How do I Export from Adobe Illustrator to Photoshop and Preserve Layers?

Question: I am a web developer and I convert design elements from Photoshop to html. Sometimes I receive the designs in Illustrator. I like to export the Illustrator files to Photoshop so they are easier to work with.
However, when I export from Illustrator to Photoshop, even if I select the option to preserve layers and text edit-ability, I get a notice that some Containers have been flattened. This generally translates into the whole document being flattened and I have little options for working with the layers in Photoshop.
Is there a more effective way to preserve the layers and edit-ability in Photoshop? Thanks!
Answer: One of the lazy Illustrator workflow habits that will make you crazy is designing all on a single layer. From the stuff I receive, this seems to happen upward of 90% of the time. The net result is you end up with a single, flattened layer in Photoshop.
Your best bet is to prep the AI files before importing them. Use AI's Layers panel to select each element, or groups of elements that belong together, and move them to their own layers. For extra credit, name the layers so they're easier to identify. I frequently need to do this (as in, "almost always") with outside AI files I'm going to place in an InDesign layout.
Comment: Thank you for the thoughtful response. At least now I know what to do.
Answer: For having objects in their own layers, you can simply work in a single layer and then at the top right corner of the Layer panel, go to panel options and click "Release to layers (Sequence)". Then follow these steps:
1. Do not use blending mode. It would be annoying but if you have even one object with blending mode applied, the whole project will be flattened in PSD file.
2. Ungroup everything. Simply Select All and press Ctrl+Shift+G bunch of times.
3. Rasterize effects. Some effects can't be exported as PSD, like Gaussian blur. You need to rasterize them first by going to Object > Rasterize from the menu. I had Drop shadow unrasterized and it was fine.
4. Do the final touch in Photoshop. There might be some overlaps caused by rasterizing in previous step. You need to fix those manually in Photoshop.
Comment: Sure @gucciferXCIV, but it will be opened as a flattened image. You won't have layers and editable texts which are what we want.
Comment: I've always just opened the original file in the program I need without problems. Photoshop will open .ai files and Illustrator will open .psd files.


Can a story be considered plagarism even though its in a different world

Question: If there are two works with the same character name and family type can it be considered a plagiarized work even though the plot is different?  One work is about two brothers raised by their father to  be supernatural hunters trying to find their mothers killer.  the other is about two brothers raised by their parents to be killers for  hire trying to survive their abusive dysfunctional marriage.
Comment: Note that apart from copyright considerations, you may also run into trademark issues.
Answer: Names of characters are typically protected by copyright. (I say typically because some very generic names used in many works, like "John Doe", are not attributable to any single original work).
So yes, it would be plagiarism. I cannot create a character named "Harry Potter" and write some other kind of story about him. The fact that you make your "family type" the same would just help to prove you really were plagiarizing that particular character.
I presume you are trying to piggy-back on the fame of some particular famous character in order create "automatic" interest for your work, but that is profiting off of the original author's imagination and marketing money spent, precisely what the copyright law is intended to protect. JK Rowling (and her assigned business partners) are the ONLY people allowed to profit from the name "Harry Potter". (Similarly for whatever name you intended to steal.)
Use your own imagination, and come up with your own fictional name.
Comment: No  actually  I just like the  first  name. as for  the  family  type  I didnt mean to   that  was accidental  . I normally use the  family  type  in  question  .  As for  piggy backing no  Iam not  even  sure if  I am  going to  publish  it  Its  just  my   calming writing  I am just  learning my  own  style  and I write for comfort but one never knows so its best  to  be careful. I would  like  to  thank  you for   you  answer though
Comment: If a single name is unique to an author (and not a word that appears in any other work, like a dictionary), it is copyrighted. For example, I would think "Darth" (as a title of a Sith Lord in the Star Wars universe) would be copyrighted, it does not appear in my giant book of names. (It could conceivably be an actual word in a foreign language; in which case I'm not certain if copyright can apply).


External payment gateway integrate in magento 2

Question: External payment gateway integrate in magento 2.
Any tutorial, link or any code please provide.
Or any Suggestion please guide
Answer: You can google about it and would find plenty of resources about how to implement / create custom payment method module for magento.
there are 2 types of payment methods :
1 - Offline Payment methods:
like , Cash on Delivery , Bank Transfer , Pay order
2- Online Payment methods
Credit card paymen etc.
you can read in details about how these work here ( Magento payment provider gateway
)
and here ( Payment gateway integrations  and also you .Download Sample Payment method code.
Comment: I just created a sample payment method but I want to integrate tiybr payment integration in it external payment gateway. So the tiybr gateway provide me html form and javascript page so I want to integrate this form in sample payment method can u pls elaborate or give reference how
Comment: you should check how module-paypal express checkout is setup. this will give you idea how to submit form. Also, you can create a phtml file and submit with js code. ( using controller call that phtml file and post your data in there ).


Backup not creating a new file

Question: I run a daily backup of my database through command prompt:
c:\sqlcmd -H localhost -Q "BACKUP DATABASE test TO DISK='c:\test.bak'"

But the new backup replaces the previous backup. Please tell me what to change so that all backups will be stored on disk.
Comment: There are some existing questions with answers that may help you: http://stackoverflow.com/questions/880487/sql-server-command-line-backup-statement and an article that will show how to append the date: http://www.howtogeek.com/50299/batch-script-to-backup-all-your-sql-server-databases/
Answer: Instead of writing your own backup solution, I would suggest you to look at SQL Server Maintenance Solution by Ola Hallengren.
If you want to use sqlcmd then you can do as below:
Save below file as backup.sql
DECLARE
    @DatabaseName sysname = N'test_kin'
    ,@DatabaseBackupFileName varchar(255);

SET @DatabaseBackupFileName =
    'C:\test\' + @DatabaseName
      + REPLACE(CONVERT(char(8), GETDATE(), 103), '/', '_') + '.bak';

BACKUP DATABASE @DatabaseName
TO DISK = @DatabaseBackupFileName with init, stats =10;

Then using sqlcmd you can do as below :
sqlcmd -S ServerName\InstanceName -i C:\YourScriptDir\Backup.sql

Answer: At least a couple of choices

Whenever you create a backup, arrange that the backup file test.bak has a unique name. There are lots of ways to do this, I usually embed the date into the filename (in the format yyyy-mm-dd, e.g. 2013-06-05 for yesterday) to ensure that alphabetical order of filename is the same as chronological order.
Use SQL agent to schedule the backup - it will take care of the names for you
Answer: If you are using an edition of SQL Server other than Express then you can use a Maintenance Plan to generate a new backup file every time a backup is made, as well as to remove old backup files if wished. Also see Maintenance Plan Wizard.

Backup not creating a new file


How to create a 301 error?

Question: I would like to create a 301 error situation in my web site. I can write the htaccess code to redirect when 301 error happen. But I don know how to check the code. Please help me.
Comment: I don't really understand what you're asking. If you're setting up a 301 redirect, try accessing the page and if it redirects you to the new page, then it works.
Comment: I know the htacess code .Redirect 301  http://jobslanda.com/301.php.  But How can I chek tje working of the site ?
Comment: you need to accept the answer of your previous questions to motivate others to answer your question.
Answer: The 301 status code means "permanent redirection." If you have a page at oldpage.html and have moved it to newpage.html, you have the oldpage.html redirect to newpage.html with a 301 code. This tells search engines and whatnot that the page has moved. So you really shouldn't be doing a catchall for redirecting these pages. This isn't like a 404 where everything can go to one page where you show a message. If a page has moved, you should be pointing to the new page.
In PHP you can use header ('HTTP/1.1 301 Moved Permanently'); to set the 301 header. I think this should get picked up by your htaccess and redirect the page.
Comment: My thinking is if you have a page with that header, it will be caught by the htaccess file and be redirected to whatever you have set. I've updated my answer with some info on 301 and why I don't think you should do what you're doing.

How to create a 301 error?


Scraping in no GUI env using selenium headless browser

Question: Currently testing my project in an environment without GUI,it is written in python in order to scrap data from facebook marketplace using selenium package and headless browser, link to the project: https://github.com/lokman-sassi/FMP-Scraper-with-Selenium , for that I'm using ubuntu 22.04 as subsystem in windows (only terminal).
The problem is, when i read a documentation about selenium, it says that i don't need the browser installed at all on my computer to work with, he will use only the driver of the browser, but i was surprised that while executing my file in ubuntu, he returned to me an error saying that i don't have chrome installed ! which is contrary to the documentation, how can i fix that issue, cause i want to scrap without the need to the browser installed on my computer
Answer: While it is true that Selenium operates in a headless environment (meaning it does not require a graphical user interface), it still requires the browser binary (e.g., Chrome, Firefox) to be installed on your system. The headless mode allows Selenium to run the browser in the background without popping up a window.
+-------------------+   +-------------------+   +------------------------+
| Your Python Code  |-->| Selenium Package  |-->| Headless Browser       |
+-------------------+   +-------------------+   + (e.g., Chrome/Firefox) |
                                      ^         +------------------------+
                                      |
                                Requires Browser
                                 Binary to Run

Install the browser binary on your system, even though you are running it in headless mode.
sudo apt update
sudo apt install wget
wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
sudo apt install ./google-chrome-stable_current_amd64.deb

After installing Chrome, make sure your Selenium script is correctly configured to use Chrome in headless mode.  *
(Note: I assume Selenium 4+, using a Service object, and executable_path has been deprecated)
from selenium import webdriver
from selenium.webdriver.chrome.service import Service as ChromeService
from selenium.webdriver.chrome.options import Options

options = Options()
options.headless = True  # Enable headless mode

# Create a Service object, pointing to the path of chromedriver
service = ChromeService(executable_path='/path/to/chromedriver')

# Initialize the Chrome driver with the service and options
driver = webdriver.Chrome(service=service, options=options)

driver.get("https://www.facebook.com/marketplace")
# Your scraping logic here


How were atoms able to form after the big bang?

