I have never understood how this was effective against a determined adversary. An arbitrary limit like 100ml is pointless when there is no limit to the number of times you can pass through the checkpoint.
I'm sure that going through security 5 times for the same flight is bound to trigger some extra screening and even if it doesn't, each time you cross through increases the likelihood of getting caught by the normal process.
Don't get me wrong, I'm sure a large part of it is just security theatre, but part of it is also just to be enough of a deterrent that a would-be terrorist chooses a different target.
Do you know that the 100 ml liquids gets scanned in the Heathrow airport? Many times they used to do a secondary scan too after the primary scan. I recall this very well because many times I was made to wait longer after my carry on arrived because they wanted to put the liquids through a secondary scan.
In many countries (Canada included) if you pass through security into the international terminal, you have to 're-enter the country' back through customs and immigration if you don't get on your flight.
Oh. So it was a security measure? I honestly thought it was a way to force you to spend money on things on the airport or abroad. Like shampoo, water, etc.
It was a reaction to a foiled terrorist attack in the UK where terrorists planned to blow up planes using liquid explosives disguised as bottles of soda.
It's also hilarious that the limit is the very metric 100ml, and not some even number of freedom units like 3 or 4 fluid ounces, like Jesus, George Washington, and bald eagles would have wanted.
The UK uses an odd mixture of both depending on context.
The use of "100ml" in airports is because using "3.519 fl oz" would be confusing to far more people. Even within the UK we use metric for small liquid measures like this (smaller liquid measures end up being weird stuff like "teaspoons" or "tablespoons").
And this isn't just because the UK uses a different fluid ounce to the US (100ml is 3.519 UK fluid ounces and 3.3814 US fluid ounces).
Anyone under the age of about 60 in the UK would had metric measurements taught to them at school as it became a mandatory to teach it in 1974. Many schools would have been teaching it already, and probably lots since the currency changed in 1971 (https://en.wikipedia.org/wiki/Decimal_Day).
The youth of today (as seen through the lens of my kids) are very metric, often defaulting to distances in meters and kilometers. Miles only seem to be used idiomatically, e.g. "he lives a few miles away".
I'm completely happy to switch between all of them not just because of my UK education covered them all, but I've lived for more than a year in the US, the UK and some European countries.
There are still plenty of examples of mixed measurement systems in the UK though.
Canned/bottled drinks are marked in ml, but a lot of that is due to the proximity to the EU and the previous ties to it. Open drinks are often sold in imperial measures (pints, etc) although spirits moved from fractions of a gill (imperial) to metric (25ml for a single, or 50ml for a double) in the mid 80s.
Of course the UK and US pints are different sizes (568ml and 473.176ml). Not just because the fluid ounces are different sizes as noted above, but also because the UK has 20 fluid ounces in a pint and the US 16 (of its) fluid ounces in a US pint.
For driving distances and speeds are based on miles, but for pedestrian distances you'll see a mixture of miles/yards or km/meters. Restricted heights (e.g. low bridges) or widths are covered in both feet/inches and meters given the number of European freight drivers on the roads here.
Occasionally you'll see some nonsense where a sign has displays both, and where the actual distance to something might be shown as "400 yards" it had almost certainly been rounded up/down to that whole number to make it simpler on the sign, but when it is converted to meters the converted value is used, so you see odd things like:
"
Whatever it is
400 yards
365 meters
"
(The UK traditionally used "metre" but that usage is quite rare now and we've mostly moved over to using "meter" like the US does.)
I'm surprised that the UK and US don't have different length miles (the US did have a different length "foot" but the "Survey foot" was discontinued in 2023).
Shots aren't necessarily 25ml, prior to metrication the legal situation had been that in England a shot was a sixth of a gill, in Scotland either a fifth or quarter depending on the establishment. The metric "Weights and Measures" legislation said each such licensed premises in the UK gets to pick, either 25ml (most common in England) or 35ml and they shall post a notice explaining to the public which volume they've chosen.
The differences in signage are because the UK's Road Traffic laws specify miles and yards still, whereas most other legislation specifies metric units, including for the waterways. So a sign legally required for an 18th century canal might say "100m" meaning metres, while an equally modern, legally required sign for a road built this century says "10m" meaning miles. This is embarrassing, but there's a strong feeling that somehow archaic unit systems are an important part of our heritage, and at least it's not as bad as when we propose getting rid of statues that celebrate slavers...
My best guess would be that slope detection could be converting the FM signal into AM. This happens in circuits where the response is strongly dependent on frequency (see [1]). A specifically designed filter is typically used, but a resonant circuit like the headphone wires could do something similar. But then you still need to get from AM to audible, and to do that you still need some sort of non-linearity in the system. Some possibility non-linearies could be a poor connection resulting in a whisker-style rectifier junction, or perhaps a magnetic permeability non-linearity in the headphone speakers. I'm sure there are others.
Related, but probably not relevant: Stereo FM broadcast signals in most parts (all parts?) of the world also contain an AM subcarrier. The primary FM carrier has the L+R audio content and is used by both monaural and stereo receivers. Stereo receivers make use of an additional AM modulated sub-carrier (+/- 38 kHz from primary carrier) to obtain L-R audio content. I don't believe this AM carrier is directly rectifiable because it does not manifest as envelope modulation in the full signal.
