46,000 Year Old Frozen Worms

Nematodes. Image courtesy CSIRO, CC BY-SA 3.0 via Wikimedia Commons.

Your freezer doesn't kill germs like high temperatures in an oven does, it only slows down their metabolism so the reproduce more slowly. One of the the reasons germs are a hazard is because they manufacture toxins as waste products. Therefore, even cooking food at normal temperatures that has "gone off", while killing the germs, doesn't necessarily render those toxins harmless. If you've ever put tomatoes or other watery food in a freezer, you'll know that they become mushy when thawed. That's because all living things are built from cells, just like Lego. The cells are like capsules of water which burst when water expands on freezing, causing a loss of structural integrity and limpness in a fruit such as a tomato (Is it a fruit or veg? That's another argument!). Half-hardy flowers such as petunias are damaged by frost for the same reason, but hardy flowers have "anti-freeze" in their cells. This prevents the cellular fluid from freezing at low temperatures, so the plants can withstand severe frosts. Possibly this is the mechanism by which this worm survived 46,000 years in permafrost, having evolved and achieved this survival technique.

Drag Acts

Image: Heavens-Above

 

The atmosphere doesn't end at a certain altitude, it just gets thinner and thinner. According to NASA however, the Karman line at an altitude of 62 miles is generally recognised as a boundary, and 99.99997 percent of Earth's atmosphere lies beneath this level. It's also speculated that a cloud of hydrogen atoms around the Earth, called the geocorona, may extend to over twice the distance between the Earth and the Moon.

The International Space Station (ISS) orbits at an altitude of 370–460 km.

Curtain Pole Polishing and Silicone Emulsions

So my curtains have been sticking for weeks on the poles and I got around to cleaning them today. It's amazing the amount of crap that builds up. I presume everyone knows that furniture polish is great for making the rings slide easily? Also good for the rails on mitre saws.

Mr Sheen contains silicone emulsion and PEG-40 hydrogenated castor oil which I presume are what do the polishing.

An emulsion is a non-soluble solid suspended in a liquid (e.g. emulsion paint or milk). More info on silicone emulsion here.
https://www.elkem.com/products/silicones/emulsion/

This is what accumulates on curtain poles. © Eugene Brennan

 

You Can't Have Too Many G-Clamps

Boots without soles. © Eugene Brennan

I'm glueing back on the soles that came off my boots after the tree planting at the Field of Dreams a couple of weeks ago. The boots are probably nearly 30 years old, but not worn much because they don't have any sole or toe protection, and I've worn out a few other pairs of safety shoes and boots in the meantime. According to CAT Footwear, the adhesive degrades (and also the soles. A new pair of safety shoes I had in storage for 9 years only lasted three weeks after I started wearing them).

Clamps for holding the glued soles onto the boots. © Eugene Brennan

Seebeck Effect Demo

A microammeter. © Eugene Brennan

See previous article about spacecraft power for an explanation of the Seebeck effect. This is a simple thermocouple I made tonight from a piece of scrap copper wire from 1.5 mm² flat T&E lighting cable and heating element wire from an old hairdrier (probably nichrome). The ends of the two pieces of wire are twisted together and the other ends connected to a microammeter. Then the twisted together ends are heated with a blowtorch. It generates 26 mV and a current of about 20 μA (20 millionths of an amp). Lots of these are connected in series or series-parallel (to increase both voltage and current) to make a thermopile for providing power in spacecraft.

Thermocouple made from copper and nichrome wires, joined at the end. © Eugene Brennan

The thermocouple was connected to a microammeter. © Eugene Brennan

....voltage was also measured. © Eugene Brennan

How Do Spacecraft Get Their Power?

Rocket engines are used for propulsion on spacecraft, but the electronics has to be powered also. Frequently solar panels are used for generating electricity. But what happens if a space probe is so distant from the Sun that it's just a pinprick of light like any other star?

The Seebeck effect

If you heat the end of a piece of wire, it establishes a thermal gradient from the hot end to the cold end. This causes charge carriers (electrons or "holes") to move from one end of the wire to the other, resulting in a potential difference or voltage between the two ends of the wire. This is called the Seebeck effect. Devices that make use of this effect are called thermocouples and there's one in your oil or gas central heating boiler for measuring the temperature inside the burner chamber. A thermocouple is made of two wires of dissimilar materials twisted or bonded together at one end and can measure temperatures of over 1000 degrees C.

