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User talk:Brekki

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Good luck! --Panic (talk) 18:24, 20 December 2007 (UTC)

title: User talk:Brekki


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User talk:MilliesMom

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Good luck! --Panic (talk) 18:24, 20 December 2007 (UTC)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

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User talk:85.16.238.229

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Sorry, but ...
Hi I´m a german Wikibookian, called Techni-Tom. If you wonder what I´m doing in here: just "stealing" some Images for Commons and my translation of The Elements. Please don´t mind, but I just leave some and my IP 85.16.238.229 (talk) 20:29, 20 December 2007 (UTC)

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User talk:80.126.150.36

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User talk:75.166.250.166

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User talk:66.45.132.20

You have been warned
In regards to your question: We do not have the actual pages from the book on Wikibooks, that would be a copyright violation and against the law. If you want the original books, might I suggest that you go out and buy them? Chazz (talk) 06:25, 21 December 2007 (UTC)

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User talk:210.246.27.148

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User talk:Dudecon

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Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.--Whiteknight (Page) (Talk) 23:09, 20 December 2007 (UTC)

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Template talk:Click

Hello! Please add a link to pt:Predefinição:Click in your template. --200.17.211.142 (talk) 23:51, 20 December 2007 (UTC)

Done thanks -- Herby talk thyme 14:56, 14 January 2008 (UTC)

Please also add th:แม่แบบ:Click into this template. Thanks ! --125.25.19.142 (talk) 14:23, 6 March 2008 (UTC)
 * [[Image:Yes_check.svg|15px| ]] Done – Mike.lifeguard  | talk 15:07, 6 March 2008 (UTC)

Deprecated?
It seems that this template has been deprecated by a software feature. Images can now be linked to using the  variable. If no-one objects I suggest we replace transclusions with simple file tags and let the template go the way of the Vogons. --Swift (talk) 06:04, 20 February 2009 (UTC)

 * I don't think this template is completely deprecated yet. Using this template you can override the title attribute, which often is shown in the form of a tooltip in graphical browsers. This currently cannot be done when using the link option with File.

 * --dark lama  13:09, 20 February 2009 (UTC)

 * Good catch. This actually exists since MW 1.14. The image "alt" attribute is set, but not the link's "title" attribute, which is what the template does. I guess this may just be poor choice of naming for the template variable.
 * The title-setting feature is only used on Template:Sisterlinks. --Swift (talk) 13:58, 20 February 2009 (UTC)
 * The alt and title attributes are set by using the description field for images when not using a file/image "type" that shows a description. I was just trying to use similar template argument names as used with File. Template.Sisterlinks isn't the only place the title-setting feature is used. I think there are many others. Template:Userbox2 is probably the latest to do so. --dark lama  14:31, 20 February 2009 (UTC)

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User talk:Mlloyd57

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Good luck! --Panic (talk) 03:49, 21 December 2007 (UTC)

title: User talk:Mlloyd57


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Wikijunior:Europe/San Marino

San Marino is a tiny country in central Europe. It is completely surrounded by Italy. The capital city is the City of San Marino. San Marino is one of the smallest countries in the world. It is not part of the European Union but it uses the Euro as its currency.

San Marino's History
Traditionally, San Marino was founded by Saint Marinus in 301 CE. Marinus was a Christian stonemason who fled to the hills that make up San Marino to avoid persecution under the Roman Empire. Before the 19th century most of present-day Italy consisted of small city states like San Marino. When all of the other small states in Italy united in the 19th Century San Marino refused to join and has never been part of Italy. San Marino remained neutral during World War I and World War II.

After World War II San Marino became the first country to be democratically ruled by a communist party.

San Marino's Geography
San Marino is the third-smallest country in Europe, with only Vatican City and Monaco smaller. The total area that San Marino covers is 61 km2 (23.5 sq mi). The climate is Mediterranean, with warm summers and mild winters. The country is completely surrounded by Italy - one of only 3 such countries in the world (the others are Vatican City, also surrounded by Italy, and Lesotho, surrounded by South Africa).

San Marino's People
The Country has a population of approximately 31,000, including 1,000 foreigners, most of whom are Italians. About 5,000 Sammarinese live in foreign countries, predominantly in Italy. The language spoken is Italian. Emiliano-Romagnolo is widely spoken also. Roman Catholicism is the predominant religion.

San Marino's Sights
Over 2 million tourists visit San Marino every year. Popular attractions include the Three Towers of San Marino, The Cathedral of San Marino and the state museum. Buying stamps and coins with the name San Marino on them is a popular souvenir for many tourists.

title: Wikijunior:Europe/San Marino


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A-level Physics (Advancing Physics)/Digitisation

Digitisation of a signal is the process by which an analogue signal is converted to a digital signal.

Digitisation & Reconstruction
Let us consider the voltage output from a microphone. The signal which enters the microphone (sound) is an analogue signal - it can be any of a potentially infinite range of values, and may look something like this waveform (from an artificial (MIDI) piano):

When the microphone converts this signal to an electrical signal, it samples the signal a number of times, and transmits the level of the signal at that point. The following diagram shows sample times (vertical black lines) and the transmitted signal (the red line):

When we wish to listen to the sound, the digital signal has to be reconstructed. The gaps between the samples are filled in, but, as you can see, the reconstructed signal is not the same as the original sound:

Sampling Rate
The sampling rate when digitising an analogue signal is defined as the number of samples per. second, and is measured in Hertz (Hz), as it is a frequency. You can calculate the sampling rate using the formula:

$$\mbox{Sampling Rate (Hz)} = \frac{\mbox{No. of samples}}{\mbox{No. of seconds}}$$

The higher the sampling rate, the closer the reconstructed signal is to the original signal, but, unfortunately, we are limited by the bandwidth available. Theoretically, a sampling rate of twice the highest frequency of the original signal will result in a perfect reconstructed signal. In the example given above, the sampling rate is far too low, hence the loss of information.

Number of Levels
Another factor which may limit the quality of the reconstructed signal is the number of bits with which the signal is encoded. For example, if we use 3 bits per. sample, we only have 8 (23) levels, so, when sampling, we must take the nearest value represented by one of these levels. This leads to quantization errors - when a sample does not equal the value of the original signal at a given sample point.

Questions
1. Take samples for the signal below every 0.1ms, and then produce a reconstructed signal. How does it differ from the original?

2. A signal is sampled for 5 seconds at a sampling rate of 20 kHz. How many samples were taken?

3. Most sounds created by human speech except for 'ss' and 'ff' have a maximum frequency of 4 kHz. What is a suitable sampling rate for a low-quality telephone?

4. Using a sampling rate of 20 kHz and 3 bits, sample the following signal, and then produce a reconstructed signal. What is the maximum frequency that can be perfectly reconstructed using this sampling rate?

/Worked Solutions/


text:
User:Trinology

I have created a new concept of 'what makes you tick?' and would appreciate feedback. Please view the paper on trinology.co.uk Your opinion could be sent to the email address given?

title: User:Trinology


text:
A-level Physics (Advancing Physics)/Digitisation/Worked Solutions

'''1. Take samples for the signal below every 0.1ms, and then produce a reconstructed signal. How does it differ from the original?'''

The high frequency elements of the signal have been lost.

'''2. A signal is sampled for 5 seconds at a sampling rate of 20 kHz. How many samples were taken?'''

$$20 \times 10^3 = \frac{\mbox{No. of samples}}{5}$$

$$\mbox{No. of samples} = 20 \times 10^3 \times 5 = 100000$$

'''3. Most sounds created by human speech except for 'ss' and 'ff' have a maximum frequency of 4 kHz. What is a suitable sampling rate for a low-quality telephone?'''

$$4 \times 2 = 8 \mbox{ kHz}$$

'''4. Using a sampling rate of 20 kHz and 3 bits, sample the following signal, and then produce a reconstructed signal. What is the maximum frequency that can be perfectly reconstructed using this sampling rate?'''

