Accidental Plant Reproduction

Branch with roots growing from section that was under gravel. © Eugene Brennan

Plants reproduce using multiple different methods. You probably know about seeds, but other ways they can reproduce naturally include sending out rhizomes (horizontal underground roots that send shoots to the surface) and above or below ground stems called stolons (AKA runners in the case of strawberries). Plants can be reproduced artificially by taking leaf or stem cuttings, by division (splitting a plant down the middle into two or more pieces using a spade or knife), budding (used for propagating roses) and grafting (used for fruit trees and other plants that don't readily grow from stem cuttings). Another method that occurs naturally and can be done manually by gardeners is layering. This involves laying a stem on the ground and covering it with soil or in the case of aerial branches, surrounding the branch with some compost and covering with a plastic bag or film. In both cases, roots eventually grow from the branch at the point where it makes contact with the moist soil or compost. Then the branch or stem can be cut off and planted and will grow independently of its parent (although technically only seeds have parents. Plants reproduced by other methods are clones ). The photos below show layering that occurred naturally on a sycamore tree down my garden. Whenever I'm doing construction I have to get rid of all the soil. I've probably disposed of tens of tonnes of stuff over the years, building up the ground or tipping it into the hedges. I had piled up some clay around the sycamore tree and inadvertently buried one of the still attached branches that was close to the ground. I had to cut the branch to get a wheelbarrow under the tree this morning and when I pulled the submerged section out of the soil, I discovered roots had sprung from the side of it. I've also seen this happening around the trunks of trees, when gravel was piled up against them.

Roots growing from end of branch. © Eugene Brennan

 

New HVDC Transformer Manufactured by Siemens

World’s first ±1,100 kV HVDC transformer. Image courtesy Siemens AG

For high voltage DC (Direct Current) transmission over 3000 km. The transformer has a rating of 587 MVA. AC (Alternating Current) is normally used for transmission because of the ease by which it can be converted to different voltages using transformers. Transmission at very high voltages of 400 kV (e.g. the line at Silliot Hill, which runs from Moneypoint power station to Dunstown 400 kV sub-station) and over is used because electric current is reduced proportionately as voltage is increased. All electrical conductors have resistance and by reducing the current, transmission losses are reduced. However AC is not without its disadvantages and losses occur with AC through the capacitance between lines and the ground. There are also inductive losses. For transmission lines > 600 km, e.g. the interconnectors connecting Ireland to Britain, DC is used to reduce losses.

https://press.siemens.com/.../worlds-first-1100-kv-hvdc...

A more detailed explanation of why such high voltages are used for transmission here:

Force of the Wind on a Surface

Generated by Bing Image Creator

Did you know that the force of wind on a surface depends on the square of the velocity? So if wind speed doubles, the force quadruples. If speed triples, the force is nine times greater and so on. Since pressure equals force divided by area, it also follows a square law.

For a jet hitting a surface (doesn't matter what the jet is made of: air, water etc), the force of the jet in newtons is:

F = ρAv²

where ρ is the density of the fluid in kg/m³

A is the cross-sectional area of the jet in m²

and v is the velocity in m/s

The higher the velocity of the fluid, the greater the force. (Think of your pressure washer jet hitting a surface).

 

What's a "newton"?

 

It's the SI (Système International d'Unités) unit of force. A force of 1 newton (1 N) exerted on a mass of 1 kg will give it an acceleration of 1 m/s². (i.e. the velocity of the mass increases by 1 m/s every second). While all objects have mass, measured in kilos, the force exerted on them by gravity is known as weight. In common usage, we measure weight in kilograms, just like we do for mass, but it is more correctly specified in newtons, the unit of force. To get an idea of the magnitude of 1 newton, it's approximately equal to the force exerted on your hand when a 100 gram weight rests on your palm. While mass stays constant, weight varies and for instance on the Moon, the weight of an object is less.

More information about the subject in this Stack Exchange discussion.

Storm Prep

© Eugene Brennan

Building a few temporary buttresses in the shed last night, just in case. Cuts should really have been made to fit into a 90 degree corner between the piece I added under the rafters and a stud, but a mitred cut will have to do. I used two 5 x 2 braces on each end wall when building it.

Science Friday Podcast — Mars Sample Return Mission. It is Rocket Science

Image courtesy NASA/JPL-Caltech

On the program this week, the team discuss the retrieval of the Mars samples collected by the Perseverance rover. Some are ready for collection on the planet's surface and 30 samples in total will be returned to Earth. The return probably wont happen until late in the next decade. It's a difficult and complex project with many parts that have to work perfectly. A launch system has to be landed on the planet first (called the Mars Ascent Vehicle). An ESA spacecraft called the Earth Return Orbiter will then capture the launched sample capsule from orbit and transport it back to Earth where the samples can be analysed. The Perseverance rover has multiple analysis instruments on board, including two types of spectrometers (an instrument that can determine the chemical makeup of a substance). However more sophisticated analysis can only be done back on Earth.