Question: How where atoms able to form after the big bang? From my understanding all the materials to form atoms were floating around and by random chance they collided and created atoms. If the universe was quickly expanding after the big bang, would the materials to form atoms be spread too thin. I am assuming that the materials would be spread very thin, since the universe was in existence for a long time before the first atoms were created.
Comment: you will find answers to all your questions in the excellent book by Stephen Weinberg, "The First Three Minutes".
Comment: Another, technical review is https://arxiv.org/abs/0809.0631
Answer: The thrust of your dilemma is that the universe would expand so much, that by the time particles cooled sufficiently for them to combine, the density would be so low that they would never interact?
That is demonstrably not the case, even without considering the clumping effects caused by gravity that later ensure that there are concentrations of matter; we know that we have atoms as well asw
galaxies, stars etc. The solution - at the epoch when the universe cooled sufficiently for protons to capture electrons, a typical electron could interact about $10^8$ times with a proton in the time it took the universe to expand significantly.
Details:
The average baryonic matter density in the universe today is about 0.2 atoms per cubic metre, most of which are hydrogen. The (re)combination of protons and electrons took place when the universe cooled to about 3000 K, at a redshift of about $z=1100$, when the density of the universe was larger by a factor of $(1+z)^3$. Thus the number density of protons and electrons was about $n \simeq 3\times 10^8$ m$^{-3}$ at that time.
Now let's say that an electron has to get within $10^{-10}$ m (about twice the Bohr radius) to interact with a proton. So the cross-sectional area for the interaction is $\sigma \simeq \pi \times 10^{-20}$ m$^2$.
The mean free path of an electron (we can consider the protons as stationary targets because they have similar kinetic energy but 1800 times the mass) is $1/n\sigma \simeq 10^{11}$ m.
This sounds a lot, but travelling at average speeds of $\sqrt{3k_B T/m_e} = 4\times 10^5$ m/s, the average electron will interact every $3\times 10^5$ s.
This is a tiny fraction of the 400,000 year age of the universe at the time of recombination, but more importantly, it is much smaller than the characteristic expansion timescale, which is given by $a/\dot{a}$, the reciprocal of the Hubble parameter at that time.
The Friedman equations tell us that the Hubble parameter was much larger back then. Assuming matter dominated the energy density (reasonably good at tis redshift)
$$H(z) \simeq H_0 \Omega_M^{1/2} (1+z)^{3/2},$$
where $H_0 \simeq 70$ km s$^{-1}$/Mpc is the current Hubble parameter and $\Omega_M\simeq 0.3$ is the present matter density of the universe expressed as a fraction of the critical density.
Thus at recombination $H(1100)\simeq 1.4\times 10^6$ km s$^{-1}$/Mpc and the expansion timescale $H(1100)^{-1} \simeq 2\times 10^{13}$ s. Thus the average electron can interact $\sim 10^8$ times with a proton before the universe expands significantly.
Answer: There is an important difference between the first atomic nuclei and the first atoms forming. Nucleosynthesis began when the temperature cooled enough that nuclei were not immediately disrupted by free-flying photons and nucleons, and ended when the temperature and density became too low to allow fusion processes (a few minutes after big bang).
At this point the temperature was still too high for atoms to form: any electron that ended up bound to a nucleus would nearly immediately be bumped away by a high-energy photon. The result was that the universe remained a plasma of free nuclei and electrons. It took until the era of recombination about 378,000 later for the temperature to become less than 3,000 Kelvin, when atoms could properly form. Since nuclei and electrons are oppositely charged they could easily find each other even at the recombination era densities.
If we assume everything is just hydrogen, and use $x$ to denote the free electron fraction (also equal to the fraction unbound protons) the Saha equation for the relative abundance equlibrium reads $$\frac{x^2}{1-x}=\frac{1}{n_H + n_p}\left ( \frac{m_e k_B T}{2\pi \hbar^2}\right) ^{3/2} e^{-\frac{E_I}{k_B T}}$$ where $m_e$ is the electron mass and $E_I=13.6$ eV the ionization energy of hydrogen. The temperature behaves as $T=2.728(1+z)$ K as a function of redshift and the density also conveniently behaves as $n_p+n_H = 1.6(1+z)^3$ per cubic meter. If you solve it for $x=1/2$ you get the time for recombination, $z\approx 1500$.
For the purpose of the question the interesting thing is that it doesn't matter how fast the redshift $z$ changes. In a universe that expanded slowly (a long period going from $z=2000$ to $z=1000$) the recombination would have proceeded just like a rapidly expanding universe - as long as the expansion was not so fast that there was no time to reach equilibrium.
How fast will we reach equilibrium? The mean free path of a particle will be $l\approx 1/\sqrt{2} n \sigma$ where $\sigma$ is the cross section. The mean speed in the Maxwell-Boltzmann distribution is $v=\sqrt{8k_BT/\pi m}$ so the mean time for a collision will be $\tau=l/v=\sqrt{\pi m/16kTn^2\sigma^2}$ The time Equilibrium will happen after every particle have had the time to collide a few times. So if we plug in $z=1500$ we get a density $n_p+n_H = 5\times 10^9$ per cubic meter and $T=4094$ K. $m\approx m_p = 1.67262\times 10^{-27}$ kg and $\sigma\approx 10^{-20}$ square meter. This gives $\tau \approx 1.524\times 10^6$ seconds (assuming my numbers and math are correct). About 17 days - way faster than the slow transition from plasma to atomic gas.
During nucleosynthesis this equilibration did not happen completely, partially because of the deuterium bottleneck that delayed everything. Had the process had time to continue long enough most hydrogen would have been burned into helium. Fortunately the expansion was fast enough back then to only produce some primordial helium.


Perspective Arc Text in Illustrator

Question: I'm attempting to create this perspective arc text in Illustrator, and having the darnedest time.
I tried creating a filled shape and applying an envelop distort with the curved shape, but that did some strange things with the text.
Any ideas?
Answer: Similar to Billy's answer... I'd use Envelope Distort (with warp, rather than mesh), to create the arch... then merely use the Free Transform Tool with it's perspective option to create the perspective...

.... then refine from there.
Answer: I think it would be quite difficult to get a good match if you were to try to do this with the whole block of text all in one go. It might be easier if you were to tackle each line of text individually. Anyway here's how I would do it.
Apply Object > Envelope Distort > Make with Mesh, set 1 row and 1 column.
Then distort it like this as shown below. Repeat for the other lines of text. I'm not saying this is easy. It's going to take a bit of experimentation and small tweaks.

It's hard to see the handles in the example above so I've circled them red. You need to be aware of where all the handles are located - not just the horizontal curve handles, but also those on the vertical sides. Adjusting these will help prevent weird letter distortion.
Answer: I guess it's drawn manually by an artist who knows what he does. Making something resembling with 2D-effects in Illustrator is possible as user Billy Kerr has already shown in an earlier answer.
The bottom line "CHAMPIONS" is tricky. It has apparent curvature to two directions. The already shown method works well for the main perspective, but the 2nd curvature can be helped substantially by dividing the job to 2 phases:

In the top line the text is made to shrink vertically towards right by inserting envelope distortion with the shown 4-gon which is used as the "top object"
The already shown envelope distort with 1 x 1 mesh makes the rest.
If you are not going to copy your example, but need a way to get plausible perspective you can use Illustrator's 3D effects. Making the text along curve can be done with the Type on Path -tool. Mode "skew" instead of the usual "rainbow" keeps letters vertical:

The curve has 2 nodes. It's drawn with the Pen.
3D effect Rotate shows it with perspective. The 3D rotation keeps the shape planar (=no 2nd curvature):

Bevel and Extrude -effect can also give the thickness, but that's another story.
Not asked: If you apply Object > Expand Appearance, Release Clipping Mask and Ungroup to the 3D-effected objects they are again editable plane objects. Complex objects may need several ungroupings.

Perspective Arc Text in Illustrator


Apple ID Password requirements

Question: As you know, the Apple ID Password must meet some minimum requirements, such as having at least one lower case letter, one capital letter, one number, etc.
So, how come sometimes I see a customer putting in a password just 4 characters long?
I am thinking probably if it is a very old password, never changed before, it can be still used as a valid Apple ID Password? Or what?
Answer: There are two types of passwords, the device passcode and the appleid password.
The device passcode gives you access to unlock the device, and it can be as short as a 4 digit PIN.
The AppleID password must be 9 (I think. It's either says "8" or "more than 8") or more characters long, contain at least one capital, one lowercase, and use at least one number or special character.
Answer: It's most likely the case that they have a very old Apple ID and haven't changed their passwords since creating their account. I don't know if Apple had lower password requirements in the early days of iTunes/Apple ID, right now they require 8 character passwords as a minimum it seems.

Apple ID Password requirements


Why and how do Advaitans reconcile that one's true nature is Atman/Brahman alone?

Question: While I understand that Upanishads try to reconcile and prove logically that Atman is the true witness, why can't it be that Subtle body alone is our true nature ?  Where and when was this subtle body created first and what happens to it after one realises his true nature as Atman? Why does Atman produce or project multiple Subtle bodies???
Answer: Why can't it be that Subtle body alone is our true nature ?
The subtle body can't be our true nature because it perishes after moksha. A Jiva is eternal.

Never was there a time when I did not exist, nor you, nor these rulers
of men. Nor shall all of us cease to be hereafter.

Gita 2.12
Self is also eternal.

Know that Reality, by which everything is pervaded, to be
indestructible. No one can cause the destruction of this immutable
being.

Gita 2.17

He who thinks him (the Self) to be the killer, and who experiences him
(the Self) as the killed – both of them know not. He (the Self)
neither kills nor is killed.

Gita 2.19

He (this Self) has neither birth nor death. Nor does he cease to be,
having been in existence before; unborn, eternal, permanent and
primeval, he is never killed when the body is killed.

Gita 2.20

O Arjuna! Know this self to be eternal, undecaying, birthless and
indestructible. A person who knows him to be so – how and whom can he
kill, how and whom can he cause to be killed?

Gita 2.21
Since both Jiva and Self are eternal then it naturally follows that the Self is the real nature of Jiva.
Where and when was this subtle body created first and what happens to it after one realizes his true nature as Atman?
There is no first creation. Subtle bodies are periodically manifested (together with the universe) and periodically de-manifested.
The subtle body perishes after moksha.
Abandoning of subtle body after moksha

The river Viraja, forms the eighth enclosure. It flows in between the
spaces of ether. It spreads over five yojanas all round. It is the
most sacred river that wards of rebirth. O bird, those who bathe
herein go to Brahmaloka where they rejoice with the four-faced Brahma.
Those who take the bath in the Viraja river abandon their subtle
bodies and attain liberation. Those alone who have realized the Self
and abide in Brahman can cross the Viraja river.

Garuda Purana, Brahma (Moksha) Khanda, Chapter X
Why does Atman produce or project multiple Subtle bodies???
It is not possible to answer this question. At most one can say is that the Atman sportingly projects the subtle bodies.
On Lila

The Supreme Spirit, being approached (at His behest) by His own subtle
Divine Power (Prakrti, Universal Nature), constituted of the three
Gunas (Dispositions called Sattva, Rajas and Tamas), looked at her
sportively, as it were, and thereby endowed her with the power of
world evolution by impregnating her with his own emanation as the Jiva
or the individual spirit.