First, calculate the length of each sample, by letting the number of samples equal 1:

$$20 \times 10^3 = \frac{1}{\mbox{Length of one sample}}$$

$$\mbox{Length of one sample} = \frac{1}{20 \times 10^3} = 0.00005\mbox{ s} = 0.05\mbox{ ms}$$

Then, we can sample the waveform and create a reconstructed signal:

To calculate the maximum frequency that can be perfectly reconstructed using this sampling rate (20 kHz):

$$\frac{20}{2} = 10\mbox{ kHz}$$


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Talk:Circuit Idea/Virtual Ground

What virtual ground is (after the Wikipedia page with the same name)
(moved and adapted by Circuit-fantasist from Wikipedia Virtual ground discussion page)

Virtual versus analog ground
Virtual ground implies ground potential at the node. Adding a component to a ground will have no effect if the other component connection is ground. There is no potential difference, hence no current flows. This may not be true for a virtual ground. In an inverting amplifier adding a capacitor between ground and the virtual ground at the (-) op-amp input can make the amplifier unstable. Stray capacitance from a probe is often sufficient. A warning should be added. Djhk 18:26, 23 September 2007 (UTC)

 * Djhk, you hate virtual ground but this is a phenomenon, fact that exists whether or not we like it. What do we do when we haven't an access to a real ground? Then we use a virtual ground (a typical example is creating of a split supply by one voltage source). Sometimes, we use a "shifted" (e.g. "lifted") ground instead an exact ground.
 * In a broadest sense, any circuit point having a voltage that is kept artificially (e.g., by means of a negative feedback) can be named virtual ground. In a literal sense, a virtual ground is a result of subtraction of two voltages having opposite polarities. We can say that a virtual ground is actually an active ground. Every active thing in this world is more stable to influence than passive one. Circuit-fantasist (talk) 17:34, 24 November 2007 (UTC)

 * You are confusing Virtual ground with analog ground. You need to split the topic into virtual and analog ground; combining the two creates confusion. Djhk 02:49, 3 December 2007 (UTC)

 * What do you mean when you say "analog ground"? What is the difference between a virtual and an analog ground? Circuit-fantasist 16:27, 3 December 2007 (UTC)

 * Analog ground is just "normal" ground, i.e. 0V. Virtual ground behaves like a nullator connected to ground. -Roger 16:34, 3 December 2007 (UTC)

 * Roger, I am not sure if the more abstract concept of nullator can help understanding the worldly virtual ground phenomenon unless you explain what a nullator actually is. Well, let's try to "decode" what "The inputs of an ideal opamp (with negative feedback) behave like a nullator, as they draw no current and have no voltage across them" means. Maybe, the Baron Munchhausen's idea of bootstrapping can help us. Circuit-fantasist 13:05, 5 December 2007 (UTC)

Analog ground
Roger, you are right. There is nothing special in the term of "analog ground"; it is just a piece of wire. Analog ground is nothing else than a separate wire connected to the real (ordinary, normal, common) ground and earmarked only for analog devices; another (just the same) wire is intended only for digital devices. In this way, analog and digital grounds are two branches of the common ground. No matter whether the ground is analog, digital or just a common ground; it is a static, passive "component" that can't resist influences, if they are too significant or, if the ground internal resistance is too high. Circuit-fantasist) 13:05, 5 December 2007 (UTC)

Virtual ground
Virtual ground is something else (excepting that it has the same zero voltage as an "ordinary" ground). Virtual ground is a unique worldly, technical, electricity and finally an electronics phenomenon; there is a great philosophy behind this idea, which deserves a special attention. In electronics, contrary to the "static" ordinary ground, virtual ground is a "dynamic" point whose potential is kept zero by artificial means (e.g., parallel negative feedback). For example, in the popular circuit of an inverting amplifier, an op-amp "observes" the virtual ground point and makes all that is possible to keep it at zero voltage (more precisely speaking, "...to keep it equal to the potential of the non-inverting op-amp input...") If we "blow" a current into this point, the op-amp will decrease its output voltage to "suck" a current from the virtual ground point; if we "suck" a current from this point, the op-amp will increase its output voltage to "blow" a current to the virtual ground point.

Generally speaking, great (circuit) ideas do not depend on the specific (component) implementation (tube, transistor, op-amp, etc.). They are non-electrical; they are eternal. In order to reveal the philosophy behind circuit ideas, we have first to show to visitors (that are human beings) examples from their human routine. These analogies will serve as educational mainstays that help understanding.

That is why, I have written the lengthy introductory part of the article about virtual ground (see the old version ) where I have shown various situations illustrating virtual ground phenomenon. Only, someone has moved them to the end of the article and finally, somebody else has removed them at all. As I can see, in this way, the article will gradually become the initial poor and "sterile" page.

This is the great paradox of Wikipedia: every narrow-minded and even anonymous visitor can edit and even remove frivolously and irresponsibly a text that is created by an editor having a philosophy about the phenomenon discussed. That is why, I have abandoned Wikipedia and started Circuit Idea. Circuit-fantasist 13:05, 5 December 2007 (UTC)

The philosophy behind the phenomenon
In the Virtual ground wikipedia page I have just tried to reveal the secret of the phenomenon, to show that it is not a "black magic" but a well-known everyday occurrence. We mustn't forget we write this encyclopedia for ordinary human beings, not for computers. Human beings can easily understand abstract electronics concepts by conveying their knowledge of life to concrete circuit phenomena. For this purpose, we have first to show some typical exemplary situations from human routine that are analogous to the phenomenon discussed, then to generalize them into a philosophy behind the phenomenon (everything in this world has own philosophy) and finally, to show the concrete circuit solutions.

Special electronics sources present concrete circuit solutions; an encyclopedia has, first of all, to reveal the philosophy behind them. In the case of the phenomenon discussed here, we have first to show in the most general (non-electrical) way that, in this case:
 * if there are two opposite (positive and negative) power sources and
 * they are connected each other by a resistive medium,
 * a zero point (virtual ground) appears somewhere along the medium and
 * the resistive medium wastes energy continuously as the carrier flows continuously.

In electronics, all the circuits with parallel negative feedback (all the op-amp inverting circuits) operate in this way.

Contrary, all the circuits with series negative feedback (all the op-amp non-inverting circuits) operate according to the opposite great phenomenon - bootstrapping:
 * if there are two identical (the both positive or the both negative) power sources and
 * the one of the sources follows the other (no matter if they are connected each other),
 * a zero difference ("differential virtual ground") appears between them and
 * no energy is wasted as no carrier flows.

Combine the two phenomenon and you can explain all the circuits with negative feedback.

A month ago, I tried to show, in a human-friendly manner, this truth about the great virtual ground phenomenon (it deserves that) by means of various analogies. Circuit-fantasist 09:10, 15 December 2007 (UTC)

A voltage divider viewpoint
For me, a virtual ground can be created either by buffering (to the degree necessary) a voltage divider to provide dual rail supplies or using negative feedback to make the potential between two points zero. For the first case the explanation is as simple as the voltage divider equation, very little elaboration should be necessary. Roger 23:32, 15 December 2007 (UTC)

 * You are right: the bare electrical device - the voltage divider, after a "little elaboration", is the simplest circuit for creating a virtual ground. Only, if we want to obtain a true zero-voltage virtual ground, we have to "move" down its ground by another negative power source (to "pull" down the lower resistor R2). Actually, this "shifted" voltage divider acts as a parallel voltage summer that sums two opposite (weighted) voltages according to the superposition principle:

VOUT = V1.R2/(R1 + R2) + V2.R1/(R1 + R2) = 0, therefore V1/R1 = -V2/R2

 * If we respect the proportion above, the output of this nice passive circuit will serve as a virtual ground; it is imperfect, "static", "soft", influenceable, etc. but yet it is an artificial, virtual ground because it has zero voltage potential without a direct connection to the "true" ground. It can serve as an analog ground but yet it is a virtual ground. Analog ground is a true, natural ground while a virtual ground is an artificial ground. Can I conclude we have come to an agreement?

