Does anyone knows a good course for depth and shadows in illustrator?

Question:
Does anyone knows a good course for depth and shadows in illustrator?
I'm searching for an online course for making the character more realistic
The left one is how i bought the photo and the right one is how I made it look like, I'm searching for a course to improve my skills and to do more complicated stuff, I'd appreciate it if anyone could send me the link of the course.
Thanks all for your time.
Comment: It seems that you are on the right track, but you should try to be more aware of light direction. It seems to come from several directions. Have a look at [this question](https://graphicdesign.stackexchange.com/q/116269/84899). Search for [questions about shadows](https://graphicdesign.stackexchange.com/search?q=shadows) on this site. Googling something like ["cel shading tutorial"](https://www.google.com/search?q=cel+shading+tutorial) might be interesting.
Comment: You should look for _illustration_ courses, I don't think you'll find a _depth and shadows_ course. The same principles would apply for any illustration, not just characters.
Answer: The following isn't a link to a course, but hopefully enough to get you started. Rather than an Illustrator specific course you might have more success searching tutorials on adding shading to drawings/illustrations, since it would be directly applicable to anything created using any graphics software. I have found Youtube to be a good source for finding drawing tutorials. This one is rather nice and is specific to Illustrator and drawing cartoon characters.
Since we don't like link only answers here on GDSE, I thought I should share my own experience on a method I have used myself.
To get more realistic shading, you need to think about the light direction, and be aware where both shadows and highlights would fall on a 3D character. Surfaces facing the light should have highlights, and those facing away from the light should be in shadow.
Here's a rough example below.  I used Illustrator's Knife Tool to cut up pieces of the design for adding shadows and highlights. I'm sure you get the general idea.
Comment: Sure, but then again it maybe adds a little depth to the figure. Indicates a second light source. With all due respect to the artist and the OP (which is something you say when you're about to say something disrespectful) it ain't exactly Disney. It would be easier to add shading to a drawing which had more 3D depth thought into the lines to begin with.
Comment: Very nice! This is mostly *shading*. Additionally one could also add some *drop shadows* from the nose, head, arms, legs, eyebrows etc. [Here](https://i.imgur.com/jnUXFPL.png) is a very quick sketch.
Comment: @Wolff, absolutely!
Comment: @Wolff just noticed the specular highlights, might be better if the light source was from the same side, or change the location of these highlights to the other side of the eyes and nose.
Answer: There are so much already said by others that I cannot add much. I do not recommend any courses, because you'll find easily tens of free video lessons about the subject. In addition there's plenty of books. 3D-like shading has been an essential skill in painting and drawing hundreds of years.
But I can suggest one thing: Start with simple things.
One could easily think that inserting solid dark and brighter areas for shading is simplest. But it isn't. Its extremely difficult because the illusion of shading needs an intuitive assumption of the 3D form. Solid color shadows and highlights give very little information of curvature.

This really is a 3D cone, but without shading it's like a triangle.
This is the same shape in the same viewing projection. Solid color highlight doesn't help much, but one can believe it's a cone if that's told. He may make that decision also by himself if the image is a part of a story, where the shape is seen from other directions like 3a and 3b.
viewing angle has been changed. I guess quite few of us would think 3a cannot be a cone and even fewer  would think 3b is not a cone. Of course they can as well be seen as plane images, but if the observer knew it's a 3D piece his first guess would be it's a cone. So the viewing projection variations surely can help 3D recognization when the shading is made with solid colors.
This has a gradient shading. Recognizing the curvature is easy, no matter the projection doesn't show the curvature of the edge of the bottom.
This is only a little more likely a cone than version 4.

Your cartoon shape can be quessed to be a 3D animal character because such characters are commonly used. But when you have started to insert solid color shadows and highlights for 3D appearance, you have seen how difficult they are to make look right. This is why you are here now. They seem to fit as well as the white in my cone 2.
Actually they probably would look better if they were drawn with consistent light direction idea. And if you had several versions of the shape seen from different directions + preferably doing something interesting, nobody including you, would see no reason to complain of the shading. Drawing enough versions (hundreds of them) would fix the style and you would have developed the needed confidence to consentrate to the story.
Start practicing with the simplest possible way. Draw only darkening gradients for 3D curvature in the shadow side. Solid darkened color presents natural way only a plane. An example:

The eyes and the nose have the gloss you gave, but your other shadings are replaced by hand painted gradients. Before it the areas were filled with their major colors.
The job has been done in Photoshop because it's there easier. I had maximally soft black brush with painting opacity about 10%. It's edge leaves a gradient. For fixing I had even less opaque soft brush eraser. I made a colored area selection with the magic wand. The selection prevented painting and erasing over the edge.
Before computers airbrushes were used (and are still used) to create gradients. Making a selection to limit the spread replaces the masks that airbrushers use.
All darkenings were made to a new top layer to be able to make the right selections with the image layer.
BTW. Believe, the most difficult part is to avoid painting on the original image layer. The 2nd difficult thing is to stop painting early enough to avoid making it look dirty. The 3dr difficult thing is to change the brush size right. Wide gradient needs a big brush.
Comment: Thank you, What editor do you use? adobe illustrator ?
Comment: @Jabareen I have many pieces of software because I make various things. Illustrator is good for vector shapes like your basic character. Making varied versions is flexible. The shading I made is also possible there, but it's slower to make, it's much faster in Photoshop or other bitmap program. My version was made 100% by editing yours in Photoshop. I wouldn't start from scratch in PS because flexible vector graphic tools are needed, I'm not one who gets his curves right straight in the fly never needing later fixes. Believe, such capable persons exist. Try Inkscape and Affinity designer, too.
Comment: @Jabareen (continued) But you'll find every program has its own peculiarities which force one to adapt his workflow to avoid clashes. If you can afford Adobe CC programs and already have some experience with them, you probably use your time better by drawing more.


Limit how many times Contact can re-enter Journey?

Question: I am working on building a journey where the Entry Source is Salesforce Data. Whenever a Contact gets loaded to a specific campaign in Salesforce they will enter Journey, receive a single email and exit. The requirement from the business is that they only want a single customer to receive this communication three times. What design options do I have to cap how many times they can re-enter this journey at 3?
Answer: If you're set on the entry source being Salesforce data, you have potentially a bigger conundrum to consider...the only way to re-enter a person into an existing Campaign is to delete the old Campaign Member record and then add them again, but that's not really how Campaigns are supposed to work.
The easiest way to do what you want (as long as you're comfortable with the above) might be to add a hidden custom field onto the Contact object that is specific to this campaign and counts the number of times the contact is entered into the Campaign (so you'd control the counter with a process in CRM). You could then either:

Use that hidden contact field getting updated to trigger the journey in Marketing Cloud and put on a filter for if the number is less than 4; or
Use the Campaign to trigger the journey and include the counter in the journey entry source. Once again you'd filter the contacts out when this number is above 3 so they don't receive the email

I would say neither option is particularly pretty (because you're adding a campaign-specific semi-redundant field to the Contact object), but would theoretically work. I would potentially be looking at the solution as a whole (as in using a CRM Campaign at all) and seeing if there is a better solution to do what you need.


if I create 'front-page.php', then how do I link to post index?

Question: I want to have a custom front page and a blog page. So I created the front-page.php file, which will include my custom markup. I don't want to have blog post index on my front page, so I created home.php to feature blog posts index. How do I link to the blog page in this case?
Answer: Since WordPress 4.5 you can use get_post_type_archive_link( 'post' ) to link to the page containing the blog posts. Depending on what you've set under Settings -> Reading, this will be either the front page, e.g. example.com/ or a specific page like example.com/news/. home_url( '/' ) always points to the front page.
Comment: after I've created `home.php` (given that`front-page.php` also exists), do I still have to add new blank page in admin panel and point to it in `settings>reading>static page>blog page`, in order to have blog posts index appear in `home.php`?
Comment: Yes. Otherwise how would WordPress know where the blog page is and when to load `home.php`?


When mutual inductance is occurring between two coils, is self inductance always occurring in each individual coil?

Question: When a coil connected to an AC generator creates an EMF in another nearby coil (mutual inductance), is self inductance simultaneously occurring in both coils?
Comment: I believe it is practically true. Self induction is more common and prevalent as compared to mutual induction. If the magnetic flux of one coil/circuit is linked with the other coil/circuit, in all likelihood, it is also linked with itself.
Comment: OK, but what if the black coil terminals are left disconnected? Is the inductance in the blue coil going to change when the two coils are brought close together (assume the blue coil is excited with AC current)?
Answer: When a current passes through a closed loop, a magnetic flux through the
cross-sectional area of that loop arises due to that current. This
magnetic flux is related to the current by the relation:
$$\phi=Li$$
$L$ is called the self-inductance of the loop and depends upon the
configuration of that loop. $L$ remains constant as long as the configuration
of the loop is not changed.
If the current in the loop changes with time, the magnetic flux through the
loop changes in proportion to the current. This change in magnetic flux causes
an electromotive force (EMF) to be induced across the terminals of the loop.
This phenomena is called self-induction. The EMF generated is given by
Faraday's law as:
$$e=-\dfrac{d\phi}{dt}=-L\dfrac{di}{dt}$$
A common misunderstanding in beginners is:

Let an AC voltage source be connected to a circular loop. As the current
  through the circuit changes, it causes the magnetic flux to change. This
  change in magnetic flux acts to change the current in the circuit which then
  changes the magnetic flux and so on i.e. we are revolving in a circle.
In other words, change in current $\rightarrow$ Change in magnetic flux
  $\rightarrow$ again change in current ... the circle never terminates.
  This is a misconception.