Srimad Bhagavata Purana III.26.4
There is also a verse in Brahma Sutra that talks of the universe as the pastime of Brahman.

But (creation for Brahman is) a mere pastime like what is seen in the
world.

Brahma Sutra II.1.33 of Sri Sankaracharya translated by Swami Gambhirananda
Comment: Great answer. But you have said subtle bodies are periodically manifested which may lead some people to believe they have been created out of nothing and new souls are created as a sport. But subtle bodies are created on top of preexisting causal body or Karana Shareera which is Anadi. So the soul which is actually the causal body got expanded into subtle body. No new souls can be created. The Vaishamya Nairgrunya Adhikarana of Brahma Sutras make it clear. The cause of converting causal into subtle is considered leela out of karuna.
Comment: @Sri Hari Kumar - your comment is very illuminating.


Why is Kerr Spacetime unstable?

Question: How do we know from the Kerr Metric that it is unstable near the Cauchy Horizon? What causes this unstability?
Comment: I assume you're referring to the **mass inflation instability**, as described in Poisson (1990), [A look inside black holes](http://adsabs.harvard.edu/full/1990JRASC..84..191P). That paper isn't specifically about rotating black holes, but it says "These features are very general and do not depen on our specialized, spherical model; our conclusions should then be valid for the case of an uncharged and rotating black hole."
Comment: I think that is an open question.
Comment: It may not be unstable see recent paper cited here https://www.wired.com/story/at-long-last-mathematical-proof-that-black-holes-are-stable/
Answer: That is a very good question. I will give you a rough argument of why we believe this to be true based on Bob and Alice. You can find a more detailed discussion at e.g. https://www.jstor.org/stable/79484.
Imagine Bob and Alice start together at $i$. Now, Bob has suicidical tendencies and decides to jump into a Kerr black hole, whereas Alice is more stable and decides to drift away to timelike infinity ($i^+$). In the penrose diagram below we represent the path of Bob with green and Alice by red.

Now, Alice decides to periodically send light signals to Bob (blue lines below). Alice lives forever as you need infinite proper time to reach $i^ +$, however Bob quickly reaches the Cauchy horizon $\mathcal{CH}^ +_R$. Nevertheless, as we can see in the picture, the light signals from Alice will all eventually reach Bob. Although Alice sends them at a fixed frequency, to receive infinite signals in a finite proper time, Bob will receive signals with an increasing frequency, that goes to infinity right before the Cauchy horizon. We call this an infinite blue-shift. In rough terms, this blue-shift translates to a spacetime instability at the Cauchy horizon, so although Kerr possesses a Cauchy horizon, we expect generic small perturbations to blow up at the interior horizon.
Further question for the reader, why does this argument fail for asymptotically de-Sitter spacetimes? In fact, recent research showed that the Cauchy horizon of near-extremal Reissner–Nordström de-Sitter is stable with respect to generic perturbations.
Comment: So what eventually happens? What does this instability cause?
Comment: The Cauchy horizon becomes a null singularity
Comment: Is this an assumption or are there analytical calculations or numetical simulations showing this?

Why is Kerr Spacetime unstable?


Why does plasmon have higher energy than phonon?

Question: In my mind plasmon is movement of electrons and phonon is movement of atoms in an lattice. movement of atoms should have a large energy because atom is larger.
Answer: Fundamentally the plasmon is at higher energy because electrons weigh much less that atoms. In fact phonons are simply plasmons of the atoms.
One can see this from the classical formula for the plasma frequency.
$$\omega = \sqrt{\frac{4\pi n q^2}{m}}$$
Assuming you have an equal concentration of free electrons and atoms, $n$ will be the same for the atom and electron plasma frequencies. However,  the nuclei have masses that are usually $10^4$ to $10^5$ times larger than the electron,  which translates to a frequencies that are over 100 times smaller for phonons compared to electrons. This is consistent with experiments seeing phonons with milli-electronvolt energies and plasmons with electronvolt energies.
Comment: What do you mean by plasmon is at higher energy? Phonons have much higher energies.
Comment: @ÁrpádSzendrei I don't understand what you are talking about. Phonons have energies on the order of milli-electronvolts, while plasmons have energies on the order of electronvolts. See the phonons of Aluminum here: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.77.024301 and the plasmon of Aluminum here https://www.sciencedirect.com/science/article/pii/B9780125444156500169
Comment: Isn't that million eV?
Comment: I think you are mistaking MeV and meV. The former is the energy scale of nuclear reactions, while the latter is energy scale of vibrations of solids. Huge difference
Answer: The phonon describes the vibrational motion in a solid.
The plasmon is a quasi particle, describing the plasma oscillation.
These quantized excitations have different energy levels, phonons in the meV range, and plasmon in the eV.
As you write you are wrong, because phonons energy is 3 orders of magnitude higher.
The difference is because phonons are collective excitations of atoms in lattice. Plasmons are collective excitations of nearly free electrons in plasma.
Phonons are important in conservation of energy, plasmon gives the color of gold.
http://iopscience.iop.org/article/10.1088/0368-3281/2/1/305
Answer: Like it's said Plasmons describe collective oscillations of charge carriers. One can derive that the energy is given by (with $n$ the charge density, $\varepsilon$ vacuum dielectric constant):
\begin{equation}
E_{p}=\hbar \cdot \omega_{p}=\hbar \sqrt{\frac{ne^{2}}{m\varepsilon} }
\end{equation}
Now you can compare it to the energy of a phonon (with $n_B$ being the Bose statistic):
$$\varepsilon _{n}({\mathbf  {k}})=\hbar \cdot \omega ({\mathbf  k})\cdot \left(n_B+{\frac  {1}{2}}\right),$$
but here you have to distinguish between optical and acoustical modes (see e.g. Kittel "Solid State Physics"). You can basically excite optical phonons (which have an higher energy than the acoustical ones) with inelastic neutron scattering.
To make a long comment short, I would suggest you can put in some numbers, but you can also argue I want to excite with same frequency (same $\omega$). Then still the Phonons have higher energy, because the Bose statistic gives you very large values for small energies. All in all the Phonons have more energy then the Plasmons.


XAMPP - Apache could not start - Attempting to start Apache service

Question: While trying to start Apache using XAMPP, I was receiving  - "Attempting to start Apache service..." message in XAMPP UI. No further details were available.
Where can I see the logs (I was running XAMPP as Admin) ?
Comment: In my case i found out that Skype was using the same port. Simply shutdown skype and it works. If ya open Xampp as admin and try to run again then it will provide you with the information of which program is occupying the port. If any at all that is.
Answer: IF PORT 80 IS NOT THE ISSUE!
Check to see if the port 80 is in use first as this can be an issue.
You can do this by typing "netstat -an" into cmd. The look for 0.0.0.0:80 under Local Address, if you find this is in use then follow the solution from @Karthik. However, I had a similar issue but my port 80 was not in use.
My XAMPP had wrong paths locations, steps to fix this:
1.Find out the Apache version you are using, you can find this by looking in Services (Control panel, Admin Tools, Services) and finding Apache in my case it was listed as Apache2.4
2.Close XAMPP.
3.Run cmd as admin.
4.execute 'sc delete "Apache2.4"' (put your version in place of mine and without the surrounding ' ', but with the " " around Apache).
5.execute 'sc delete "mySQL"', again remove the '' when you type it.
6.reopen XAMPP and try starting Apache
If you are having trouble with FileZill, Mercury, or Tomcat you could try it here too, but I have not tested that myself.
Hope this helps!
Comment: There is a _netstat_ button on the right side of xampp control window as well if you wanted
Answer: I realized it was a port issue since I was running IIS and other web servers in my machine. But I was more interested to see a detailed error message with the port number in the UI.
Seems like it was not logged in the UI or log file (at least in my case), but in the Event viewer (Control panel -> View Event Logs). Under the Even viewer -> Windows Logs -> Application
I could see a permission error something like the below one:

An attempt was made to access a socket in a way forbidden by its access permissions.  : AH00072: make_sock: could not bind to address 0.0.0.0:443

To fix this permission issue for SSL port, Please change the below line in httpd-ssl.conf (C:\xampp\apache\conf\extra)
 # When we also provide SSL we have to listen to the
 standard HTTP port (see above) and to the HTTPS port

     Listen xxx

Replace XXX with any valid port number that is open in your machine
If you are having issues with Port 80, then change the httpd.conf file (C:\xampp\apache\conf)
# Change this to Listen on specific IP addresses as shown below to
# prevent Apache from glomming onto all bound IP addresses.
#
#Listen 22.214.171.124:80
 Listen 127.0.0.1:8000

I have also summarized other solutions that I came across:

Most often Skype blocks the Apache port. So terminate it and try again.
Find the process id (PID) that is using the Blocked port ( netstat -ano) and kill the corresponding process in Windows Task Manager.
Comment: +1 for sharing the path in the event viewer (Even viewer -> Windows Logs -> Application) I wouldn't find it myself and helped me solve the issue.
Comment: Keep in mind that it's good practice to also change the line lower in httpd-ssl.conf `www.example.com:80` (replace 80 with the port you are using for httpd)
Comment: You can find the **Event Viewer** easier by typing **`eventvwr`** in the Command Prompt.
Answer: For those who have accidentally (or not) changed one of the .conf files and apache does not run even after trying all the above solutions.
One easy way to track where the issue is located, is to run Apache via command prompt:
(On windows) : open command prompt as admin then navigate inside the bin folder of Apache , next run
httpd in order to run apache

C:\xampp\apache\bin\httpd

For my case it was :

someone had added a virtual host in the specific file that caused the problem . I commented the lines and Apache ran fine.
Comment: httpd -t will check your config files for any syntax errors. this can be quite usefule
Answer: start xampp (as administrator),
(1) right click C:\xampp\xampp-control.exe, and run as administrator.
(2) unistall service module and then install service module.
(3) now try start the apache and mysql.
Answer: Check your DocumentRoot path (in httpd.conf); a typo there can cause this problem.
Answer: Had the same issue while updating to PHP7.2
Problem:
First I closed skype and then checked whether port 80 is not an issue. How you can check that? See @AlexT comment above.
In my case, port 80 wasn't an issue. So now I had to figure out what was wrong. So I checked Error Logs Control Panel > Even viewer > Windows Logs > Application and found following error against Apache2.4

httpd.exe: Syntax error on line 520 of C:/xampp/apache/conf/httpd.conf: Syntax error on line 18 of C:/xampp/apache/conf/extra/httpd-xampp.conf: Cannot load C:/xampp/php/php7ts.dll into server: The Apache service named is not a valid Win32 application.

