Sensei
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Posts posted by Sensei
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I would advise against PNG for photos, jpg whilst lossy is good for busy images, PNG is more suited to large blocks or lines.
I always use PNG, when not using PSD (PhotoShop Document).
Pretty good is also EXR file format (it can have even 32 bit floating point number per channel, while PNG/JPG have 8 bits unsigned integer per channel). Obviously at cost of file size.
Especially photos taken by digital camera, at full res, saved automatically to JPEG,
if we will load it in Photoshop or other 2D image processing software,
and then do some processing like rescale down,
and we will save it yet again in JPEG,
it will introduce even more errors due to double saving in lossy compression file format.
Make a test: ten times load same photo, and save in JPG, load it again, save in JPG, repeat..
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"Experts have argued for decades about the wisdom of broadcasting into space."
Except we've been doing that for decades
Except it does not work this way.. These sun system receive nothing but noise, with plentiful of data lost, not possible to decode properly.
To send radiowave data to long distances, there is needed precise directional antenna.
Even to send/receive data to satellite or spacecraft like Voyager that's pretty close in cosmic scale distances, rotation of antenna/receiver by fraction of mm mean lack of signal, or issues with sending/receiving..
And we need to send data in direction where will be object after years (hundred/thousands for 1000+ ly), not where we see it now.
TV signal sent in the past is certainly not directional, and not in direction of any known star or planet.
We often cant receive radio from broadcasting station that's just a few hundred km away, not to mention a few thousands.
Some lucky can receive signal when they're in good location, because photons reflected from troposphere.
Coverage
https://en.wikipedia.org/wiki/Coverage_%28telecommunication%29
Coverage map of broadcasting stations:
https://en.wikipedia.org/wiki/Coverage_map
Radiowave propagation:
https://en.wikipedia.org/wiki/Radio_propagation
Tropospheric scatter to reach larger distances:
https://en.wikipedia.org/wiki/Tropospheric_scatter
They mention 300 km reasonable distance.
1000 km with pretty demanding equipment.
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That's the first time I work with hardware.
Then IMHO you should start from something simpler.
Make f.e. LED counter, going from 00 to 99 for instance.
Have hardware register in binary format (some use binary coded decimal, and BCD addition, 8 bits = 2 digits each one with 0...9 digits, 10..15 values in 4 bits not used),
that's converted to decimal format,
which is later used to turn on/off LEDs forming digits.
It's plentiful of work IMHO,
see how complex breadboard he has on this video:
ps. For a start I would try making radio receiver playing music by speaker. It's easier to make than LEDs digital counter. Start from generating sinusoid wave for speaker from oscillator/timer. That you can adjust with potentiometer. Amplifier that takes microphone input signal, amplifies it, and sends to speaker in f.e. 2nd room. Then adding part for radiowave receiving will be just piece of cake.
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Without affecting any other output of [math]f(x)=x^2[/math], can you figure out how to modify the function such that [math]f(3)=\pi[/math] ? The modified equation must still produce all other outputs of [math]f(x)[/math] and only change the output of [math]f(3)[/math] such that it would produce the following sequence (ignoring negatives in the example):
{..., 0, 1, 4, [math]\pi[/math], 16, 25, 36, ...}
If you have read this post carefully, you might be able to figure out the missing piece:
[math]f(x)=x^2 \, + \, ?[/math]
In programming we're dealing with it every single day dozen of times.
In C/C++ it would be f.e.
y = ( x==3 ) ? M_PI : x*x;
Comparison can be replaced by subtraction
x'=x-3
Now we need to check whether x' is 0 or not.
sgn() can do it:
x''=sgn(x')
Is it allowed to use sgn() in this challenge?
https://en.wikipedia.org/wiki/Sign_function
sgn() returns -1 if input is negative, +1 if input is positive, or 0 if it's 0.
So, after sgn() we need to use abs() to turn -1 to +1:
abs(sgn(x-3))
Now output will be only 0 and 1.
(We can notice that abs(sgn(x)) is also equal to sgn(x)^2, -1*(-1)=+1 and +1*1=+1)
We need to reverse it by using (1-abs(sgn(x-3)))
this way if we multiply it by anything, if x!=3, will be multiplied by 0, and canceled.
[math]f(x)=x^2+(-9+\pi)*(1-\left|sgn(x-3)\right|)[/math]
abs(x)=sgn(x)*x
so
sgn(x)=abs(x)/x (except x=0)
and
abs(x)=sqrt(x*x)=(x^2)^0.5
so
sgn(x)=((x^2)^0.5)/x (except x=0)
If you can make sgn() (any way) using just add, sub, multiply, divide, power, sqrt, etc. you can finish my logic.