To clarify how a balance is achieved, consider an AC voltage applied to an
ideal (zero resistance) loop. We will solve the circuit by applying KVL. The
voltage applied is:
$$V(t)=V_0 \sin(\omega t)$$
A current $I(t)$ is established in this loop. The misconception is that
a change in $V$ causes a change in $I$. Since $I$ is changed, the magnetic flux
also changes, which would cause self-induction, changing the net voltage across
the loop. Hence the existing electric field changes so the current will again
change and so on. But this misconception has a flaw. By KVL, the sum of
voltages around the loop must be zero i.e.:
$$V(t)+ \text{induced emf} =0$$
The astonishing fact is that there is $0$ Electric field inside the wire of the
loop because the resistance of the loop is $0$. For a current to flow in an
ideal inductor there is no need of $E$. The varying current only exists to
counter the applied voltage.
We know that induced EMF is related to the current in the loop by:
$$e=-\dfrac{d\phi}{dt}=-L\dfrac{di}{dt}$$
This relation tells us that the current is a function of induced EMF. Since
induced EMF is also a function of applied voltage, the current is a function
of applied voltage and can be calculated. This is also the expression for an
ideal inductor and the solution is, as we know:
$$I(t)=\dfrac{V_0}{\omega L}\cos(\omega t)$$
This explains why, despite the circle of reasoning, the current can be found
as a function of applied voltage. This is because the induced EMF has to be
equal to the applied voltage. In fact, the changes in quantities are related by
a differential equation whose solution will give us the value of unknown
current.
Consider two loops as shown:

(source: talkingelectronics.com)
There are two loops, blue and black. When the black loop is not present, the
current in the blue loop is $i_1$. This current is constant and there is no
self-induction; the battery has zero voltage since the loop is perfectly
conducting. For the time being, consider this battery as a short circuit.
What happens when the black loop is placed in the vicinity of the blue loop? As
the blue loop is moved to approach the black loop, the magnetic flux through
both the blue and black loops change with time. This causes an induced EMF to
appear in both loops. Both loops are ideal conductors, so we do not need any
$E$ inside their wires to cause a current.
Suppose the initial current flowing through the black loop was $i_2$. Both
$i_1$ and $i_2$ will change when the loops approach each other, but how?
Let the blue loop be loop$1$ and the black loop be loop$2$. The magnetic flux
crossing the black loop due to the current in the blue loop is
$\phi_{12}(x,t)$. This flux is related to $i_1(t)$ by the equation:
$$\phi_{12}(x,t)= M_{12}(x)i_1(t)$$
$M_{12}(x)$ is a function of the distance $x$ between the two loops and their
configuration. This parameter $M(x)$ is called mutual inductance. If $x$ is
not changed, the mutual inductance will remain constant.
Similarly, the magnetic flux crossing loop$1$ due to current in loop$2$ is:
$$\phi_{21}(x,t)=M_{21}(x)i_2(t)$$
If both loops have the same configuration, they create the same pattern of
magnetic field around them when passing the same current. So
$M_{12}(x)=M_{21}(x)$ for similar loops and may be denoted simply as $M(x)$ in
that case.
The magnetic flux existing in loop$1$ due to its own current $i_1$ is:
$$\phi_{11}(t)=L_1i_i(t)$$
The magnetic flux in loop$2$ due to $i_2$ is:
$$\phi_{22}(t)=L_2i_{2}(t)$$
The EMF generated in loop$1$ and loop$2$ are:
$$e_{11}=-\dfrac{d\phi_{11}}{dt}$$
$$e_{22}=-\dfrac{d\phi_{22}}{dt}$$
$$e_{12}=-\dfrac{d\phi_{12}}{dt}$$
$$e_{21}=-\dfrac{d\phi_{21}}{dt}$$
For KVL to hold, the condition is:
$$e_{11}+e_{21}=0=e_{22}+e_{12}$$
But $e_{11}$ and $e_{22}$ represent self-induction in loop$1$ and loop$2$
respectivly. So $i_1$ and $i_2$ both vary with time. Both $\phi_{12}$ and
$\phi_{21}$ will also change due to changes in $i_1$ and $i_2$ and any change
in $x$. So we can simplify $e_{12}$ as:
$$e_{12}=-\dfrac{d\phi_{12}}{dt}
        =\dfrac{d(M(x)i_1(t))}{dt}
        =\dfrac{dM_{12}}{dt}i_1+\dfrac{di_1}{dt}M_{12}$$
$e_{12}$, the induced EMF in loop$2$, is produced by a change in x and/or
a change in loop$1$ current, $i_1$. The phenomena of inducing an emf in a loop
by changing the current in some other loop is called mutual-induction. If
$L_1$ is small, we can visualize loop$1$ as a bar magnet and self induction
will only be observed in loop$2$. Further, if we assume loop$2$ has resistance
$R_2$ very large compared to $L_2$, we will see no self induction but simply
Faraday's law i.e. $e_{12}=i_2R_2$.
Now let's deal your specific question:

"When a coil connected to an AC generator creates an EMF in another nearby
  coil (mutual inductance), is self inductance simultaneously occurring in both
  coils?"

To analyze this, consider again the previous loop$1$ and loop$2$, replacing the
DC battery with an AC voltage source. The distance $x$ between the loops is not
changed. Both loops are perfectly conducting and have comparable
self-inductances and equal mutual-inductances. Since both the loops are ideal
conductors, $E$ inside the wires of both will be $0$.
$$-\dfrac{d(\phi_{11}+\phi_{21})}{dt}+V_0 \sin(\omega t) =0 \implies V_0\sin(\omega t)=L_1\dfrac{di_1}{dt}+M\dfrac{di_2}{dt} \tag{1}$$
Also:
$$\dfrac{\phi_{22}+\phi_{12}}{dt}=0 \implies L_2i_2=-Mi_1+k \implies i_2=-M/L_2i_1+k$$
Using this value of $i_2$ in eq 1 we get
$$V_0\sin(\omega t)=(L_1-\dfrac{M^2}{L_2})\dfrac{di_1}{dt}$$
Let ${L_1-\dfrac{M^2}{L_2}}=\alpha$. Then we get an expression for $i_1$ as:
$$i_1=-\dfrac{V_0}{\omega \alpha}cos(\omega t)$$
We see $i_1$ varies with time and hence $i_2$ also so both the loops undergo
self-induction and mutual-induction. This was a very conditioned analysis.
Resistance was ignored but the thing is even including the resistance both
self-inductance and mutual-inductance will occur.
Answer: Imagine two coils, coil 1 and coil 2 with (self) inductance $L_1$ and $L_2$.  If the two coils are not coupled, we have:
$$v_1 = L_1 \frac{di_1}{dt}$$
$$v_2 = L_2 \frac{di_2}{dt}$$
Now, if the coils are coupled, we have:
$$v_1 = L_1 \frac{di_1}{dt} + M\frac{di_2}{dt}$$
$$v_2 = M\frac{di_1}{dt} + L_2 \frac{di_2}{dt}$$
where $M$, the mutual inductance is given by
$$M = k\sqrt{L_1L_2}, \, 0 \lt k \le 1 $$

When a coil connected to an AC generator creates an EMF in another
  nearby coil (mutual inductance), is self inductance simultaneously
  occurring in both coils?

First of all, your question is oddly phrased.  Obviously, if either (self) inductance is zero, the mutual inductance is zero in the above formula.
But, perhaps you're asking something else.  If for example, coil 2 is not connected to a circuit, then $i_2$ is zero so there can be no self induced voltage.
However, there can be a mutually induced voltage across coil 2 due to a changing current in coil 1.
Regardless, the (self) inductances $L_1$ and $L_2$ must be non-zero for there to be non-zero mutual inductance $M$.
Answer: Yes, sometimes it is negligible, like in the case of two coupled loop. But it would be important for two coils where each has large number of turns.


Pintura OR Perserve 2.0 - Production Ready?

Question: I'm very interested in this framework, coupled with a NoSQL backend like MongoDB.
Basically, my blue-sky vision is this:
ExtJS/Pintura/MongoDB.
I would probably plug in Rhino as the js engine.
Is there anybody here using Pintura in a production environment?
What are the pitfalls?  What is your general experience?
Thanks.
Answer: Very excited about Pintura too, but I'm struggling getting this setup right now. Personally one of my requirements for something that's production ready would be good documentation. It's a bit confused right now, unsure of how much of the old Persevere docs are applicable, and I had to do a lot of manual changes before I could get the /example that came with Pintura to run.
In conclusions: looks like Alpha software to me!


Is double AES-CBC encryption with the same key and IV unsafe?

Question: If some plaintext encrypted twice with the same AES function (CBC-mode), same IV and same key, is it possible to retrieve either the key or the plaintext?
Comment: Key no (AES is believed to protect the private key against any attacks other than related key attacks).
Answer: No, it is not possible.
The encryption step of CBC is $c_i = E(c_{i-1} \oplus p_i)$. When you double encrypt, the previous block ciphertext gets XORed with an independent block cipher output. The only place where something weird could happen is the beginning.
If you assume that the (identical) IV $I$ is prepended to the ciphertext, as is common, you get $I, E(I \oplus p_1), ...$ after the first encryption and then:
$$I, E(I \oplus I) = E(0), E(E(0) \oplus E(I \oplus p_1)), ...$$
This is wasteful, easily detectable due to the encryption of the zero block in every message, but not decryptable by an attacker. If the IV is not prepended, it is even more clearly not an issue. (However, there is no reason to believe it would be a good idea to do this either.)


I live in Maryland and work in Virginia. Do I need to file multiple state tax returns?