Which means I had installed wrong PHP version. Actually I downloaded win64 version while the required version was Win32 for me.
So I downloaded correct version from: Download PHP 7.2.0 extracted it in C:/xampp/php folder, restarted the apache and it worked :)
Comment: This helped me. I had done the same thing. You'd think it would be written somewhere.
Answer: I had the same problem but it was because I had a previous version of xampp already installed and I tried to install a newer version. I had installed the newer version in another file directory (I had named the file directory xampp2). I solved the problem by uninstalling the newer version, renaming the old one (I renamed it xamppold) and I installed xampp again.
I guess if you haven't installed   xampp in another file directory , it should be enough to reinstall xampp. If you are worried about your files , you always can make a backup before reinstalling xampp.
I solved the problem after watching the xampp activity log (the list of the bottom) and realizing xampp was trying to open the custom file path but I had another route path. If the first option didn't work, at least you can scroll up in the activity log and see what's error you get while starting as admin and trying to re install the Apache module or trying to start the module.
You may wander why I didn't just simply uninstall the whole thing from the beginning , and the answer would be because I had to tweak a couple of things in xampp for some different projects (from changing the ports , to add .dll to run mongo.db in Apache), and I was just too lazy to re-do everything again :b
I hope my answer can be helpful for anyone since this is my first time writing in stackoverflow :)
Cheers
Answer: I had the same issue, executing "setup_xampp.bat" in xampp folder solved my issue.
Comment: Thank you mate. this works for me. i had no config and port issue. I tried it as a last resort your answer. This saved me from reinstalling the whole windows. since i changed my pc HD to another pc and this was the issue. you are a savior !
Answer: In my case, with the same problem and Xampp window, I had copied \apache\conf\extra\httpd-vhosts.conf entries from an old Xampp version to a newly installed one so I could continue to open local projects in browsers. One of the vhosts paths was wrong. After deleting that entry Apache started without problem.
The reference by @Karthik to "in the Event viewer (Control panel -> View Event Logs" saved me time. It's all too easy to presume Xampp logs will point to the problem. It doesn't.
Answer: Also check if your xampp is installed in the main directory like C or D or E and not in or within a folder of that directory? i.e. ( "D:/Xampp" or is it "D:/something/Xampp") if its not in the main path of the directory, it will show this error.
copy your xampp directory from "D:\Something\Xampp"  to  "D:"
So it becomes like this "D:\Xampp"
and the issue will be resolved.
Answer: There are several reason.

443 port or 80 port are used in another application.
For example, VM is using 443.
If you use VM, please change xampp 443 port to another port in httpd-ssl.conf file.
documentroot
if there is not index.php or index.html in DocuementRoot, Xampp does not work.
You can search and change DocumentRoot in httpd.conf file.
This is my experience.
Hope this help you.
Answer: Starting Xampp as a console application (simply by doubleclicking xampp_start.exe in the Xampp root folder) was the only thing that worked for me on Windows 10 (no Skype, no Word Wide Web Publishing Service). WampServer and UwAmp also didn't work.
Answer: My scenario was different after I tested all the possible options. If you have changed the ports and still get the same problem, well here's something you can try out. This was done in Windows 7.
Step 1: Confirm the cause of the error by going to Control Panel -> System and Security -> Administrative Tools -> Event Viewer -> Windows Logs -> Application -> Error. Mine said "The Apache service named  reported the following error:

httpd.exe: Syntax error on line 424 of C:/xampp/apache/conf/httpd.conf: Cannot load c:\xampp\php\php5apache.dll into server: The specified module could not be found." So I needed to change \php5apache.dll to the version of my php and apache version installed which was php7apache2_4.dll

Step 2: To get the correct name for your .dll php and apache file, got to C:\xampp\php. You will see something like php7apache2_4.dll with other files in the folder.
Step 3: Go to C:/xampp/apache/conf/httpd.conf and edit the configuration file and change "c:\xampp\php\php5apache.dll" to "c:\xampp\php\php7apache2_4.dll" in my case. Make sure you open the file as administrator save changes made.
Step 4: Run the xampp server and everything should work fine. Do not forget to shut down the xampp server before doing the changes to the apache configuration file.
Hope this helps. Cheers! :)
Answer: I had a hard-coded IP in httpd.conf and my local IP had changed which was causing my issue, changed IP over and all worked again
Answer: Try to install x86 version of XAMPP. The default XAMPP version on their website is x64 (maybe because I'm using x64 Windows 7).
download link here
Answer: I had this issue when I installed under Program Files, which they do not recommend due to write issues. This might only be a problem if you are not logged in as an admin and use a password to install. I just uninstalled and installed in a directory that did not need admin privileges.
Answer: Make sure Apache didn't get Disabled in Services (Control panel, Admin Tools, Services).  If it's Disabled then Set it to Manual and it should run.  That was my case, I found Apache Disabled.
Answer: Solution for my particular scenario (It had been working a couple days before getting borked):
Port 80 was not the problem, but something I had done while messing around with Services and Startup.

Type msconfig on Windows' Start menu
Click System Configuration

Screenshot for System Configuration

In the Services tab, search for Apache24 (Click "Hide all Microsoft services" in the checkbox at the bottom of the window to make it easier to find)
If its checkbox isn't checked, check it

If it was already checked, then this guide isn't going to help. However if it is:

Click OK, your PC will have to restart
Try once again! In my case Apache was already running once I opened Xampp
Answer: I had the same issue.Just click on services button.Then find apache and right cick > properties > set startup type as Automatic/ Manual. Now close apache and try again.It will work!
Answer: For me it wasn't a port or service issue; I had to re-run the XAMPP setup script. Although this didn't directly fix the issue for me, the script was much more verbose than the XAMPP log, pointing me in the right direction to actually solve the problem.
From the XAMPP GUI, click on Shell, type set, press Tab to autocomplete to the setup_xampp.bat file, and then press Enter to run it.
In my case I got the following output:
[ERROR]: Test php.exe failed !!!
[ERROR]: Perhaps the Microsoft C++ 2008 runtime package is not installed.
[ERROR]: Please try to install the MS VC++ 2008 Redistributable Package from the Mircrosoft page first
[ERROR]: http://www.microsoft.com/en-us/download/details.aspx?id=5582

This particular error is misleading. Although it specifies the Visual C++ 2008 Redistributable Package, PHP 7.4.x requires the Visual C++ 2019 Redistributable Package.
After installing that and following the prompt to restart, sure enough I'm now able to start Apache as normal.
Answer: make sure no space in front of the port number if you ever edited it.
Answer: From Xampp control panel, click on config (next to Apache), then choose Apache(httpd.config), search for listen 80 and change the port to another port.
Answer: If nothing works with you, I would suggest you download MAMP and use it instead.
It does the same thing, if not better.
Answer: Comment this lines from httpd.conf:
# Virtual hosts
#Include etc/extra/httpd-vhosts.conf

In the case you're using them it may solve.
Answer: A nice way to debug Apache errors by running the command line,
on windows, click on shell then type httpd
Answer: when i run xampp control panel normal:

I had been run
I can't start apache
So, I will run it with administrator:

I can run apache


UINavigationController isn't pushing/displaying view

Question: New to iOS and objective C. Trouble with custom UINavigationController while developing an iPad app in XCode simulator. Appreciate your help greatly !

Created project (view based application) in XCode. Application currently has two views. Home Page and a Detail View. Want a Home Page like Facebook or Linkedin iPhone App Home page...where you have bunch of icons/images on the home page, and click on each to get more details
(With limited knowledge) concluded Home page can't be TableView, SplitView or TabBarView. Don't want any tabs or table view style in Home page (as explained above). So couldn't start XCode project with "Navigation Based Application" template
Didn't add UI elements from IB to MainWindow.xib, rathar homepage UI elements are in the otherView.xib created by the project template. The project template, assigns rootViewController to otherViewController within appDelegate.didFinishLaunchingWithOptions method. self.window.rootViewController = otherViewController.
Added a NavigationController through IB to otherView.xib. Added outlet for navigationController. otherView.h has following
UINavigationController *navigationController;
@property (nonatomic, retain) IBOutlet UINavigationController *navigationController;
referencingOutlet for navigationController is connected to File's Owner
When App is launched Home Page (served by otherViewController) comes up. When clicking on an icon in Homepage (an ImageView with Button behind), Detail View doesn't show up, if I call
[self.navigationController pushViewController:DetailViewController animated:YES];
(within the action method, that's handling touchUpInside for that button.)

but detail view shows up if I do either
self.view = DetailViewController.view;
or
[self.view addSubview:DetailViewController.view];
So doesn't seem to be a problem with DetailView loading it's nibfile etc.
No problem also in button click/touch event capture etc.
A. When I examine the navigationcontroller in the debugger, it has both the two viewControllers in its stack, with rootView/ Home page at index 0, and Detail View at index 1. navigationController is not null. Any ideas on what am I missing ?
B. Do I need to add a navigationBar to both the home page (in whose view navigation controller is added) and the detail view ? I have added a navigationBar to the detail view. I don't need a navigation bar in the home page UI.
C. When the detail view shows up through the addSubview call or self.view assignment (as mentioned above), the navigationBar doesn't show the back button (which should say "Home").
Both view Controller is setting appropriate title , using self.Title = "Home" or "Detail".
Appreciate your help. Thanks
Answer: In the appDelegate, you need to make navigation controller a property and then write:
self.window.rootViewController = self.navigationController;

in application didFinishLaunchingWithOptions: method.
Then push otherViewController onto its stack. I think the mistake you're making is adding UINavigationController to UIView instead of the other way around, which is the correct way!
Answer: what you should do too in your xib file,
make sur that you view is in a navigationcontroller
the tree of your xib file should like this :

your appdelegate
window
navigation Controller
navigation bar
and your rootviewcontroller


Setting up Ubuntu-Server with intel GPU for custom resolution

Question: Short Version:
How can I disable the DisplayPort and display-cloning completely and only use VGA with a custom resolution of 1920x240 (15KHz) on a CRT. Might involve the creation of a custom xorg.conf