 * This text is very important as it dethrones a widespread misconception - that the virtual ground is an electronics phenomenon inherent only of op-amp inverting circuits. Virtual ground is an electrical phenomenon; it had existed plenty of time before the ubiquitous op-amp to appear. Circuit-fantasist 08:07, 19 December 2007 (UTC)

An op-amp viewpoint
Again, a virtual ground can be created either by buffering (to the degree necessary) a voltage divider to provide dual rail supplies or using negative feedback to make the potential between two points zero. The second case is simple too. Vo = A*(V+-V-), let A->infinity then (V+-V-) must -> 0 if Vo remains finite. Or just use two of the basic negative feedback opamp assumptions: Rin is infinite and V+ = V-. Roger 23:32, 15 December 2007 (UTC)

 * You have suggested using the classical viewpoint at op-amp circuits with negative feedback that has been reigning from dozens of years in electronics resources: Vo = A*(V+-V-), let A->infinity then (V+-V-) must -> 0 if Vo remains finite.

 * The trouble of this explanation is that it does not explain anything. It works well, if you have no time for lengthy explanations (or, if you just do not like to explain circuits) but yet you would like your students (readers) to get to know something about op-amp circuit operation; then you just toss this one-line "explanation" to them and they will not ever bother you asking "naive" questions. Another example is Ohm's law. You can present it as a fraction a = b/c and then to speculate how a depends on b and c without showing that a is a flow-like, b is a pressure-like and c is an impediment-like quantity, without speculating what causes what, how a voltage and current sources behave, what the resistor does, etc.

 * But this approach fails completely, if you want readers to understand really the circuit operation. For the first time, I saw this text in 1975 when I entered the university and was trying without success to understand what an op-amp really does in this strange circuit with two resistors. What is wrong with this presentation?

 * The problem is that there is no TIME in this Vo=A*(V+-V-) explanation. The op-amp is considered as a non-inertial, proportional device that acts momentarily (the input and the output voltage change simultaneously). Only, if you try to understand the circuit in this way (how the op-amp has achieved the equilibrium), you will get into a vicious circle. The paradox is that, in order to understand op-amp amplifying circuits, we have to think of the op-amp not as an amplifier but as an integrator, as something slow, inertial and "thinking" that observes the virtual ground and reacts if it tries to change. The best way of understanding the op-amp behavior is to imagine that we perform its functions (i.e., applying the synectics's empathy). The truth about op-amp circuit operation is hidden rather in the transition time interval where the op-amp reacts to a sudden input change than in the next calm settled state when it "sleeps" (...to be continued...) Circuit-fantasist 08:07, 19 December 2007 (UTC)

 * I see no problem with using the differential amplifier equation to prove/explain virtual ground. If you're explaining virtual ground in the context of an opamp circuit then you should assume your audience understands how opamps operate. If they have a problem understanding it at this point, then their understanding of opamps is probably not sufficient. In which case they should go back and understand the ideal differential amplifier equation.Roger 16:17, 17 December 2007 (UTC)

Voltage divider versus op-amp viewpoint
I usually think of the two examples of virtual ground as being completely different, but if you prefer to think of them as two special cases then thats just as valid. The negative feedback case to me is the "truer" virtual ground since it behaves exactly like ground (within limits) and is actually at 0V. Roger 16:17, 17 December 2007 (UTC)

Is virtual ground a relative concept?
The divider case is a bit different since the voltage is usually not at 0V, but we simply decide to make every voltage relative to the virtual ground. So if we have a 10V supply and divided it down to 5V we could define 5V to be our new (virtual) ground and now we have a +5V, -5V supply. There isn't really any circuitry involved, it just goes back to the fact that voltages are always relative to some reference. Roger 16:17, 17 December 2007 (UTC)

 * Wonderful, this is another clever trick that complements the example above. There, we have "pulled" down the lower resistor by another additional negative power source, in order to "move" down the divider's output voltage until it becomes equal to zero (a virtual ground). Here, you suggest just to abandon the true old ground and to make the existing 5V output voltage serve as a new (virtual) ground. I think this text (especially, "...voltages are always relative to some reference...) can describe very well Fig. 4b. Circuit-fantasist 18:04, 17 December 2007 (UTC)

A virtual ground is another ground
Only, I am a little confused on this arrangement... Is this really a virtual ground? I'm asking this question because, when we create a virtual ground, there is a true ground as well and the two grounds have zero voltages (regarding to what?); no, they have the same voltages. Virtual ground is another ground; it is a "copy" of an existing true ground. In this arrangement we have only one ground. What kind of ground is it? Virtual or true? It seems that it is a true ground... Circuit-fantasist (talk) 18:34, 17 December 2007 (UTC)

It seems, in order to say that we have a virtual ground, another (real) ground has to exist; so, virtual ground is a counterpart of a real ground. In all the circuit diagrams of the article (see the old version), there is a real ground (the common point between the two power sources) and there is a virtual ground (even if it is a voltage divider's output). Circuit-fantasist 18:47, 18 December 2007 (UTC)

Can a virtual ground be relative to itself...
I think this is getting back to the problem that the term "virtual ground" isn't clearly defined, perhaps anywhere. I'll get back to this issue when I reply to Wtshymanski's post below. Anyway, yes, it is a virtual ground, relative to itself. Relative to real ground it is +5V (i.e. there is a p.d. between real and virtual ground). Of course in your example real and virtual ground just happen to have the same voltages relative to real ground, hence no confusion. See for examples. Roger 18:57, 17 December 2007 (UTC)

...or a virtual ground can be relative only to an existing ground?
The "relative to itself" concept sounds very intriguing and philosophical but I am not sure if I have made sense of its meaning. For now, I continue holding "relative to existing ground" concept. I have the feeling that I have finally realized what a virtual ground is and how to define the term. Here is my story about the scope of the virtual ground term; this is a tale about the evolution of a natural ground into a virtual one (we might move later this text to Ground although this page is maintained by very difficult wikipedians that are not inclined to such natural discussions). Circuit-fantasist 18:47, 18 December 2007 (UTC)

A tale about virtual ground evolution
...Voltage is a differential quantity; so, to process "true" voltage signals we need differential-input (-output) devices. If we want to deal with single-ended voltages (potentials) that is usually more conveniently, we need a voltage "mainstay" (a ground) where to connect one of the device terminals and regarding to which to measure the voltages (potentials). For this purpose, we usually use one of the power source terminals as a natural, true, genuine ground; thus, we can deal with only positive or only negative voltages. If we want to have both positive and negative voltages, we use an internal power source point as a ground (for this purpose, we usually connect two or more voltage sources in series and in the same direction, see Fig. 4a). If there is no such a compound power source, we create an artificial but still real ground, for example, by using the bare voltage divider (see Fig. 4b). This ground is a real one simply because there isn't any other ground (more precisely speaking, there is such a point somewhere inside the source but we have no access to it). Finally, we "clone" the ground (no matter it is true or artificial) by making another circuit point (virtual ground) follow the ground; for this purpose, we usually make an op-amp with negative feedback do this donkeywork:)... Circuit-fantasist 18:47, 18 December 2007 (UTC)

title: Talk:Circuit Idea/Virtual Ground


text:
Playing a Video Game

Pre-Play

 * /Casual or Hardcore?/
 * /Choosing the Right Type of Video Game/
 * /Hardware/
 * /Health Issues/
 * /Information to Have/

Mid-Play

 * /Need Help?/
 * /100 Percent/

Post-Play

 * /Discussing the Game with Others/
 * /Reviewing the Game/
 * /Helping Others/
 * /Replaying the Game/

title: Playing a Video Game


text:
Flying the Disc

Flying discs (including Frisbees) can be thrown in many ways. All involve spinning the disc to give it gyroscopic stability, and accelerating its mass to a certain velocity. Without spin, a disc will wobble and fall; without velocity, the disc will not go anywhere. Using these two guidelines, any number of throws are possible. Most discs are designed to create lift when thrown with the flat side up.

Right-side up
Right-side up throws are all similar in that they react the same way to the tilt of the disc when it is released. A disc thrown right-side up will accelerate in the direction of the low end of the disc. A disc tilted leading-edge up will lose speed at the end of the throw and make a gentle landing; if tilted sideways (known in aeronautics terms as roll), it can curve around objects.

There is a language for describing throws that curve. Both descriptions are relative to the direction the person is facing and intends to throw. This axis is marked in red in the picture.