Question: I live in Maryland and commute everyday to Virginia for my job. I do not have any rental property in Virginia. Do I need to file multiple state taxes?
Answer: Maryland , Virginia, and Washington DC have a reciprocity agreement. You fill out all your taxes based on where you live not where you work.
I have worked for a company headquartered in Maryland, but in the DC office, while living in Virginia. The only tax form was for Virginia. The state W-4 was for Virginia.
If you had your employer send your state income tax withholding to the wrong state, you will have to file a form with that state to get that money back.
I was never in the situation where I had rental income in one state while living in the other, so I cant answer how that would change things.
Answer: You probably do. I don't know what having rental property has to do with anything, what's important is whether you have income in the State. You're a resident of Maryland, so you need to report your worldwide income on your Maryland State tax return. But you earn income in Virginia, so that State has the right to tax you first. As such you file a non-resident return in Virginia and report (and pay the tax on) your Virginia income. You can probably deduct that from your Maryland taxes, as many neighboring States have reciprocity agreements, but verify that.
Comment: A +1 answer. And still is, for the generic headline question. mhoran's answer specifically clarified for this state combo.


Teamviewer view doesn't refresh, but still controls

Question: I'm using Teamviewer to work remotely on my lab machine. When Teamviewer connects I can see the desktop of the remote machine, but then the view freezes. However, I can still control the mouse and keyboard. This happens even when I'm hard wired into the same network as the remote machine. Has anyone seen this or have an idea on the problem?
Answer: I am not 100% sure of the root cause (I suspect it's a Teamviewer version disparity), but the solution was, on the client side, to go to Options > Remote control and select Custom Settings under Quality. Then, under custom settings, check the box for Improve application compatibility.
Comment: To update, this is still an issue 7 years later, even with clean installs of (the same version of) Teamviewer. This solved it for me too.


Grab the oldest 100 files out of thousands and zip them up but also create a listing of those files that I can cat out later

Question: I was wondering if there is a way to grab the oldest 100 files from a directory that has a 1000 or more in it with the same prefix (cdr12345.csz, cdr32342.csv, cdr 98876.csv, etc..) and list the names of those 100 files out to file.txt, that I can cat out and read later, and then zip those 100 files up.    I can only do 100 at a time, so how can I just get the oldest 100 first?  Caveat is that the zip file must be under 500 mgb.
Answer: In terms of identifying the oldest 100 files, you can do something like:
ls -1tr /path/to/directory/cdr* | head -n100 > filelist.txt

The -1 will list one file per line (not strictly needed here), the -t will sort by modification time, newest first, and the -r will reverse the sort order (i.e., will make it list newest last).  Pipe that output to head -n100 will list the first 100 lines (i.e., the 100 oldest files).  I then redirect the output of that to filelist.txt -- that file contains the names of the 100 oldest files.
You could then zip those files with:
zip backup -@ < filelist.txt

That will create a file called backup.zip with the content of the files in the filelist.txt.  The -@ option instructs zip to read the file names from standard input, and the redirection provides that list from the file.
Once you've tested that much and see if it does what you want, you could then remove the files in filelist.txt:
xargs rm < filelist.txt

That'll leave you with:

filelist.txt the list of the oldest files
backup.zip the content of the oldest files

Note that this doesn't address your 500MB file size limit.  One approach would be to examine the zip file's size after you create it, and if it's too big, decrease the number of files you include in the archive.
Comment: Thank you, Gents!  This is great!  Is there anyway to pass a date value to make sure I am getting the current date?  I may need to do this but don't see it as a requirement, YET...
Comment: Also, the -@ does not jive with gzip.
Comment: @ScottMick `gzip` won't take a collection of files and produce a single file, so you'll end up with 100 separate files.  You could use plain ole `zip` (like you said in your question), or you could use `tar` in conjunction with `gzip`.
Comment: Thank you! The modification I made was to use `ls -1t` since the `r` option was doing the opposite of what is expected (MacOS)
Answer: The command
ls -1tr | head -n 100

will give you a list of the 100 oldest files in a directory.
You can save that output to a file (e.g. zip.in).  You can then use that file to create a zip file.  For example:
zip zipfile.zip $(cat zip.in)

In terms of the zip file having to be under 500MB, you can calculate the total size of the individual files to see if they exceed 500MB.  However, since zip is doing some compression though, this is not accurate.  You will only know once the zip file is created.
You could add each file in the zip.in list one at at time to zipfile.zip.  After adding each one, you could then check the size of zipfile.zip to see if it exceeds 500MB.
Answer: While saving and re-parsing filenames can be tricky, if your filenames don't contain spaces or newlines, you can deal with them less carefully. I'll show a method using zsh where the filenames are never parsed directly.
Gather the filenames into an array:
files=( cdr*.csv(om[-100,-1]) )

This says to match filenames that start with cdr and end with .csv, but to order those files by their modification times and then select only the 100 oldest of those.
You can the print those to a file in various ways, such as:
print -l $files > filelist.txt
printf 'File: %s\n' $files

To create a zipfile of those files, then:
zip zipfile $files

... where in each instance, zsh replaces the $files variable with each element. A more careful way of doing the same expansion would be to use ${files[@]} instead.


Can LiFePo4 batteries be charged using an SMPS with adjustable voltage output?

Question: Some Switched Mode Power Supplies offer a potentiometer to adjust their output DC voltage. Mean well's LRS-350-24 power supply for instance has an adjustable range of 21.6 ~ 28.8V. Can it be used to safely charge an 8 LiFePo4 prismatic cell battery pack (with BMS)?
Comment: If there's a BMS, then yes. If the PSU doesn't like back feeding, then use a diode in series with the V+. IF there's too much current when the battery if dead, a small power resistor inline with V+ can limit the current to the battery to keep it within safe operating limits.
Answer: No, an adjustable constant voltage supply can't be used to charge batteries, because a power supply is not a charger.
A power supply like the LRS-350-24 tries to keep the output supply voltage constant. For example you can set it to 26V.
A somewhat empty LiFePo4 could have 22V.
When connecting a power supply to battery, the battery will try to pull the voltage down to 22V while sinking current from supply, and the supply tries to raise the voltage to 26V by pushing current into battery.
So as the battery can sink a large amount of current, the power supply cannot push enough current to rise the voltage to 26V setpoint.
The power supply overcurrent limit triggers and it shuts down to protect itself. This specific supply will go into hiccup mode so it constantly starts up momentarily until overcurrent limit triggers again.
Many power supplies also can't handle being connected to an external voltage supply, i.e. the battery, and will damage.
So a power supply cannot be connected to battery directly.
You mentioned in comment lab/bench supplies which are different. They have also a settable current limit which does allow for pushing charge into battery with constant current at battery voltage until battery no longer takes that much current and then battery is float charged at constant voltage.
But as lab/bench supplies are also not battery chargers, they are unable to detect when battery is full and stop float charging at constant voltage to prevent overcharging and damage to battery.
And that's why batteries need to be charged with chargers, not power supplies. The power supply can be used to provide a power to a charger between the power supply and battery.
Comment: @A.Jesin That's the problem, anyone can make a Youtube video, and claim anything they want in it. Things made in a video might be wrong or dangerous, done as a one-off joke just for the subs. It may even be fake. You don't know that. You should be aware that charging batteries incorrecely can make them explode or burn down your house. Trying what the video does is just wrong and the real problem is people not underatanding it's wrong because even the Youtubers did it. Learning if some source is credible or not is difficult, but always double check if something is true/real or false/wrong.
Comment: Well said. Well said. However, it is possible to use a current limited power supply (such as a lab supply) to charge Li-ion batteries IF: a) the battery is balanced, and b) the top voltage is set to the equivalent of 3.4 V / cell (for LFP). Indeed that is what base stations (in telecom towers) do.
Comment: Wouldn't the battery's BMS stop the float charging once full?
Comment: @dandavis No, the BMS will cut off when it detects overcharge, because the charger didn't end in time and damage or fire is about to happen. That's like leaving brakes off your car/bike because you have an airbag or a helmet for cases when you need to stop.
Comment: Thanks for the detailed answer. In this YouTube [video](https://www.youtube.com/watch?v=ulWpwg4z27M) the host uses an SMPS to charge his lithium battery pack. Even though he calls it a "charger" the Aliexpress link in the description opens an SMPS product page.


phpBB Password Authentication on Custom Site

Question: I have been looking for the past few hours on how to user the phpBB login script on a custom site.  I think I'm just not searching for the right things.
A while ago, I created a phpBB site and have over 900 members registered through phpBB.  I am currently face-lifting this site and redoing the user registration along with all of the other custom code I have.
My problem is, I want the users to be able to log in as usual, though I want to input them into my new database so everything can run smoothly.  I mainly need their username, password and old ID#, but I don't know how to use phpBB's password authentication or where to find it
The statement needs to look something like this:
<code>On Login, grab username and password variables:
    if the username is not in MY database, check phpBB database.
        If the username is in phpBB database, check to see if the password is correct **(This is the part I don't know how to do)**
            If the password is correct, input the username, user ID and the password (encrypted my way) into MY database
                Login
            If the password is incorrect - error
        if the username is NOT in phpBB database - continue
    if the username is not in MY database - input username and encrypted pass into my DB
        login
</code>
Where can I find a script to authenticate the phpBB user's passwords?  I don't care how the script is done, I know that's a secret, I just need to be able to authenticate passwords so that I can make sure it's the same user
I do have access to the phpBB database, I just need a way to authenticate their password
Answer: I would rather delete the quesion, but here's the answer:
Check here: http://sunnyis.me/blog/secure-passwords/
and when you download the PasswordHash.php, change all of the $P$ to $H$.  It will work.  Strange how it creates a password, every time it creates, it's different.  But the CHECK part of it makes sure it checks it correctly, no matter what hashed pass it creates.


Where can I find information on corporate bonds (especially those rated as "junk") ?