Long Version:
I'm struggeling with a RetroPie installation in Ubuntu Server that I'd like to use on a SONY PVM 15KHz CRT monitor.
As soon as RetroArch kicks in everything is fine, games are displayed via CRTswitchRes-function and look awesome on the screen - just the linux environment gives me a hard time.
I chose to use so called "Super Resolutions" which are super-wide (e.g. 1920x240) and look correct when fed to the CRT. In order to be able to navigate the frontend, the console has to be set to something similar and there are some pitfalls which I'd like to work out.
First things first, this is the hardware I'm using:
HP Compaq Elite 8000 Ultra Small Desktop
email@example.com, 8GB DDR3, intel GMA 4500
DisplayPort (to Samsung Monitor), VGA (to CRT with custom cable)
The main problem seems to be, that Xorg cannot do anything, because the CRT doesn't give any infos via EDID. Also I've read that with intel you must not use display-cloning, otherwise the system always uses resolutions that both monitors are capable of.
In short: xrandr output is always:
Can't open display
The Version of Ubuntu doesn't really matter, I tried 14, 16 and 18 LTS with the same results: RetroArch works, console doesn't. I don't want to switch to Ubuntu-Desktop because I'd like this to be as slick as possible.
Right now I'm trying to work with 18.10 LTS.
So, regardless of RetroPie, I tried my best to get the desired resolution:

created an EDID binary and referenced it in /etc/default/grub
tried many different parameters in grub file
patched the kernel with this: https://github.com/TiBeN/15khz-arcade-pkg/blob/master/doc/15khz-package-documentation.md
installed intel drivers xf86-video-intel and xserver-xorg-video-intel but both gave me performance issues in RetroPie.
Since auto-creation of a xorg.conf fails I tried to make my own, but the frontend won't even boot because I just don't know what to put in there.

Some system information that I collected:
<code>hwinfo --gfxcard

07: PCI 02.0: 0300 VGA compatible controller (VGA)
  [Created at pci.366]
  Unique ID: _Znp.QUyWiVSQCGD
  SysFS ID: /devices/pci0000:00/0000:00:02.0
  SysFS BusID: 0000:00:02.0
  Hardware Class: graphics card
  Model: "Intel 4 Series Chipset Integrated Graphics Controller"
  Vendor: pci 0x8086 "Intel Corporation"
  Device: pci 0x2e12 "4 Series Chipset Integrated Graphics Controller"
  SubVendor: pci 0x103c "Hewlett-Packard Company"
  SubDevice: pci 0x3648
  Revision: 0x03
  Driver: "i915"
  Driver Modules: "drm"
  Memory Range: 0xf0000000-0xf03fffff (rw,non-prefetchable)
  Memory Range: 0xe0000000-0xefffffff (ro,non-prefetchable)
  I/O Ports: 0x1230-0x1237 (rw)
  IRQ: 31 (33735 events)
  I/O Ports: 0x3c0-0x3df (rw)
  Module Alias: "pci:v00008086d00002E12sv0000103Csd00003648bc03sc00i00"
  Driver Info #0:
    Driver Status: i915 is active
    Driver Activation Cmd: "modprobe i915"
  Config Status: cfg=new, avail=yes, need=no, active=unknown

08: PCI 02.1: 0380 Display controller
  [Created at pci.366]
  Unique ID: ruGf.xwJ9cLl4Ut2
  SysFS ID: /devices/pci0000:00/0000:00:02.1
  SysFS BusID: 0000:00:02.1
  Hardware Class: graphics card
  Model: "Intel 4 Series Chipset Integrated Graphics Controller"
  Vendor: pci 0x8086 "Intel Corporation"
  Device: pci 0x2e13 "4 Series Chipset Integrated Graphics Controller"
  SubVendor: pci 0x103c "Hewlett-Packard Company"
  SubDevice: pci 0x3648
  Revision: 0x03
  Memory Range: 0xf0400000-0xf04fffff (rw,non-prefetchable,disabled)
  Module Alias: "pci:v00008086d00002E13sv0000103Csd00003648bc03sc80i00"
  Config Status: cfg=new, avail=yes, need=no, active=unknown

Primary display adapter: #7

++++++++++++++++++++++++++++++++++++++++++++++++++++++

hwinfo --monitor

20: None 00.0: 10002 LCD Monitor
  [Created at monitor.125]
  Unique ID: rdCR.k6CV94ujG82
  Parent ID: _Znp.QUyWiVSQCGD
  Hardware Class: monitor
  Model: "SAMSUNG SyncMaster"
  Vendor: SAM "SAMSUNG"
  Device: eisa 0x01ae "SyncMaster"
  Serial ID: "HS3P601288"
  Resolution: 720x400@70Hz
  Resolution: 640x480@60Hz
  Resolution: 640x480@67Hz
  Resolution: 640x480@72Hz
  Resolution: 640x480@75Hz
  Resolution: 800x600@56Hz
  Resolution: 800x600@60Hz
  Resolution: 800x600@72Hz
  Resolution: 800x600@75Hz
  Resolution: 832x624@75Hz
  Resolution: 1024x768@60Hz
  Resolution: 1024x768@70Hz
  Resolution: 1024x768@75Hz
  Resolution: 1280x1024@75Hz
  Resolution: 1600x1200@60Hz
  Resolution: 1280x1024@60Hz
  Resolution: 1280x960@60Hz
  Resolution: 1152x864@75Hz
  Size: 408x306 mm
  Year of Manufacture: 2007
  Week of Manufacture: 24
  Detailed Timings #0:
     Resolution: 1600x1200
     Horizontal: 1600 1664 1856 2160 (+64 +256 +560) +hsync
       Vertical: 1200 1201 1204 1250 (+1 +4 +50) +vsync
    Frequencies: 162.00 MHz, 75.00 kHz, 60.00 Hz
  Driver Info #0:
    Max. Resolution: 1600x1200
    Vert. Sync Range: 56-75 Hz
    Hor. Sync Range: 30-81 kHz
    Bandwidth: 162 MHz
  Config Status: cfg=new, avail=yes, need=no, active=unknown
  Attached to: #2 (VGA compatible controller)

++++++++++++++++++++++++++++++++++++++++++++++++++++++

lspci | grep VGA

00:02.0 VGA compatible controller: Intel Corporation 4 Series Chipset Integrated Graphics Controller (rev 03)

++++++++++++++++++++++++++++++++++++++++++++++++++++++

glxgears -info

Error: couldn't open display (null)

++++++++++++++++++++++++++++++++++++++++++++++++++++++

xrandr

Can't open display

++++++++++++++++++++++++++++++++++++++++++++++++++++++

ls /sys/class/drm/

card0  card0-DP-1  card0-HDMI-A-1  card0-VGA-1  controlD64  renderD128  version

++++++++++++++++++++++++++++++++++++++++++++++++++++++

/etc/default/grub

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=saved
GRUB_SAVEDEFAULT=true
#GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=0
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
#GRUB_CMDLINE_LINUX_DEFAULT="gfxpayload=640x480x16,640x480 video=card0-VGA-1:640x480@60ec"
GRUB_CMDLINE_LINUX_DEFAULT="video=card0-VGA-1:640x240ec drm_kms_helper.edid_firmware=card0-VGA-1:/lib/f$
GRUB_CMDLINE_LINUX="quiet splash consoleblank=0 video=card0-VGA-1:640x240ec drm_kms_helper.edid_firmwar$

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
GRUB_GFXMODE="640x240x32 ; 640x240x24 ; 640x240x16"
GRUB_GFXPAYLOAD="640x240x32 ; 640x240x24 ; 640x240x16"

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"

++++++++++++++++++++++++++++++++++++++++++++++++++++++

</code>
Picture of the set
Everything works as soon as RetroArch kicks in
1920x240 looks perfect on the CRT
Answer: I wasn't aware that if I trigger xrandr over SSH the "Can't open display" message was the expected output. I got it sorted out and was able to create a modeline that works for my needs.


Attach rim joist to post supporting roof

Question: I am going to build a small deck for a front porch to replace a concrete slab. The slab had a column that held up a post going to the roof above.
If I replace the slab with a deck, the corner post needs to go through the deck to support the roof overhang of the house above it. What are my options for accomplishing this? Should I have a post go all the way from a footer to the roof and then attach my deck to it somehow? What are the choices? Notching? What about making my footer come up high enough so that the rim joists of the deck can rest on it?  Another alternative might be to pour or build a column of concrete (with brick or stone on it) and then attach the deck to that somehow.
The picture shows the old column that I tore out. There is a temporary support in place now. The old column was hollow, made from 1x lumber. Should I go back with a solid 6x6 post?. That seems overkill, not to mention how heavy it would be to lift it up there.
Thanks for any and all ideas.
Answer: It is mostly a style and preference choice.  The original half inch lumber post is probably not structural, though it could well have been a cheap replacement for one which was more substantial.  From what I can see of the eves, a 4x4 or 6x6 post is appropriate.  Some jurisdictions require heavier columns beyond a certain length, usually about 10 feet.  Raising a 6x6 post is not that hard with a helper or two, or straightforward solo job with block and tackle attached to the temporary support.
A properly designed and built deck should have no trouble supporting a post.  You could build the deck with an equivalent support which is not in the way:  slanted support, temporary horizontal truss, etc.
If you like the look of a stone or concrete base, it should not rest on the deck.  Build it into the ground (depth as required for freezing conditions in your climate) and finish the column on top of it.  Build the deck around the column—it does not need to be tied together and it is probably better there be a small gap (1 inch?) to allow for independent settling.
You could also support the roof with a 45° to 60° post fastened to the side of the house.


