On a project I worked on recently one file contained a comment reading something like:// The below code is unnecessary but the program// does not work if it is removed.// With the code commented out everything is fine.
The group of people involved in that area of code were also masters of redundancy and inefficiency. Their code could often be rewritten and shortened to 20% of its original length. Not BY 20%, TO 20%.
How does painting your roof white either generate more electricity or improve the usage efficiency of what is already generated? Putting solar cells on lots of californian roofs would be a good idea, but I think you are misremembering the bit about painting them white. I remember an article many years ago in, I think, New Scientist, possibly Nature, that mentioned painting most roofs in Los Angeles white, which may be the same article. Assuming my memory is any better than yours, it went on to say that the increase in reflected sunlight, rather than it being absorbed by the buildings, would drop the temperature of the area by a few degrees on the sunniest days, and lead to a dramatic fall in the amount of smog forming.
It is possible to build a 'light valve' which will pass light in one direction but block it in the other, but I cannot think of any efficient way to make the return direction act as a mirror instead of an absorber. The valve relies on two polarisers and an anisotropic crystal with a particular electro-optic property, which always rotates the direction of the polarization of the light passing through it the same way, no matter whether the light is going forwards or backwards. 'Forwards' and 'backwards' are very specific directions with respect to the crystal axis and the direction of the electric field being applied. The required KTP crystals (or is KDP used?) are somewhat pricey and generally small and the required alignment between all components has to be pretty accurate, so although it is fairly simple to set this kind of thing up in a lab it is not something that could be economically mass produced in front of every solar panel.
I did my PhD on polarization effects, so know a bit about them. Whether I can explain in layman's terms is another matter, but here goes...
Light may be considered to act as both a particle and a wave, but for our purposes we'll stick to waves. Imagine looking at an unfiltered, unpolarized light source. The light is travelling towards you but each little bit of light is a wave which may be orientated up and down, or side to side, or anywhere inbetween, as it travels. (I'm ignoring what is known as circular polarization for now.) You can consider a polarization filter as a grill. Only the waves which line up with the grill will get through intact. Waves which are partly aligned will pass through the amount that does line up. Waves which are at right-angles to the grill will not get through at all. The light which does not get through is absorbed. If you take evenly distributed unpolarized light, which is what solar cells pretty much get from the sun, then you can only get 50% of the light through into linear polarization with a single filter. You can change one polarization into another efficiently, but the initial conversion from unpolarized to fuly polarized causes 50% loss. However, a 50% polarization followed by an 80% conversion within the solar cell still gives you an overall 40%, which is much better than current cells.
Here's something to think about: If you shine light through 2 polarizers which are crossed at right-angles then no light gets through. This is because the light coming through the first polarizer is all aligned at 90 degrees to the orientation of the second polarizer and is hence completely blocked. If you now add a third filter at 45 degrees between the other two then you start getting light through. Adding a filter has increased the amount passing through. Explaining why, I'll leave as an exercise for the reader.
Drop one end of the cable out of the window, carry it across to the base of the other building. Drop a piece of string out of the window of the second building (keep hold of one end!) and tie the string to the cable. Pull the cable up to the window. If you couldn't work that one out then you must obviously be an arts student.
Dark current is the unwanted signal noise leaking into the CCD detectors when they are 'dark'. i.e. not illuminated. One source of this noise is thermal effects, which is reduced by cooling the detector. Peltier devices and a large heatsink can reduce the temperature by about 30 degC. Liquid N2 is somewhat more drastic.
Increasing the aperture of a telescope has two effects: More light is collected. (Since astronomical telescopes are usually used to look at dim objects this is normally considered an advantage.) To reduce the diffraction effects and so increase the spatial resolution.
When observing the sun, the second of these is still required but the first is a problem. The sun provides too much light, especially in the infrared, to observe safely. The solution is to place a filter over the front of the telescope which cuts down the amount of light entering the scope. This reduction generally needs to be of the order of 1:1,000,000. Filters at the back end of the telescope, directly in front of the eyepiece/camera, are not safe. All the heat from the sun passes the scope through and is focused through this small filter. They can then easily crack or melt.