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In case anyone's even remotely interested I'd sell it for $500 plus shipping.
I appreciate time and invention that you spend on it. It looks nice.
But from business point of view, did you thought about it.. ?
Make pool in the Internet (there are free survey services) asking them how much people would be willing to pay for it.
Personally if I would be collecting elements, I would go to any electronics shop and get transparent drawer box, like this one (~ 30mm x 23mm x 17mm per cell) from Conrad:
It's for $6 retail. And there is needed 4-8 such. Giving $48 for all.
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And you think you can get about one and a half sheets for $10-20
Because I was thinking about completely different method of production.
"Reasonable price for item regardless of method of production" (current one is pretty time consuming).
$35 per 1m2 sheet is retail price.
Companies can get them much cheaper in large quantity.
Or buy pellets, melt them and fill matrix by them self.
I was thinking about buying plastic pellets like these:
http://www.ebay.com/bhp/plastic-pellets
50 lbs = 22.7 kg for $65 (also retail price)
and fill matrix with entire 200 cells by melted plastic.
1000x1000x4mm with density 1g/cm3 is approximately 4 kg mass.
22.7 kg / 4 kg/sheet = 5.675 sheets. Reducing price of sheet to $65/5.675 = $11.4
If width is 1000mm, 32 columns, 1000/32=31.25mm per cell width (and height, and depth).
It's area 1000x219 (31.25*7) = 0.219 m2, front and back double it,
and area for borders between cells horizontal & vertical.
Total area ~0.914 m2. So one sheet (if we go sheet-way, not melted-plastic-to-matrix-way) is enough.
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At a rough guess, it's about 200 pieces of plastic.
There is only 118 elements.
As long as each element is in it's own box, and it's own cover it's 118*2=236 pieces of plastic.
But it's not the only way to make it. Single horizontal piece of plastic can have "cuts" for vertical one piece of plastic.
So in minimum case there is needed 31 pieces vertical * 6 horizontal + 4 surrounding + 2 front/back = 192.
Although some manufacturer could make entire 32 x 7 array of boxes as single piece matrix, plus 118 covers, glued on top of them after filling.
Heh, if only. Just a sheet of 48x24x1/4in acrylic at Home Depot runs $65 ..
Here it costs 1000x1000x4 mm $34.9 inc. VAT.
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Why not check out some of Sensei's posts and consider building yourself a cloud chamber. I did it whilst at school and it is pretty amazing to spot Sub atomic particles in a home made experiment.
Alternatively building Cockcroft-Walton generator (I have 50+ kV), produce Hydrogen from electrolysis of water, fill up-side-down round-bottom glassware flask by gas, put electrodes, and turn on CW generator to ionize Hydrogen gas (or any other gas obtained from some chemical reaction).
Then split light emitted by it, on prism, to obtain spectral lines on white wall f.e.
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And for a couple of months, Google wants me to solve many kaptchas to deserve the right to be a target of their ads. They claim "abnormal queries" despite I use it normally. Annoying.
Sounds like somebody have google-keyword-searching-bot. Installed on machine, or somebody else in neighborhood network.
captchas are appearing when too many queries are send to google server.
or when they detect that IP is f.e. Tor network.
Do you have Google account? Are you all the time logged in?
Bring some friend laptop to home. Connect it to your network. And try whether his/her machine is behaving the same.
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They'd be pretty expensive mostly because there's a lot of labor involved in putting them together.
How come? It's just a piece of plastic..
Reasonable price IMHO is $10-$20.
Would love to hear some comments.
Personally I would prefer to have 32 columns (not special separated region for Lanthanides & Actinides).
How are you going to keep gases?
They will be empty boxes?
It would be fun to have them hermetic and filled with gas, and just connectors exposed, which after providing high voltage would start emitting light like discharge tubes..
Although it's way way beyond simple plastic container.
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I maybe one of the greatest scientist who ever live now
If you're the real scientist, in quantum physics, then you should no problem to answering following questions:
- what is energy (in eV) emitted by Hydrogen atom going from n=5 to n=2 excitation state?
- what is decay energy of Thorium-134, and what is decay mode? Either in eV and Joules. If you would provide velocity of products of decay, you would be master.
Please attach calculations for verification for either question.
PREPARE to intellectual battle...
Are you ready for it? Then answer above questions..