RX and TX pins on esp32

Question: hello guys i'm new to this field i really need your help i want to wire a GSM module (SIM808) to a ESP32 board using the TX and RX pins so the pins are labeled RX and TX no pin number like the others how can i declare them in the code.
i already tested the code on an arduino uno on pins 0 and 1 (RX and TX) and it works fine here is the board i'm using :
i already tried using pins 16 and 17 but didn't work i need to try using pins number 40 and 41 according to image below
Comment: "Didn't work" is not very descriptive. Please show your code and how you have connected the module. It may be good to known that the ESP32 has a very flexible serial port configuration and serial I/O can be mapped to most of the GPIO pins.
Comment: Tx and Rx is used by Serial port for your Serial Monitor. Unlike Arduino Uno, which only has one Serial port, ESP32 has 3. You can use the TxD2 (GPIO17) and RxD2(GPIO16) for connecting to your SIM808 module. You uses the port with `Serial2.begin(115200)`.
Answer: First off, thank you for all the guidance and support you've provided. As a beginner in the world of Arduino and embedded systems, it's been tremendously helpful.
The main issue I was facing had to do with not knowing how to declare the TX and RX pins in my C++ code, especially when these pins weren't labelled with their GPIO numbers like the others on my ESP32 board. After a bit of research and reading through your comments, I learned that these pins can simply be declared using their GPIO numbers, which are indicated on the schematic of the board.
For instance, to utilize RX0 and TX0, they need to be declared as 3 and 1 respectively. Here's an example:
<code> #define RXD 3  //RXD
    #define TXD 1  //TXD

    HardwareSerial SIM808(2);

void setup()
{
  //
  //
   SIM808.begin(9600, SERIAL_8N1, RXD, TXD);
}
</code>
I was able to get the SIM808 module working with this method, but I'm noticing that the system isn't always consistent. Sometimes it takes a long time to execute commands, which is something I will have to look into.
I just wanted to express my gratitude for the warm welcome and helpful guidance I've received here. This being my first post, I was worried about asking a "dumb question," but the community has been nothing but supportive.
As I continue to learn and explore more about embedded systems, I'm sure I'll be back with more questions, and hopefully, in time, some answers of my own to contribute!
Comment: this is a very bad advice. You want to use SoftwareSerial on hardware Serial pins? and this hardware Serial is already wired to the USB chip which communicates with the computer. You can use Serial2 on RX2/TX2 pins. Serail2 already exists as an object and is initialized for the pins. (as already mentioned in the comment below the Q)
Comment: Don't use SoftwareSerial on a device that has enough hardware serial ports to do the job.
Comment: can you provide more information about SoftwareSerial and HardwareSerial to help me better understand and also i'm running out of pins in my project is there any solution to reduce the number of pins or use the same pins for multiple purposes?
Comment: Hach Rbh, https://en.wikipedia.org/wiki/Bit_banging

RX and TX pins on esp32


web traffic capacity of the SharePoint

Question: how we can find out the web traffic capacity of the SharePoint farm by using a Microsoft Visual Studio Team System project file?
Answer: check out this link:
https://technet.microsoft.com/en-us/library/ff758659.aspx
After the test environment is functional, it is time to create and fine-tune the tests that will be used to measure the performance capacity of the farm. This section will at times make references specifically to Visual Studio Team System (Team Test Load Agent), but many of the concepts are applicable irrespective of which load test tool you use.
You can also use the SharePoint Load Test Kit (LTK) in conjunction with VSTS for load testing of SharePoint

web traffic capacity of the SharePoint


which Lie algebra admit a left symmetric algebra structure?

Question: Hello,
I have a some questions, but first I must point out some definitions.
A left symmetric algebra LSA is given a a vector space $V$ equipped with a bilinear product $\cdot$, which is not necessarily associative but satisfies:
$$(x\cdot y)\cdot z-x\cdot(y\cdot z)=(y\cdot x)\cdot z-y\cdot(x\cdot z)$$
to such algebra is associated a Lie algebra structure given by the bracket
$$[x,y]=x\cdot y-y\cdot x$$
This algebraic structure of LSA is important in geometry:
1) Affine structures: if a manifold $M$ is equipped with a linear connection $\nabla$ which is flat and torsion-free then the space of its vector fields $\mathcal{X}(M)$ is a LSA for the product
$$X\cdot Y=\nabla_XY.$$
2) Symplectic Lie groups: if $(G,\omega)$ is a Lie group with a left invariant symplectic form so we can bring $G$ an affine connection (linear, flat, torsion-free) which is left invariant
$$\omega(\nabla_xy,z)=-\omega(y,[x,z])$$
and its Lie algebra $\mathcal{G}$ is an LSA for the product $x\cdot y=\nabla_xy$.
My question is:
1) What are the Lie algebras that admit a structure of LSA? Only solvable ones, why not semi-simple?
Comment: @darij: yes, more precisey a *left* pre-Lie algebra. Here's the nLab link *de rigueur*: http://ncatlab.org/nlab/show/pre-Lie+algebra
Comment: See the paper of J. Helmstetter, Radical d'une algèbre symétrique a gauche, Ann. Inst. Fourier, 29, 4(1979), 17-35. He defines the radical R(A) of an LSA A to be the largest left ideal contained in the kernel of a→trR(a) where R(a) is the right multiplication operator, and gives several equivalent characterizations of this ideal. If A=[A,A] this forces R(A)=A, which forces the underlying Lie algebra to be solvable. That no semisimple Lie algebra admits a compatible LSA structure follows.
Comment: LSA = what Gerstenhaber calls a pre-Lie algebra?
Comment: Have you looked into the various papers by Dietrich Burde on the subject?  For instance: *Simple left-symmetric algebras with solvable Lie algebra*.  Manuscripta Math. 95 (1998), no. 3, 397–411 (plus later correction in the journal).
Comment: Many thanks, José and Jim for your comments!

You can see the related topic, (mathoverflow.net/users/16578), Which Lie algebra admit symplectic forms, http://mathoverflow.net/questions/71766 (version: 2011-07-31)
Answer: As said, semisimple Lie algebras over a field of characteristic zero do not admit an LSA-structure. There are several proofs. Basically it relies on Whitehead's lemma for semisimple Lie algebras, saying that $H^1(\mathbb{g},M)=0$ for all finite-dimensional $\mathbb{g}$-modules $M$.
 On the other hand, not all solvable Lie algebras admit a compatible LSA-structure. There are even nilpotent Lie algebras not admitting such structures, see Y. Benoist's paper "A nilvariete non-affine", and this paper here. The proof is difficult and shows that such counterexamples can be constructed by $n$-dimensional Lie algebras not admitting a faithful linear representation of degree $n+1$.


How to define new classes from a change detection raster layer

Question: As part of my thesis, I'm looking at the atmospheric and landscape effects of the 2018 wildfire in the Algarve. As part of the process, I want to estimate total biomass loss so I have classified two Landsat 8 images (pre and post-fire, 5 and 6 classes respectively) and performed a land cover change analysis using SCP plugin. I'm still fairly new to QGIS/remote sensing so am struggling to understand the output from the change detection and how I can produce a layer showing classes which have changed/calculating total biomass loss from the vegetation classes.
Comment: The key to understanding the 'change raster' is that you have a 'before raster' with 6 classes and a 'after raster' with 7. Now 6 * 7 = 42, which is the number of classes in your 'change raster'. As such, each of the classes in your 'change raster' corresponds to a combination of classes between 'before' and 'after'. Now you just need to spend time identifying which number in the 'change raster' corresponds to which pair of input classes.
Answer: How to calculate change in total biomass
Use a spreadsheet to make the following calculations.

Assign a biomass per square meter value to each landcover category. These are the fundamental assumptions on which your analysis is based, so they need to be the best estimates you can make. If your biomass per square meter values aren't reasonable, then your final calculated change in total biomass results will be equally unreasonable. Since you're doing a thesis on this topic, I assume you have enough information and knowledge to make this estimate. If not, that should probably be an entire separate question.
For the pre-fire raster, multiply biomass per square meter by the area (in square meters) of that landcover type. This gives you total biomass in landcover type 1, total biomass in landcover type 2 etc. Repeat for the post-fire raster.
Add up the total pre-fire biomass in landcover type x values calculated in step two. Repeat for post-fire values. This gives you total biomass pre-fire and total biomass post-fire.
Subtract total biomass pre-fire from total biomass post-fire. This gives you change in total biomass.
Answer: have a look at this:
https://docs.qgis.org/2.8/de/docs/training_manual/rasters/changing_symbology.html
choose singleband pseudocolor for your percentage band.


What kind of paint should be used on old plaster and lathe walls?

Question: Are the steps to painting a plaster and lathe walls, house is early 1900's, the same as any other type of wall? What type of primer should be used? What type of paint? On the internet I read about the walls need to breathe and latex may prevent  'breathing' and moisture will build up.
Answer: On a home this old there will be layers of oil based paint and possibly additional layers of Latex paint. The biggest concern is good prep work (cleaning removing loose material) and a Quality paint. I have used both oil and latex on Victorian era homes with excellent results. It is really an opinion question today.
Answer: Old buildings were designed to breathe. Masonry used lime based mortar, and plaster used on lath is also lime based and porous. This meant there was flow of moisture in and out as temperatures etc changed. Using latex paint or any emulsion usually results in damp as it stops this breathability. Everyone then paints over damp patches with damp seal. This causes damp to rise (rising damp) etc etc.
If you're doing it properly, use a lime wash. You can mix up about 40 Litres (8 Gallons) for about £5. Lime wash is also breathable, and you can mix up your own quite nice colours using different materials (if you're keeping it traditional).
A good example is Kew Palace, London, which I'm pretty sure has been lime washed externally with the addition of brick dust to give it a nice orangey red colour. If using externally, mix in some linseed oil as it gives it some water resistance. Other options, are crushed coal dust for a black/grey (depending on ratios), or Westerham Sand for yellow.
Comment: This question is over 2 years old so it's unlikely the asker is still paying attention.  However, this is a great answer.


post processing edge

Question: new to blender,checking edge in post processing shows up characters wireframe while rendering,like the toon effect,but not the wireframe,what am I supposed to do(blender 2.76),normal render(without edge works fine)
Answer: Turn down the Threshold. Edge looks for edges based on z-depth. Threshold changes the limit for this. If threshold is high, or your model is low poly, it will get too many edges.

post processing edge


Accuracy of measurements in Google Earth

Question: Can anyone point to a resource that lists the accuracy of measurements taken in Google Earth?
Comment: How accurate are you looking for? metre/feet or nano-metre/inch?
Comment: Feet would be sufficient.  Was really just looking for any sort of information on it.
Answer: Apparently, the measurment ruler is not accurate over long distances > 5,000 km.
Google's offical stance says, "makes no claims as to the accuracy of the coordinates in Google Earth. These are provided for entertainment only and should not be used for any navigational or other purpose requiring any accuracy whatsoever".
Comment: http://www.google.com/support/forum/p/earth/thread?tid=465ccd707c3a9f04&hl=en is the official stance
Comment: @Mapperz that's the accuracy of the imagery coordinates.  Distance calculations could be much less accurate than that.  @art A quick test (measuring a great circle of 40,000 km) suggests the accuracy is pretty good--far greater than one would expect from the orthographic projection used.  What are you citing when you refer to "long distances > 5,000 km"?
Comment: Thanks for the response.  Can you add a link to the page where you found the official stance?
Comment: @whuber, the 5K km distance was just a blog conversation that I hit on a google search.
Answer: In 2011 two brazilians published an article about it, and they concluded that:
*the error is just 0,44% for line measurements;
*the error is just 3,54% for polygon measurements;
*the error is just 1,39% for perimeters calculation;
Based on these results they concluded that you can use Google Earth as a good source for mapping in scales smaller than 1:150000, assuming the planimetrical error as 0,1 mm.
Of course this is just a case of study, and these results depend on your area of study. I suppose that in the US the results may be even better.