More info on the retrieval project on the NASA website here.

Intelligent Displays

I was just looking at the small versions of these on shelves in Eurospar the other day. The price of an offer was missing and I asked an assistant to do a price check. He said there was a problem sending the price to the device. I hadn't realised they were screens until then, although I was aware of the technology of intelligent price display labels. Presumably the display is similar to the E-ink types used on a Kindle, not needing a backlight and visible in bright ambient lighting conditions. I thought they were just pieces of card.

Radiator Desludging

Draining a radiator. © Eugene Brennan

 I was doing some maintenance on one of the radiators today. It was only heating up on one side and bleeding didn't fix it. So I suspected sludge or spongy rust inside. A 2 l milk container fitted around the feed pipe acted as a funnel and stopped water draining onto the floorboards. Had to make an adapter for the garden hose from my ever-growing-larger hoarded scrap collection and then gave the rad a flush. Seems to have cleared the blockages.

Adapter for connecting hose to radiator. © Eugene Brennan

 

Hose connected to radiator. © Eugene Brennan

Flushing radiator. © Eugene Brennan

All Shapes and Sizes

A variety of 9 V batteries. Image courtesy Lead holder, CC BY-SA 4.0 via Wikimedia Commons. 

Nowadays, if you go to a shop to buy batteries, apart from the coin cells, the chances are you'll only have five types to choose from, if even that. Those are the AA, AAA, C and D sizes and the small, square 9 Volt PP3 (Also designated as type MN104 or 'E'). In the 70s, there were a multitude of battery types, now pretty much obsolete or hard to come by. So in addition to the PP3, there were several different sized 9 V batteries with different capacities, made for powering portable transistor radios and other electronic appliances. A 6 V battery with two spring terminals on top was available for powering lantern type torches with handles, and a smaller 4.5 V battery (3LR12) with two, flat springy brass terminals on top was available for slim, flat pocket torches. The cylindrical, handlebar-mounted style of bicycle lamp we use today hadn't been invented or at least wasn't common and Ever Ready bicycle lanterns were more the norm. These were powered by a 3 V No. 800 battery, composed of two, 1.5 V cells in series, the two cells arranged side by side, with springy brass terminals. Other types of batteries included the U14 for gas lighters and Ever Ready 3V No. 8 batteries (not sure what these were for, possibly small torches).

 

What's the difference between a cell and a battery?

 

Cells work on the principle of potential differences created between dissimilar metals or other material (e.g. carbon) placed in an electrolyte (a chemical solution, paste or gel). So for instance one type of cell technology is the Leclanché cell. This is a wet cell (using a liquid electrolyte) invented in the 19th century, The dry version of the Leclanché cell is the zinc carbon "battery" which we used before alkaline batteries became widely available in the late 70s and early 80s under the Duracell and Energiser brands. Cells only produce around 4 volts maximum (for lithium ion) and 1.5 volts for alkaline or zinc carbon. To get higher voltages, we connect cells in series in a chain, so the voltages add up. We call the collection of cells a battery. A car battery has six cells connected in series to give a nominal 12 volts. Each cell produces 2 volts nominally. (In reality a fully charged car battery gives out over 13 volts).

This Wikipedia article lists all the current and obsolete battery types, giving details about their uses.

Image courtesy Lead holder, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Plasma Lighters

First there were gas lighters that used fairly big, now obsolete types of zinc carbon batteries for heating an incandescent filament. They didn't produce a flame, so they were usually used for lighting gas cookers and "Kosangas" type portable heaters. The gas lighters and cigarette lighters we have now incorporate a piezoelectric cell, operated by pressure suddenly applied to the cell when a trigger was squeezed. This creates a high voltage spark that ignites gas stored in the lighter. I wasn't aware of these new types of lighters though. Plasma lighters don't need gas and instead produce a plasma between the electrodes (an arc) for lighting things. Sort of like a Taser, but the electrodes are closer together so the arc is hotter. It reminds me of when I had an old induction coil out of car and use to set pieces of timber on fire with the arc. With the lights switched off, the purple glow of corona discharges at sharp points was interesting too. Corona discharge is a phenomenon that can be seen on very high voltage power lines in humid conditions or pointed objects during thunderstorms (known as St. Elmo's Fire). It's effectively a "leak" of electrons through the air at points of high electric field strength. However the leak isn't sufficient to cause a full breakdown of the air and the formation of an arc. Electrical equipment that operates at high voltage is designed to reduce the number of points and sharp edges on conductors which may cause corona effects. Corona can potentially lead to arcing or other damage. It also generates EMI radio interference.

Corona discharage on a power line. Nitromethane, CC BY-SA 3.0

What's the Difference Between a Theory and a Theorem?