 

A thermocouple measuring circuit. Image courtesy Wtshymanski, CC BY-SA 3.0 via Wikimedia Commons

Thermopiles

Now as you may be aware, if you connect lots of batteries in series, e.g. AA cells end to end, the voltages add up. So for instance in a transistor radio, four AA, 1.5 V cells give 6 V for powering the radio. The electromotive force (EMF) or voltage generated by a single thermocouple is typically small, of the order of tens of microvolts per degree of temperature difference between its hot and cold end. If hundreds or thousands of thermocouples are connected together in series, they can generate useful voltages. This arrangement is called a thermopile. If all the junctions between the wires are made hot, and alternating junctions are kept cold, the device can generate electricity to power things. Thermopile powered radios, running on oil lamps, were used in remote areas of Russia in the past where electricity and batteries were unavailable.

 

Radioisotope thermoelectric generators (RTG, RITEG)

A radioisotope thermoelectric generator is a thermopile that uses a radioisotope source to heat the hot junctions of a thermopile while the other junctions are kept cool. The radioisotope source is typically materials such as uranium or plutonium. RTGs can generate hundreds of watts and were used in the Voyager 1 and Voyager 2 spacecraft, launched in 1977. The Perseverance Rover on Mars is powered by a 110 W RTG using Plutonium-238 as a heat source.

References

NASA. (n.d.). Mars 2020: Perseverance Rover - NASA Science. NASA. https://science.nasa.gov/mission/mars-2020-perseverance

Rowe, M. (2020, October 23). Thermocouples: Simple but misunderstood. EDN. https://www.edn.com/thermocouples-simple-but-misunderstood/ 

Thermo-electric generators. (n.d.). http://www.douglas-self.com/MUSEUM/POWER/thermoelectric/thermoelectric.htm

 

 

 

BBC World Service — How Green is AI?

Generated on request by Bing Image Creator.

I heard the first part of this at 2:30 am this morning on the BBC World Service, then fell asleep. Pioneering computer scientist Sasha Luccioni has just been announced as one of the people on the BBC 100 Women list. She was talking with presenter Zoe Kleinman about the increasing amounts of energy being used by AI. 

The BBC World Service originally broadcast on shortwave in Europe, but transmissions on the SW bands ceased in 2008. It also broadcast to Britain on MW. It still broadcasts on 198 kHz LW when BBC Radio 4 closes down at 1:00 am. This was useful for anyone with a bedside radio having an LW band. I've been listening to it and Radio 4 on and off since the 80s. However with the amount of electronic gadgets in a house nowadays generating EMI, including chargers, burglar alarms and broadband modems, that's increasingly difficult because of the interference. However next year it's planned that transmission will cease on LW, so we'll have to listen using an app or Internet enabled radio.

Mill Stream Gauging Station

© Eugene Brennan

Some more technical information here on the gauging station at the bridge over the Mill Stream on the Mass path. The station measures water level and flow rate. It was constructed in 1999. The weir on the downstream side of the bridge is a flat-V type, not rectangular as I suggested in an earlier post. These structures are used in hydrometrics for measuring flow. They can be rectangular, V-notch, broad-crested etc. The idea of a weir is to cause water to backup behind it and change in level. By measuring the level of water above the base of the weir, flow rate can be calculated. In theory, flow rate can be calculated knowing the cross sectional area of flowing water and measuring its velocity. Simply multiplying the two parameters together gives flow rate. So for instance if a stream is 2 m wide and 1 m deep, and water flows at 1.5 m/s, flow rate is 2 x 1 x 1.5 = 3 cubic metres per second. However, this would still require water level to be measured because it varies depending on whether there's high or low flow. More significantly however, velocity varies within the flow. (Fast in the middle of a stream and slower towards the edges and bottom because of drag). So making a velocity measurement at one point would be inadequate. Using a weir simplifies the calculations. Various types of weirs have been studied and empirical equations worked out (i.e. by making measurement from models, not worked out analytically) giving flow rate versus water level. Level is usually measured using an ultrasonic transducer that sends out a sound beam and detects an echo. Knowing the transit time of the beam and the speed of sound, distance can be measured to the water surface, which is then converted to a level measurement (similar to the way an ultrasonic measuring tape works).

The Spire of Dublin and Dampers

The Spire of Dublin. Image courtesy Vmenkov. CC BY-SA 3.0 Unported via Wikimedia Commons.

Did you know The Spire in Dublin has a shock absorber? Technically these are called dampers and your car and even your washing machine has them to reduce vibrations. Dampers are also used on doors, cupboard drawers and even toilet seats to slow their movement. Many large structures such as bridges need dampers to reduce oscillations caused by wind or vehicular traffic.