Source: Lopes, E. E.; Nogueira, R. E. Proposta Metodológica para
validação de imagens de alta resolução do Google Earth para produção
de mapas. In: Simpósio Brasileiro de Sensoriamento Remoto, 10,
Curitiba, PR, 2011. Anais: São José dos Campos: INPE, 2011.
Source link (in portuguese):
https://www.researchgate.net/profile/Ruth_Nogueira/publication/266032536_Proposta_Metodologica_para_Validacao_de_Imagens_de_Alta_Resolucao_do_Google_Earth_para_a_Producao_de_Mapas/links/54ff4e900cf2672e224563eb/Proposta-Metodologica-para-Validacao-de-Imagens-de-Alta-Resolucao-do-Google-Earth-para-a-Producao-de-Mapas.pdf
Answer: After just installing a break water and knowing all the dimensions, i checked it on google earth to see how close the eye in the sky is, on 470 ft it showed 477 ft, I tried google earth pro it did not make a difference. I have used it before and it seemed the accuracy was better. The location used was 48d38'59.33"N x 123d33'07.23"W The long leg of the east to west break water sections is accually 470'7" x 20' wide.
Comment: This particular problem seems to have been fixed. With Google Earth 188.8.131.5213 (Build Date 4/11/2012) I get 470'7" to within about a foot.
Answer: I have measured The University of Kentucky's Commonwealth Football Stadium in Lexington, Ky.
Goal Line to Goal line is supposed to be 100yds or 300'
Google had the distance, goal line to goal line up the hash-marks at Commonwealth at 299.09'. Off by .0030%.
Have measured base paths (90') at MLB stadiuons and found same degree of accuracy.
Answer: Google Earth with Landsat GeoCover scenes over a global sample of 436 control points located in 109 cities worldwide. Landsat GeoCover is an orthorectified product with known absolute positional accuracy of less than 50 meters root-mean-squared error (RMSE). Relative to Landsat GeoCover, the 436 Google Earth control points have a positional accuracy of 39.7 meters RMSE (error magnitudes range from 0.4 to 171.6 meters). The control points derived from satellite imagery have an accuracy of 22.8 meters RMSE, which is significantly more accurate than the 48 control-points based on aerial photography (41.3 meters RMSE; t-test p-value < 0.01). The accuracy of control points in more-developed countries is 24.1 meters RMSE, which is significantly more accurate than the control points in developing countries (44.4 meters RMSE; t-test p-value < 0.01). These findings indicate that Google Earth high-resolution imagery has a horizontal positional accuracy that is sufficient for assessing moderate-resolution remote sensing products across most of the world's peri-urban areas.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3791001/#idm140287651201472title
Comment: What is this??? You just did copy/paste the abstract of the article partially and unnecessary parts of the webpage.


Can a fun pack unlock the level?

Question: I've beaten the first level, and I've had an opportunity to move around the hub area, and I see that there are bonus levels I could walk into if I had the right characters, but it doesn't say I have to have the level packs. Could I just put in Bart and play the Simpsons level, or is there also new bonus level somewhere that requires the homer level pack?
Answer: There are three different types of levels.

The main storyline of the game. This is started when a new game is started, and after the first little bit, the heroes make it to the hub area (called Vorton). The storyline is continued by jumping through the portal on the pad in the game. This generally follows WildStyle, Batman and Gandalf's adventures but you can play using any characters that you own.
In the game's hub world, on the floor above the portal pad (accessible from the elevator to the left of the portal pad), there are Adventure Worlds, which are open-world bonus levels for each universe (DC, Simpsons, Portal, Jurassic World...), and those levels require any character from that franchise, be it fun pack, level pack or team pack.
The levels from the Level Packs are accessed by having the character on the pad (in any of the positions), then jumping through the portal. At this point the game gives you the option of continuing the story, or playing the level from the level pack.
Comment: To clarify, are the bonus levels different from the levels of a level pack?  Also, you say "levels from the level packs" - does each level pack come with one level or multiple levels?
Comment: What do you mean by "level"? I put Chell on the base, then jumped through the portal. I had the opportunity to play Chell's level. I took it. I started playing it last night. At about the third checkpoint (after I had built the companion cube and the turret), it was time for bed, so I turned it off and didn't finish the "scenario", but I had been through several different test chambers (test  chambers are in portal and portal 2).
Comment: I've been having an interesting time trying to explain what area I am in at any given time to my boyfriend. "I thought you said you played through the Portal level already!" I eventually came up with something like "Starter pack story level", "DLC story level", "Hub worlds." But even that's pretty awkward...
Comment: Yeah, I've been using similar terms, but they're still not clear (i.e. [Some] of the hub worlds are only accessible by other purchases)

Can a fun pack unlock the level?


If Electrical flux is no. of field lines passing through the area then why the formula is $E$ dot $A$ (Area)?

Question: I have been taught that flux is no. of field lines passing through the surface. But my question how  does the formula for calculating electric flux is matching with the above statements?
The formula for electric flux is $E \cdot S$. How does the field lines is getting by the dot product of $E$ and $S$ (area vector). May be i am not able to understand the relation between the field lines and field strength? Please someone explain?
Comment: How can one count field lines? Area * E is the only logical thing.
Answer:
Let me state just in case, that when we refer to a surface vector we refer to the orthogonal vector that points away from the surface:

The actual formula for flux is not the cross product (which increases when things become perpendicular), but the dot product (which increases when things become parallel), which is obviously what happens here, since the flux is gonna become larger when the surface vector becomes parallel with the electric field:

And finally, the most important, what actually is the number of "electric lines" is the flux itself, not the electric field. The field is more like the density of lines, which is the number of lines in an area of size 1 (that is why a bigger field means the strength is higher at that point, while a bigger flux can just be that you took into account a bigger area). That is why the flux is the field (density of lines [n of lines/area]) multiplied by the area! :).

(In this last picture, the electric field in the left panel, is higher than in the right panel, because you see way more lines per area unit, they are more "condensed" -> higher electric field.
But if the electric field lines in the left, when we do zoom out stop in that area and the rest is empty of lines, but in the right panel if we zoom out, there keeps appearing new ones at some point taking enough area the left panel will have higher total flux, even when in the centre it has a weaker electric field. )


Can every first order phase transition be tuned to a second order phase transition?

Question: Is every first order phase transition related to a second order phase transition by the tuning of some coupling? In practice is the expectation that the this tuning can usually be done in the lab. (By playing with the temperature, density, magnetic and electric fields and/or particle numbers.)
Answer: I suppose the answer is no. Consider a transition between the solid-state phase and the gas or liquid phase. Gas and liquid phases are translationally invariant. In a solid crystal, translational invariance is broken due to the presence of lattice. According to the acepted point of view, a continuous transition between phases with different symmetries is impossible. This in particular is a reason for the absence of critical points in solid-liquid phase transitions.
Comment: I think your statement is confusing. Almost the opposite is in fact true: Second order phase transitions are (always, I think, perhaps not for QCP and/or topological phase transitions) related to spontaneous symmetry breaking. In the Ising model this is clear. You go from a phase with Z_2 symmetry to a phase where the lattice breaks this symmetry. However, if you turn on a magnetic field then this field already explicitly breaks the symmetry and so you can move around the critical point and in fact both phases will be considered to have the same symmetry, namely no Z_2 symmetry.
...
Comment: Good point. Any point that is locked in by first order phase transitions cannot be tuned to the second order phase transitions without passing through a first order phase transition. Of course you could just do that, I did not add the criteria that you could not. Thinking of it in these terms I guess my question was whether every phase diagram has a second order phase transition.
Comment: For the liquid-vapor transition again you could theoretically write an hamiltonian, I think, where there would be a phase transition between liquid and vapor breaking a Z_2 symmetry. This hamiltonian would have to be constrained to move on the line of the first order phase transition.

In practice in the lab you always have access to both the pressure and the temperature  (and not just to some weird combination of them restricting you to the first order phase transition line) and so basically you always have an explicit breaking of the Z_2 symmetry. ...
Comment: Just like in the Ising case using a magnetic field. So the two regions are considered to be in the same phase. A good answer on this question is given in https://physics.stackexchange.com/a/61421/130040. In conclusion I don't think this is a very good answer.
Answer: There is an Ising model I've modified that displays both first and second-order phase transitions, and I do employ tuning to magnetize the cellular automaton.
Tuning in this example is the frustration of the system between its Moore and von Neumann neighborhods. When the neighborhoods are tuned from 4 and 5 cells up to 6, the system enters a ferromagnetic transition.


Do Spectre(-NG) and Meltdown affect Mill?

Question: Given what is publicly known about the Mill CPU, would it be affected by Spectre(-NG) or Meltdown style attacks? Why/why not?
Answer: Mill had published a sort of white paper on the extent of their vulnerability to Spectre and Meltdown. Since we don't know much about Spectre-NG yet (probably the first wave would come out on 7th May 2018), I am going to rely on my assumption that the new variants attack the Hypervisor and Intel's secure guard extension.
The attacks on hypervisor (using software level speculative execution) definitely can affect Mill's hardware or probably any hardware in general. Here is the relevant section from the whitepaper:

There is little that a vendor can do about victim code that deliberately loads from an attacker supplied address without checking the validity of the address first; such code is a bug, plain and simple. Exploitable speculation introduced by the compiler as an optimization is also a bug of
  course, but more insidious because inspection of the victim source will not reveal the problem.
The Mill is a very wide-issue machine, which allows the compiler to improve performance by carefully interleaving speculative execution using meta-data and predicated (conditional) instructions. For example, it is common for the two legs of an if-statement to be interleaved and both sides executed unconditionally but with one side masked out via meta-data or not used by subsequent conditional instructions.

As for attacks on Intel's secure guard extension:
According to the white paper, Mill architecture seems to be secure against such attacks.


