Press Release From the ESB About Potential Releases From the Poulaphouca Reservoir

Poulaphouca Lake. © Eugene Brennan

Water isn't released directly into the River Liffey south of Ballymore Eustace from the Poulaphouca reservoir — it's discharged indirectly from the Poulaphouca dam into a compensatory lake in Ballymore. This acts as a buffer, protecting the river from huge surges and flooding. Although it's not related to surges on the river, a surge tank adjacent to the Liffey bridge over the gorge on the N81 protects the pipes, or penstocks, that deliver water to the turbines in the generating house from hydraulic shock.

The compensatory lake also creates a pressure head for the Golden Falls hydro station as well as providing an amenity for fishing and water skiing. "The Flood" on the River Liffey is caused when water is discharged from this lake through the Golden Falls dam. The Poulaphouca reservoir has been acting a buffer up until now, holding large quantities of water from recent rainfall. The lake is fed by both the River Liffey and Kings River, in addition to some minor streams. However, water levels have increased by almost 2 metres, requiring water to be released. Since the Golden Falls lake is also almost full, this means that large quantities water must also be released from the Golden Falls dam into the Liffey at Ballymore Eustace to allow room for water being discharged from the Poulaphouca lake.

In a recent press release by the ESB, quantities haven't been specified and they say "there may be a need to pass through some of these additional inflows over the coming days."

Flows haven't been higher than 33 m³/s (cubic metres per second) in recent years. However, according to the Kilcullen Diary, they were at 55 m³/s in 2000 when a controlled, 24-hour discharge was necessary. this caused floodind in Kilcullen and other regions downstream.

Forecasted flow for the day, with values at 00:00, 08:00, 18:00 and 24:00 from the Golden Falls dam is available here on the ESB hydrometric page. 

Golden Falls dam. © Eugene Brennan

 

Devils Tower, the Hill of Allen, the Valley Park and Close Encounters of the Third Kind

Devil's Tower in Wyoming. Ben Stephenson from Cleveland, OH, CC BY 2.0 , via Wikimedia Commons

If you were watching Close Encounters of the Third Kind this afternoon (I hadn't seen it for maybe 15 years), you would have seen the towering rock formation that's used as a plot device and features in the end of the movie when the huge spaceship appears and the aliens emerge. This is Devils Tower in Wyoming, classed as a butte and possibly a laccolithic formation, composed of igneous rock. A butte is an isolated hill with steep, often vertical sides and a flat top. Igneous rock began as molten rock or magma that originated from inside the Earth, and then cooled.

Top 100 Cool Science Facts for Kids!

Photo courtesy Geralt on Pixabay. Text overlay © Eugene Brennan

Why is the sky blue? 

What is air made of? 

How many stars are there? 

World of wonder fun science facts that every child should know! This article covers space, nature, technology, engineering, elementary mathematica, chemistry, physics and biology.
Science is fascinating and tries to explain how everything in the world and outer space works. Science gives us the answers to questions like "What is electricity?" and "How does an aeroplane fly?" Read on and learn 100 more cool science facts! 

Super Human Strength and an Injury on Church Mountain

Fence on Church Mountain, Co. Wicklow. © Eugene Brennan

In 2019 I was making my way down a gully on Church Mountain near Hollywood with my bike slung over my shoulder. I had cycled half-way up on the trails at the back of the mountain and was going to go further, but it was getting late in the day and I decided it would be wise to head home before it got dark. The gully was peppered with lots of rocks, covered in wet, slippery moss and algae and difficult to navigate. I was distracted by an annoying off-lead dog belonging to walkers behind me which kept barking at me. I lost my concentration, slipped and started to fall backwards, my bike pulling me down (which is why it's never a good idea to carry a ladder over your shoulder on a stairs).

Terminal Velocity of a Human, Free Fall and Drag Force

© Eugene Brennan

We all know that when an object is released from a certain height, it starts to fall. This, of course, is due to gravity, or more specifically the gravitational force of attraction between the object and the Earth. The force of gravity causes the object to accelerate and increase in velocity as it falls downwards towards the Earth. In actuality, both the Earth and the object are mutually attracted to each other, and the Earth moves upwards at the same time. However, since it's so massive in comparison to a small object and the force is so small, its movement is minuscule. 

How to Calculate the Sides and Angles of Triangles Using Pythagoras' Theorem, Sine and Cosine Rule

In this tutorial, we'll first learn the absolute basics about triangles. Then we'll learn about trigonometry which is a branch of mathematics that covers the relationship between the sides and angles of triangles.