Safety notice: The only safe filters for observing the sun are those designed for the job. They are usually thin plastic, sometimes glass, with a metal coating on both sides. Always check the filter is firmly fixed in place and has no scratches or pinholes. It is this filter type which was used in the eclipse safety glasses a few years back. When observing by eye, with no telescope, binoculars or other magnification, welder's No 14 glass or fully exposed and developed black and white film negatives are also safe. (Not colour film or b&w film developed with a colour process - it is the deposited metallic silver used in the b&w process which provides the protection.) NOTHING else is considered safe.
You can get cooled CCD cameras, and the astrophotographical community has been using them for years. (Well, those than can afford them anyway.) The cooling is required to reduce the 'dark current' within the camera itself during long exposures, not to remove incoming heat.
Re:Encryption and compression make a lot of sense.
on
PKWare Zips to Growth
·
· Score: 1
The zip compression does not generate a data stream starting with PK. That is just the start of the zip header. However, you are correct in that the compressed data does have to have at least some sections following a defined format even if the contents themselves are unpredictable.
Making tables is not especially difficult, although I wouldn't fancy the job of carving or engraving the element details on each of those tiles. The furthest I've taken things is a coffee table with a Penrose tiling mosaic top. Cutting a few hundred tiles to an accuracy of better than 1 degree at each vertex took weeks. If you have the confidence and dexterity to modify cases without slashing your wrists open on torn aluminium there is no reason why you shouldn't give basic joinery a try.
"By definition a standard drm is less secure than a proprietary one," says Gregg Makuch, senior product manager for mobile product and services at Seattle-based Realnetworks.
You cannot implement DRM without some form of encryption and time after time, closed proprietary encryption routine have proved to be flawed. Security through obscurity cannot be relied on to remain secure.
Examine three possible scenarios:
1) They develop a perfect, crack proof, implementation,either proprietary or open standard. Great (for them)! But how likely is this to happen?
2) They develop a flawed (crackable) implementation of an open standard. This is quickly broken and all media content released up to that point, which will be comparatibly little, becomes available. They patch the flaw and issue an automatic upgrade to the firmware. (This is likely to be possible - if they want to control content then they are likely to want to have control over the platform too - and if it isn't, well, people often upgrade their phones quite often anyway.) Then version 2 gets cracked, and so on until they get it right, probably at about version 5.
3) They develop a flawed implementation of an proprietary method. This gets cracked too of course, but probably takes a little longer. Hence, a greater volume of content is now available unprotected. The patch and recrack cycle continues until they get it right.
From the media owner point of view scenario 1 is preferable and they lose out the most with scenario 3. Scenario 2 is a workable compromise.
Most star light (and nebula glow through either reflected star light, or absorbed and re-emitted star light) is at two wavelengths, approx 650nm and 500nm. From memory, these correspond to the hydrogen alpha and oxygen III lines.
The dark adapted human eye loses a lot of its colour sensitivity, so images seen at night tend to be 'black and white', but even so, it is much more sensitive at 500 than 650nm. This is why nebula such as M42/43 (The 'Great' Orion nebula) and the nearby Horsehead nebula look to be a pale blue-green to the eye. The types of colour film used in astrophotography, and CCD cameras, are highly sensitive to 650nm, but 500nm falls into the less sensitive area between two of the colour emulsion layers of film. This means that photographs come out pink.
When comet Shoemaker-Levy broke up and hit Jupiter the impact 'scars' for several of the individual pieces grew to larger than the Earth. 1500 square miles is nothing.
Doesn't a laser, by definition, produce one, and only one, frequency? Why yes! Actually, no. A laser gain medium will amplify light of any frequency within a certain bandwidth. The cavity will be stable for any wavelength which is an integer fraction of the cavity length. The combination of these can select a single wavelength if you design the system correctly and the gain medium bandwidth is sufficiently narrow but it is also possible to build a system where there are multiple wavelengths present.
What do consider to be the definition of a laser? The acronym stands for Light Amplification by Stimulated Emision of Raditaion. There is nothing about producing a single frequency. Restricting a laser to a single frequency is as much an engineering design problem as anything else.
DVDs, or more accurately, the contents of the DVD, will eventually pass into the public domain, but since copyright law has been amended repeatedly to extended the copyright duration we are unlikely to ever see any current content be released. A summary here shows copyright expiry times depending on the content creation date. The current expiry time for corporately owned content is 95 years minimum. This table is probably specific to US law, but that will be a close, probably exact, match to the Berne Convention which is in force throughout most of the western world.