 * Inside-out (i-o) throws (green paths) occur when the thrower releases the disc in such a way that it initially comes towards the throwing axis (inside-). However, the disc is tilted with the side closest to the body highest, which causes the disc to curve away from the thrower (-out).
 * Outside-in (o-i) throws (blue paths, sometimes also called a bender) follow the opposite path. The thrower releases the disc moving away from the throwing axis (outside-), but with the side of the disc closest to the body lowest.  This tilt causes the disc to bend back towards the thrower (-in).

Backhand
This is probably the most commonly learned throw, and also one of the most powerful. There is a long windup for the throw, both in terms of path length and time.

 * Grip: Fingers are curled under the disc's rim, and the thumb is placed on top of the disc to hold it in place. The index finger may either be on the edge of the disc (to help aim), or four fingers may be tucked underneath the rim (to aid power).

 * Throw: The thrower draws the throwing arm across the body to build velocity for the disc. During this movement, the arm straightens out. As the arm becomes straight, the wrist is flicked, to impart spin.  After release, the arm usually points towards the target.

Variations
The backhand is an excellent general-purpose throw. Several modifications have been created; some are listed here.

 * The High Release: Used to get around an object (or a person), the High Release is thrown above the thrower's shoulder, mostly powered by the flick of the wrist instead of the arm and shoulder.

 * The Air Bounce: By putting downward pressure on the trailing edge (back side) of the disc as it is released, this throw will sail a short distance at a low height, then "bounce" up into the air. This is done by pressing down with the thumb, which is on the trailing edge at the point of release. Skilled throwers can execute this throw such that the disc travels under a parked car.

Forehand
This throw (also known as the flick or the two-finger, or the side-arm in the UK) is a staple of the disc fan's repertoire, as well as the bread-and-butter throw of Ultimate players. Focused in the wrist, this throw takes little time to execute.

 * Grip: The index finger is extended and laid along the rim of the disc. The middle finger is placed against the index finger for power, or pressed on the bottom of the disc pointing towards the middle for accuracy.  Varying the middle finger from these positions allows for the throwing of curves.  The edge of the disc is tucked under the thumb.  The disc is cocked back at the wrist, and the arm is extended out from the body.

 * Throw: A flick of the wrist imparts spin off the middle finger as well as some forward velocity. Some snap of the lower arm can provide additional power.  After release, your index finger should point to your target.

Note that 90% of this throw is below the elbow, and most of that at the wrist. A common mistake is to attempt to use the upper arm and shoulder to add power to the throw. Usually, this results in little or no spin being imparted on the disc, which causes it to fall quickly. It's also common for the flick of the wrist to pull the outside edge of the disc up; to compensate, hold the disc somewhat loosely, so that the outer edge hangs down slightly. Experiment with the cocking and flicking motions to determine how best to produce a level throw.

As you learn how to throw a flick, it may help to tuck your elbow in towards your body; this is a bad habit to get into if you play Ultimate, but may assist with preventing you from using too much shoulder and arm. As you improve, work on extending your arm out away from your body. Advanced throwers will note that the arm and wrist action is much like a bullwhip cracking sideways; the addition of whip-like motion in your upper arm, shoulder, and even upper body (by rotating the hips) can impart more power onto your throw, but is difficult to control.

Variations
The forehand is an extraordinarily versatile throw, and can be adapted to many different situations.

 * Most upside-down throws (see below) use the forehand grip and throw, and are therefore variants of the forehand to some degree.

 * The High Release: Used to get around an object (or a person), the High Release is thrown above the thrower's shoulder, and is completely powered by the flick of the wrist. In order to be thrown flat so that it will travel without curving, the middle finger is pulled in to the edge of the disc with the index finger and the outer edge of the disc is rotated down, so that the disc lies at a slight angle to the line of the knuckles.

Push Pass
The Push Pass: A little-used variant of the forehand, it is thrown with a grip similar to a backhand (index finger on the outer rim of the disc, thumb on top, fingers curled underneath) but is released on the forehand side. The wrist "pushes" the disc forward while spin is imparted "backwards" by rolling the disc off the index finger. A final flick of the index finger finishes the release. Frequently, very little spin is actually imparted, which makes this throw tend to flutter and fall more often than not. However, with practice the thrower can add much more spin to this throw and it may become useful over short distances. It is also useful in Ultimate as the typical form of this throw can be placed in the region between a defender's body and extended arms.

Beach Thumber
The Beach Thumber (also known as a Peach) is unpopular in Ultimate circles due to its unpredictable flight path and proximity of release to the thrower's body. Its primary advantage is that it can be a very hard, very accurate throw, and therefore useful for those uncomfortable with the staple throws of the game, the forehand and backhand.

 * Grip: The thumber derives its name from the grip: it is thrown on the forehand side with the thumb under the rim and the rest of the hand against the outside of the disc. The arm should also be tucked against the side, and the elbow bent. Keeping the disc parallel to the ground, (any tilt and it will fall) cock your wrist back so your thumb is pointing as far back as you can.

 * Throw: To release, simply flick your wrist forward. Spin is imparted off the flat part of the thumb; power can be gained by rotating the body at the hips.  A flat release is critical to a successful thumber.  After release, the flat part of the thumb should point towards the target.

Overhand
The Overhand (also known as the waffle, discus, wrist-hook, chicken wing, or biscuit in the UK) varies in popularity among ultimate players, because the alternative, the traditional forehand, allows greater sideways arm extension, useful in moving the disc around defenders. The Overhand is most useful when the disc is caught above the head and must be thrown quickly without changing grip. It is similar to the Hammer in that release typically (but not always) occurs above shoulder level, but comes with a different set of drawbacks. This throw is often used in attempts at The Greatest.

 * Grip: The fingers of the hand are spread out over the top, with the thumb under the disc and perpendicular to the rim. For greater control, extend the index finger along the rim, as in the control grip for the forehand.

 * Throw: Hold your arm horizontal and behind you, then quickly bring it forward, snapping the wrist laterally as you release. Typically, release occurs at or above shoulder height, although it is possible to release at waist height or lower. The whole body and arm can be allowed to rotate, and the forearm must move very quickly to impart enough momentum to send the disc a significant distance. For maximum power, the entire body rotates, as in the ancient discus throw seen in track and field events; for a right-hander, the torso starts leaning right, and ends leaning left. Wrist snap is especially important, as the throw has no stability without a strong spin.

The Overhand is a situationally dependent throw. It can be extremely useful in the right situation, especially when there is no time to change grip. But the fact that the thrower typically must lean in towards the defender on release hampers its effectiveness for ultimate. This throw is popular for advanced catch and freestyle, but some ultimate players deride it as the "Useless", the "Push Noodle", or even the "Nazi Throw" as when the throw is finished, the arm is in the Nazi salute.

Duck
The Duck (also known as a bear claw, a duder, or a useless) is thrown with a similar grip to the waffle, except it is the backward version of it. While the waffle is thrown with counter-clockwise spin (for right handers), the duck is thrown with clockwise spin. It is usually thrown with the arm out to the side or above the head. It is called the duck due to the shape of the gripping hand during the throw, as if making a duck shadow puppet. This throw is used in attempts at The Greatest (jumping out of bounds and throwing the frisbee back in to play while in the air).

Upside-down
A disc thrown upside-down has a very different flight path than one thrown right-side up. Lift is applied towards the rounded side of the disc; if the disc is completely upside-down, the lift is now propelling the disc straight into the ground. Thus, these throws typically have a stronger arc to them, tend to bank or roll as they fly, and are much harder to catch. Where a right-side up throw tends to spend a considerable portion of its flight path at a catchable height, an upside-down throw tends to land abruptly at a certain point.

To facilitate discussion, the following convention is used: a disc that is level and flying right-side up is considered to be flying at 0 degrees relative to the ground (DRtG). A disc that is level and flying upside-down is considered to be flying at 180 DRtG. A disc that is flying exactly vertically would be at 90 DRtG, etc.

Hammer
The Hammer is one of the more difficult throws to master, despite being gripped just like a normal forehand throw, and the throwing motion being relatively natural. Hammers are difficult to aim well due to their high, arcing flight path, and their tendency to catch any amount of wind.

 * Grip: Identical to the forehand, when throwing a hammer one grips the disc under the thumb, with the index finger extended against the underside of the disc for stability and the middle finger pressed against the inside rim to impart spin.