What's Covered in the Tutorial?

• Polygons and the Definition of a Triangle
• The Basic Facts About Triangles
• The Triangle Inequality Theorem
• Different Types of Triangles
• Using the Greek Alphabet for Equations
• Sine, Cosine and Tangent
• Pythagoras's Theorem
• The Sine and Cosine Rules
• How to Work Out the Sides and Angles of a Triangle
• Measuring Angles
• How to Calculate the Area of a Triangle

Printer Ink Experiment

Printout using Quink fountain pen ink. © Eugene Brennan

I'm fed up buying inkjet cartridges for my Lexmark printer, which usually dry up and stop working. I was speaking to a technician about this and he said that the advice from manufacturers is that inkjet printers really need to be "exercised" every week or two by printing a couple of pages to prevent this happening. I predicted this in the 90s when I bought my first inkjet printer, having owned a fountain pen and knowing that the nib occasionally dried up. The print nozzles in inkjet printer heads are only a few tens of microns in diameter, so it's not unexpected.

A Book of Sketches by Stephen Leacock: A, B and C, the Human Element in Mathematics

From the Project Gutenberg

This was the final chapter in a book called Literary Lapses, written in 1910 by the author Stephen Leacock. It was one of the short stories included in the Exploring English anthology, one of the three books we studied for the Intermediate Certificate. The other two books were devoted to prose and poetry.
In the story, Stephen humorously personifies A, B and C as they negotiate the algebra problems encountered in maths problems.
The book is in the public domain and copyright has elapsed, hence the reason I have copied a portion.

Simple Machines: How Does a Lever Work?

© Eugene Brennan

What Is a Lever?

A lever is a simple device that works by changing the input force needed to do work and move something. Some levers do this by magnifying the force applied to them. In this tutorial, we'll explore how levers are used in our everyday lives and then learn the simple physics of how they work.

Examples of levers. © Eugene Brennan

The Lever: One of the Six Classical Simple Machines

The lever is one of the six simple machines which were defined by Renaissance scientists hundreds of years ago.

Another Faulty LED Street Lamp

From the DeadSure app for reporting faulty street lighting.

Too early to make a judgement, but something tells me these new LED street lights are less reliable than the older sodium ones. Which makes sense, considering sodium lamps are simpler and purely electrical/electromechanical, whereas LED lamps have more working parts— not moving parts, but semiconductors—that can fail. I reported this one that I noticed tonight because the upper path in the Valley Park seemed dark. There may be a couple more not lighting, further out the road closer to St. Brigid's Well.

LED lighting theoretically has a lifespan in the tens of thousands of hours (30,000 to 40,000 hours). However, in reality it can be less than this because the driver electronics fails.

57 Modes and Nothing Wrong

Bicycle rear light. © Eugene Brennan

Mystery light.

I've bashed it almost to the point of cracking the lens, put it in the freezer for half an hour while turned on and left a strong magnet in its vicinity and it still won't turn off. Yet when I'm cycling, after 100 m or so, it manages to turn itself off. And that keeps happening. The only thing I can think of is that deceleration in a certain direction is bending a spring in a clicky button. Or maybe it's condensation on the PCB. Or possibly constant vibration rather than large shocks.

Anyway, I hate the way they don't put proper switches on these things instead of buttons for changing modes that inevitably cause them to switch off on bad roads. It's difficult to get a decent backlight anywhere. I've tried eBay, Amazon and AliExpress.

 

Archimedes' Principle, Buoyancy Experiments and Flotation Force

Archimedes' principle. © Eugene Brennan

What is Buoyancy?

We've all experienced buoyancy. If you throw a football into water, it floats on the surface. In a swimming pool, you can float on your back and large ships float in the sea. Even things that sink such as stones, experience a buoyant force, but the force is insufficient to keep them afloat. Buoyancy is a force that pushes up on the underside of an object that's placed in a fluid. The fluid doesn't have to be water, it can be a gas such as air and helium balloons experience buoyancy, causing them to rise upwards.

How to Understand Electricity: Volts, Amps and Watts Explained on Appliances

© Eugene Brennan

This comprehensive guide for consumers and students explains everything about volts, amps and watts and how they apply to home appliances and circuits. The equations are really quite simple, and you'll find some examples on how to apply them to home appliances.