Generated by Bing Image Creator

Contrary to the popular use of the word in everyday language, a theory in science is something that models observed behaviour and is true, but not absolutely so. E.g. The theories of special and general relativity. So a theory isn't a postulation or idea which may or may not be true. E.g. that there is water under the surface of some planet. Theories can be updated to more accurately describe something. So for instance the laws of motion don't work at velocities near the speed of light, so the special theory of relativity caters for that scenario. Theorems unlike theories however can be absolutely proved using axioms. E.g. the triangle sum theorem which states that all the angles in a triangle add up to 180 degrees.

Mars Curiosity Rover: Lessons Learned on Wheel Design

Public domain image courtesy NASA/JPL-Caltech/MSSS.

"The anomalous wheel wear suggests that loads and terrains representative of actual operational conditions were not adequately simulated during life testing"

 

The tyres are made from aluminium. According to this recommendation by JPL, metal fatigue and single event punctures caused by wind-eroded, immobile pyramidal shaped rocks was responsible for the damage.

The Curiosity rover has travelled over 20 miles on the surface of Mars since it landed on the red planet in 2011 as part of the Mars Science Laboratory mission. The robot is about the size of a small car and weighs around 900 kg.

5 Live Science Podcast — Jocelyn Bell Burnell and Pulsars

Image produced using Bing Image Creator.

In this 5 Live Science podcast, Northern Ireland native Jocelyn Bell Burnell talks with Dr Chris Smith about radio astronomy and her discovery of pulsars. These are rotating neutron stars that emit beams of electromagnetic radiation from their magnetic poles, the radiation sweeping the Universe like a lighthouse beam. Neutron stars are extremely dense. Atoms are mostly empty space, a simplistic model resembling our Solar System with electrons existing in outer orbitals and a nucleus at the centre. However just like the Solar System, there is lots of space between the electrons and nucleus. In a neutron star, gravity squeezes everything together so tightly that nuclei in adjacent atoms pack up against each other. The result is super-extreme density and according to Scientific American, a ping-pong ball sized piece of a neutron star would weigh over a billion tonnes.

https://www.bbc.co.uk/sounds/play/p0kds1xg

Linked content, courtesy the BBC. The BBC in no way endorses content on this blog.

Video From Photos Using AI — Turning Your School Photos into Videos

Image created by Bing Image Creator

Many of us over a certain age don't have any "home movies" of ourselves from when we were young and just handfuls of photos, not like the hundreds or thousands that parents take of their kids today. Imagine if you could turn your photos into home movies?

I've been playing with this AI, video generating online application called Hailuo AI that can turn photos into videos. You might remember Pic Me, the animated TV series for pre-school kids where a child's face was cut out and pasted onto an animated body that got up to all sorts of activities. However this AI technology is light years ahead. Once an image is uploaded, just like with Dall-E, Bing Image Creator or other AI image generating application, a text description of what the video should look like is provided is provided by the user. The application then effectively "skins" the person in the image and wraps their outsides around wire frames it can animate.

The results are somewhat mind boggling. Try it on your old school photos.

Pump Post Mortem

Checking the capacitance of the run capacitor. © Eugene Brennan

I've been doing a post mortem on my central heating pump. The shaft is spinning freely, there's very little rust internally and just as predicted, the run capacitor for the motor had failed, a part that would have cost about €5 to €8. I thought the leads for the capacitor might have been held by spring clamps, just like the power cable, but the pump was facing inwards when in situ, so I couldn't get at them to check. It turned out they were crimped onto the connector plug terminals. So the replacement capacitor's leads would have had to be joined to the existing leads, soldered and heat shrinked. According to the plumber, the pump would have swivelled out for access and the threads aren't sealed with Plumber's Mait, washers are used for sealing. So I'll be fitting a new one myself the next time, or probably this one with a replacement capacitor. (I've fitted two pumps before in the workshop).

 

WARNING! If you're ever checking mains capacitors, make sure they're discharged first, because they can potentially be charged to almost 400 V DC and lethal.

 

Circulating pump. © Eugene Brennan

Not much sludge accumulated in the pump. © Eugene Brennan

Motor run capacitor. © Eugene Brennan

Pump details. © Eugene Brennan

Sailing By

Image generated by Bing Image Creator

You may have heard Joe Duffy's segment the other day on Liveline about the BBC Shipping Forecast, broadcast at 00:48 on BBC Radio 4, before the station closes down at 1 am. On LW, the frequency then carries the BBC World Service. For some, the forecast is like a soothing mantra, the repetitive structure and intonation or melody of the words easing them off to sleep. In this documentary, local man Al Ryan who is a BBC presenter, amongst others, speak about the forecast which celebrates its centenary this January.
https://www.bbc.co.uk/sounds/play/m002699p