 * Throw: Swing the throwing arm over the head, turning the disc upside-down (somewhere between 90 and 180 DRtG) and throwing it up at an angle. The wrist flicks to impart spin off the middle finger, just like when throwing a forehand.

A hammer, when thrown properly (and in no wind) by a right-handed thrower, will arc up and to the left as it moves away from the thrower. As it flies, the disc will roll over until it is completely upside-down (180 DRtG), falling down and to the right again. Ideally, it should reach its target at between 135 and 180 DRtG to make catching it as easy as possible.

However, hammers are notoriously difficult to throw "properly". Common failure modes include:
 * the Blade (also known as the Knife in the UK), in which the disc does not turn over at all, but instead keeps its original orientation towards the ground. Blades tend to fall very sharply and quickly and are difficult (and often painful) to catch.  However, it can be used very effectively in low wind conditions when throwing over an obstacle, as the blade has a speed-to-catch advantage over a hammer.
 * the Double Helix, when the disc over-rotates past 180 DRtG. These throws tend to float as they fall, drifting right and then left again (for a right-handed thrower) before landing flat.

A Blade can be corrected by increasing the angle of release (closer to 180 DRtG); a Double Helix can be corrected by decreasing it. Experimenting with the angle of release should produce a happy medium which works for the individual thrower. Angle of release will also affect the horizontal travel of a hammer, which is difficult to judge even in the lightest breeze. The near-vertical release of the hammer makes them highly susceptible to crosswinds, blowing them well off target. Hammers rely on spin for stability even more than most throws; a hammer thrown with insufficient spin will flop about as it flies, making the receiver's job even more difficult.

A hammer, like most throws, can be released with any amount of angle and pitch and at any strength. A hammer released at nearly-180 DRtG and straight ahead (i.e. with a pitch close to 0) will stay mostly flat and fly directly at a receiver. This throw is difficult to block (in Ultimate) but tends to arrive very fast and at an unpredictable angle, since it often flies like a Double Helix. Hammers are often last ditch efforts in a game of Ultimate when the thrower has reached a stall count of 8 or 9 and needs to get rid of the disc; either as a "punt" or "hail mary" to a deep in the end zone. (See also the Scoober, below.) A Blade can also be thrown intentionally; this is commonly called a Roller in disc golf, as they tend to hit the ground and roll for long distances if thrown very near 90 DRtG.

Wheel of Death
The Wheel of Death (also known as The Corkscrew, The Bammer and The Bowler) is the “backhand version” of the hammer. It is a very difficult throw to master, and not very useful. The throwing motion is nearly as unnatural as possible. The wheel of death inherits all of the limitations and challenges of the hammer, and it has a few of its own.

 * Grip: Identical to the backhand

 * Throw: Swing the throwing arm more over its shoulder than over the head, turning the disc upside-down (somewhere between 45 and 90 DRtG) and throwing it up at an angle. The action is somewhat similar to bowling a cricket ball.

The wheel of death, when thrown properly (and in no wind), should fly in a path entirely similar to that of the hammer, only with left and right directions interchanged; this is, perhaps, its only advantage. The wheel of death has many more disadvantages than advantages, however. These disadvantages include:

 * The rotation of the forearm required to throw a wheel of death prevents the arm from being fully extended above the body.

 * The forearm's awkward position during the throw can make a release with sufficient wrist snap to keep the disc stable painful to the wrist of the thrower.

Furthermore, the wheel of death can fail in all of the ways a hammer does, plus, if any upward pressure is placed on the trailing edge of the disc, the throw will air-bounce downwards, resulting in a highly deceptive flight path and a very short pass. Due to its myriad of deficiencies, the wheel of death is not generally implemented as anything more than a curiosity.

Scoober
Another upside-down variant of the forehand, the scoober (also known as the "Spoon pass" or Hiawatha) is similar to a hammer, but thrown over the left shoulder for a right-handed thrower instead of over the head. The scoober is an advanced throw that travels in a path similar to the hammer, although it cannot be thrown as far because it relies almost exclusively on the wrist for power. The scoober can be an effective short-range (10 to 20 yards/meters) throw and is used in ultimate for breaking the mark and against zone defenses.

 * Grip: Identical to a forehand or hammer.
 * Throw: Stepping towards the backhand side, hold the disc upside down and bring the throwing arm across the body. Leading with the elbow, swing the throwing arm forward and flick the disc off the middle finger (as in a forehand), releasing the disc somewhere between 140 and 180 DRtG. The steeper the angle of release, the more similar the path of the scoober will be to that of a hammer, and thus may the double helix pattern be avoided.

A variant of this throw is termed the blind scoober. Rather than being thrown over the left shoulder (by a right-handed thrower), a blind scoober is thrown backwards with an outstretched arm without ever looking to see where the intended receiver is. Though rarely successful, the comedic value of the throw is unquestionable.

Other throws are also known as a scoober; these seem to vary by geography. The hammer is sometimes referred to as a scoober.

Thumber
The Thumber (not to be confused with the Beach Thumber) is an advanced throw that is rarely used in competitive play, compared to the Hammer or standard forehand. It has a flight path that is the mirror-image of the Hammer (arcing high and to the right for a right-handed thrower). It can be useful when the disc needs to drop quickly and fly with an opposite helix to the Hammer.

 * Grip: The thumber derives its name from the grip: the disc is held upside-down with the thumb tightly against the rim and the rest of the hand against the outside of the disc.

 * Throw: Cock the arm backwards, then bring it forward and snap the wrist to impart spin. The disc should be approximately 135 DRtG at the point of release.

Viggiano/Underhand Hammer
The "Viggiano" is a throw without much power, but it is remarkably stable, considering its aerobatic nature (because the disc ends up in a 0 DrtG orientation). Its initial flight path is similar to that of the hammer, but opposite (flipped 180 degrees) about a plane that is horizontal relative to the ground. When thrown correctly, the disc will initially fly at about 80 degrees relative to the ground, but will turn right side up in mid-flight and remain as such, flying much like a weakly-thrown backhand after the turn. The short-windup throw is useful for short-distance passes only, but is especially helpful if no one else, including a blocker, expects it. For instance, if another player is trying to block your throw, you may be able to throw the disc underneath and around his or her arms. Typically, in competitive ultimate, however, this throw seeing that it is released to close to the body is often frowned upon unelss the thrower is being marked very tightly. It is very easy on the joints to throw.

 * The Grip: The grip is identical to that of the hammer

 * The Throw: Start with a straight arm rested against the side of the body, in a neutral position (the top of the disc will naturally face the side of the body). Bring the arm forward in a partial upside-down arc, keeping the arm relatively straight, and flick the wrist up prior to release to impart spin, simultaneously twisting the wrist slightly in a clockwise manner (as though one is tightening a typical-thread screw). At release, the disc should be at about 80 DrtG and waist to chest height. Alternatively, one can wind-up prior to the throw by moving the arm backward a few tens of degrees in order to impart more kinetic energy to the spin and achieve more distance.

Variation: Reverse Viggiano: This throw is similar to the Viggiano, except one starts with the top of the disc pointing away from the side of the body, with the thumb underneath and two fingers on top. Like the Viggiano, the disc will initially have a vertical orientation (about halfway between right side up and upside-down), with the top of the disc very slightly facing the sky (280 DrtG) and turn in mid-flight, flying right-side up (0 DrtG) the rest of the way. The throw is different in that one twists his or her wrist in the opposite way prior to release (i.e., counter-clockwise, as though one is loosening a typical-thread screw) and flicks his or her wrist toward the front of the body to impart spin, much in the same way a cellist flicks his or her wrist with the bow hand toward the cello while playing.

title: Flying the Disc


text:
User talk:66.46.70.58

Join Us!
-- – Mike.lifeguard  | talk 16:52, 21 December 2007 (UTC)

title: User talk:66.46.70.58


text:
User talk:152.16.249.177

Radiation Oncology
Welcome to Wikibooks. Thanks for your contributions to the Radiation Oncology wiki! — Brim (talk) 17:16, 21 December 2007 (UTC)

title: User talk:152.16.249.177


text:
Chess Opening Theory/1. d4/1...d5/2. c4/2...e6/3. Nf3/3...Nf6/4. g3

=Catalan Opening=

Theory table
.