Question: I've been searching a number of financial sites and I can't seem to find a way to browse for companies that are selling bonds, and what rates/durations those bonds are at. How does one go about finding this kind of information? Ideally I'd like an interface that's as intuitive to use as a stock ticker. Specifically I'm looking for junk bonds. It could be I'm just using bad google queries...
Answer: Bond information is much tougher to get.  Try to find access to a Bloomberg terminal.  Maybe you have a broker that can do the research for you, maybe your local university has one in their business school, maybe you know someone that works for a bank/financial institution or some other type of news outlet.
Part of the reason for the difference in ease of access to information is that bond markets are dominated by institutional investors.  A $100 million bond issues might be 90% owned by 10-20 investors (banks, insurance co's, mutual funds, etc.) that will hold the bonds to maturity and the bonds might trade a few times a month/year.  On the other hand a similar equity offering may have several hundred or thousand owners with daily trading, especially if it's included in an active stock index.
That being said, you can get some information on Fidelity's website if you have an account, but I think their junk data is limited.  Good luck with the hunt.
Answer: You can get junk bond information on any brokerage site (particularly if you have a brokerage account), such as Etrade, and look for bonds that have junk level credit ratings.  Investment grade is S&P: rated BBB- or above, or Moody's: rated Baa3 or above.  Below that is considered junk.
Just go to the bond desk , e.g, on Etrade:  Trading-->bonds--> (see below)

You can see how it asks you to search by various fields


Which is more standard in large enterprises: RAID5 or RAID10?

Question: Which is more standard in large enterprises: RAID5 or RAID10?
Answer: They both are. It depends on the application using the array, the number of disks in the raid group and the IO requirements of the applications sitting on them.
For example a file server probably doesn't need RAID 10 as the bulk of the data is just sitting there with a few users opening and closing files through out the day.
An OLTP database may need a combination of RAID 5 and RAID 10 while a data warehouse will probably need all RAID 10.
Comment: +1 for the sane answer "They both are. It depends on ..."
Comment: +1, situational on how heavy write usage is.
Answer: I work on directly on a customer base of about 2500 medium to very large businesses (think Sony-size), and currently RAID 5 is more common from what I see in their configs.  That is, however, likely due to a few factors, like people still using older RAID controllers that don't support RAID10, people still thinking disk space is expensive, and the fact that with caching and such, web content often doesn't need to be sitting on a RAID 10 when a RAID 5 will do.
The most common configs that I see are something like RAID 5 for web content, RAID 1 for OS drives, RAID 10 for database data files, and sometimes a RAID 0 for something like tempDB.
RAID 5 vs RAID 10 isn't really an either/or thing.  You need to look at the application and figure out what is best for the use case.
Comment: "In my ideal world it would all just be RAID 10 I think". I'm glad it is *your* ideal world. Depending on the nature of the application, RAID10 can have a performance hit compared RAID5. Take IBM's(Rocket now) U2 database servers. RAID5 can have up to 50% increase in read performance for a correctly configured RAID5 as opposed to the same disks as RAID10.

**Horses for Courses**. Do some research on how the disks will be used and which RAID configuring matches your goals best.
Comment: Hi Dan, I think you misunderstood me.  I was more trying to make a tongue-in-cheek comment about being lazy and slapping configs together.  I can see how the tone isn't really conveyed though, so I'll remove it.
Comment: I feel this answer gives me exactly the information I was looking for in order to decide which raid type to use for a specific task, and some history on why current configurations are the way they are.
Comment: RAID 0 shouldn't ever be used on a database serer, even for tempdb.  If you loose a single disk the SQL Server will be down until someone goes and puts hands on the server to replace the disk, and put the array back together.
Comment: I was telling you what I see, not what I recommend.

Incidentally, failover can be implemented for tempdb pretty easily.
Answer: It shouldn't matter -- you shouldn't pick technologies because they're popular, you should pick them because they work.  On the other hand, if you're trying to do a rigorous study on RAID levels, a question on serverfault isn't exactly the right way to go about it.
Having said all that, I would say that without a doubt RAID 5 is the more popular of those two choices.  Plenty of hardware RAID cards don't support RAID 10 (although thankfully these are becoming far less common than they used to be), and lots of people don't like the idea of wasting half their disk space (because they're stuck in the days when disk platters were actually expensive).
Comment: (and lots of applications perform better on RAID5). RAID10 isn't superior, RAID5 isn't superior. They both have their uses depending on many issues. See Mr Denny's answer
Comment: "many issues" -- like whether or not you actually want to keep your data.  2TB SATA drives take a *long* time to rebuild in a RAID5 array.
Answer: I believe RAID 5 is increasingly considered nigh-on-useless, due to the time taken to rebuild a large array after a single disk fails, and the risk of a second failure (i.e. a catastrophe!) during this time.
We just switched to RAID 6 -- I considered RAID 10, but depending which second disk fails, that still feels prone to significant loss if a second disk fails during a rebuild...
Comment: +1 for "but depending which second disk fails, that still feels prone to significant loss..." I stress this in my storage presentations.
Answer: At the institute I am working at we have Petabytes of RAID 6 or double parity RAID 5. While we only have Terabytes of RAID 10.
Answer: "More Standard" isn't a clear enough question, certainly you'll find MORE R5 in large organisations simply because it's been around longer and is supported in more, and older, array controllers. R10/01 is however becoming more prevalent and important to those looking for consistent database performance.
Comment: s/database/first form normal database(most)
Answer: I've a personal preference for RAID 10 but RAID 5 does have advantages.  OK, so storage isn't expensive but the number of drive slots in your server is limited, and 5 will just give you more storage for any given number of drives.
Otherwise, what everyone else said.
Answer: Much of my experience shows RAID 10 for the drives in the server, but then connected to some form of SAN for "actual" storage.
Or skip RAID entirely (from the "machine's" perspective) when looking at virtualization on SANs.


Liquid simulation on GPU

Question: I would like to implement 2D liquid simulator using GPU. I'm looking for some "simple" algorithm, that can be ported to GPU. I have this for GPU computing class. I have chosen this, because I find it very interesting. But I'm not as good in physics as I'm in programming. What do you suggest? Should I choose something else :-), or is there something I can do?
Answer: You could look into Lennard-Jones Fluids.  It should be rather straight forward to implement.
Answer: What aspect of liquid behaviour do you want to simulate? The answer will entirely depend on what you intend to achieve; otherwise you're likely to end up with a monstrously complicated solution that's accurate in many situations.

Liquid simulation on GPU


Deleting a bad answer after a remark

Question: In this question, I get a good reaction why the answer is not good, so I want to delete it. However, the persons who made the comments spend some time on it; should I immediately remove the answer or should I let them know to remove it? It feels bad to remove an answer including their comments 'immediately'.
Comment: Funnily enough, I was about to open a Meta question on this particular question too! Specifically on the use of the voting and commenting. As I had received negative words from one user about the way I had reacted tot he answer. As this is meta, is seems like a place to get your opinion of it! In my eyes, I downvoted the answer for the reason of it not being relevant to *that particular question*. I did acknowledge that it was good for other things though. I left a comment which explained my reasoning and thinking, so that the answer could be improved. You edited your answer.....
Comment: .....and I removed my downvote. I believe I went the right way about it, but apparently someone disagreed. I did acknowledge the good points of the answer, I gave my reasons for the downvote, and removed it once those reasons were addressed. In my opinion, the answer improved because of it. Because of that, in my opinion what I did was actually help rather than just being negative as someone seemed to think. I don't like downvoting things and leaving without saying why, and I would hope you appreciated the way I did things. Feel free to let me know your opinion on it!
Comment: @KevinKruse Yes, you are right, I updated the question.
Comment: @MCG Thanks for the comments.
Comment: The general stance on SE is that comments are not particularly important or valuable. Questions and answers are.
Answer: The entire purpose of comments is to induce the poster to modify a post (question or answer). You have two options — either make modifications or don't. Modification could also mean deleting.
Don't worry about the comments. Comments that become irrelevant after modification will probably get deleted.

Deleting a bad answer after a remark


Alcohol as a working fluid?

Question: Alcohols with their lower boiling point and overall non-toxicity, could they be used as a turbine working fluid instead of steam water?
Comment: Can they carry as much heat per unit volume?
Comment: Ask you grandfather how methanol anti freeze worked out for cars in 40s' and 50s'.
Comment: @PcMan I know, it was suggested so the OP would do some research into the situation.
Comment: Methanol is toxic , likely most are toxic except ethanol.
Comment: "Alcohols with their ... overall non-toxicity" Are you sure about that? I mean, it's an interesting question, but the premise seems flawed.
Answer: Yes - for certain applications. Low-energy, low-temperature, small installations, possibly 'accessory' power where providing a bit of weak rotary power to some point of machinery would be difficult but a good heat gradient is at hand and can be utilized - generally things where you have a heat source above your alcohol boiling point but not providing nearly enough heat to make sense with a steam turbine.
There are numerous problems associated with possibility of leaks, evaporation, cost, non-negligible toxicity, flammability, and a lot of other headaches simply absent in case of water - and while they don't matter much in case of small to tiny installations, they become significant with anything larger. And then there's the significant problem: latent heat of evaporation of alcohol is vastly smaller than that of water, meaning you're getting much less work out of the Carnot cycle, you're wasting heat, it's simply inefficient comparing to water. And again, if you have some waste heat that would be radiated out anyway, you can tap into it with a simple small alcohol-based engine and it will work just fine providing some meager work which can be used, e.g. for regulation through mechanical circuitry, gentle stirring, slow forced circulation and so on, without need to provide other sources of power - a side-task to whatever the machine is doing. But if you think about employing it as the primary "target" of your thermal power production, in order to e.g. produce electricity, it's a very bad choice of working liquid.
Comment: @J... alcohol vapor (boiled off alcohol) mixed with air is quite explosive. Not very high energy... if in small amounts.
Comment: Also, alcohols are universally flammable.  If it leaks...you have a problem.
Comment: Yes, that would be the problem I was alluding to!

Alcohol as a working fluid?