I've been down to McMurdo for a research trip. A couple of things that outsiders find surprising is that most of the people there are support staff and only a small fraction (maybe 20% or so) are the scientists. The support staff are basically people from all walks of life... fireman, carpenters, cooks, mechanics, etc. Basically everyone you need to make a modern city run. However, because of the selection processes, those folks are almost all extremely talented and at the top of their specialties. The number of "swiss army knife" individuals I met with very broad skill sets was astounding. The challenges associated with living and working down there tend to draw quirky and motivated individuals like bugs to a light. And many return year after year. It's a wonderful community.
I second this. I picked up one second hand a while back. The placard indicates it was built in 1997. It needed a good cleaning and had clearly seen a lot of use, but is perfectly functional. The shower arm was showing slight signs of rust around the hole but getting replacement parts is trivial as the design hasn't changed in decades.
Seems to work OK for me. I will point out that it is very "coarse" and only has 4 possible settings. Perhaps not the best choice for a slider, but perhaps they made that UI choice just to match the other sliders?
Strictly you can NOT actually get perfect models with 100% prediction for any coil design because magnetic fields can only be solved directly with Maxwell's rather than the simple algebraic equations being used by this app. That's generally OK because getting close is more important than perfect. You ALWAYS must physically build things like coils and validate them empirically by testing if you need "perfect". There is no other way (even using a 3D FEA using Maxwell's equations won't give you perfect either).
Very nice project. Much better than dealing with the raw tables/curves from Fair-Rite which seem to have been photocopied again and again over the ages.
Really nice of them to release this. However, unless I'm missing something, the HDL for the FPGA on the Time Card is not part of the release. It looks like it uses a proprietary IP core from NetTimeLogic
I built out a simple "technology access" solution for my late grandma about five years ago. It was just some simple scripts running on a raspberry pi. The scripts would fetch emails from a gmail account, extract the attachments, and display them on loop. The subject line of the email, sender and the date were overlayed on the image.
The advantage over those IoT picture frame products was that I could use any display I wanted. A cheap 32" TV was perfect. This was key as her vision degraded. The approach also allowed anyone in the family with email to send her photos, no proprietary apps or accounts required.
She passed away mid-Covid and I didn't get to see her in her final 6 months, but she always bragged of her "picture machine." I think she was the envy of many of her fellow nursing home residents!
For anyone in a similar situation I'd suggest trying with a regular PC or iPad first and seeing how that goes.
Maybe 7 years ago I set my parents (late 70s) up an old PC with Linux and a Gmail account. I was living in another continent so needed a way to send photos to them. Before this the most technologically advanced thing they had used was a VCR - and even that they had issues with. I was expecting they'd try it for a week then get frustrated and never use it again - and probably not say anything until the next time I visited.
Well the opposite happened, they really took to it. My dad even setup an online store trading LEGO. Yes of course there were issues (it took maybe 3 months of video calls to explain how to copy and paste), but they got there in the end.
The other week my uncle (same age, they are twins) talked through setting up my father on Zoom and he joined in a video call with a social group they went to. My mother doesn't use the computer as she has arthritis (and I don't think my father let's her :D), but flicking through Google Photos on an iPad lets her keep up with the grandchildren.
Kudos to you for doing that, and I'm sorry for your loss. I set up something similar a couple years ago for my 94-yo grandmother with failing eyesight, though my solution was a bit more off-the-shelf; I set up an old 32" TV and chromecast as a smart picture frame that would rotate through images from a specific Google Photos album. I then sent out a link and gave write access to the album to all of our family. Unfortunately it's now getting to the point where she even has trouble seeing those pictures. We also had success setting her up with an Echo with our Amazon Prime (got Unlimited Books) account to facilitate her listening to Audible books; every couple weeks or so we make her a curated list of Audible titles on Prime and she checks off which ones she wants and someone will load those up for her. The best part is that with her newer hearing aids, the Echo can play straight into her head over Bluetooth!
My other grandma have an iPhone that she barely know how to use (she still have the old one on the wall she love). I first call her, than tell her to tap the green button if she she want to use camera (switch to FaceTime).
This works great for us to keep contact.
Though both of this is solutions only allow us to initiate the contact. Here the Yayagram is brilliant!
I do that with my mother and it works well. However, it wasn't easy at all to set up, and she couldn't have done it on her own. The timing was fortunate since I got it for her before the pandemic.
Many modern FPGAs now include dedicated logic for config SRAM "scrubbing." This logic continuously checks config frame checksums to identify upsets. These can then be fixed in real-time either using the error correction properties of the checksum technique, or from the non-volatile config memory (typically NOR flash). It's also important to note that only a subset of the SRAM config bits are critical for a given application. Usually this is a small percentage of the overall array.
If even higher levels of reliability are needed, there are rad-hard-by-design FPGA families (e.g. Xilinx Virtex 5QV). These have a special config SRAM cell that has more charge storage sites than a conventional SRAM cell. It is less area efficient than a conventional SRAM cell, but geometry of the charge storage sites ensures that a single cosmic ray can't flip the state of a majority of them. Essentially the cell can self-correct, no scrubbing required.
People everywhere, regardless of their race, religion, politics, or wealth are generally decent and primarily interested in making a better living for themselves and their family.
Some may see this as an obvious fact about human nature. However, for someone like me who grew up viewing the world through the lens of the US media, I used to think otherwise. Travel fundamentally changed my views in this regard.
