Recent content by Mark R

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Anyone in the UK? How does VAT work for Amazon purchases?

Yes. You are right, to a point. You do occasionally see some fiddling like this going on - if you check adverts for businesses for sale, you see a suspicious number for sale with annual sales just a sliver below the VAT threshold. However, the advantge isn't quite as big as you might think all...
- Mark R
- Post #8
- Sep 5, 2018
- Forum: OT Discussion Club
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Anyone in the UK? How does VAT work for Amazon purchases?

There are minimum limits for a seller to charge VAT. If a seller's total business turnover is below a certain level, then they do not need to charge VAT (and in fact, to reduce admin for the tax authorities, the tax authorities often say that small sellers are not allowed to charge VAT). If a...
- Mark R
- Post #6
- Sep 5, 2018
- Forum: OT Discussion Club
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HOLY

Maybe it's just me, but I am disturbed by the question. WTF is a television license? I don't think they have those in the UK. Did you perhaps mean a television licence?
- Mark R
- Post #24
- Mar 17, 2018
- Forum: OT Discussion Club
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Florida pedestrian bridge collapses onto roadway, cars. Was up for 5 days

There was no other support structure. The "suspension" cables were apparently not intended to be load bearing stays, and instead were a stiffening element for damping of wind induced oscillations. The bridge was intended to be a completely self supporting truss. The thing that is interesting...
- Mark R
- Post #87
- Mar 17, 2018
- Forum: Politics and News
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Is this OK encryption?

This encryption system was considered unbreakable at the time it was invented, and for some time afterwards, such that it became legendary and known as "the undecipherable cipher". That, however, was in 1553 and while it took 300 years for encryption theory to discover how to break it, things...
- Mark R
- Post #20
- Jan 24, 2018
- Forum: OT Discussion Club
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speed of gravity

I just thought I'd post an interesting update, as no one else seems to have done so yet. A subsequent gravitational wave observation (GW170817) of binary neutron star merger and the timings of the corresponding near-simultaneous optical/gamma ray observations from the distance of the source at...
- Mark R
- Post #181
- Nov 6, 2017
- Forum: Ask a Technical Professional
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Distributing points across the surface of a sphere

Anyway. I thought I'd post the code and an explanation of how it works. By modelling the system as electrostatically repelling charges constrained to a spherical surface, it is possible to find the optimal solution. I wasn't able to find an analytical solution, but the problem is numerically...
- Mark R
- Post #2
- Oct 29, 2017
- Forum: Programming
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Distributing points across the surface of a sphere

I was thinking about this problem, as it comes up obliquely at work, albeit as a solved problem as part of a piece of equipment. So, I set about thinking how to solve this. There's not a lot to find on the internet about this, so I actually had to do this from scratch. Anyway, I had a fun...
- Mark R
- Thread
- Oct 28, 2017
- Replies: 2
- Forum: Programming
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"We Do Not monitor user activity nor do we keep any logs." (VPNs)

You need to read the small print carefully: From pureVPN's T&C: In this case, the FBI had precise times at which the events occurred. Even though the VPN provider may not have had any logs about what activity was taking place, they did have logs about which IPs were making incoming...
- Mark R
- Post #5
- Oct 8, 2017
- Forum: Security
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electrolytic copper

You need to watch the current: Industrially, this is usually done at about 200 A/m2 - a high voltage is not required. 3-5 V should be sufficient and will avoid heating. There are a few additives which might help a bit - add a bit of sulfuric acid (check out a hardware store for drain cleaner...
- Mark R
- Post #6
- Aug 21, 2017
- Forum: Ask a Technical Professional
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electrolytic copper

Substances with soluble sulfates will go into solution. The solution will therefore gradually increase in concentration of things such as zinc and magnesium, if these are present in the anode. Magnesium is too reactive and will not be electroprecipitated from an aqueous solution. As copper is...
- Mark R
- Post #2
- Aug 19, 2017
- Forum: Ask a Technical Professional
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What Is Meant By "Inline UPS"?

Typically large UPSs for industrial or data center are online, although some can be configured into a standby mode, if desired. However, there is a difference between the switching used in an industrial grade UPS and a home/SOHO grade UPS. Low cost UPSs use a mechanical relay to switch from...
- Mark R
- Post #11
- Aug 18, 2017
- Forum: OT Discussion Club
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speed of gravity

There is, from the detection of gravity waves by the LIGO instrument. Under current models, if gravity travelled slower than the speed of light (because it was carried by massive gravitons), then you would expect the velocity of gravity waves to depend on wavelength, a phenomenon known as...
- Mark R
- Post #180
- Jul 16, 2017
- Forum: Ask a Technical Professional
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Best GPGPU framework

I'm going to need to use the GPU for a project for reasons of brute force computation. I've only ever used DirectX, and while my work is image based, the computations are such that they would be best done with a more general framework, and while they could be done with pixel shaders, I'm...
- Mark R
- Thread
- Jun 27, 2017
- Replies: 4
- Forum: Programming
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London Burning

Thought I would post an update, because this is still all over the UK news and this is turning into a major problem nationally. Investigation is focused on the building cladding. However, many other violations have come out. It turns out that natural gas had been installed in individual...
- Mark R
- Post #53
- Jun 27, 2017
- Forum: Politics and News

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