Re:Shouldn't royalties go to the COMPOSERS?
on
Ring-Tone Royalties
·
· Score: 5
Every now and then somebody with a midi capable phone asks 'Can I convert a.wav/mp3 to midi?' on comp/alt.music.midi. There is software to do it, but your mileage may vary. After somebody asked this on/. some time ago I started writing a package, WaveGoodbye, available here, but this is designed for polyphonic conversion which phones cannot handle (yet). This is now the most capable of the free wav->midi conversion programs, and can rival the commercial packages at piano music conversion. The version 1, Windows only, binary is freely available and version 2 is currently under development. I am considering releasing the source for this and taking it cross platform. Any Kylix developers out there interested? The alt.music.midi faq (linked from the above link, unless it has moved again) contains a list of poly- and mono-phonic conversion programs. Polyphonic conversion is very difficult and still a topic of research in many university media groups. Monophonic conversion is easier and these programs are generally more accurate.
The UK population is, I think, about 50-60 million. The proportion owning mobile phones recently reached 60%, surpassed in the world only by some of the Scandanavian countries. That's about 35 million cell phones. 13 million calls a day seems reasonable.
The last fs laser I used could be optimised to put out an average power of about 100mW with a pulse rate of about 40MHz. A piece of matt black card held in the beam would smoke, and could be a good way of finding the beam at times. (It was infrared.) White card would reflect too much, so stayed cool. You could wave your arm through the beam, but you wouldn't want to stay still.
Now the maths:
The intensity profile over time of each pulse was roughly gaussian with a FWHM time of 80fs. (Full Width Half Maximum is the width of the gaussian at the point it rises/falls through the level half of the maximum. Since gaussians decay towards zero but never quite reach it you cannot measure 'start' and 'stop' times. If you assume a square pulse of the FWHM width the numbers are about 10-20% out, but I cannot remember which way off hand.) This beam could be focused down to a 20um diameter spot (area=3.1E-10 m^2)
100mW / 40MHz = 2.5nJ per pulse
2.5nJ / 80fs = 31kW (+/- 20%) peak pulse power
31kW / 3.1E-10 m^2 = 10^14 W/m^2
100TW per square meter is a huge power density, but these are the kind of levels that non-linear optical physics works at. There were losses through the various components in the system - we were doing experiments which required a fair amount of kit - but we usually ran at 1/3 to 1/2 of this.
The 100mW output femtosecond laser was powered by a 2m long Nd:YAG providing 8W of laser power. (Waving your arm through that beam left holes, but at least laser wounds are self cauterising and, believe me, you only ever do it once.) The power supply for that was almost 1m high, ran off the 3 phase supply and required water cooling. The pump laser required water cooling. Even the fs laser required cooling - I built a tiny water cooled peltier unit which would work perfectly for cooling today's high speed processors.
So, not exactly battery powered and hand held.
I was working with fs lasers from 1994-8. Back then there were very few available commercially and they cost quite a bit, about $100K with the necessary ancilliary equipment. The research group I was with built a couple ourselves that ran with 80fs and 20fs pulses. (The world record was about 6fs at the time.) The lasers were built on 4'x2' optical tables, but most of this space was only required to provide a large enough external cavity to slow the pulse repetition rate down. The core components within the inner cavity were all mounted on an 18" track. The main problem was stability - the slightest knock would ruin the alignment. The whole system was on top of a 10'x5' stone table to reduce vibration. Putting half a dozen fans, HDDs, CDs, etc near it would have been a disaster.
By the late 90s commercial lasers were lower cost (but still not cheap) and would fit in about 2'x1'. I suspect they are a little cheaper and a little smaller by now, but not greatly so.
At a guess: Outcast. This used a voxel engine rather than polygons, so 3D accelerator cards had no effect. The only thing that mattered was raw CPU power. Having said that, the graphics were very impressive and the forest area truly amazing. It is difficult to realistic draw even a static tree and outcast could be showing dozens, all blowing in the wind.
>Only if the decibel level was doubled, you would think of it as twice as loud.
Normal quiet conversation is generally about 60-65dB. Concorde taking off directly overhead (which is LOUD) is about 120-130dB. There is more than a factor of two here.
A factor of 10dB is a doubling in energy and apparent volume is related to the root of the energy, so doubles with every 20dB.
