For material properties:
http://www.matweb.com/
plastics: Maizey Plastics
On CalculiX:
http://www.dhondt.de/
Solid models:
3D content central: http://www.3dcontentcentral.com
Grabcad: http://grabcad.com/
Creating high quality plots in Octave
Physics:
The Feynman Lectures on Physics, Volume I
Dynamics:
MIT OCW engineering dynamics
MIT OCW modeling dynamics and control
MIT OCW dynamics
Matlab & Math:
MathWorks
Science blogs to follow:
Empirical Zeal
The Loom
Not exactly rocket science
Projects to follow:
Open Hardware
Sunday, December 9, 2012
Monday, August 6, 2012
My computer fan starts up, but that is it.
I use an ancient desktop computer. Since its purchase, it has been struck by lightning and consequently had its main board replaced. I since added 2GB of RAM to bring the total memory up to 2.5GB.
(At this point, I realise, it might be sensible to add all the specifications of all the different parts of this computer. But I don't feel like figuring that out now, so this paragraph will just serve as a reminder to maybe add it later.)
One day the house power tripped suddenly. I reset the trip switch, but when I returned to my computer, I found that it would not switch on. Normally, when I press the power button it and would light up in red and later become green. When I now press the power button, only the red light would light up, both the computer's fans would start running, but the computer would not boot up.
So here is the trouble shooting process I followed:
1. I checked the computer's fuse (located near the main power supply). It was still intact.
2. I disconnected and reconnected all the cables. Still: red light, fans running but no booting up.
3. I unscrewed the cover and checked for any loose cables or obvious signs of problems inside the tower. Found none.
4. I heard somewhere that the main board might make a specific sound when you press the power button, which could help diagnose the problem. When I pressed the power button, I heard a single peep sound. Google revealed that this sound implies that the main board is not blown. I took this as good news.
5. Something else I read advised me to press the power button and keep it depressed for 10 - 15 seconds when you switch the computer on/off (? I cannot remember which one.) Apparently this is some kind of reset function. But it made no difference to my computer.
6. So, I dug up the main board's diver and documentation. Something else I read suggested that the power button's red light might mean that something is wrong with the CPU. The main board documentation described how to install the CPU, so I uninstalled and re-installed it, in an attempt to check all the connections. Still no difference made to the computer.
7. The main board documentation also described how to reset the CMOS. In my case, this entailed putting a two-pin bridge that was connected on the left and middle pins of three pins, on the right and middle pins. Wait a few seconds and put the bridge back into its original position. This worked! The computer booted up. The green light replaced the red light. And all my data was just as I left it.
So, I learned quite a few computer trouble shooting tricks from this experience (since in this case you cannot exactly switch it off and back on again...).
Other pieces of useful information I found in my reading:
When exploring the insides of a laptop, remember to disconnect the power and also remove the battery
It is just as simple to replace or increase laptop RAM as desktop RAM, just unscrew the screw on the bottom of the laptop...
Before touching RAM, it is advisable to ensure that your hands are static-free. Apparently, this can be accomplished by touching the screw on a light switch. I am not exactly sure why (yet).
I still don't know what went wrong with the computer and why it happened. Maybe I will find out...
There. I wrote it down for future reference. And just maybe I can help someone else googling “fans are running but computer won't boot up” - which is basically what I did.
(At this point, I realise, it might be sensible to add all the specifications of all the different parts of this computer. But I don't feel like figuring that out now, so this paragraph will just serve as a reminder to maybe add it later.)
One day the house power tripped suddenly. I reset the trip switch, but when I returned to my computer, I found that it would not switch on. Normally, when I press the power button it and would light up in red and later become green. When I now press the power button, only the red light would light up, both the computer's fans would start running, but the computer would not boot up.
So here is the trouble shooting process I followed:
1. I checked the computer's fuse (located near the main power supply). It was still intact.
2. I disconnected and reconnected all the cables. Still: red light, fans running but no booting up.
3. I unscrewed the cover and checked for any loose cables or obvious signs of problems inside the tower. Found none.
4. I heard somewhere that the main board might make a specific sound when you press the power button, which could help diagnose the problem. When I pressed the power button, I heard a single peep sound. Google revealed that this sound implies that the main board is not blown. I took this as good news.