Omit made up columns from results

Question: So I have a complicated INSERT query which puts information into a relational table based on information pulled from another table and with given variables.
Here's the query:
INSERT INTO relational (class_id, teacher_id, student_id)
VALUES (
    (SELECT `id`,
        (`name` = "John Smith") as exact_score,
        (`name` RLIKE "[[:<:]]John Smith[[:>:]]") as reg_score,
        (MATCH (`name`) AGAINST ("John Smith")) as match_score
    FROM `teachers`
    WHERE (`title` RLIKE "[[:<:]]John Smith[[:>:]]" || MATCH (`title`) AGAINST ("John Smith"))
    ORDER BY
        CASE WHEN exact_score = 1 THEN exact_score END DESC,
        CASE WHEN reg_score > 1 THEN reg_score END DESC,
        CASE WHEN reg_score = 0 AND exact_score = 0 THEN match_score END DESC),
1, 1);

The regex is required because the name might be Mr. John Smith or John Smith PH.d, and the match is required because the name might be jon smith When the stored name is actually just John Smith.
The select query yields the results I am looking for 90% of the time, but the only real column that I need from it is id. The problem I'm running into is with the INSERT's expected column count vs. the column count that is returned by the query.
Right now the INSERT basically looks like this:
INSERT INTO relational (class_id, teacher_id, student_id) VALUES ({{returned id (desired)}}, {{exact score (undesired)}}, {{reg score (undesired)}}, {{match score (undesired)}}, 1, 1);

The last 1, 1 is provided by variables.
My question is, is there a way to select columns for the sake of ORDER BY, but then to omit them from the results?
Answer: There is no need to use VALUES; simplify the insert to
INSERT INTO t (class_id, teacher_id, student_id)
    SELECT id, 1, 1 FROM ...

To get rid of extra columns, make an extra level of SELECT:
SELECT a, b
    FROM (
        SELECT a, extra, b FROM ...
         ) AS x

But, you probably won't have any extra columns if you do
ORDER BY
    IF (`name` = "John Smith", 2,
        IF (`name` RLIKE "[[:<:]]John Smith[[:>:]]", 1,
            MATCH (`name`) AGAINST ("John Smith")
       )   )

Omit made up columns from results


inter-rater agreement for data with nominal and ordinal responses

Question: I'm trying to determine inter-rater reliability for ratings produced by 4 unique raters, with four possible ratings, NA, 0, 1, 2 corresponding to a quality judgement. I am interested in the distance between ordinal ratings, but also need to take into account the nominal rating NA which are valid responses.
Is there any way I can do this with Krippendorff's alpha or some alternative estimate of inter-rater agreement? Should I just treat all responses as nominal?
Thank you!
Answer: If NA is not really a separate category but just the notation for missing data, you can use a generalized formula for inter-rater agreement that allows for missing data and weighting schemes. Then act like you have three ordinal categories: 0, 1, 2.
If NA is a separate category that actually has meaning, ask whether that category is part of the ordinal scale with the other categories. If it is, then you can just treat it as -1 or 3 or wherever it belongs in the scale. If it isn't, then you could perhaps create a custom weighting scheme that gives ordinal credit to 0, 1, 2 and nominal credit to NA:
$$
\pmatrix{
& \text{NA} & 0 & 1 & 2 \\
\text{NA} & 1.0 & 0.0 & 0.0 & 0.0 \\
0 & 0.0 & 1.0 & 0.5 & 0.0 \\
1 & 0.0 & 0.5 & 1.0 & 0.5 \\
2 & 0.0 & 0.0 & 0.5 & 1.0\\
}
$$
Comment: Hi, thank you for your super helpful response! NA is a separate category and doesn't have a place on the ordinal scale with the other categories. Regarding creating custom weighting schemes for Krippendorff's alpha in R, would you be able to suggest any reading on how to go about doing this (for beginners to inter-rater agreement). Thank you again for your time!
Comment: I put together a little example for you using my agreement R package. https://rpubs.com/jmgirard/custom_weights


On finite sums and products

Question: I'd like to get a good book on finite summations and products before I study infinite series more in depth next year.  The book should cover geometric/ harmonic sums and prove different formulas for finite products.  Some geometric intuition thrown in with the algebra/ induction would of course be a plus.  Does anyone have a good recommendation?  If no such book on just finite sums and products exists then do you know of a good book which covers them as part of a broader topic?
Answer: I'm not sure if it's exactly what you're looking for, but just about any intro to combinatorics (enumerative combinatorics) would contain a lot of these kinds of things.  One book that comes to mind is "Discrete Mathematics and its Applications" by Rosen.  It is a text for intro proof writing (so it'll contain induction and the like) and will certainly see a lot of finite sums involving binomial coefficients (and it may help you learn to count).

On finite sums and products


How do you reduce blunders in the end game?

Question: I have a very strong opening and middle game but somehow when it comes to checkmate I always make blunders and end up being the one who loses. Someone told me that my weakness is I am too focused on my pawns only. I guess that's right because I always try to defend my pawns no matter how small the exchange was. Is there a way to change my playing type from defense to offense/aggressive?
Comment: Could you please clarify what you mean by "when come to checkmate"
Comment: Could you please add some example games of yours? Situations where those problems occured? Just because there was a Mate in 3, doesn't necessarily mean you were in an endgame. In general, to better recognize mating patterns, I would recommend chess puzzles.
Comment: Can you show us some examples? Are you drawing these conclusions from engine analysis alone?
Comment: @Hauptideal when the game is done and I check it there are some moves that require only 3 moves again to check mate but it can't be seen by me so I keep making blunders until I lose
Comment: It seems that you are confusing what is called a "mating attack" and an "endgame" in chess. Unlike in shogi, they are two very different phases !
Answer: If you are failing to win won endgame positions then the first thing you need to do is to learn the simple checkmates - K+Q vs K, K+R+R vs K, K+R vs K, K+B+B vs K. If you don't know how to checkmate then you can't win unless your opponent does you a favour and resigns.
The second thing you need to learn is how to play king and pawn endgames. The first of these is K+P vs K. Whether this is a draw or a win depends on the positions of the three pieces plus whose turn it is. You just need to learn these otherwise you won't what is a winning position and which isn't and you won't know which positions to aim for.
The third thing you need to learn is the importance of playing with the king. When the "safe" part of the endgame starts most of the time the critical thing to do is centralise the king. The king is a powerful piece in the endgame and if your opponent succeeds in centralising their king and you fail then you are probably going to lose.
The fourth thing you need to learn is the importance, when you are a pawn up in a what looks like a drawish position, of a timely pawn sacrifice. Sacrificing an extra pawn can often divert the enemy king away from the action and let your king into the position to attack your opponent's other pawns. If you are fixated on defending all your material this can be a particularly hard habit to break.
Comment: I'll just leave this here https://lichess.org/study/wukLYIXj
Comment: thank you for your help but I don't learn that way, I don't memorize it. I learn by practice
Answer: I don't think you necessarily need to play more "aggressively". You need to get your priorities right (including piece activiy).
To make fewer blunders, it is essential to study the endgame, in particular theoretical endgames, and how to deliver checkmate with minimal material.
Furthermore, you need a general strategic understanding of what to do in the endgame.
If you do not have the theoretical knowledge and a roadmap / plan, then it's very hard to play an endgame accurately, as usually the time on the clock is low. Not knowing what to play for leads to wasted time in the endgame pondering about what to do when the plan should be clear, leaving you more susceptible to time-trouble blunders.
What could a roadmap look like to help you prioritize moves, so that you do not passively defend pawns instead of delivering a checkmate or achieving other goals?
Look at this example made by ChessMood and read GM Grigoryan's explanation.
Your first and foremost goal is to checkmate the opponent's king. Therefore, you should always be aware of tactics, even in the endgame. The endgame is still chess, and the chess principles still apply. So look for tactics and seek to improve your piece activity.
Typically, the goal in an endgame is to promote a pawn to a queen and win with the extra material. How do you promote pawns?
You need to get a passed pawn. You can do that by winning pawns from the opponent (e.g. by creating and exploiting weaknesses), by pushing a pawn majority, by breakthroughs and other means.
When you study endgames, you'll often find that it's not only the number of pawns, but also their quality (e.g. strong connected or protected passed pawns), as well as piece activity that counts in an endgame.
You'll have to use your pieces to guard and escort your passed pawn to promotion. Your opponent will try to block its way to promotion (or seek counterplay).
When you are on the defending side, try to exchange as many pawns as possible. This makes it much easier to reach a theoretical draw, e.g. king and pawn vs king where you have the opposition, the Philidor position, Vancura position, rook pawn with wrong bishop and so on.
A very important tip is to play actively. Instead of passively defending pawns, it is often better to activate all your pieces (including the king) and seek active counterplay or counterattacking an enemy weakness.
Especially rook endgames can be drawn one or even two pawns down when your king and rook are active. Contrary to that, if your rook and king are inactive and you have a lot of weaknesses to defend, it can be much harder to hold a draw even if the material is balanced.
However, in pawn endgames, the side with the extra material will usually win, if the other side does not have any special resources such as a far advanced outside/connected/protected passed pawn.
This shows you that it is important to study endgames and endgame strategy. It is more important to study endgames than to study opening theory beyond the opening principles as a beginner.
Work on your endgames! I can recommend Silman's Endgame course.
Edit: Note, that you do not always need to execute a mate in three, when you choose another winning move in time trouble that you know for sure wins (e.g. because you know the procedure to promote a pawn).
You can still make practical choices. Maybe your problem is not solely missing the mate, but blundering away a position in time trouble that is winning anyhow, even without the immediate mate, because you do not know what to do and how to win such a position.
Comment: You wrote this response as if OP is 1800+. I think it's pretty clear that they are nowhere near the level where this advice would be helpful.
Comment: thank you, I think I confused between aggresively and actively. now I will play actively


Install OpenType fonts in Texlive

Question: Maybe this topic has already been discussed, but I haven't found anything clear about it! I bought Garamond Opentype fonts by Adobe, so I have *.otf font files. I'd like to use it in my thesis, but i can't install it in TexLive 2011! I've downloaded pad.zip file from http://www.ctan.org/tex-archive/fonts/psfonts/w-a-schmidt, and after long hours I sucessfully converted .otf to .pfb. Then I used Crossfont to obtain the .afm file... and now? Do I need any other file? I read that using autoinst may help, but how?
Please, help!
Comment: Are you willing and able to use either XeLaTeX or LuaLaTeX instead of (pdf)LaTeX? If so, you could use either of these programs to good effect since they can load and use `.otf` fonts directly, without any need to create pfb, afm, and other files.
Answer: The package by Walter Schmidt is meant for the Type 1 fonts.
For the use with (pdf)latex, try the fonttools with autoinst. This script generates all necessary files including a LaTeX package. It is well documented. However, you won't have math support.
As Mico suggested, you can use XeLaTeX or LuaLaTeX with the fontspec package to use the otf directly.
Comment: I've seen that FontPro started with rudimentary support for Adobe Garamond, can I hope for further development?
Comment: @mafp The Garamond files were written by the original MinionPro project team. My time is very limited at the moment and I am also not that much interested. The actual adaptation using MnSymbol shouldn't be hard so I could give some starting hints.
Comment: That would be great.
Comment: @mafp Let's do it via PM. Please write me an email. Please let me know whether you understand German so I could copy/paste what I've written before.