I see another problem running at 1280x1024. Some years ago I had some training as a projectionist with one of the top university film societies in the UK. (At least, they regularly won the British Film Society award for University Film Society of the Year, so they must be reasonably good.) The projection equipment was old but good, the screen large, the audio equipment bang up to date and superb (they had Dolby Digital long before most mainline cinemas) and the seating, over which they had no control, was absolutely awful.
That resolution has an aspect ratio of 1.25:1 which nothing uses these days. I think 16mm film used that but all 35mm ratios were wider. Generally the ratio has been getting wider over the years. Modern films are generally in Widescreen or Scope aspect ratios: 2.85:1 or 3.15:1 if my memory serves me right. So are we going to see long thin pixels or a return to narrow screen formats. To emphasize the point: on a relatively small cinema screen, 5m wide, a scope ratio film would be shown with pixels 1.5cm high but 4cm wide. The Screen 1 auditorium in almost any cinema has a much larger screen than this. Anybody sitting near the front would have no trouble making out each pixel.
1.start a blank worksheet in excel 97 2.press F5 key 3.type X97:L97 4.hit enter 5.press tab once 6.you should be in row m 97 7.hold ctrl and shift and click the chart wizard button 8.(the little bar graph) 9.use the mouse to navigate (sensitive control) 10.left button goes forward right goes back-- Find Excel Shrine
Happy flying.
BTW, if you try this without DirectDraw available then you get a nicely animated credits list instead.
That is just chromatic aberations in the lens. If you look through the centre of the lens there will be no problem, but it will get worse towards the top/bottom/sides. I am badly short-sighted, -6.5 diopters, with fairly large lenses ( I don't like these tiny 1 inch round spectacle frames - they effectively give you tunnel vision ) so the aberations are quite bad at the corners of my specs. Modern lens design has produced aspherical thin lenses which much more powerful than the old spherical ones and which cut down on the aberations causes by such lenses (spherical aberations) but until somebody start lenses with one layer of one glass and one layer of a different glass (eg crown and flint) then chromatic aberations cannot be resolved. I do not even want to consider what such lenses would cost, aspherical lenses are bad enough.
Slashdot Mirror
On a project I worked on recently one file contained a comment reading something like: // The below code is unnecessary but the program // does not work if it is removed. // With the code commented out everything is fine.
The group of people involved in that area of code were also masters of redundancy and inefficiency. Their code could often be rewritten and shortened to 20% of its original length. Not BY 20%, TO 20%.
How does painting your roof white either generate more electricity or improve the usage efficiency of what is already generated? Putting solar cells on lots of californian roofs would be a good idea, but I think you are misremembering the bit about painting them white.
I remember an article many years ago in, I think, New Scientist, possibly Nature, that mentioned painting most roofs in Los Angeles white, which may be the same article. Assuming my memory is any better than yours, it went on to say that the increase in reflected sunlight, rather than it being absorbed by the buildings, would drop the temperature of the area by a few degrees on the sunniest days, and lead to a dramatic fall in the amount of smog forming.
It is possible to build a 'light valve' which will pass light in one direction but block it in the other, but I cannot think of any efficient way to make the return direction act as a mirror instead of an absorber. The valve relies on two polarisers and an anisotropic crystal with a particular electro-optic property, which always rotates the direction of the polarization of the light passing through it the same way, no matter whether the light is going forwards or backwards. 'Forwards' and 'backwards' are very specific directions with respect to the crystal axis and the direction of the electric field being applied. The required KTP crystals (or is KDP used?) are somewhat pricey and generally small and the required alignment between all components has to be pretty accurate, so although it is fairly simple to set this kind of thing up in a lab it is not something that could be economically mass produced in front of every solar panel.
I did my PhD on polarization effects, so know a bit about them. Whether I can explain in layman's terms is another matter, but here goes...
Light may be considered to act as both a particle and a wave, but for our purposes we'll stick to waves.
Imagine looking at an unfiltered, unpolarized light source. The light is travelling towards you but each little bit of light is a wave which may be orientated up and down, or side to side, or anywhere inbetween, as it travels. (I'm ignoring what is known as circular polarization for now.) You can consider a polarization filter as a grill. Only the waves which line up with the grill will get through intact. Waves which are partly aligned will pass through the amount that does line up. Waves which are at right-angles to the grill will not get through at all. The light which does not get through is absorbed. If you take evenly distributed unpolarized light, which is what solar cells pretty much get from the sun, then you can only get 50% of the light through into linear polarization with a single filter. You can change one polarization into another efficiently, but the initial conversion from unpolarized to fuly polarized causes 50% loss.