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lack of video showing a plane hit the Pentagon,
Why are you saying so.. ?
@ 1 minute 27 second is hit.
@ 1 minute 26 second we see object flying (just one frame).
As we can see CCTV camera is taking 1 FPS (frame per second). This can be estimated using car a few seconds prior crash.
American Airlines Flight 77
https://en.wikipedia.org/wiki/American_Airlines_Flight_77
was Boeing 757-223
as we can read on airplane website, max cruise speed is 850 km/h = 236.11(1) m/s.
Although they probably flied much faster (because of rapid drop of altitude prior hit).
Distance = Velocity * Time,
Time is quantized in steps 1s, 2s, 3s, etc.
That's why object is visible just on one frame. If it would be moving slower, or CCTV would be working at higher FPS, it would be recorded on more frames..
The real investigator could even estimate speed of object prior crash from such video (for higher precision there would be needed experiment in real world near Pentagon, to calculate distance visible from camera (it's fisheye-like, so it's distorting view)).
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PIC means Peripheral Interface Controller.
You need to have electronics that you will control by your chip.
The simplest case is control of LED.
Say you write code for turning on light for 1 second, then turning off light for 1 second. Upload it to chip. And LED is starting blinking.
If you want 2 seconds delay, you need to upload new program.
Or complicate electronics and code to allow user to change it by potentiometer.
Chip won't do anything by itself. It needs stuff it will control.
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Total energy of n photons is given by:
[math]\sum\limits_{i=0}^{i<n}{h*f_i}[/math]
or
[math]\sum\limits_{i=0}^{i<n}{\frac{h*c}{\lambda_i}}[/math]
For visible light:
[math]400nm\leqslant\lambda_i\leqslant700nm[/math]
For pretty monochromatic laser light with peak at 532nm (+-10nm):
[math]522nm\leqslant\lambda_i\leqslant542nm[/math]
Do you see light.. ?
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Can You please explain me what they are capable of?
Control electronics that you will make.
f.e. electric engines, LEDs, light.
Robotics. Automation.
Is micro chips programming an expensive hobby or a cheap one?
I don't think so.
As long as you won't be blowing them everyday.
$50-$100 for a start.
Take a look also on Arduino:
https://www.youtube.com/watch?v=b2CFKx5ASUY
search for Arduino @ YouTube videos.
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PICs are programmed in their own assembler.
f.e.
http://www.microchip.com/forums/m466343.aspx
It's nothing familiar to anything that you know like high level language such as Pascal.
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The organic solvents can't damage the metal itself.
How come?
f.e. acetic acid is organic polar solvent.
And with many metal it's going into reaction creating acetate.
f.e.
Zn + 2CH3COOH-> Zn(CH3COO)2 + H2
(This one is pretty slow at room temperature)
If there is reaction between metal and solvent, then how come it's not "damage of metal".. ?
Hi just want to ask, I've bought Nd ingot also ,but they come in small pieces (5mm-10mm) and was previously immerse in certain kind of mineral oil. so there's a dark surface on the metal, is there any chemical that can wash away this dark surface without hurting Nd metal itself too severely? I've thought about diluted HNO3, but just afraid the Nd will react with it and won't left me anything behind, cause my Nd ingots are quite small.
If you will polish, or do whatever you can to remove oxide layer, and leave on air again, it will go into reaction with oxygen sooner or later..
Quote from
https://en.wikipedia.org/wiki/Neodymium
"Metallic neodymium has a bright, silvery metallic luster, but as one of the more reactive lanthanide rare-earth metals, it quickly oxidizes in ordinary air. The oxide layer that forms then peels off, and this exposes the metal to further oxidation. Thus, a centimeter-sized sample of neodymium completely oxidizes within a year"
ps. There is needed such solvent which reacts with oxide layer, but not with metal alone.
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Level nine.. ?
Are you scientologist.. ?
Only serious and professional replies please.
It's very easy: build one.. If you manage to do so..
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@Fuzzwood,
had cancer 6 years ago, surgeon made a minor mistake, it had serious consequences.
In a sense, it has put my life on hold. close to being back to where I can have a life.
Still, with posting in here, if it does work, then at least I'll know better how to phrase everything
or what the concerns are about such an experiment.
You mean that near death experience, inspired you to become scientist.. ?
IMHO you should start from buying equipment. For a start:
- distillation set up: Graham condenser, Dephlegmator, retort stand, few clamps different models (to hold condensers, to hold round-bottom flask etc.), hot plate for heating.