Install OpenType fonts in Texlive


What happens to my bitcoins when I die?

Question: What happens to my bitcoins when I die?
Are they lost in the network?
Comment: They go to live on a farm where they-- oh wait, when *you* die.
Answer: This depends a lot on how you handle your wallet. If you are careful about it and make sure you have an off-site backup of your wallet (or use a deterministic or paper wallet, etc) then you can easily pass your wallet and all the coins it contains to anyone you choose in the same ways that you can pass on other property.
Of course if you're the only person with access to the wallet and have not planned anything then yes, your bitcoins will be "lost in the network."
Comment: IF you have significant value in bitcoin, I would make sure that this is included in your will and that your executor knows how to deal with them so that your heirs can make use of your estate.
Answer: You may just store your bitcoins with the method also used by https://www.casascius.com/ ... so it will be like paper-money stored in a sock under your bed.
Answer: You can set up a transaction/contract that would express your will to transfer specific bitcoins to another person:
Contracts. Example 4: Using external state:

Scripts are, by design, pure functions. They cannot poll external
  servers or import any state that may change as it would allow an
  attacker to outrun the block chain. But we can make transactions
  connected to the world in other ways.
Consider the example of an old man who wishes to give an inheritance
  to his grandson, either on the grandson's 18th birthday or when the
  man dies, whichever comes first.
To solve this, the man first sends the amount of the inheritance to
  himself so there is a single output of the right amount. Then he
  creates a transaction with a lock time of the grandson's 18th birthday
  that pays the coins to another key owned by the grandson, signs it,
  and gives it to him - but does not broadcast it. This takes care of
  the 18th birthday condition. If the date passes, the grandson
  broadcasts the transaction and claims the coins. He could do it before
  then, but it doesn't let him get the coins any earlier, and some nodes
  may choose to drop transactions in the memory pool with lock times far
  in the future.
The death condition is harder. As Bitcoin nodes cannot measure
  arbitrary conditions, we must rely on an oracle. An oracle is a server
  that has a keypair, and signs transactions on request when a
  user-provided expression evaluates to true.
...

I'm not sure whether this mechanism is flexible enough to be used if you are not certain which amount should be transferred or from which address (because you may want to perform some operations with the bitcoins after you have set up the "inheritance transaction"; perhaps, you can simply generate and store such a transaction every time the amount or the address changes).
Comment: What happens if the son dies before the old man and before turning 18? Coins are sent to a dead wallet?
Comment: @Thomas By default, yes, of course, AFAIU. But probably, you could take care of that condition in the contract, too: what to do if the son died too early.
Comment: Will also need to support the case they both die at the same time (and before the son's 18th birthday). And so on, might become complex (with low probability, ok...)
Answer: Eventually, technology advances may enable cracking of the keys allowing access to your Bitcoins. This would be the digital equivalent of salvage or treasure hunting.
Until then, they're lost.
Comment: Any crack that could recover "lost" coins could also recover live coins, so before that level of break is attained, I expect the network's security to have been upgraded.
Comment: Yes, but that doesn't occur everywhere instantaneously. You can still use old wallets with the latest Satoshi client. Any keys that are not updated become fair game, increasing both the incentive for holders to keep up to date, and motivation to break existing systems.
Answer: It's up to you what you want to happen with your bitcoins when you die. The bitcoins are in the possession of whomever has the wallet and the passphrase needed for it. If you want someone else to inherit your bitcoins, you need to arrange for a way for them to obtain the wallet and passphrase. Perhaps a safety deposit box containing the password or a memory stick containing the wallet.
Bear in mind though that a backup of the wallet will only contain 100 future addresses. If you perform more transactions than that since the backup was taken, they won't be stored on the memory stick unless you ensure you send your bitcoins only to addresses that will have existed when the wallet was backed up.
Answer: Most of us will probably want our bitcoins to go on to our family members when we die.
If you're the only one with access to your private key, however, that is unfortunately impossible.
The best solution to this is to "shard" your private key into shares and distribute those shares to various members of your family. With Shamir's Secret Sharing Scheme, you can require that M shares of the N total shares created be required to reconstruct the private key.
Here is a very straightforward, easy to read python implementation of Shamir's Secret Sharing: https://github.com/rxl/secret-sharing.
All you need to do to shard your private key is the following:
<code>>>> from secretsharing import BitcoinToB32SecretSharer
>>> shares = BitcoinToB32SecretSharer.split_secret("5KJvsngHeMpm884wtkJNzQGaCErckhHJBGFsvd3VyK5qMZXj3hS", 3, 5)
['B-RJ6Y56OSUWDY5VAAGC6XLSTM64CAJ2LPBNB7NKATJCWC7VSHIP5DQIVMR6OGJ4GB', 'C-CT5R24XAR5B732JWYQKSYOYBSF5VHI73HLY24QCFRJR5XUW64C4JWYN6SRGWVCUG', 'D-T54KX27OPEAGZ7TNK5WOFK4WFPZKEXUHNKPWLWDXZQNYPT3WPV3P5IGQTD7HAJDG']
</code>
In this case, 3 out of 5 of your family members would have to come forth upon your death and combine their shares in order for your private key (and your bitcoins) to be recovered.
The process for recovering private keys would be as follows:
<code>>>> BitcoinToB32SecretSharer.recover_secret(shares[0:3])
'5KJvsngHeMpm884wtkJNzQGaCErckhHJBGFsvd3VyK5qMZXj3hS'
</code>
Comment: And then your family members fight to death to get as much as they can from the recovered coins (as they get access to all the coins instead of split coins). To prevent that, each individual needs to have a private key that he/she does not share with others (but still need the public part of others to make use of it).
Answer: You leave them in your will, along with the gold you buried in a secret location.
Answer: I am using a website called www.planneddeparture.com. It is a Digital Legacy platform that keep all my social media accounts, pics, contacts, docs as well as bitcoins safe. Pretty much like dropbox but with the difference that I can assign beneficiaries and leave them instructions of what to do with my digital belongings when I am gone. I have used it for 2 months now and have assigned beneficiaries to almost all my belongings including my bitcoins. I have read some of the comments and must say that some solutions are quite old fashioned and risky. There are plenty if platform on the web that deal with your digital assets. Have a look and decide for yourself. I happen to use PlannedDeparture and I am feeling quite secure about my bitcoins and other data.
Comment: The community's consensus is against centralized solutions to such problems.

What happens to my bitcoins when I die?


understanding holomorphic Functions

Question: I'm a bit unsure about how to know when a function is holomorphic or not for example:
$$ f(z)= 2Re(z)-iz^2 $$
for what values of z is f holomorphic
Answer: The function $z \mapsto i z^2$ is holomorphic, so it is sufficient to check if
$z \mapsto 2\operatorname{re} z$ is holomorphic. However, if it was
holomorphic it would be an open map, which is impossible since the range is
constrained to the real line, hence it is not holomorphic anywhere.
Answer: write $z=x+iy$, $f(z)=2x-i((x^2-y^2)+2ixy)=2x+2xy-i(x^2-y^2)$
Write $g(x,y)=2x+2xy, h(x,y)=-x^2+y^2$.
$\partial_xg=2+2y$, $\partial_yh=2y$. So Cauchy Riemann are not verified, it is not holomorphic.