However, a 50% polarization followed by an 80% conversion within the solar cell still gives you an overall 40%, which is much better than current cells.
Here's something to think about: If you shine light through 2 polarizers which are crossed at right-angles then no light gets through. This is because the light coming through the first polarizer is all aligned at 90 degrees to the orientation of the second polarizer and is hence completely blocked. If you now add a third filter at 45 degrees between the other two then you start getting light through. Adding a filter has increased the amount passing through. Explaining why, I'll leave as an exercise for the reader.
Drop one end of the cable out of the window, carry it across to the base of the other building. Drop a piece of string out of the window of the second building (keep hold of one end!) and tie the string to the cable. Pull the cable up to the window.
If you couldn't work that one out then you must obviously be an arts student.
Dark current is the unwanted signal noise leaking into the CCD detectors when they are 'dark'. i.e. not illuminated. One source of this noise is thermal effects, which is reduced by cooling the detector. Peltier devices and a large heatsink can reduce the temperature by about 30 degC. Liquid N2 is somewhat more drastic.
Increasing the aperture of a telescope has two effects:
More light is collected. (Since astronomical telescopes are usually used to look at dim objects this is normally considered an advantage.)
To reduce the diffraction effects and so increase the spatial resolution.
When observing the sun, the second of these is still required but the first is a problem. The sun provides too much light, especially in the infrared, to observe safely.
The solution is to place a filter over the front of the telescope which cuts down the amount of light entering the scope. This reduction generally needs to be of the order of 1:1,000,000.
Filters at the back end of the telescope, directly in front of the eyepiece/camera, are not safe. All the heat from the sun passes the scope through and is focused through this small filter. They can then easily crack or melt.
Safety notice: The only safe filters for observing the sun are those designed for the job. They are usually thin plastic, sometimes glass, with a metal coating on both sides. Always check the filter is firmly fixed in place and has no scratches or pinholes. It is this filter type which was used in the eclipse safety glasses a few years back. When observing by eye, with no telescope, binoculars or other magnification, welder's No 14 glass or fully exposed and developed black and white film negatives are also safe. (Not colour film or b&w film developed with a colour process - it is the deposited metallic silver used in the b&w process which provides the protection.) NOTHING else is considered safe.
You can get cooled CCD cameras, and the astrophotographical community has been using them for years. (Well, those than can afford them anyway.) The cooling is required to reduce the 'dark current' within the camera itself during long exposures, not to remove incoming heat.
The zip compression does not generate a data stream starting with PK. That is just the start of the zip header. However, you are correct in that the compressed data does have to have at least some sections following a defined format even if the contents themselves are unpredictable.
Another one is
19
----
95
Cancelling out the nines works too.
Making tables is not especially difficult, although I wouldn't fancy the job of carving or engraving the element details on each of those tiles. The furthest I've taken things is a coffee table with a Penrose tiling mosaic top. Cutting a few hundred tiles to an accuracy of better than 1 degree at each vertex took weeks.
If you have the confidence and dexterity to modify cases without slashing your wrists open on torn aluminium there is no reason why you shouldn't give basic joinery a try.
"By definition a standard drm is less secure than a proprietary one," says Gregg Makuch, senior product manager for mobile product and services at Seattle-based Realnetworks.
You cannot implement DRM without some form of encryption and time after time, closed proprietary encryption routine have proved to be flawed. Security through obscurity cannot be relied on to remain secure.
Examine three possible scenarios:
1) They develop a perfect, crack proof, implementation,either proprietary or open standard. Great (for them)! But how likely is this to happen?
2) They develop a flawed (crackable) implementation of an open standard. This is quickly broken and all media content released up to that point, which will be comparatibly little, becomes available. They patch the flaw and issue an automatic upgrade to the firmware. (This is likely to be possible - if they want to control content then they are likely to want to have control over the platform too - and if it isn't, well, people often upgrade their phones quite often anyway.) Then version 2 gets cracked, and so on until they get it right, probably at about version 5.