'''1. d4 d5 2. c4 e6 3. Nf3 Nf6 4.g3'''


text:
User:Portlandiaman

I'm into math and science, and I will be reading and maybe editing the books on music theory, and you may see me edit or create a book on how to play classical guitar. Currently I am working on the book Algebra 2 and Music Theory.

title: User:Portlandiaman


text:
Chess Opening Theory/1. d4/1...Nf6/2. c4/2...g6/3. Nc3/3...d5

=Grünfeld Defence=

This is the classic starting position of the Grünfeld Defence, although d5 can be delayed if White has delayed e4 which typically happens if Nf3 is played at some stage.

Black plays d5 and challenges White's occupation of the center. White has a range of choices, the main one is to exchange the pawns on d5 to displace Black's pieces.

During the 1920s, European chess was in revolution, with the entry of the Nimzo-Indian Defence into mainstream opening theory. The masters of the day termed this the "Modern style". Then, in 1922, a well-known master named Ernst Grünfeld came up with a new system that started bashing the great masters of the day, including Alekhine, Kostic, Sämisch, and Colle. This came to be known as the new "hypermodern" style, and Grünfeld, true to hypermodern tastes, showed in pure form how the previously accepted classical dogma could be wrong, and that a pawn center could be an object of attack as well as a boon.

The main battleground of philosophies is the Exchange Variation, 4.cxd5 Nxd5 5.e4 Nxc3 6.bxc3. White's pawn center gains space, but Black has excellent play along the long, dark diagonal from a1 to h8, and can eventually target d4 with moves like ...Bg7, ...Rd8, ...c5, ...Nc6, and occasionally ...Qa5. Eventually he may also bring a bishop to fianchetto on the other diagonal, targeting e4.

The more classical moves are 4.Nf3, 4.Bf4, and 4.Qb3, which are more conservative ways to fight Black's system. The pawn center still remains, but Black's counterplay is still adequate. The most positional move is 4.Bg5.

Theory table
.

'''1. d4 Nf6 2. c4 g6 3.Nc3 d5'''


text:
User talk:Natu~enwikibooks

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Good luck! --Panic (talk) 18:29, 21 December 2007 (UTC)

Playing A Computer Game
Hey. Just wanted to let you know that I'm working hard on improving the quality for Playing a Video Game. ~VNinja~ 18:51, 30 June 2008 (UTC)

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Natu. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Natu~enwikibooks that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

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Renamed
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title: User talk:Natu~enwikibooks


text:
User talk:Electricmic

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Good luck! --Panic (talk) 18:29, 21 December 2007 (UTC)

title: User talk:Electricmic


text:
Famous Theorems of Mathematics/Number Theory/Prime Numbers

This page will contain proofs relating to prime numbers. Because the definitions are quite similar, proofs relating to irreducible numbers will also go on this page.

Definition of Prime
A prime number p>1 is one whose only positive divisors are 1 and p.

Basic results
Theorem: $$ p $$ is prime and $$ p|ab $$ implies that $$ p|a $$ or $$ p|b $$.

Proof: Let's assume that $$ p $$ is prime and $$ p|ab $$, and that $$ p\nmid a $$. We must show that $$ p|b $$.

Let's consider $$ \gcd(p,a) $$. Because $$ p $$ is prime, this can equal $$ 1 $$ or $$ p $$. Since $$ p\nmid a $$ we know that $$ \gcd(p,a)=1 $$.

By the gcd-identity, $$ \gcd(p,a)=1=px+ay $$ for some $$ x,y\in\mathbb{Z} $$.

When this is multiplied by $$ b $$ we arrive at $$ b=pbx+aby $$.

Because $$ p|p $$ and $$ p|ab $$ we know that $$ p|(pbx+aby) $$, and that $$ p|b $$, as desired.


text: Talk:Famous Theorems of Mathematics/Number Theory/Prime Numbers


text:
Talk:Famous Theorems of Mathematics/Set Theory

Definition of Sets
I think this page might be a perfect location for the proof that not all collections of objects are sets. I don't remember exactly how this proof goes so I will think on it and post it here, so that if someone deems it worthy to go on the page they can shift it over. -Rekov (talk) 19:28, 21 December 2007 (UTC)


text:
User:Random832

I'll likely respond quicker to messages left at w:User talk:Random832.

title: User:Random832


text:
Talk:Vehicle Identification Numbers (VIN codes)

At the top right of this talk page is a list of all subpages under this book; in order to make sure no orphans are created. Random832 (talk) 20:06, 21 December 2007 (UTC)

GFDL attribution note: The history for several sections derived from VIN is found in the "Overview" section. Random832 (talk) 22:20, 21 December 2007 (UTC)

Pls check for me wat year model is this car
WAUZZZ8K28A036296 Jperny (discuss • contribs) 12:52, 15 March 2017 (UTC)

KMHDH41CBGU657926 Fanansh (discuss • contribs) 13:36, 7 June 2017 (UTC)


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User talk:Rekov

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Good luck! --Panic (talk) 20:34, 21 December 2007 (UTC)

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User talk:Random832

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Good luck! --Panic (talk) 20:34, 21 December 2007 (UTC)

Vin Code Book
Thanks for the work on Vehicle Identification Numbers (VIN codes) EvanCarroll (talk) 17:38, 23 December 2007 (UTC)

title: User talk:Random832


text:
Vehicle Identification Numbers (VIN codes)/Overview

Vehicle Identification Numbers (VINs) are used to uniquely identify motor vehicles. Prior to 1980 there was not an accepted standard for these numbers, so different manufacturers used different formats. Modern day VINs consist of 17 characters that do not include the letters I, O or Q.

Parts of the VIN
Modern Vehicle Identification Number systems are based on two related standards originally issued by the ISO in 1979 and 1980, ISO 3779 and ISO 3780, respectively. Compatible but somewhat different implementations of these ISO standards have been adopted by the European Union and the United States of America.

The VIN is composed of the following sections:

Vehicle Descriptor Section
The 4th through 9th positions in the VIN are the Vehicle Descriptor Section or VDS. This is used, according to local regulations, to identify the vehicle type and may include information on the platform used, the model, and the body style. Each manufacturer has a unique system for using this field. Most manufacturers since the 1980s have used the 8th digit to identify the engine type whenever there is more than one engine choice for the vehicle. Example: for the 2007 Chevrolet Corvette U= 6.0L V8, E= 7.0L V8.

North American Check Digits
../Check digit


text:
Vehicle Identification Numbers (VIN codes)/Check digit

This does not seem to work for Australian VIN numbers.

One element that is fairly consistent in VIN numbers is the use of position 9 as a check digit, compulsory for vehicles in North America and used fairly consistently even outside this rule except in the United Kingdom where the check digit is not used.

Method
The process for calculating a VIN check digit is as follows:
 * 1) Substitute each letter in the VIN with a digit according to the transliteration table below.
 * 2) Multiply each digit in the resulting number with its respective weight according to the table below.
 * 3) Sum the resulting products.
 * 4) Divide the sum by 11 and take the remainder. This remainder is the check digit. If the remainder is 10, use X as the check digit.

Transliterating the numbers
Transliteration consists of of substituting letters with digits according to the table below. I, O and Q are not present in the table because they cannot exist in a valid VIN. Numerical digits use their own values and are not changed by transliteration.

Weights used in calculation
The following is the weight factor for each position in the VIN. The leftmost digit is position 1. The 9th position is that of the check digit. It has been substituted with a 0, which will cancel it out in the multiplication step.

Worked example
Consider the VIN, where the underscore will be the check digit.

 * 1) Each letter in the VIN is substituted with a digit according to the transliteration table. Digits in the VIN are unchanged. This results in the Transliterated row.
 * 2) Each transliterated digit is multiplied with a weight according to the weights table. The weights for each position are reproduced here in the Weights row. Elementwise multiplication results in the Products row.
 * 3) The products are summed to 351.
 * 4) The sum 351 is divided by 11, yielding a remainder of 10.
 * 5) Since the remainder is 10, the check digit is X.

