Stress Patterns

Here are some more pictures taken at the ASE show. 

These show the stress patterns which are visible in our set square after it is exposed to polarised light, for these images we have used a polarised light source from a standard LCD computer screen instead of our normal lightbox.

The LCD screen has a polarising film in it at 45 degrees to the vertical so only a single sheet of polarising film is needed to produce an effect.

Set square with out Polarising Film.

Stress patterns within the set square viewed through a sheet of Polarising Film.

Demo of the Stirling Engine

A short demo from our stand at the ASE exhibition in Liverpool last week.

This is our model of a Stirling Engine, which is running from a cup of hot water. 

This model is mostly made out of cardboard with a few metal pieces.

Amazing World

I have found an amazing video cropping up on my news feed a lot in the last few days and decided to take a look at it.
Well I cant keep it all to myself it is an amazing piece of footage from the International Space Station. 


What a truly amazing planet we live on.


I do just wish this as a little slower so I could appreciate the detail a little more.



Earth | Time Lapse View from Space, Fly Over | NASA, ISS from Michael König on Vimeo.


Time lapse sequences of photographs taken by Ron Garan 
fragileoasis.org/​bloggernauts/​Astro_Ron and the crew of expedition 
28 & 29 onboard the International Space Station from August to October,
2011




List of clips:
1. Aurora Borealis Pass over the United States at Night
2. Aurora Borealis and eastern United States at Night
3. Aurora Australis from Madagascar to southwest of Australia
4. Aurora Australis south of Australia
5. Northwest coast of United States to Central South America at Night
6. Aurora Australis from the Southern to the Northern Pacific Ocean
7. Halfway around the World
8. Night Pass over Central Africa and the Middle East
9. Evening Pass over the Sahara Desert and the Middle East
10. Pass over Canada and Central United States at Night
11. Pass over Southern California to Hudson Bay
12. Islands in the Philippine Sea at Night
13. Pass over Eastern Asia to Philippine Sea and Guam
14. Views of the Mideast at Night
15. Night Pass over Mediterranean Sea
16. Aurora Borealis and the United States at Night
17. Aurora Australis over Indian Ocean
18. Eastern Europe to Southeastern Asia at Night

Space debris

This Sunday another Satellite is due to come crashing down to earth. The German ROSAT satellite finished its service in 1999 after nearly 7 years more service than was originally planned. It was planed that the satellite that was launched in 1990 would function for 18 months but was only shut down in 1999. ROSAT was designed in the 1980's when the end of life of satellites was not really considered so it was not built with its own propulsion system, like modern satellites, which enables their re-entry conditions to be controlled to ensure that they land in an uninhabited area of the globe. 

The chance of this satellite causing harm to anyone is higher then the previous uncontrolled decent at 1 in 2000. Some confusion was noted in the run up to the UARS decent, this is not the chance that you as an individual will get hurt, but that someone somewhere on the planet will get hurt. 

The satellite is predicted to fall somewhere between 53° N and 53°S which unfortunately covers most of the worlds landmasses. The exact location or timing cannot be predicted at the moment due to changes in the radiation from the sun causing the upper atmosphere to expand and contract changing the 'pull' of the atmosphere on the satellite. 

Increased solar activity expands the atmosphere and increases the 'pull' advancing the descent of ROSAT by a small margin each time. 

Following ROSAT_Reentry on twitter helps to get an understanding of when the satellite will enventually fall, the current prediction is Space-Track #ROSAT Predicted Decay 2011-10-23 05:03 GMT ± 48 Hours as @ 2011-10-20 08:06 GMT

With a window of +/- 48h there is still a large margin of uncertainty. But it does look likely that the satellite is no longer going to be visible from the UK, unless the descent is at the right  time so that some  of the burn up in the atmosphere is visible. 

In other space related news, look to the skys this evening as there is supposed to be some Orionid activity. Meteors to you and I :D

How To - Reusable Coffee Cup Sleeve

A quick how to to make a reusable sleeve for take away coffee cups. 


I have made a number of these in different mediums before, I knit them and sow them but I know that these skills are not available to all so here is a more accessible version of the reusable sleeve. It's is made from foam rubber sheets - which are easy to work with and come in a variety of colours.