Resonance 

 

All objects have a natural frequency that they tend to vibrate at. The phenomenon is called resonance and that's how musical instruments work. A column of air in an organ, string on a guitar or bell will vibrate or oscillate at its natural frequency when struck, plucked or vibrated using a reed. If you blow over the mouth of a bottle, the air inside vibrates at a certain pitch. Resonance frequency depends on several factors including physical dimensions, speed of sound in air and mass of the object that's resonating. So in an organ or piano, the longest pipes or strings respectively give the lowest notes. Large structures can resonate due to strong winds and eventually the oscillations can build, ultimately leading to destruction of the structure. (Think of pushing a child on a swing and pushing at the right moment causes the swing to extend further and further).

 

What's a damper?

 

Dampers are used to reduce oscillations so that they continue to decrease in size and die out.

A mechanical damper is typically a cylinder with a piston and also an external coil spring. The viscous damper is connected to the object being damped. As the piston slides along the cylinder, filled with air or oil, viscous friction slows it's movement, converting the energy of the oscillating object into heat and reducing the amplitude of oscillations and causing them to decrease in amplitude.

The Spire of Dublin

 

The Spire in Dublin is a 120 m tall structure and to reduce potentially damaging oscillations, a damper is built inside its structure. The reciprocal of resonance frequency is the period. This is the length of time it takes to do one complete oscillation. So if a guitar string vibrates 100 times a second (100 Hz), the period of the oscillation is 1/100 = 10 mS. The period of The Spire has been analysed as 3.65 seconds. That means when it's oscillating, it sways backwards and forwards once every 3.65 S. To absorb the oscillations and damp them out, the damper was tuned to this frequency. It consists of two large masses, 2 tonne weight in total, attached to the inside of the structure by viscous dampers. You can read more in this article.

Home Maintenance Blues

© Eugene Brennan

Lot's of things to fix this week: shower doors sticking and heating not working. I think the circulating pump is stuck in the oil boiler. Will investigate and try to unstick it before the plumbers get involved.

Edit: Just as predicted, the pump was stuck and this isn't so good. These pumps usually have a slot at the end of the impeller shaft (under a screwed on cover) that can be turned to unstick the shaft. Not much hope of doing that because of the way it was plumbed, facing away and up against the insulation. Anyway a few taps with the handle of a mallet unstuck it (Don't hit these with anything hard. In fact, don't do any of this at home unless you understand basic safety procedures working around electricity)
Chances are it may be on the way out, but fingers crossed. I've saved €230 for the moment.

The Mill Stream in 2015, Kinetic Energy and the EPA's National Hydrometric Programme

Flow wasn't quite as strong today, but it could be once all the rain from last night soaks through the ground and makes its way into watercourses. This video was from October 2015 after a long, wet autumn. The water level was up to the 4th rung from the top of the ladder (half a rung spacing lower today in the video at the end of this post). At some stage, I want to do back-of-envelope calculations to see what the max energy output would be if the stream was harnessed. Kinetic energy can be calculated simply by measuring width, depth and speed of the flow to get cubic metres per second and working from there. Surface speed could be checked by timing how long it takes something floating on the surface to pass between two points. Speed wouldn't be constant from surface to bottom of the flow or from centre to the banks because of friction, but the streambed under the bridge is smooth and level, as are the walls, so velocity profile is known for such shapes (This is effectively a rectangular weir, used by the EPA to do hydrometric measurement). 

 

Data for the "Kilcullen Stream" is available here on the EPA's HydroNet website. (Isn't this the "Mill Stream")? 

 

Data available on the EPA's HydoNet website. Image courtesy EPA.

 

What's the tube at the side of the bridge?

 

This is the stilling chamber of what's called a gauging station by the EPA. The stilling chamber is used to make the surface of water less turbulent so that stream level can be measured with an ultrasonic sensor (which needs a level surface to get a reliable echo for measuring distance). I'm not sure whether they actually use a logger here to measure levels continuously. There's no antenna for telemetry, so possibly data is downloaded every so often or more likely transmitted using a GSM modem over the mobile phone network. A Yuasa type battery would power a setup like this because the electronics only has to wake up every 15 minutes or so, take a measurement and then go to sleep again. (Similar to the way a wireless doorbell sounder only wakes up every second or so to detect a button push). There's also a scale at the station for taking manual depth measurements.

More information about the EPA's National Hydrometric Programme is available here.

 

 Mill Stream December 7th, 2024

 

Science Friday Podcast — Oliver Sacks Interview

Created on request by Bing Image Creator

 

In an interview from 2007, presenter Ira Flatow talks about the brain with the late Oliver Sacks, neurologist and author of Migraine and The Man Who Mistook his Wife for a Hat. The latter is a fascinating anthology of case studies of people with various neurological conditions, worth reading. The book is presented as a collection of 24 essays, dealing with loss of brain function and heightened abilities or skills in patients with autism or having prior exposure to drugs.