3) They develop a flawed implementation of an proprietary method. This gets cracked too of course, but probably takes a little longer. Hence, a greater volume of content is now available unprotected. The patch and recrack cycle continues until they get it right.
From the media owner point of view scenario 1 is preferable and they lose out the most with scenario 3. Scenario 2 is a workable compromise.
Which is most likely to happen?
Most star light (and nebula glow through either reflected star light, or absorbed and re-emitted star light) is at two wavelengths, approx 650nm and 500nm. From memory, these correspond to the hydrogen alpha and oxygen III lines.
The dark adapted human eye loses a lot of its colour sensitivity, so images seen at night tend to be 'black and white', but even so, it is much more sensitive at 500 than 650nm. This is why nebula such as M42/43 (The 'Great' Orion nebula) and the nearby Horsehead nebula look to be a pale blue-green to the eye. The types of colour film used in astrophotography, and CCD cameras, are highly sensitive to 650nm, but 500nm falls into the less sensitive area between two of the colour emulsion layers of film. This means that photographs come out pink.
When comet Shoemaker-Levy broke up and hit Jupiter the impact 'scars' for several of the individual pieces grew to larger than the Earth. 1500 square miles is nothing.
Doesn't a laser, by definition, produce one, and only one, frequency? Why yes!
Actually, no. A laser gain medium will amplify light of any frequency within a certain bandwidth. The cavity will be stable for any wavelength which is an integer fraction of the cavity length. The combination of these can select a single wavelength if you design the system correctly and the gain medium bandwidth is sufficiently narrow but it is also possible to build a system where there are multiple wavelengths present.
What do consider to be the definition of a laser? The acronym stands for Light Amplification by Stimulated Emision of Raditaion. There is nothing about producing a single frequency. Restricting a laser to a single frequency is as much an engineering design problem as anything else.
DVDs, or more accurately, the contents of the DVD, will eventually pass into the public domain, but since copyright law has been amended repeatedly to extended the copyright duration we are unlikely to ever see any current content be released. A summary here shows copyright expiry times depending on the content creation date. The current expiry time for corporately owned content is 95 years minimum. This table is probably specific to US law, but that will be a close, probably exact, match to the Berne Convention which is in force throughout most of the western world.
Every now and then somebody with a midi capable phone asks 'Can I convert a .wav/mp3 to midi?' on comp/alt.music.midi. There is software to do it, but your mileage may vary. After somebody asked this on /. some time ago I started writing a package, WaveGoodbye, available here, but this is designed for polyphonic conversion which phones cannot handle (yet). This is now the most capable of the free wav->midi conversion programs, and can rival the commercial packages at piano music conversion. The version 1, Windows only, binary is freely available and version 2 is currently under development. I am considering releasing the source for this and taking it cross platform. Any Kylix developers out there interested? The alt.music.midi faq (linked from the above link, unless it has moved again) contains a list of poly- and mono-phonic conversion programs. Polyphonic conversion is very difficult and still a topic of research in many university media groups. Monophonic conversion is easier and these programs are generally more accurate.
The UK population is, I think, about 50-60 million. The proportion owning mobile phones recently reached 60%, surpassed in the world only by some of the Scandanavian countries. That's about 35 million cell phones. 13 million calls a day seems reasonable.
The last fs laser I used could be optimised to put out an average power of about 100mW with a pulse rate of about 40MHz. A piece of matt black card held in the beam would smoke, and could be a good way of finding the beam at times. (It was infrared.) White card would reflect too much, so stayed cool. You could wave your arm through the beam, but you wouldn't want to stay still.
Now the maths:
The intensity profile over time of each pulse was roughly gaussian with a FWHM time of 80fs. (Full Width Half Maximum is the width of the gaussian at the point it rises/falls through the level half of the maximum. Since gaussians decay towards zero but never quite reach it you cannot measure 'start' and 'stop' times. If you assume a square pulse of the FWHM width the numbers are about 10-20% out, but I cannot remember which way off hand.) This beam could be focused down to a 20um diameter spot (area=3.1E-10 m^2)
100mW / 40MHz = 2.5nJ per pulse
2.5nJ / 80fs = 31kW (+/- 20%) peak pulse power
31kW / 3.1E-10 m^2 = 10^14 W/m^2
100TW per square meter is a huge power density, but these are the kind of levels that non-linear optical physics works at. There were losses through the various components in the system - we were doing experiments which required a fair amount of kit - but we usually ran at 1/3 to 1/2 of this.