The check digit is added to the VIN:.

The VIN consisting of  (seventeen 1's) has a valid check digit. This can be used as a test case to verify a check digit algorithm.


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Vehicle Identification Numbers (VIN codes)/Model year

The model year is encoded in position 10 of North American VIN codes. Besides the three letters that are not allowed in the VIN itself (I, O and Q), the letters U and Z and the digit 0 are not used for the year code. Note that the year code can be the calendar year in which a vehicle is built, or a model or type year allocated by the manufacturer. The year 1980 was encoded by some manufacturers, especially General Motors and Chrysler, as "A" (since the 17-digit VIN wasn't mandatory until 1981, and the "A" or zero was in the manufacturer's pre-1981 placement in the VIN), yet Ford and AMC still used a zero for 1980. Subsequent years increment through the allowed letters, so that "Y" represents the year 2000. 2001 through 2009 are encoded as the digits 1 through 9, and subsequent years are encoded as "A", "B", "C", etc.


text:
Vehicle Identification Numbers (VIN codes)/Vehicle Descriptor Section

The 4th through 9th positions in the VIN are the Vehicle Descriptor Section or VDS. This is used, according to local regulations, to identify the vehicle type and may include information on the platform used, the model, and the body style. Each manufacturer has a unique system for using this field; look under "Manufacturer Specific" at Vehicle Identification Numbers (VIN codes) for some manufacturer-specific systems. Most manufacturers since the 1980s have used the 8th digit to identify the engine type whenever there is more than one engine choice for the vehicle. Example: for the 2007 Chevrolet Corvette U= 6.0L V8, E= 7.0L V8.


text:
Vehicle Identification Numbers (VIN codes)/Vehicle Identifier Section

The 10th through 17th positions are used as the Vehicle Identifier Section or VIS. This is used by the manufacturer to identify the individual vehicle in question. This may include information on options installed or engine and transmission choices, but often is a simple sequential number. In fact, in North America, the last five digits must be numeric.

Japan Model Year
One consistent element of the VIS is character number 10, which is required (in North America) to encode the model year of the vehicle.

North American Plant Code
Another consistently-used element (which is compulsory in North America) is the use of the 11th character to encode the factory of manufacture of the vehicle. Although each manufacturer has their own set of plant codes, their location in the VIN is standardized.


text:
Talk:Vehicle Identification Numbers (VIN codes)/Vehicle Identifier Section

GFDL attribution note: The history for several sections derived from VIN is found in the "Overview" section.


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User talk:DanielLC

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Good luck! --Panic (talk) 23:37, 21 December 2007 (UTC)

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User talk:Drturbo

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Good luck! --Panic (talk) 23:37, 21 December 2007 (UTC)

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User talk:Dan Pelleg

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Good luck! --Panic (talk) 23:37, 21 December 2007 (UTC)

Hebrew
Thanks for the help with the Hebrew WikiBook! --CocoaZen (talk) 18:01, 31 December 2007 (UTC)

 * Thanks again for the fixes on Hebrew/Nouns --CocoaZen (talk) 03:02, 28 January 2008 (UTC)

 * My pleasure! Dan Pelleg (talk) 23:45, 15 February 2008 (UTC)

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text: Category:Book:Epidemiology

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User talk:Roli~enwikibooks

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Good luck! --Panic (talk) 00:03, 22 December 2007 (UTC)

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Roli. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Roli~enwikibooks that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

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Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 05:26, 19 April 2015 (UTC)

title: User talk:Roli~enwikibooks


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User:Thereen/Sandbox

This is a lab for books or sections I'm developing (slowly but surely), additions I am planning, and notes about books already developed by others. As this is a wiki, feel free to edit this page as you like but please do not vandalize it. Vandalism is a waste of both my time and yours.

=Horticulture/Container Gardening=

Containers
Plastic

Metal

Terra Cotta

Found containers Margarine containers and colanders,

 * Vertical Gardens - different designs, reasons, basics. Preferred plants.
 * Terrariums ../Cactus/

Planting Seeds
(link to seeds and planting, section saying container specific stuff.)

Links

 * Flowers
 * Foods (/Herbs (basil, thyme, dill)/Lettuce, /Sprouts, /

=LGBT= LGBT History \ LGBT Literature \ LGBT Young Adult Literature \ LGBT Media

LGBT World History
Mine LGBT history for leads, and Cultural Anthropology/Marriage, Reproduction and Kinship. JSTOR, Google Scholar, of course. Request transwikis if applicable.

Would have to be structured as a comparative world history text?

 * Content may include:
 * Western European:
 * Cretan pederasty
 * Sappho
 * Ancient Greece
 * Ancient Rome
 * Bath Houses
 * World Wars and Homosexuality in Western Europe
 * 20th Century Riots
 * Pride Parades around the world
 * North America:
 * Stonewall
 * Kinsey
 * Two-Spirited Indigenous Peoples of North America
 * World Wars and Homosexuality in North America (ie. Migration to New York, San Fran)
 * Civil Rights Movements (Persons of Colour, Feminist)
 * Marriage and the 21st Century in North America
 * Africa:
 * Eastern European:
 * Asia and the Pacific:

I could easily break this into separate country-specific histories, starting with Canadian.

=Feminism= Restructure. Book is currently structured as a history text, little to do with theory or practice. Could this book be more than a history book? Could it work like an intro to ws? All forms of oppression are connected.)

title: User:Thereen/Sandbox


text:
User:Albedo

uk:b:Albedo

uk:b:Albedo

title: User:Albedo


text:
User:I18n

This is an alias of. Please contact me at m:user talk:. Thanks! →  :     special:Listusers/sysop version all messages Common.css Common.js Monobook.css Monobook.js wikivar Last update: [ ↺] validator.w3.org

special:Gadgets and MediaWiki:Gadgets-definition
The main purpose of this account is to test functions from special:Gadgets at various wikis:

 * FindMe:
 * Wikis with given User Name:

→ commons:special:Gadgets  commons:MediaWiki:Gadgets-definition  → commons:user:

→ search MediaZilla for « user: »

→ search MediaZilla for « Gadget »

012443
→ 012443 · "unable to activate the chekboxes in the « Gadget = #prefsection-10 » section in « special:Preferences » at Hebrew Wikipedia with Opera"

012680
→ 012680 · "the inclusion of « empty » special pages with should either generate valid or no code"

other open issues
...

title: User:I18n


text:
User talk:I18n

m:…/global.css · m:…/global.js · global account information · global user contributions
 * SITENAME: · language: : [#top  ] · [#top  '''] · [#top  ] · [#top  ] · [#top  ] · [#top  ] · [#top  ] · [#top  ] · [#top  ] · [#top  ] · [#top  ] · [#top  ] · [#footer #footer]
 * local curent version: · versions at b: · c: · d: · m: · mw: · n: · q: · s: · t: · v: · voy: · w: · wikt: · w:en: · m:special:sitematrix# · template:Wikivar · m:
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 * [#top your] [#top local preferences] · [#mw-prefsection-personal Einstellungen ] · [#mw-prefsection-rendering Preferencias ] · [#mw-prefsection-editing Préférences ] · [#mw-prefsection-rc Preferenze ] · [#mw-prefsection-watchlist Настройки ] · [#mw-prefsection-gadgets 设置 ] · [#mw-prefsection-betafeatures تفضيلات ] · [#mw-prefsection-betafeatures העדפות ] · [#top मेरी वरीयताएँ ] · [#top Preferoj ]
 * user /     :  user:  · [/?title=special:ListUsers&limit=1&username= rights] · all subpages T · /common.css · /common.js · /previous user page · archives archived talks · b: · c: · d: · m: · mw: · n: · q: · s: · t: · v: · voy: · w: · wikt: · w:en: · w: · en:
 * [#top local WLH] · [#top local RC] · [#top local logs] · [#top local watchlist] · [#top local ontributions] · local mediawiki:Common.css · local mediawiki:Common.js · local mediawiki:Gadgets-definition · local notifications
 * PAGEID: · [https:/?curid=#top links here] · [https:/?curid=&action=purge# purge ↺] · [https:/?curid=&action=edit&section=0# section=0] · REVISIONID: · [https:/?oldid=# permanent link] · (layout: 2015-09-07…d LTR RTL short)
 * testing and validation links: BiDi issues · gadget issues · related languages / dialects: w:foo: · w:bar:

Welcome to  !