Electricity 101: Understanding the Basics

In this tutorial, you'll learn about:

• Volts, watts, amps
• Power consumption of appliances and kilowatt hours (kWh)
• Ohm's law and resistance
• Resistivity and how it affects the resistance of a material
• Fuses and how they protect wiring and appliances
• How electricity is produced
• Devices used to measure voltage, current and resistance
• The effects of electric and magnetic fields
• Conductors, insulators and superconductors
• The basics of AC and DC
• Arcs and sparks
• Power supplies and voltage regulation
• Tracking electricity usage in the home

How to Solve Projectile Motion Problems: Applying Newton's Equations of Motion to Ballistics

Public domain image by Prosaica on Pixabay

Physics is an area of science which deals with how matter and waves behave in the universe. A branch of physics called mechanics deals with forces, matter, energy, work done and motion. A further sub-branch known as kinematics deals with motion and ballistics is specifically concerned with the motion of projectiles launched into the air, water or space.

Conversations with ChatGPT: Shallow Truss Forces

t history

Created by ChatGPT

You said:

When a force acts down on the apex of the truss, the forces in the tie can be greater than the load acting down on the apex. And if the slope of the truss becomes very shallow, the tension force in the tie can become huge and tend to infinity as the angle of the slope tends to zero.

"Bridges Finished"

Excerpt from the Dublin Gazette, 1768. Image attribution: Virtual Record Treasury of Ireland

Creative Commons License CC BY-NC 4.0 (Attribution-NonCommercial)

Both the Virtual Record Treasury of Ireland and JSTOR are rich sources of historical records. The former attempts to at least partially replace records which were destroyed when the Public Records Office, located in the Four Courts, was destroyed by a large explosion and fire, possibly triggered when Free State forces shelled the building in 1922 at the outbreak of the Civil War. JSTOR (Journal Storage) is a "digital library of academic journals, books, and primary sources founded in 1994". The excerpt above is one of the several Kilcullen-relevant references in the Dublin Gazette, an official newspaper of the Irish Executive, the British-controlled government in Ireland based at Dublin Castle, between 1705 and 1922.

(Thanks to Liam Kenny on the Harristown Station FB page for letting me know about this, which was referenced in Irish Stone Bridges, O'Keeffe & Simington, Blackrock, 1991)

Conversations With ChatGPT: Flight Ceiling of Aircraft

Created with Grok.

You said: 

“Hello.”

ChatGPT said:

Hey there! How’s it going? What’s on your mind today?

You said:

“Would it be possible for more advanced passenger aircraft to fly at higher altitudes? I know there would be less oxygen, so there would be an issue with engines running efficiently, but there would be less drag also.”

Sub-Atomic Particles are Points

Created by Grok

Classical physics portrays subatomic particles as being like snooker balls—hard spheres with a charge. In this model, known as the Bohr model, the nucleus of an atom is made up of positively charged protons and chargeless neutrons. Negatively-charged electrons whizz around the nucleus, so the whole arrangement is like a mini solar system. Electrons when they move are what constitute an electric current, and an electrical generator simply "pumps" electrons. Electrons are also what are involved in chemical reactions: e.g. when hydrogen and oxygen combine to make water, or sodium and chlorine react to form sodium chloride, common table salt.

Work at Dunstown 400kV Substation

Groundworks at Dunstown 400 kV Substation. Image © Airbus, Maxar Technologies.

On a section of land adjacent-to and SE of the existing substation.

Maybe extra transformer capacity being added or other electrical infrastructure. I'm going to have to visit Google Earth, rather than Google Maps, as the former has historical satellite imagery.

 

Edit: Possibly preliminary groundworks for this: The connection of a "a high-capacity 400 kV (kilovolt) underground electricity connection between Dunstown substation in Co Kildare and Woodland substation in Co Meath." This is part of the Kildare-Meath Grid Upgrade (or Capital Project 966).

Microgeneration and Athgarvan Mill

Athgarvan corn mill in 2001. © Eugene Brennan

I've added links below to a list of electrical power generating sites in Ireland in a Wikipedia article, and also written answers from a Dáil Éireann debate of Tuesday, 26 Jan 2010 on the Oireachtais.ie website. There may be sites that generate lower output, not listed in these resources. According to a list referred to by Minister Eamon Ryan and provided by EirGrid and ESB Networks, Athgarvan Grain Company Limited's installation in Athgarvan was generating 20 kW from its small hydro turbine. (The owner showed me this in 2001, but I can't remember anything about it). Also Silliot Hill was generating 1.255 MW from methane produced by the landfill. An installation at Celbridge Mills was listed as generating 55 kW.