5. Something else I read advised me to press the power button and keep it depressed for 10 - 15 seconds when you switch the computer on/off (? I cannot remember which one.) Apparently this is some kind of reset function. But it made no difference to my computer.
6. So, I dug up the main board's diver and documentation. Something else I read suggested that the power button's red light might mean that something is wrong with the CPU. The main board documentation described how to install the CPU, so I uninstalled and re-installed it, in an attempt to check all the connections. Still no difference made to the computer.
7. The main board documentation also described how to reset the CMOS. In my case, this entailed putting a two-pin bridge that was connected on the left and middle pins of three pins, on the right and middle pins. Wait a few seconds and put the bridge back into its original position. This worked! The computer booted up. The green light replaced the red light. And all my data was just as I left it.
So, I learned quite a few computer trouble shooting tricks from this experience (since in this case you cannot exactly switch it off and back on again...).
Other pieces of useful information I found in my reading:
When exploring the insides of a laptop, remember to disconnect the power and also remove the battery
It is just as simple to replace or increase laptop RAM as desktop RAM, just unscrew the screw on the bottom of the laptop...
Before touching RAM, it is advisable to ensure that your hands are static-free. Apparently, this can be accomplished by touching the screw on a light switch. I am not exactly sure why (yet).
I still don't know what went wrong with the computer and why it happened. Maybe I will find out...
There. I wrote it down for future reference. And just maybe I can help someone else googling “fans are running but computer won't boot up” - which is basically what I did.
Tuesday, April 3, 2012
Solar flares (that won't end the world in 2012)
To everybody that is freaking out about recent solar flares and causing sunscreen prices to skyrocket (see what I did there): don't. Solar flares are normal and as long as you are within the earth's atmosphere, the earth's magnetic field will protect you from them - as it has been doing for a quite a while now. It is however justified to be concerned about GPS functionality, power grids and astronauts on the surface of Mars... who can all malfunction with exposure to solar flares.
How the earth's magnetic field protects the earth's atmosphere from the solar wind: http://www.physicscentral.com/explore/action/solar-1.cfm
How the earth's magnetic field protects the earth's atmosphere from the solar wind: http://www.physicscentral.com/explore/action/solar-1.cfm
Monday, February 7, 2011
Components of Effective Communication / Relationships
Components of Effective Communication / Relationships:
- respect
- reasonability
- honesty
- respect
- reasonability
- honesty
Monday, January 24, 2011
Harry Potter quotes
Book II: Harry Potter and the Chamber of Secrets
"'Ginny!' said Mr Weasley, flabbergasted. 'Haven't I taught you anything? What have I always told you? Never trust anything that can think for itself if you can't see where it keeps its brain."
*
"It's our choices, Harry, that show what we truly are, far more than our abilities." - Dumbledore
Book III: Harry Potter and the Prisoner of Azkaban
" 'So, the first question we must ask ourselves is, what is a Boggart?'
Hermione put up her hand.
'It's a shape-shifter,' she said. 'It cab take the shape of whatever it thinks will frighten us most.'
...
'The charm that repels a Boggart is simple, yet it requires force of mind. You see, the thing that really finishes a Boggart is laughter. What you need to do is force it to assume a shape that you find ammusing.'
'We will practise the charm without wands first. After me, please ... riddikulus!'"
*
"'Dementors are among the foulest creatures that walk this earth. They infest the darkest, filthiest places, they glory in decay and despair, they drain peace, hope and happiness out of the air around them. Even Muggles feel their presence, though they can't see them. Get too near a Dementor and every good feeling, every happy memory, will be sucked out of you. If it can, the Dementor will feed on you long enough to reduce you to something like itself - soulless and evil. You'll be left with nothing but the worst experiences of your life.'
...
'It was horrible,' said Neville, in a higher voice than usual. 'Did you feel how cold it went when it came in?'
'I felt wierd,' said Ron, shifting his shoulders uncomfortably. 'Like I'd never be cheerful again...'
...
'The fortress is set on a tiny island, way out to sea, but they don't need walls and water to keep the prisoners in, not when they're all trapped inside their own heads, incapable of a single cheerful thought. Most of them go mad within weeks.'