- round-bottom flasks 50mL-1000 mL,
- beakers 50mL-1000 mL,
- graduated cylinders 50mL-250 mL.
- pocket jeweler's weigh 100 g/+-0.01g, 500 g/+-0.1 g
For learning about quantum physics, spectral lines of different gases etc., behaving of light, optics:
- discharge tubes: Hydrogen, Helium, Neon, Krypton, Xenon, Nitrogen, Oxygen, CO2 f.e.
- source of high voltage, such as Van der Graaf generator, Cockcroft-Walton generator.
- prism
- Young's slits different models, diffraction grating, polarization filters (at least two)
- at least three laser models, red, green and blue.
You will also have to have source of CO2, dry ice to buy, or from reaction.
The easiest one is to take baking soda NaHCO3 and acetic acid CH3COOH.
Reaction NaHCO3 + CH3COOH -> CH3COONa + CO2 + H2O will release plentiful of carbon dioxide for further experiments.
Additionally you will have sodium acetate for other experiments. It's interesting substance. Search YouTube for details.
Fill flask by water, connect to distillation set up, turn on hot plate, and distill water. You will have any amount of it. And gain experience in distillation process.
Once you will have 1L distilled water in beaker, place in it electrodes and turn on electricity.
And you will see nothing happens. No bubbles of gas from either electrode. Ampere meter will show 0 A current.
Add salt, and bubbles will start appearing and ampere meter will show I>0 A.
Clean up beaker, and use tap water - there will be gas. Not as much as with salted water. But enough to be visible.
Clean up beaker, and use again distilled water. Turn on electricity. And put in it piece of dry ice.. and tell us, or better record on video all experiments, what happens.
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When a current is passed through water, it might increase the amount of electro-magnetic energy associated with a water molecule.
In what way is electro-magnetic energy (i.e. light) "associated" with a water molecule?
And why would you expect this to increase?
Feel free to use mathematics in your reply.
Well, temperature of water is increased while passing current through it.
So it'll emit photons in not visible range (as always with such low temperatures as 273.15 K-373.15 K) microwave/infrared region of spectrum.
Use any IR thermometer on boiling water to read temperature change from distance (because of emitted radiation from body).
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This must be real world experiment or can be 3D simulation.. ?
Plenty of 3D applications have physical particle simulation systems built-in.
https://www.youtube.com/watch?v=0Drl97e8vP4
There are calculated collisions between particles each other, and normal objects in scene (collision objects, the one that you specify).
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I rather suspect that I could buy "off the peg" a calorimeter that's accurate enough to measure the heat added to your system by the magnetic stirrer,
I really would like to see it.
It might be accurate enough to measure +-0.050 J difference in burned sample, but it won't measure it by itself.
If you turn off stirring, temperature won't be uniform anymore, but create gradient of temperatures inside of device (sealed) water container. Making reading from thermometer not reliable anymore.
Even my hot tea that I just measured has 57.5 C at near top, and 54.5 C at bottom (measured by my -50 C...+300 C thermometer with +-0.1 C precision)
If stirrer engine has U=5 V voltage drop, and I=0.05 A, that's 0.05 J/s introduced to system at worst maximum.
(just example data for electric engine, the real data would be from 2nd voltage/ampere meters)
If volume of water in container is 100 mL = 100 g, 4.1855 J/K*g * 100g * 1 K = 418.55 / 0.05 = 8371 seconds wait for increase water temperature by 1 C..
but that you have not accounted for.
But is it really needed? You should rethink it.
If stirrer is turned on, its engine has pretty much the same power when stirred liquid has temperature T0=25 C, and when T1=50 C, or when it has T2=75 C.
It's always introducing exactly (+-) the same amount of energy to the system, regardless of whether heating element is turned on or off.
That's the sort of system that lets you measure the 4.1855 KJ/Kg K which you need to use in your system.
You also misunderstood what I am interested in measuring in my device, in the first place.
4.1855 J/K*g is just example. I don't need to measure it. But can measure it, if I would like to.
But what I wanted to really measure is amount of energy radiated away by body.
Again.
We have T0=25 C initial temperature.
Device is turned on. Voltage on voltage regulator slider is adjusted to reach temperature f.e. 50 C.
If T is still going up, voltage is adjusted to smaller value, if T is going down too fast, it's adjusted in reverse direction.
Adjust until we reach equilibrium T=const, and some U on regulator.
When it does not change, we can read amount of energy radiated away by body.
Repeat the same with T=70 C, or any other.
The key is to have constant temperature reading.
Amount of energy introduced to system by stirrer is constant, regardless at which T we're currently working.