BBC World Service — The Deepest Man-Made Hole in the World

Kola Superdeep Borehole. Image courtesy Andre Belozeroff, CC BY-SA 3.0 via Wikimedia Commons.

I was listening to this in the early hours of the morning. Witness History is a short factual insert in the BBC World Service schedule in which the interviewer speaks to someone who was present at events of historical importance. In this program, the presenter Rachel Naylor was talking with Prof David Smythe, a geophysicist who worked at the Kola Superdeep Borehole site in Russia for four months. The borehole was drilled to a depth of 12 km.

Chopping Off My Finger and Fingerprints

Image created on request by Bing Image Creator.

I’m reading Chapter 8, “The Human Touch” of Irish physicist Laurie Winkless’s book Sticky: The Secret Science of Surfaces.

In 2014, I was doing a spot of gardening at the entrance into my house. The Virginia creeper growing along the wall had covered over the gate pier and was threatening to swallow the gate as well, so it was time to get it back under control. I started to cut it back with a secateurs and after a few minutes of snipping, I ended up on autopilot: snip, pull back, snip pull back, while thinking about other things and losing concentration. I lost visual contact with the secateurs under a clump of vegetation just as a car blew its horn on the road. I looked up while doing one more snip, and felt a dart of sensation, but strangely not intense pain. (Like those stories of people having their leg bitten off by a shark and not being in agony straight away). Realising immediately what I had done, I was terrified of looking down to see what damage I had caused. “Luckily”, I had only cut a piece off the tip of my forefinger the size of half a baked bean, Gross alert! (which I recovered later that day). I went into survival mode straight away. I wrapped my finger in kitchen towel and made my way down to my GP’s clinic. They said they couldn’t do anything with it, and gave me a letter for A&E. Someone gave me a lift into Naas Hospital and after a short wait, an emergency technician dealt with the wound. First they gave me several anaesthetic injections in my finger (not pleasant) and then irrigated the open wound (which was equally unpleasant and uncomfortable). Maybe it hadn’t fully kicked in, but the anaesthetic only seemed to work on pain nerves and not all the other types of sensors and nerves in skin that are sensitive to touch, temperature, pressure etc.) To cut a long story short, my finger totally recovered after a few weeks and even though I had completely lost the top of it and the fingerprints, it magically regrew, complete with prints. It’s still a little bit sensitive when I touch things (with a slightly uncomfortable sensation like when you hit your “funny bone”, presumably due to raw nerve endings), but not something I consciously think about. In the chapter of Laurie Winkless’s book about skin, we learn how it’s a sense that’s unappreciated in its complexity and ability to detect many different sensations. We can also detect roughness on surfaces only a few atoms thick and fingerprints apparently have “roots”, which allow them to grow, luckily for me.

Toyota's Portable Hydrogen Cartridges

Portable Hydrogen Cartridge (Prototype). Image © Toyota. Source: Toyota UK Media Site.

Toyota have shown off their new hydrogen cartridges at the Japan Mobility Show 2024, according to HydrogenFuelNews.com. The cartridges are an alternative to filling a fuel tank with hydrogen. While hydrogen can power an internal combustion engine directly, a more efficient option is to convert hydrogen into electricity using a device called a fuel cell. The current produced by the cell can then power electric traction motors in an FCEV (Fuel Cell Electric Vehicle). Capacity wasn't specified for the cartridges, but another source suggests it's 4.7 l of liquid hydrogen at 525 bar. That would equate to 329 g (liquid H₂ has a density of 70 g/l compared to 1 kg/l for water). According to a resource provided by the Center for Sustainable Resources at the University of Michigan, hydrogen has a low volumetric energy storage density of 8 MJ/l for liquid hydrogen (mega joules per litre), compared to 32 MJ/l for petrol. Hydrogen does have the highest energy density by mass however of any fuel. That 329 g estimate of liquid hydrogen at an energy density of 120 MJ/kg (versus 44 MJ/kg for petrol) equates to approximately 11 kWh. What range would that give for an FCEV with a typical efficiency of 60% fuel to wheels? Toyota UK didn't have any further detail or a press release on the technology when I asked them, however here's an interesting article on The Conversation about hydrogen cars.