 * This is an alias of ·לערי ריינהארט·T·m:Th·T·email me· 04:25, 22 December 2007 (UTC). ·לערי ריינהארט·T·m:[//meta.wikimedia.org/wiki/user_talk:%D7%9C%D7%A2%D7%A8%D7%99_%D7%A8%D7%99%D7%99%D7%A0%D7%94%D7%90%D7%A8%D7%98?action=history Th]·T·email me· 09:22, 9 September 2015 (UTC)

title: User talk:I18n


text:
Horticulture/Rubus pensilvanicus

Rubus pensilvanicus (Pennsylvania Blackberry or Wild Blackberry), is a thorny bramble native to eastern North America.

Description
The canes are green at first but then turning dark red, usually ridged, with copious straight spines. The leaves are compound, usually bearing 5 or 7 leaflets. The flowers are white with large petals, bourne in mid-spring. The fruits are large aggregates of black drupelets, thich are somewhat sweet and often used for jams and jellies.

Uses
While rarely planted, the wild blackberry does provide showy flowers and fruits, and is attractive to songbirds and other wildlife. Like all Rubus species, it can serve as a host to diseases that can affect the cultivated types.

title: Horticulture/Rubus pensilvanicus


text:
Horticulture/Saponaria officinalis

Soapwort (Saponaria officinalis) is a common perennial plant from the carnation family (Caryophyllaceae). Other common names are Bouncing Bet and Sweet William.

The Latin name is derived from the toxic substance saponin, contained in the roots. It starts producing a lather when in contact with water. The epithet officinalis indicates its medicinal functions. However, it acquired its common name through utility in cleaning. Soapwort's native range extends throughout Europe to western Siberia. It grows in cool places at low or moderate elevations under hedgerows and along the shoulders of roadways.

In the northern hemisphere soapwort blooms from May to September, and in the southern hemisphere October to March.

Description
The plants possesses leafy, unbranched stems (often tinged with red) grow in patches, attaining a height of 70 cm. The broad, lanceolate, sessile leaves are opposite and between 4 and 12 cm long. It's sweetly scented flowers are radially symmetrical and pink, or sometimes white. Each of the five flat petals have two small scales in the throat of the corolla. They are about 2.5 cm wide. They are arranged in dense, terminal clusters on the main stem and its branches. The long tubular calyx has five pointed red teeth.

Uses
Soapwort has various medicinal functions as an expectorant and laxative, but care should be taken when used as saponins may be toxic. An overdose can cause nausea, diarrhoea and vomiting.

Despite its toxic potential, soapwort finds culinary use as an emulsifier in the commercial preparation of tahini halva and in brewing to create beer with a good "head". In India, the rhizome is used as a galactagogue.

title: Horticulture/Saponaria officinalis


text:
A-level Physics (Advancing Physics)/Resistivity and Conductivity

Resistivity and conductivity are material properties: they apply to all examples of a certain material anywhere. They are not the same as resistance and conductance, which are properties of individual artefacts. This means that resistivity and conductivity only apply to a given object. They describe how well a material resists or conducts an electric current.

Symbols and Units
Resistivity is usually represented by the Greek letter rho (ρ), and is measured in Ω m. Conductivity is usually represented by the Greek letter sigma (σ), and is measured in S m−1.

Formulae
The formula relating resistivity (ρ) to resistance (R), cross-sectional area (A) and length (L) is:

$$\rho = \frac{RA}{L}$$

Conductivity is the reciprocal of resistivity, just as conductance (G) is the reciprocal of resistance. Hence:

$$\frac{1}{\sigma} = \frac{\frac{1}{G} \times A}{L} = \frac{1}{G} \times \frac{A}{L} = \frac{A}{GL}$$

$$\sigma = \frac{GL}{A}$$

You should be able to rearrange these two formulae to be able to work out resistance, conductance, cross-sectional area and length. For example, it all makes a lot more sense if we write the first formula in terms of ρ, A and L:

$$R = \frac{\rho L}{A}$$

From this, we can see that the resistance of a lump of material is higher if it has a higher resistivity, or if it is longer. Also, if it has a larger cross-sectional area, its resistance is smaller.

Questions
1. A material has a conductivity of 106 S m−1. What is its resistivity?

2. A pure copper wire has a radius of 0.5mm, a resistance of 1 MΩ, and is 4680 km long. What is the resistivity of copper?

3. Gold has a conductivity of 45 MS m−1. What is the resistance of a 0.01m across gold connector, 0.05m long?

4. A strand of metal is stretched to twice its original length. What is its new resistance? State your assumptions.

5. Which has the greater resistivity: a plank or a piece of sawdust, made from the same wood? 6. What is the relation between time and resistance and length? /Worked Solutions/


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Horticulture/Thymus 'Spicy Orange'

'Spicy Orange' is a hybrid cultivar of ../Thymus/ grown for its strong flavor and sweet, citrus-like scent.

Description
'Spicy Orange' is a low, spreading thyme with sharp awn-shaped leaves and pale purple flowers.

Growing Conditions
As with most thymes, good drainage is essential, otherwise not picky about soils.

Uses
A very strong flavored herb when used fresh. Also grown as a scented ground cover, and tolerates some foot traffic.

Propagation
Propagate by cuttings or division.

Harvest
Best used as a fresh herb. Cut growing tips 1-2" long, cool and refrigerate until ready to use.

Pests and Diseases
See ../Thymus/

title: Horticulture/Thymus 'Spicy Orange'


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A-level Physics (Advancing Physics)/Resistivity and Conductivity/Worked Solutions

'''1. A material has a conductivity of 106 S m−1. What is its resistivity?'''

$$\rho = \frac{1}{\sigma} = \frac{1}{10^6} = 10^{-6}\mbox{ }\Omega\mbox{ m} = 1\mbox{ }\mu\Omega\mbox{ m}$$

'''2. A pure copper wire has a radius of 0.5mm, a resistance of 1 MΩ, and is 4680 km long. What is the resistivity of copper?'''

$$\rho = \frac{10^6 \times \pi \times (0.5 \times 10^{-3})^2}{4680 \times 10^3} \approx 168 \times 10^{-9} \mbox{ }\Omega\mbox{ m} = 168\mbox{ n}\Omega\mbox{ m}$$

'''3. Gold has a conductivity of 45 MS m−1. What is the resistance of a 0.01m across gold connector, 0.05m long?'''

First, work out resistivity:

$$\rho = \frac{1}{45 \times 10^6} = 22.\bar{2} \times 10^{-9}\mbox{ }\Omega\mbox{m}$$

Then, substitute everything possible into the resistivity formula:

$$22.\bar{2} \times 10^{-9} = \frac{(\pi \times (0.5 \times 0.01)^2)R}{0.05} \approx 1.57 \times 10^{-3}R$$

$$R \approx \frac{22.\bar{2} \times 10^{-9}}{1.57 \times 10^{-3}} \approx 14.2 \times 10^{-6}\mbox{ }\Omega = 14.2\mbox{ }\mu\Omega\mbox{ }$$

'''4. A strand of metal is stretched to twice its original length. What is its new resistance? State your assumptions.'''

The material does not change, so resistivity is constant. Length doubles, and we know that volume must be constant.

V = AL

A = V/L

$$\rho = \frac{RA}{L} = \frac{R(\frac{V}{L})}{L} = \frac{RV}{L^2}$$

$$R_{old} = \frac{\rho}{1} \times \frac{L^2}{V} = \frac{\rho L^2}{V}$$

When we double L, we get:

$$R_{new} = \frac{\rho (2L)^2}{V} = \frac{4\rho L^2}{V} = 4 \times R_{old}$$

We are assuming that ρ and V are constant.

5. Which has the greater resistivity: a plank or a piece of sawdust, made from the same wood?

Sawdust and a plank are artefacts, not materials. Hence, they do not have a resistivity. Even if they did, they are made of the same thing, so they would have equal resistivity.