research, but some of us try to be realistic about the capabilities of what we are developing ;-)

I'm sure graphene will be useful for some things but so far there are still some fundamental problems that need to be solved before using it for high-speed electronics for wireless applications or digital logic. We'll see how it does.

3 days ago
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Military Laser/Radio Tech Proposed As Alternative To Laying Costly Fiber Cable

MattskEE Re:Imminent Domain (150 comments)

Is the domain about the happen any time now?

Check your own grammar before pointing out somebody else's mistake. ;-)

about a month ago
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Military Laser/Radio Tech Proposed As Alternative To Laying Costly Fiber Cable

MattskEE Re:Rain attenuates the radio signal (150 comments)

Implemented well it should have a slightly lower latency because the propagation of signals in air is faster than in fiber optics. But the delay from customer to the ISP is probably only a small part of the latency anyway.

about a month ago
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LG's 0.7mm Smartphone Bezel Is World's Narrowest

MattskEE Re:Usability Nightmare (63 comments)

Cynical much? One phone does not need to be all things to all people in order to be successful. Not all of us need cases on our smartphones: in my 4.5 years of smartphone usage and two smartphones I have yet to damage my uncased phones in any way.

Since you need a case on your smartphone you should buy a different one, others of us enjoy the beautiful design of a tiny bezel. But I hope to keep my phone at least another 1-2 years so I'm not in the market currently.

about a month and a half ago
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Integrated Circuit Amplifier Breaches Terahertz Barrier

MattskEE Re:We use stuff like this (81 comments)

Why does the 3D printing matter? Some people do make ultra high frequency waveguide with 3D printing - in the case I'm familiar with they "printed" it on a stereolithgraphy machine out of a polymer, then gold plated all of the surfaces. It may have some applications for complex waveguide circuits which are not possible to make by other methods in a given size constraint. However, getting the plating thickness just right on such a small scale when you have to plate the inside of the long and super narrow waveguide tubes is difficult and conventional machining techniques are often faster and cheaper, and can have higher material quality than a printed or plated material.

The point of the Northrop Grumman work is that the circuit is integrated on a chip, so the waveguide interconnect will be relatively simple and simple objects can generally be made better, faster, and cheaper, by conventional techniques.

about a month and a half ago
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Integrated Circuit Amplifier Breaches Terahertz Barrier

MattskEE Re:Not solid state... (81 comments)

No, the electron transport in vacuum tubes is in a vacuum. Vacuum is not a solid.

about a month and a half ago
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What Will It Take To Make Automated Vehicles Legal In the US?

MattskEE Re:For Starters (320 comments)

If that is the rationale, then the car needs to be 100% automated, under all circumstances, with all liability going to whoever made the damned thing.

I don't see why that would be necessary. Effectively you are saying that insurance over the lifetime of the vehicle should be factored into the purchase price instead of allowing people to buy insurance policies. That's not a bad idea but I don't think that it should be a requirement.

Instead this can be treated like any product: you buy an insurance policy to cover damages and go after the manufacturer in cases of negligent manufacturing or design flaws.

about 2 months ago
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Haier Plans To Embed Area Wireless Chargers In Home Appliances

MattskEE Re:Sounds wasteful and stupid ... (61 comments)

They claim to use far-field power transmission (i.e. radiated power) rather than near field inductive coupling. The transformer analogy only works for near-field transmission but it tends to be difficult to get range. Far-field will be radiating power all over the place.

about 2 months ago
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Haier Plans To Embed Area Wireless Chargers In Home Appliances

MattskEE Re:Sounds wasteful and stupid ... (61 comments)

If power is transmitted using near-field methods such as the direct inductive coupling used in RFID, most cell phone wireless chargers, and electric toothbrush chargers then the power transmission is coupled directly to the recipient device, and if the device is removed and the transmitter is still running then very little power is radiated away. This is potentially quite efficient. If you use far-field transmission then power is being radiated away whether a device is there to receive it or not. In order for it to be efficient you need high antenna gains to focus the power into a narrow beam the size of your receiver antenna aperture and beamforming to actively steer it. Otherwise the antenna is just spraying a broad beam of power in the general direction of the receiver like your sprinkler analogy.

They say it's using far-field transmission of power:

WattUp's RF transmission, which operates at 5.7MHz and 5.8MHz, is referred to in the industry as "far-field" wireless charging. Energous is not the first company to come up with the idea.

At such low frequencies it would be very hard for them to implement high gain antennas and beam forming. Also at such low frequencies I wonder how it can really be far field since the receiver will be well within a quarter wavelength of the transmitter.

More information is needed to fully answer the question, but this sounds like a convenience feature rather than an efficient one.

about 2 months ago
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When will the first successful manned Mars mission happen?

MattskEE Re:oil discovery = terraforming (219 comments)

Isn't it nice not to have any locals complaining about extinction-size impacts?!