Amount of energy from environment introduced to system is constant, regardless at which T we're currently working.
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What you've described is a kind of calorimeter.
Sort of.
Quote from link:
"It does not account for the heat loss through the container or the heat capacity of the thermometer and container itself."
Mine device is designed for measuring this loss.
Typical calorimeter is insulated as best as they can make it. To keep heat inside of device.
While in mine device insulation is not needed. Because what is radiated away is what we want to measure. Not energy released during burning f.e. (as there is nothing to burn in it).
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Thermodynamics. How to precisely measure energy released by body.
Imagine circuit with resistor (heating element) with resistance R.
There is also voltmeter, ampere meter connected.
[math]I=\frac{U}{R}[/math]
and
[math]P=I*U=I^2*R=\frac{U^2}{R}[/math]
R is constant (would be hard to control it in heating element underwater).
Heating element is placed in water (or other liquid) with mass m, and volume V.
There is also precise thermometer, stopwatch, and magnetic stirrer to uniformly spread energy in liquid.
At the beginning temperature is ambient T0 read from thermometer. Say 25 C.
(ambient temperature is when amount of energy released by body equals amount of energy received from environment)
We're heating it to T1, say 50 C.
Electrons are accelerated, and while passing through heating element, they lose their kinetic energy and resistor is heated, and indirectly liquid.
We read voltage drop on heating element from voltmeter. And read quantity of electrons Q/e, Q=I*t from ampere meter and stopwatch.
Einput=I*t*U
We can make equation to calculate energy needed to heat liquid with mass m, from T0 to T1:
[math]4.1855 \frac{J}{K*g} * m * (T_1-T_0) = ~ I*t*U[/math]
Calculate amount of energy needed to heat 1 gram of substance by 1 K:
[math]4.1855 \frac{J}{K*g} = ~ \frac{I*t*U}{m * (T_1-T_0)}[/math]
Calculate amount of energy needed to heat 1 mole of substance (water in example):
[math]4.1855 \frac{J}{K*g}*18.015\frac{g}{mol} = ~ \frac{I*t*U}{\frac{m}{18.015\frac{g}{mol}} * (T_1-T_0)}[/math]
[math]75.4 \frac{J}{K*mol} = ~ \frac{I*t*U}{n * (T_1-T_0)}[/math]
(etc. etc.)
It's idealized equation: when no energy is lost by emitting photons (in this case in microwave and infrared region of spectrum), nor by air gas particles taking part of energy.
I was thinking how to precisely measure amount of energy released by body to environment and influencing our idealized equation.
And came up with idea to use voltage/current regulator.
If we supply more energy to our system, than is released, temperature will increase.
Tcurrent must by higher than ambient temperature T0.
Einput>Eradiated, Tnew>Tcurrent, Tcurrent>T0
If we supply less energy to our system, temperature will decrease (only to T0).
Einput<Eradiated, Tnew<Tcurrent, Tnew>=T0
But if we use voltage/current regulator to precisely set value, with precision counted in mV, or uV, or better, temperature will be constant. Neither grow, nor fail.
Einput=Eradiated, Tnew=Tcurrent=constAnd we will know exactly how much is radiated as photons or heat.
This experiment could be performed at couple different temperatures, increased by f.e. 10 C.
And receive set of data f.e.:
Einput(T0+10)
Einput(T0+20)
Einput(T0+30)
....
Einput(T0+70)
Which will be placed on graph with temperature in x axis, and Energy/Current/Voltage/Power in y axis.
Second experiment: change area which has contact with air, while mass and volume remain the same.
To compare how results changes with area exhibited to air.
Third experiment: compare plain liquid graph, with graphs obtained with liquids which have metal radiator different shape and size.
Thus we will be able to measure efficiency of different radiator models.
Fourth experiment: repeat everything, with different liquid than water. And compare data with water on graph.
Best Regards!0
What hobbies does science offer?
in The Lounge
Posted · Edited by Sensei
If you will invent time-machine that works..
You need to install plugin
http://www.openexr.com/photoshop_plugin.html
Search for "Photoshop exr file format" or so in Google.
For me RAW can be useful.
Because it's extremely easy to make loader in C/C++.
BMP is nearly-RAW. It has just bitmap header structure at beginning of file, that we need to skip. The rest is up-side-down RAW.
Make a test: write same picture in JPG (test various compression levels), and in PNG, load them in Photoshop. Put to layers. Use subtraction mode between layers. It will show difference introduced by lossy file format.