...
'I did think of Voldemort first,'said Harry honestly. 'But then I - I remembered those Dementors.'
'I see,' said Lupin thoughtfully. 'Well, well ... I'm impressed.' He smiled slightly at the look of surprise on Harry's face. 'That suggests that what you fear most of all is - fear. Very wise, Harry.'"
"'Ginny!' said Mr Weasley, flabbergasted. 'Haven't I taught you anything? What have I always told you? Never trust anything that can think for itself if you can't see where it keeps its brain."
*
"It's our choices, Harry, that show what we truly are, far more than our abilities." - Dumbledore
Book III: Harry Potter and the Prisoner of Azkaban
" 'So, the first question we must ask ourselves is, what is a Boggart?'
Hermione put up her hand.
'It's a shape-shifter,' she said. 'It cab take the shape of whatever it thinks will frighten us most.'
...
'The charm that repels a Boggart is simple, yet it requires force of mind. You see, the thing that really finishes a Boggart is laughter. What you need to do is force it to assume a shape that you find ammusing.'
'We will practise the charm without wands first. After me, please ... riddikulus!'"
*
"'Dementors are among the foulest creatures that walk this earth. They infest the darkest, filthiest places, they glory in decay and despair, they drain peace, hope and happiness out of the air around them. Even Muggles feel their presence, though they can't see them. Get too near a Dementor and every good feeling, every happy memory, will be sucked out of you. If it can, the Dementor will feed on you long enough to reduce you to something like itself - soulless and evil. You'll be left with nothing but the worst experiences of your life.'
...
'It was horrible,' said Neville, in a higher voice than usual. 'Did you feel how cold it went when it came in?'
'I felt wierd,' said Ron, shifting his shoulders uncomfortably. 'Like I'd never be cheerful again...'
...
'The fortress is set on a tiny island, way out to sea, but they don't need walls and water to keep the prisoners in, not when they're all trapped inside their own heads, incapable of a single cheerful thought. Most of them go mad within weeks.'
...
'I did think of Voldemort first,'said Harry honestly. 'But then I - I remembered those Dementors.'
'I see,' said Lupin thoughtfully. 'Well, well ... I'm impressed.' He smiled slightly at the look of surprise on Harry's face. 'That suggests that what you fear most of all is - fear. Very wise, Harry.'"
Tuesday, June 29, 2010
Thermoluminescence vs. Incandescence
Thermoluminescence is a form of luminescence that is exhibited by certain crystalline materials, such as some minerals, when previously absorbed energy from electromagnetic radiation or other ionizing radiation is re-emitted as light upon heating of the material. The phenomenon is distinct from that of black body radiation.
Incandescence is the emission of light (visible electromagnetic radiation) from a hot body due to its temperature. The term derives from the verb incandesce, to glow white.
Incandescence is the emission of light (visible electromagnetic radiation) from a hot body due to its temperature. The term derives from the verb incandesce, to glow white.
Monday, June 7, 2010
Yeats - First poem in (1936) Oxford book of modern verse (on the Mona Lisa / La Gioconda)
She is older than the rocks among which she sits;
Like the Vampire,
She has been dead many times,
And learned the secrets of the grave;
And has been a diver in deep seas,
And keeps her fallen day about her;
And trafficked for strange webs with Eastern merchants;
And, as Leda,
Was the mother of Helen of Troy,
And, as St. Anne,
Was the mother of Mary;
And all this has been to her but as the sound of lyres and flutes,
And lives
Only in the delicacy
With which it has moulded the changing lineaments,
And tinged the eyelids and the hands.
Like the Vampire,
She has been dead many times,
And learned the secrets of the grave;
And has been a diver in deep seas,
And keeps her fallen day about her;
And trafficked for strange webs with Eastern merchants;
And, as Leda,
Was the mother of Helen of Troy,
And, as St. Anne,
Was the mother of Mary;
And all this has been to her but as the sound of lyres and flutes,
And lives
Only in the delicacy
With which it has moulded the changing lineaments,
And tinged the eyelids and the hands.
Subscribe to:
Posts (Atom)