The Martian robots will be pretty pissed off though.

about 2 months ago
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Z Machine Makes Progress Toward Nuclear Fusion

MattskEE Re:Meanwhile in a suburban garage... (151 comments)

You take one Ampere-second (i.e. 1 Coulomb) of electrons per second, and accelerate them.

about 2 months ago
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No Nobel For Nick Holonyak Jr, Father of the LED

MattskEE Re:The Nobel Prize Committee blew it (276 comments)

The blue LED may have been harder than the red LED for the reasons that you give, but Holonyak did make some key accomplishments including the demonstration of a ternary alloy semiconductor and tuning the bandgap and thus color by varying alloy composition which has paved the way for achieving all of the different colors for LEDs in use today and is also used for the InGaN emission layer in the blue LEDs.

An alloy semiconductor instead of having, for example, one group III and one group V element in perfect 50% ratio in a uniform crystal structure mixes it up and uses two or more group III elements and two or more group V elements. In the case of Holonyak he used two group V elements: Arsenic and Phosphorous. At the time at least some people did not think that an alloy semiconductor would even work, and it is a little weird because the crystal structure is now non-uniform where a given group V crystal site contains one element or the other at random. In fact this randomness does slow down the electrons. Holonyak also showed that the bandgap could be tuned by varying the relative concentrations of the group V elements. You can read more about him in a nice IEEE profile.

I don't know enough about the history to say who should have gotten the Nobel, but certainly no matter who they selected somebody would have been snubbed.

about 2 months ago
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2014 Nobel Prize In Physics Awarded To the Inventors of the Blue LED

MattskEE Re:It's a boring choice (243 comments)

There isn't a limit of one prize per invention or discovery. The Physics and Chemistry Nobel prizes are frequently awarded decades after the original work was done.

The Nobel prize announcement did state that the significant impact of this invention was a factor in the selection. In addition to the huge commercial and societal impact of the work these researchers' work had a major scientific impact on the entire field of growth and properties of nitride semiconductors. LEDs are certainly the biggest application of nitride semiconductors but their work has also paved the way for nitride transistors in wireless and power electronics applications.

about 2 months ago
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IBM Solar Concentrator Can Produce12kW/day, Clean Water, and AC

MattskEE Re:12kW/day? (268 comments)

Yes, it's a very crude estimate, and more of a summertime number too here in the US.

In the US I would refer them to PV Watts which will take examine a database of historical solar data and tell you how much daily energy to expect through the year for different types of setups, even including solar panel fixed angle or angle tracking systems. But it will not take into account your point on the effect of diffuse light on concentrated systems.

about 3 months ago
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IBM Solar Concentrator Can Produce12kW/day, Clean Water, and AC

MattskEE Re:12kW/day? (268 comments)

It could also be 12kW peak, which with typical sunlight variation over a day would work out to around 60kWh per day.

Most of the time I see a non-technical article about solar with a kilowatt figure it's the peak power available from the cells, and as a first estimate you can multiply the peak solar power by 5 hours to get the daily output.

about 3 months ago
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WSJ Reports Boeing To Beat SpaceX For Manned Taxi To ISS

MattskEE Re:Hmmm .... (200 comments)

Boeing doesn't do development work without a contract. So, when they got a contract to start development of their capsule, they started.

And then they stopped working on it as soon as the contract ran out. They're waiting on a new contract to resume work.

And this is a part of why aerospace/defense contractors are so expensive for the government to employ, and I say that having worked at some of them. Stringing together multiple contract awards to try to get to a larger goal, and continually going through the proposal writing process. A commercial company with a goal can strive continuously towards it in a more efficient manner, and the goal is success, not hours billed on a cost plus contract.

about 3 months ago
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Artificial Spleen Removes Ebola, HIV Viruses and Toxins From Blood Using Magnets

MattskEE Re:Woohoo!! (106 comments)

The nanoparticles are magnetic, not magnets, which is an important different. It means that the nanoparticles will be attracted to an external magnetic field when it is applied, but they will not be attracted to each other.

Buckyballs were banned because if you swallow permanent magnets they can attract each other and could potentially pinch two parts of your intestine together, or other such unpleasant things which would be bad for you.

Swallowing permanent magnets: Bad idea.
Swallowing magnetic nanoparticles: Good idea assuming it passes the relevant medical trials for safety and effectiness.

about 3 months ago
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To Really Cut Emissions, We Need Electric Buses, Not Just Electric Cars

MattskEE Re:Everything old is new again (491 comments)

It's my understanding that the electricity for the trolley buses is free.

If San Fran owns the power plant it means that they have paid for the cost of construction and ongoing operating and staffing costs, and by using the power internally rather than selling it they are paying the opportunity cost of not selling it and making money.

Free in this case just means a cost that appears in a different ledger.

about 3 months ago
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$10 Bet Brings Researchers Closer to Industrial Scale Graphene Production

MattskEE Re:Confusing summary - here's my version (74 comments)

Well in addition to falling apart in your hands there are some concerns that free graphene can be carcinogenic in a similar fashion to asbestos... so I'll let you try the hammock first ;)

about 3 months ago

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