This is a simple pattern which uses a tab to keep it together and so can come apart to store it in its flat form in a bag or folder. 


For this project I used a pre existing sleeve as a template and added a tab and slot to secure the ends together. 


Instructions:


1) Open out the existing sleeve to get a pattern:

2) Work out the best placement on the foam sheet to ensure the minimum wastage:

3) Draw around the sleeve in a Biro or other thin pen:

4) Trace the outline in a thicker marker, adding a tab to one end and a cutout to the other. You need to make sure that the width of the cut out is the same size as the connection for the tab:

5) Cut out the design. The foam sheet is easy to cut with a standard pair of kitchen scissors. It is better to leave the tab too large to start with rather than cut it too close and find that the sleeve wont stay together: 

6) Connect up the two ends. Recutting the tab smaller if necessary till you get a good fit:

7) Place holder around your hot beverage. Or pre used cup which is being used as a template, as the case is here:

8) The foam rubber will take decoration of many types. Here I have drawn a simple design on in permanent marker. Finally a use for my sisters stash of sharpies! :p 

9) The beauty of the flexibility of the foam rubber and this closure method is that you can create a reversible sleeve. Decorate one side in a funky manner and have the other side plain or with your company name/logo on it so that the sleeve will serve for both social coffees and those with important business meetings: 

And voilà one simple way to ensure that you don't burn your fingers on a hot coffee and you make a small little difference in the number of coffee sleeves which make it to a landfill, and reduce the number of trees needing to be cut down. 
If you are not so bothered by the environmental impact of the take away coffee it is still a nice way to personalise the coffee on the go experience. :D

What do the spectrums mean?

Previously I have shown images that I have taken of the spectrum captured using my home-made spectrograph and plain and simple diffraction grating slides, but what do the images captured actually mean?


I will start by explaining what visible light is in relation to the electromagnetic spectrum then


Visible light:
This is one section of the Electromagnetic (EM) spectrum which is visible to the human eye. Light (and other electromagnetic radiation) travels as a wave but unlike sound energy, which vibrates the air particles to transport the signal away from the source, it does not need particles to travel through since it is a vibration of the magnetic and electric fields. This enables light to reach us from the sun, through the vacuum of space. 

This image shows the different wavelengths of the visible light spectrum. Red light has a lower frequency (therefore a larger wavelength ~700nm) and violet light has a higher frequency (smaller wavelength ~400nm), outside of these wavelengths the human eye is unable to pick up the signal contained by these waves. 


Colours are perceived by the eye due to different proportions of the different wavelengths being absorbed and reflected by different surfaces. A surface which appears Red will be reflecting the EM radiation which corresponds to the red section of the spectrum whilst absorbing the other wavelengths. 
Colours which are not a direct wavelength colour (Red, Orange, Yellow etc) can be made up by mixing light of different wavelengths. 


'White light' is made in a similar fashion and is composed of light of all the different wavelengths. 


Images of the spectrum:


The fact that white light is made up of the whole spectrum can be shown simply by shining a light through a prism which uses the difference in densities of the glass and air to bend the light. Light of different wavelengths reacts to the change in densities by a different amount so they bend at different angles causing the spectrum to spread out. 

This process is replicated in the diffraction grating but in a way that means it is possible to have a 'flat' material rather than the traditional bulky prism. 


The images I took previously of the spectrum from an incandescent bulb shows the same complete coverage of the spectrum and all at a similar intensity.

Whereas the spectrum of the energy saving light bulb shows bands of higher and lower intensity throughout the visible spectrum. 

The differences between the two spectra are due to the processes that the bulbs use to create 'white light' (I will discuss this in a later post). But what do the actual spectra mean?


Well, certain elements will give off light at specific wavelengths, called an emission spectrum, which is controlled by the actual structure of the atom in question. 


here is an example of an emissions spectrum for Carbon:

This shows the intensity peaking at specific wavelengths. Using spectroscopy scientists can ideantify the elements in a substance. This is mostly used in astronomy, where scientists will use the emissions spectra for stars or distant galaxies to identify what elements are present and giving off light.

Is back in business

I am back in business now :D

Hopefully I will have a number of new things to go on here in the coming weeks.

Till then...