understanding holomorphic Functions


Time measures in fantasy worlds

Question: I wonder, what could be a good way to provide time measures in a fantasy universe. I don't mean the calendar which is covered in the question: Out of this world... Giving it time?, but measures like hours, quarters and minutes.
When it's obvious for me that I won't write "5 kilometres from here", would it be satisfactory to write "an hour of a way from here" (pardon if it's not a proper grammar way to say that in English, I write stories in my native language)?
Is it reasonable to provide exact time measures in worlds without clocks, basing it on sundials or magic? Sundials could be an answer for hours (perhaps with the passing hours announced by bells or anything), but they're not accurate for any shorter measures.
Or is it better to pick up some in-universe measure, like the length of popular local prayer? F.e. we use Ave Maria in Poland for that.
Comment: I'm not sure how much basis in reality it has, but in some comics I read, native Americans measured the passage of time by how long it takes to smoke a pipe - one pipe = 30 minutes. Two hours would be "four pipes ago". If your world is primitive enough and doesn't have constructs like hourglasses and such, a device like that might be a good solution - like Ave Maria you mentioned.
Comment: For distances one could use mile in the old sense of a thousand paces, perhaps using your language's word for thousands.  I.e., three miles would be "three thousands", with paces being implied.
Comment: In Cynthia Harnett's novel *The Load of Unicorn*, a time measure mentioned is "a paternoster while" (i.e., the time taken to say the Our Father (Lat., *Pater Noster* prayer). In the context of the passage, the fact that the time unit is a prayer is relevant: something like, *Wait there long enough to say a prayer. And, while you're waiting, say the prayer!*
Comment: I find it unique and it could really strengthen an atmosphere of a story, thanks! If you change it from comment to an answer, I'll be glad to upvote it.
Answer: Once a physics professor told me that we, in daily life, measure distance with time. In fact he is right. If somebody aks - "how far away is the mall?", we answer "It's fifteen minutes away". That means that measures are always relative to normal everyday standards, not scientific ones.
In old days, moon or sun was a good way to measure time: "It will happen in three moons".
Also horse and walk speed are good for distances: "Castle Rock is two days from here".
You need to keep in mind that the knowledge of time was somewhat well developed even in ancient societies.
Celts, Mayans, Egyptians, they all were quite skilled in it and could predict even solar events.
Please check the Jewish calendar ( https://en.wikipedia.org/wiki/Hebrew_calendar)
Also, note that meal times are not something that every society has. Brazilians Indians eat when they were hungry, not in specific times.
Your problem is how normal people use time, since they lack the knowledge and means scholars did. Like I said, they would rather use common nature to do that. The best approach for me is to separate scholar from normal context. A sage would know and measure time in a more technical way, a normal person would express it in daily units.
Looking at CLockeWork answer, a priest would more complex ways to know at what times the bell should be ringed, and could talk among other priests according such more accurate standards. The salesman from the street, could just say "by the third bell".
When I do write, I try not to use normal measuring units for a fantasy world and apply what I wrote before. Castle rock is not fifty kilometers away, it's a day away. There's an book (or a movie, I don't remember quite right) where the lord of the realm conduces a lot of candle burning experiments to try to determine what is the best way to determine time measuring.
One thing I suggest is to look the Net for such kind of standards.
This page talks about horse travelling times
http://voices.yahoo.com/realistic-horse-travel-fantasy-fiction-novels-455939.html
Comment: Measuring distance with time is culturally dependent. It's a lot rarer in Ireland than I've heard it is in the USA.
Answer: How much do you suppose that your fantasy world resembles our own world? And how much do you want to deal with made-up units of measure?
I don't suppose that the people in a fantasy world would speak English, but fantasy novels written for an English-speaking audience normally have all dialog in English. Perhaps you could explain that by saying that the dialog is translated, but I think most readers and writers don't even think about the issue.
Likewise, you could simply have the characters talk about time in hours, minutes, and seconds, and if anyone questions it, say, yes yes, the time units are translated from whatever units these people use, just like the language is. I suspect most readers wouldn't even notice it.
If you do invent your own units of time, you then have to explain them to the reader. Like if a character says, "The knights from King Throbnar will arrive in 20 framnians" ... is that a few minutes? Hours? Months? You could include some narrative to explain the time unit, but that seems like it would be an awkward interruption in the flow of a story. You could include some dialog where one character explains the units of time to another, but that is likely to be awkward. You either get that lame "as you know" dialog -- when was the last time someone said to you, "I'll be back in an hour -- you know, that's one twenty-fourth of a day, or about 3000 heartbeats" -- or some obviously contrived scene where you suddenly introduce a teacher explaining time-keeping to a group of children or some such. If I felt it necessary to use made-up time units, I'd try to find a way to introduce them naturally, to give some context where it's clear at least roughly how long the time unit is, without unduly calling attention to it. Like, "I'll be there in a framnian! she cried, as she raced down the stairs." I think the reader would get the idea that a "framnian" is a small unit of time, in the same ballpark as a second. Or, "Well son, you're ten lamnings old now. You're a man." The reader would presumably guess that "ten lamnings" must be what we'd call somewhere in the mid to late teens.
Don't suppose that ancient or medieval people did not understand precise time-keeping. "Minutes" and "seconds" were invented by the ancient Babylonians circa 2000 BC. Ancient people used sundials and water clocks to measure time fairly precisely. While I'm not familiar with the Mercedes Lackey story someone here mentions where her characters measure time by making marks on candles, she didn't invent that: it was a method used by ancient people. The main catch to time-keeping back then was not being able to keep track of time in general -- they could do that -- it was being able to keep track of time while moving. The various mechanical devices people had for measuring time didn't work if you moved them around. Tip your hour glass or your water clock over and it quits working. It wasn't until the late 1700's that portable time keeping devices were invented.
Comment: "I suspect most readers wouldn't even notice it." I agree. I have read fantasy books, and the mention of a number of hours or miles has slipped in unnoticed. Later, when I thought about it, I realised that it didn't matter; it's a translation for the benefit of the reader.
Comment: It's not my piece of work, I'm only beta reading it. But your guidelines are very good and helped, thanks.
Comment: I've decided to accept this answer as it was the biggest help in the particular case, focused on short measures of time and contained useful advices about imagined measures. Thanks once again.
Answer: I understand your concern; minutes at least are very much a reflection of an age of clockwork and in a world with no such machines detailed measures of time jar the reader. I don't know the exact setting of your world, by which I mean that if it's medieval that allows for wildly different tech to if it's Aztec, but here are a few general suggestions:
Hour glasses — It isn't unreasonable for a character to carry an hour glass, this would track minutes, but it would require the character to know the hour is up and to turn it over
Sun tracker — a device that can be held up to the sky to measure the sun in points of its decent or rise towards its zenith
Sun dial — a fixed device and so it would be hard for the character to actively track the time
Water clock — same as for sun dial
Bells — Churches would ring bells every hour based on a sun dial
Time could be measured in shadows or points, but honestly in the time fantasy tends to be set in time would likely be measured in quarters of a day. So sun rise, zenith, sun set and midnight. I would simply say:

The walk would take half a day.
  We won't get there before high sun.
  They rode through the night.

There's no need to be specific to the minute in this setting: everything took a long time.
Comment: Absolutely, though only really good for watching time, it's so easy to not notice that an hour glass has finished :-)
Comment: I agree, an hour glass is a very wise option when we need to measure a particular amount of time and can focus on the glass itself, so we are aware when that time actually passes.
Answer: If the units of time are established, then yes, that's a good way - providing you add the mode of transportation.

Five minutes of leisurely walk away
Eight hours of forced march
A fortnight on horseback
an overnight train ride
Three hours of flight on dragon back
Two days by a blimp
Walk ahead for three prayers, then turn left.
Thirty generations in an ark traveling at speed of light.