 

References: 

 

Toyota showcases technology developments towards a sustainable future. Toyota Media Site. (2024, October 8 ) https://media.toyota.co.uk/toyota-showcases-technology.../

Toyota and woven planet develop new portable hydrogen cartridge prototype to power everyday applications. Toyota Media Site. (2022, June 2). https://media.toyota.co.uk/toyota-and-woven-planet.../

Hydrogen factsheet. Center for Sustainable Systems. (n.d.). https://css.umich.edu/.../facts.../energy/hydrogen-factsheet

Tsakiris, A. (n.d.). Analysis of hydrogen fuel cell and battery efficiency. https://c2e2.unepccc.org/.../analysis-of-hydrogen-fuel...

Hydrogen storage | Department of Energy. (n.d.). https://www.energy.gov/eere/fuelcells/hydrogen-storage

Mystery Aircraft and Beat Frequencies

Antonov An-12BK. Image courtesy Richard Vandervord via Wikimedia Commons. CC BY-SA 4.0 International.

Didn't manage to get the camera out in time, but I noticed the distinctive beat frequency of multi-prop engines. (Quite loud for the altitude). I checked with FlightRadar24 and it was an Antonov An-12BK cargo aircraft, flying at 22,000 feet on a flight from Porto to Prestwick and operated by Ukrainian Cavok Airlines.

What are beat frequencies?

 

When two sound waves of different frequencies interact, the waves subtract and the difference in frequency creates a tremolo effect, resulting in a periodic rise and fall in volume. (Basically the peaks or troughs combine and reinforce or cancel each other out. ) The phenomenon is sometimes noticed when two musical instruments with different pitches are played together. Beat frequencies also occur with radio waves, electrical signals and coherent light waves.

The animated GIF below show a red and green sound wave, initially at the same frequency and in phase. The two waves add together to form a blue sine wave that's greater in amplitude. As the frequency of the green wave slowly changes, the resultant blue waveform changes in amplitude, modulated by a beat frequency. See link also in the comments to a YouTube demo, showing the phenomenon with two tuning forks.

Anyone who's doing their Junior Cert will probably be able to do the maths and find the resultant of two sine waves of different frequencies added together, requiring the trigonometric identities at the end of the maths tables to do the calculations (Are these still available from the Government Publications Sales Office?)

 

More information on beat frequencies here:
https://en.wikipedia.org/wiki/Beat_(acoustics)

 

Beat frequency. The blue waveform is the sum of the red and green waves. Animated GIF courtesy Adjwilley via Wikimedia Commons. CC BY-SA 3.0 Unported.

 

Plumbing Tip

Gate valve. © Eugene Brennan

Identify where all your water valves are for shutting off supplies in an emergency. Tie a label on the pipe close by, or write the function on the wall behind with a thick marker. Gate valves (the one with the red knob in the photos) can and do seize, so it's a good idea to "exercise" them by turning off and back on again at least once a year. Gate valves turn off clockwise. Quadrant valves usually turn off when the lever is at right angles to the pipe. Mini inline valves can be turned off with a screwdriver and are off when the slot is at right angles to the pipe.

Quadrant or ball valve. © Eugene Brennan

Mini inline valve. © Eugene Brennan

 

Facts About ∞

Image created on request by Bing Image Creator.

 

Infinity, usually represented in maths by the symbol ∞ isn't a number. If it was, you could just add one and get a bigger number.
There are an infinite number of infinities. This can easily be proved mathematically, using a few lines of equations.
1/0 isn't infinity. It's undefined. Try it on your calculator.
We can talk about numbers approaching infinity using a concept called limits, and that's a useful tool in maths to work things out.
The symbol was invented by the English mathematician John Wallis in 1655.
Some numbers, known as irrational numbers, can't be represented as a fraction. They require an infinite number of decimal places to be completely defined. Examples are pi (Symbol π. We pronounce it as "pie" but it's actually pronounced "pee" in modern Greek.) Even some rational numbers such as 1/3 require an infinite number of decimal places to be completely defined 1/3 = 0.3333... with 3 recurring.

Lime Scale and Tea Problems

Lime in water in Kilcullen is causing lots of hassle, for me anyway. The shower door guides are now seizing up, so I'll have to do some maintenance. It also coats surfaces, acting like a sponge, which then soaks up vinegar used for removing it, corroding chrome plating. I could plumb in a descaling filter in the attic, but then I'd have to be buying filters. Also the feed for the attic is on a different line to the kitchen tap, so that would mean another unit.

Anyone else have problems?

Have you had difficulty making proper tea since we switched over to the Barrow supply? Once upon a time, a Barry's tea bag would make nearly two cups of tea. Now it takes nearly two bags to make one cup. It's a known fact that lime in water not only makes getting a lather on soap difficult, but tea making is also difficult because of it.