The 100mW output femtosecond laser was powered by a 2m long Nd:YAG providing 8W of laser power. (Waving your arm through that beam left holes, but at least laser wounds are self cauterising and, believe me, you only ever do it once.) The power supply for that was almost 1m high, ran off the 3 phase supply and required water cooling. The pump laser required water cooling. Even the fs laser required cooling - I built a tiny water cooled peltier unit which would work perfectly for cooling today's high speed processors.
So, not exactly battery powered and hand held.
I was working with fs lasers from 1994-8. Back then there were very few available commercially and they cost quite a bit, about $100K with the necessary ancilliary equipment. The research group I was with built a couple ourselves that ran with 80fs and 20fs pulses. (The world record was about 6fs at the time.) The lasers were built on 4'x2' optical tables, but most of this space was only required to provide a large enough external cavity to slow the pulse repetition rate down. The core components within the inner cavity were all mounted on an 18" track. The main problem was stability - the slightest knock would ruin the alignment. The whole system was on top of a 10'x5' stone table to reduce vibration. Putting half a dozen fans, HDDs, CDs, etc near it would have been a disaster.
By the late 90s commercial lasers were lower cost (but still not cheap) and would fit in about 2'x1'. I suspect they are a little cheaper and a little smaller by now, but not greatly so.
At a guess: Outcast.
This used a voxel engine rather than polygons, so 3D accelerator cards had no effect. The only thing that mattered was raw CPU power. Having said that, the graphics were very impressive and the forest area truly amazing. It is difficult to realistic draw even a static tree and outcast could be showing dozens, all blowing in the wind.
Guinness merged with another company a few years ago. Diageo is the name of the new company.
>Only if the decibel level was doubled, you would think of it as twice as loud.
Normal quiet conversation is generally about 60-65dB. Concorde taking off directly overhead (which is LOUD) is about 120-130dB. There is more than a factor of two here.
A factor of 10dB is a doubling in energy and apparent volume is related to the root of the energy, so doubles with every 20dB.
I see another problem running at 1280x1024. Some years ago I had some training as a projectionist with one of the top university film societies in the UK. (At least, they regularly won the British Film Society award for University Film Society of the Year, so they must be reasonably good.) The projection equipment was old but good, the screen large, the audio equipment bang up to date and superb (they had Dolby Digital long before most mainline cinemas) and the seating, over which they had no control, was absolutely awful.
That resolution has an aspect ratio of 1.25:1 which nothing uses these days. I think 16mm film used that but all 35mm ratios were wider. Generally the ratio has been getting wider over the years. Modern films are generally in Widescreen or Scope aspect ratios: 2.85:1 or 3.15:1 if my memory serves me right. So are we going to see long thin pixels or a return to narrow screen formats. To emphasize the point: on a relatively small cinema screen, 5m wide, a scope ratio film would be shown with pixels 1.5cm high but 4cm wide. The Screen 1 auditorium in almost any cinema has a much larger screen than this. Anybody sitting near the front would have no trouble making out each pixel.
1.start a blank worksheet in excel 97
2.press F5 key
3.type X97:L97
4.hit enter
5.press tab once
6.you should be in row m 97
7.hold ctrl and shift and click the chart wizard button
8.(the little bar graph)
9.use the mouse to navigate (sensitive control)
10.left button goes forward right goes back-- Find Excel Shrine
Happy flying.
BTW, if you try this without DirectDraw available then you get a nicely animated credits list instead.
That is just chromatic aberations in the lens. If you look through the centre of the lens there will be no problem, but it will get worse towards the top/bottom/sides. I am badly short-sighted, -6.5 diopters, with fairly large lenses ( I don't like these tiny 1 inch round spectacle frames - they effectively give you tunnel vision ) so the aberations are quite bad at the corners of my specs. Modern lens design has produced aspherical thin lenses which much more powerful than the old spherical ones and which cut down on the aberations causes by such lenses (spherical aberations) but until somebody start lenses with one layer of one glass and one layer of a different glass (eg crown and flint) then chromatic aberations cannot be resolved. I do not even want to consider what such lenses would cost, aspherical lenses are bad enough.