Only if the mode of transportation is well established or obvious, you can skip it in giving distances. And they are nice in giving the reader a rough clue while leaving the writer a lot of wiggle room.
I don't know about other countries, but in Poland hiking route distances are given in hours and minutes (of normal walk), because two tracks of the same length may vastly differ in difficulty - and so, time estimate is much more meaningful than distance.
Answer: Mercedes Lackey's Valedmar series has established candles (of a specific although unexplained size) which burn steadily enough to be marked off and used for timekeeping. So "three marks" (that is, however long it takes the candle to melt down three of the marks carved or painted on the side) is three hours.
I have never heard of measuring time in prayers (because people don't all speak at the same time and cadence — a New Yorker speaks much faster than someone from Mississippi), but if your fantasy world doesn't have Catholicism, you could also use poems. That would allow you to write the poem as an epigram or to open a chapter, which might also give you an opportunity for symbolism.
Comment: Very interesting point with the candles. That's also a brilliant idea to use such poem or a song as an element of the plot, thanks!
Comment: +1 for the candles, they could even be kept in storm lanterns to make them portable
Comment: @DarekWędrychowski She also had a character use an "alarm candle," for want of a better term: the candle was set in a metal bowl and had a bell in the wax. When it melted down to the bottom (three hours or whatever) the bell would fall into the bowl and chime. Time's up!
Answer: One thing to remember is that our concept of time and specifically splitting much of our experience into units of time ("he held his breath for a second" and "I'll see you in 15 minutes" and "It will take 3 hours to walk to the next village") is very modern and evolved in the context of timepieces of increasing accuracy.
Prior to accurate time pieces, people made limited reference to units of time. A monk might refer to hours of the night (although these varied in length by season) and a Roman might refer to time by a sun dial (again of variable length by season) but this was not how the common person thought of time.
It is in fact anachronistic to have your farm boy or girl in a setting analogous to Earth earlier than the Renaissance (and probably much later in most places) talk about seconds and minutes.
However, I think you'll find that most references to a specific passage of time are unnecessary. In the examples above, "he held his breath for a moment", "I'll see you shortly", "it will take all morning to walk to the next village"
Answer: Just by way of example. This year I am writing a blog of fairy tales and have evolved a system for the folk to tell the time without the widespread use of definite timepieces. The day in any major settlement is split into a number of bells (presumably the bell ringers have hourglasses or similar to keep track of when the bell should be rung).
The bells run like this: 6am Morning Bell, 9am Market Bell (signifying that the market should now be fully open), 12pm Noon Bell, 3pm The Day Bell (signifying the market should soon wind down and close) 6pm Evening Bell, 12am Midnight Bell.
It's an organic system but it does give my characters a useful way of measuring time.
Comment: The way I think it works, or I imagine it working is that the bells tell everyone to do something or to change "rhythm", so people hear a bell and if they're doing morning stuff they figure "that must be noon bell" and switch to post-noon stuff. If you're not sure which bell it was then I guess you would just ask someone nearby.
Comment: Out of curiosity, are they different bells or bell patterns? Otherwise you hear A bell and you know it's A time, but for example in the extremes of seasons or if you're blind or indoors, you won't know WHICH bell.
Comment: I'm not so sure if in a typical fantasy universe anybody would care for disabled people. It's pretty much modern thing. But on the other hand, there's no need to pick up all the bad things from the real world.
Answer: There are some interesting units that really do exist that are seperated by society, or not widely used anymore.
Measure (sun) - I don't remember if it was the Aztecs or Incans, but one of these groups measured the length of the day by the span of the sun.I think there's something like 34, and since they were near the equator, the passing of seasons wasn't as noticable. So one measure was somewhere around 24 minutes.
The Original Roman Calander - The original calander that the romans used was based on a solar day, but a lunar year. Over time, this grew to be a problem as seasons didn't match up with the month (i.e. spring was shifting into summer because the year was 11 days short). Perhaps as something interesting, your 'time' could be inaccurate; pocketwatches often had to be readjusted for being off time because they weren't as accurate based off the releasing of a coiled spring.
The English Mile - This changed with every king for a few centuries until the 1600's. It was because the distance of the foot changed with the length of the king's foot. The Roman mile (another fun one, as Hadrian's Wall is 80 Roman miles, but only 74 SI miles) is shorter than the SI mile by some 400 feet.
Wheels - An English distance measurement of how far a standard wagon wheel rolled in a full rotation. While I don't know the actual distance (that old pi-r-squared thingie) this was a common mode of measurement, as it didn't shift with every monarch. I think it was around 3 yards. I think its origins start with the Romans.
Blocks - We use this measurement still, and it isn't clearly defined at all. Supposedly it is 250 squared feet of city space, but it changes to whenever the next perpendicular street intersects your direction of travel, and has no value in the countryside.
Seasons - Before ancient man realized that the sun didn't go around the earth, some civilizations measured time in Seasons. They may thought that the world was flat and at the center of all this stuff called the universe, but it wasn't hard to count upon Winter and Summer unless you lived near the equator (in which you still have dry and rain season). The word 'year' was substituted with one of the seasons.
Astrological Projection - Since celestial navigation was extremely important to both land and sea travelers (maps hadn't really been invented until neat the 14th century) some things were based upon the movement of the stars, which Venus (the Autumn Star) was one of the Primes. This wasn't accurate at all (Venus has a 255 day year) but it did set a sort of measuring stick.
Lunar Calander - Yes. The calander was once ruled by the moon. 28 day months, 356 day years. Do the math. Put in thirteen months and you got a 364 day year. Just don't mind that you're lagging 5 days every 4 years. (Surprisingly, it was Julius Caeser that figured this out. Thus, the Julian Calender. We now use the Gregorian Calender)
Comment: Not clear to me why someone who held to a geocentric universe would be more likely to use seasons to measure time than someone with a heliocentric universe. Either way, seasons are pretty important to farmers, and until fairly recent times, 90+% of people were farmers.
Comment: I take it that when you say that maps weren't invented until the 14th century, you are referring to some level of accuracy in maps. The ancient Babylonians had maps by at least 2000 BC. http://www.atamanhotel.com/catalhoyuk/oldest-map.html
Comment: Yes, seasons played a great role in works of Emil Zola or Władysław Reymont. Or George R. R. Martin, in a bit different way.
Comment: @Jay Yes I was referencing to topographical maps, and though some did exist well before the 14th century, their accuracy and legitimacy was extremely poor (as we know them). Often guides were used (someone who knew the route), as well as the construction of roads, roadsigns, and landmarks. Stripmaps existed as far back as early Greece and late Egypt, but most times, you were probably better off asking for directions from locals as to the nearest town/watering hole/government facility.
Answer: One additional thought: Maybe the way you give time should depend on whether it is done by the narrator or by one of the protagonists. The narrator is telling the story to a present-day reader, so unless the narrator is supposed to be a person of that fantasy world, it would be natural if he tells times the way he expects the audience to understand. So if the narrator tells us "they only needed about five minutes" that seems normal to me, even if the concept of a minute is not known in that world. On the other hand, if some protagonist said "I'll be back in five minutes" in a world where you'd not expect minutes to be known, it would sound strange.

Time measures in fantasy worlds


Bugged Serena quest in Soul Cairn

Question: I was doing the quest where Serena and I enter the Soul Cairn and I put all the stuff in, but now she won't give her blood and follows me everywhere. This is preventing me from doing any other quest and can't sneak because she is around. How do I fix this?
Comment: Can you please give us the name of the quest so that a more accurate answer can be given.
Comment: What platform are you on? PC, Xbox, PS?
Answer: The quest is Chasing Echoes and you are trying to open the Soul Cairn, correct? The Elder Scrolls Wikia page lists a few known bugs with suggestions for fixing them.
On PC, you would find this bug relevant:

After all the ingredients have been gathered, Serana stops moving and thus she will not cut her arms and the quest will not progress, to fix this, type setstage dlc1vq04 90 in the console after speaking with Serana.

On xbox/playstation, you would want to refer to this bug:

Sometimes when placing the items in the Portal Vessel nothing will happen other than the loss of the items. The quest will not be able to be continued if this happens and an earlier save will have to be loaded to try again.

The UESP page for the quest lists similar bugs and has additional suggestions for fixing them on the PC. Keep in mind that on console, you will most likely have to load an earlier save.
Answer: reload and setfollowercount to 0. worked for me. hope this helps. if your playing on xbox or ps, then ditch all your follower including your wife. serana is really clingy and jealous i suppose coz after i ditched everyone and loaded just before initiating the quest. it fixed the bug. hope it helps my guy.

Bugged Serena quest in Soul Cairn


What's the difference in using the internal formatting and using TEXT to format cells?

Question: What's the difference in using the Formatting drop-down and using =text() to format cells? Which one overrides the other or take priority? It seems I'm having some formatting conflict that is breaking my =unique() range and causing duplicates. Even though the rows looks the same, they are not de-duplicated.
Answer: in essence, =TEXT() is superior over "drop-down" internal formatting because of higher priority:

note: keep in mind that =TEXT() will convert the input into an actual chunk of text regardless of forcing numeric output with "0.0". to convert it back you need to use =VALUE()
note2: on 3rd image you can see that internal formating overrode function formula, however, this is a purely visual issue eg. in a sense we could say that internal formatting is superior in terms of visual outputs - otherwise not.
Comment: @AllenSierra yes, "whatever" you use the final output is text, however, that "whatever" needs to be a valid mask (like dd, mmm, yyyy, #, 0, hh, mm, ss or even @). on behalf of your Note2 question... yes and no. yes for picture 3 but no for picture 1 - on which internal formatting "crippled" the actual value
Comment: Thank you! I have always been wondering what I should be putting in the 2nd param of Text() to force things to become "plain text". Turns out whatever I use it'll still be plain text?

I'm not quite sure if I understand the second part of Note2, do you mean that the drop-down only changes what is displayed, but not the actual value used for calculation? i.e. It can show 6decimal accuracy but uses only 2decimal to calculate if I used text("X", "0.00")?


Does an Adventurers League DM get XP awarded for running Lost Mine of Phandelver?

Question: I am about to start running a Lost Mine of Phandelver group and I am wondering if I would get any experience credit from running it. If so, how much would it be?
Answer: As of Season 6, the rules for allocating DM experience have changed. The rules in the AL Dungeon Master's Guide (contained in the D&D Adventurers League DM Pack) trump all previous guidance, including that contained within the individual products.
The new system is based on runtime and average party level. For modules, use the published runtime and published average party level. For hardcovers, use the actual runtime and the actual average party level.
The same package includes a content catalog, listing all the available hardcovers and modules. Despite the packaging, Lost Mine of Phandelver counts as a hardcover.
Answer: A DM gets (300 XP + 150 gp) x (tier of play) per episode, where the tiers of play are as defined on PHB p.15. Note that episode is not a play-session: it's a "part or chapter" of the published adventure.
You can find this rule in Section 2 of the Adventurer's League Player's Guide; it's p.13 in the season 3 version linked.
Comment: Does this answer cover the change in DM experience noted in the answer above this one? What is the Season to which this rule applies and is current?


How can I fix corrupted shortcut icons?

Question: One of my computers was showing really bad graphics problems, not only in Windows but also in the BIOS. I replaced the graphics card and most problems went away - except the .LNK shortcut icons in Windows Explorer and on the desktop (see attached image).
What is causing this corruption, and how can I fix it? How do I get the icons to appear properly again?
It seems that the icon rendering itself is broken, not the actual ICO image. I tested this by choosing different icons for some of the shortcuts. The effect was a less damaged icon, but damaged nevertheless. The best case was like the center-left icon in the image: "Neu starten".
This is Windows XP Pro SP3, on an nVidia GeForce 5500FX 256MB card. Previous card was ATI Radeon 9800XXL.
Answer: Maybe the XP Icon Cache (Iconcache.db) is damaged, try deleting this file

C:\Documents and Settings\ [Your Name] \Local Settings\Application Data\Iconcache.db

as described here
Answer: Its because the image cache was corrupt. It's a file called Thumbs.db and its hidden. Select show hidden and system files in directory properties and then delete Thumbs.db in any folders with corrupt icons.

How can I fix corrupted shortcut icons?


Congestion control in transport and network layers in TCP/IP

Question: Why do we need congestion control in BOTH the transport layer and network layer in TCP/IP model. Cant we be good enough with control in just one of the layers only? And how do they differ?
Comment: Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer.
Answer: The two methods serve slightly different purposes.  As @Zac67 points out, not all transport protocols have flow control, so it makes more sense to have it in the IP layer.
Without ECN, the only way a router can signal congestion is to drop the packet.  The ECN bits in the IP packet make it possible for routers to signal that there is congestion without having to drop to packet, improving efficiency.  It is also easier for the router to modify the IP packet without having to inspect higher layer protocols it may not be aware of.
ECN is really a binary indication -- there is congestion, or there isn't.   TCP flow control is more variable and allows the sender and receiver to adjust the flow for optimum efficiency.
TCP can modify its window size based on ECN.  Different operating systems handle it differently.
ECN is not widely used and most OS's have it disabled by default.
Wikipedia has a good article on it.
Answer: Some transport-layer protocols have congestion control (like TCP), some don't (like UDP). IP's network layer doesn't care about congestion either.