Electric bicycle and an electric scooter

Question: Assuming that an electric bicycle and an electric scooter use the same motor and battery, which has more autonomy? that is, which makes more kilometers / miles per battery charge cycle? Obviously each vehicle logically has a different transmission and size of wheels.
Comment: I wonder what you are after? If you are making a point, this is the wrong forum. But could it also be seen as a continuum: what's the difference between a "bicycle" and "scooter", really? It may end up being human linguistics, and again the question is misplaced.

If you need an answer, as @kamran points out, you'll need to provide more info. Or is "bicycle, of course (since it's lighter) - but does it matter?" :) a good enough reply?
Comment: a scooter has much smaller wheels so I sense that for each turn of the engine covers a much smaller area, although I also believe that the engine needs less effort (I have no clear this relationship)
Comment: Maybe I should clarify that when I refer to scooter I mean an electric skateboard two wheels, like a Segway but with a handlebar
Comment: A Segway has two large wheels on the sides. Scooters have small wheels in front and back. Fundamentally different devices. In some parts of the world, the term "scooter" refers to a small motor cycle like a Vespa.
Answer: Take a random electric bike and another electric motorbike, the base idea of designing them would be fairly similar: just a frame holding a battery and 2 wheels together. There is not that much difference between the two of them. Though I would say that the "bias" with electric motorbike is better (it is automatically assumed that it has a better range)
The transmission... I would say that have fairly similar layout, though the electric bike (or some of them) has the option for "pedalling" (use just like a normal bicycle), and again, the pedals can also be removed, practically making the electric bike an electric motorbike.
Comment: Maybe I should clarify that when I refer to scooter I mean an electric skateboard two wheels, like a Segway but with a handlebar
Comment: Again, it depends a lot. Other than the fact that the electrical bike can be moved by pedals as if it is a normal bicycle, there is no major distinction between an electric scooter and an electric bike. The important part is other factors, most notably the battery and the over weight (passenger, dry weight and packages) of the vehicle.
Answer: It depends on the efficiency of the design, the wind drag, the quality of rejuvenative breaking.
The factors most influential in performance are not the form factor alone. Also both the scooter and electrical bike do not necessarily need a transmission as the torque can be adjusted electronically.


Shouldn't we get rid of year numbers in tags?

Question: I'm afraid that setting a year number in the tag can be too obvious and too easy for newcomers. Shouldn't we use product numbers, like 6.1 for 2011SP1, instead to give us some more space to flame the askers with proper tags?
Comment: What does 'give us some more space to flame the askers with proper tags' mean?
Comment: Have you heard of fools day?
Comment: It's clear this was an April Fool's joke after the fact. Not that we would, but let's be sure we don't tease actual askers with [answers that joke about procedures](http://www.catb.org/esr/faqs/smart-questions.html#idp30009456). I think the most humorous part is the "Mr. P" imposter got stuck with the name for a month. :-P
Answer: There isn't anything we can do to change the fact that the version of SDL Tridion is done with the year of release. Even though internally there is a version number used, I don't think we should deviate from what is communicated externally.
Marking a question with 6.1 would be just as good or bad as marking it with 2011, the only difference being is that with 2011 most will understand its related to SDL Tridion 2011, not everybody knows the internal version numbering.
We discussed if we should use tridion-2011 or 2011 and decided to follow Drupal and go with tag simplicity.
I don't agree that just a few of the questions tagged with 2011 actually are about SDL Tridion 2011, for me it gives a clear reference that this version is being used, where the answer could be different if it was about version 2009 or 2013. Right now 2011 will become a highly used tag, because most customers are on that version, but I think we will see a rise of the 2013 questions soon with the fresh release. That to me gives enough meaning and concept to that tag.
I tend to agree that the version tags might not be very useful for search engines, on the other hand a question about a different version might not always lead you in the right direction. So i'm definitely not in favor of changing 2011 to something like 6.1 (and still think that 2011 is better than tridion-2011) but agree that on some questions it might be valid to remove the tag.

In reference of the day you posted this, yes the joke is on me :D
Answer: There's an inherent problem with these vague, overused tags — they hurt the search engine findability of your content. Search is the lifeblood of this site, and your top tags rarely describe the question at all.
As much as you say "Version tags should be used only when necessary to provide context to the question, and not to simply state that you are using SDL Tridion 2011", they are becoming the most [over]used tags on the site.
Very few of these questions are actually about (for example) Tridion 2011 issues, specifically. Ideally, tags should identify the top key concepts in your question, and rarely does the version number do that. And to make matters worse, nobody outside this site is going to be searching for "2011" to find your content. All you've done is create a small collection of catch-all tags that apply to just about every question.
I agree that these tags should be renamed to something more descriptive. See if perhaps the approach Magento took is better suited to your product version labeling — https://magento.stackexchange.com/tags. But longer term, I would consider removing these tags where they are not truly one of the top concepts in the question.


Does the Help Action reveal the location of a Hidden and Invisible creature?

Question: Let's say I have a Pact of the Chain imp who is invisible and takes the Hide action to gain extra protection (harder to direct attack rolls to an unknown location). Then, he uses the Help action. Is his location still unknown since he has not left the heavy obscurement / invisibility that allows hiding? Or does Helping reveal the location? Or would it depend How they help (can it be done in a way so as to not reveal a location)?
Answer: It depends on what is the imp is doing (but the answer is probably "it breaks stealth")
Are they flying around a foe, trying to distract them in the middle of battle? They will no longer be hidden. They will still be invisible, but their location will be known (fluttering in the air next ot the foe).
Are they holding a lantern, directing light on the trap you are trying to disarm? They will no longer be hidden (everyone knows where they are by the light source they are carrying).
I can't think off the top of my head anything helpful they could do that wouldn't break their stealth, but there probably are examples.
As always, begin and end with the fiction (a line from Dungeon World). The player says what the imp is doing in the game world, and the GM rules from there.
Comment: To be more precise, you should say that they are no longer Hidden. I don't think there is a "stealth" condition to break. There is only a Stealth check to see if you become Hidden.
Answer: Until you are discovered or you stop hiding … PHB p.177
That's what ends hiding - being discovered or stopping; Helping is not mentioned. If you can Help without doing either of those things, you are still hidden.
Hard to see how you can find a way to Help without doing one of those things but all power to you if you can.


How can I measure the mode content of a LASER beam?

Question: The symmetry of a stable optical resonator determine that Hermite–Gaussian functions will be formed. In multimode optical fibres, these will be LP modes instead. I am interested wether one can measure the actual mode content, e.g. determine which mode contributes which fraction of the intensity (or electric field + phase). Is this experimentally possible? How fast does the content change over time (between the different modes)? Can one measure this without prior knowledge of the mode shape?
Answer: You can't infer the mode content, at least practically and reliably, from intensity measurements alone even if you do know the modeshapes unless the number of modes present is small. You can, for example, estimate the purity of a single, fundamental mode if the degree of contamination is small. For a small number of modes, there is a trick that you can use to help you, especially in the case of a fiber.
Suppose the modeshapes as a function of transverse position  $\vec{r}$ are $\psi_i(\vec{r})$. Then, assuming you don't want to know phase, you wish to find the $|\alpha_i|^2$ given a measurement of:
$$|\psi^t(\vec{r}_j)|^2 = \left|\sum\limits_i \alpha_i\,\psi_i(\vec{r}_j)\right|^2\tag{1}$$
We expand the above to find:
$$|\psi^t(\vec{r}_j)|^2(t) = \sum\limits_i |\alpha_i|^2\,|\psi_i(\vec{r}_j)|^2 + \sum\limits_{j\neq i} 2 \mathrm{Re}\left(\alpha_i\,\alpha_j^\ast\,e^{i\,\phi_{i\,j}(t)}\right)\tag{2}$$
where the $\phi_{i\,j}(t)$ are randomly time-varying phase delays between modes that arise as the fiber strains or as the laser cavity mode-hops owing to temperature and other environmental variations. You can speed this variation up by deliberately vibrating the laser cavity or piezoelectrically modulating the fiber, measuring the total intensity over a transverse plane and averaging the measured values of $|\psi^t(\vec{r}_j)|^2$ as you do so. The idea here is that the off-diagonal terms (the terms in the $\sum\limits_{j\neq i}$ that involve the $e^{i\,\phi_{i\,j}(t)}$ factors) will average to nought owing to the random variations in the $\phi_{i\,j}(t)$ with time. Once you have measured this average (you know when you have because the average stops varying with time), you have:
$$\langle|\psi^t(\vec{r}_j)|^2\rangle = \sum\limits_i |\alpha_i|^2\,|\psi_i(\vec{r}_j)|^2\tag{3}$$
which, given enough points $j$ on the transverse plane, and given we know the mode intensity shapes $|\psi_i(\vec{r}_j)|^2$, can be analyzed by a linear regression for the weights $|\alpha_i|^2$ of the mode intensities $|\psi_i(\vec{r}_j)|^2$. So you can in theory infer the $|\alpha_i|^2$ in this way. The practical problem is that, unlike the mode amplitudes, the mode intensities are often not even close to being orthogonal, so that the linear regression, unless there are only very few modes of very different intensity profile present, will become badly numerically conditioned. You should use a singular value decomposition for your linear regression to check this.
As for how fast the content changes: for a fiber, the mode intensity content should not change unless the illumination conditions change. The phases between the modes will change at a speed in proportion to the fiber length: for a very long fiber of several kilometers, the phases between the modes vary over many, many cycles per second, so the cross terms in (2) can vary in at hundreds or even kilohertz rates. For a laser, the answer to this question depends very much on the physics giving rise to the variation. Slow, temperature induced changes are typically at a few hertz rate. Mode hopping can be very violent, and even happen in the megahertz range.

Follow Up Question by OP

.... How would it change if I were able to measure the phase as well? Is it then possible?

Essentially you then have access to $\psi(\vec{x})$ as a complex field and you're doing interferometry. If you know the modes, they are orthogonal, and you can then find their complex weights by linear regresssion, which will now work well owing to the orthogonality. But you do need to know the mode shapes as you can see from the following: a complex function can be resolved into a superposition of different complete orthonormal sets: the orthonormal sets are not unique. Do a nontrivial unitary transformation on any basis and you have an equally workable - and different - basis.
Comment: Thanks for this detailed answer. How would it change if I were able to measure the phase as well? Is it then possible?
Comment: @DaP See my updates.


Which drivers to install on Ubuntu 16.04 LTS?

Question: I am new to Ubuntu. Can you please tell which drivers to install for basic and proper functioning of the system?
Comment: Ubuntu is likely to work out of the box for you. If it doesn't, please come back with more specific questions and problems that you encounter. Your current question is too vague.
Comment: also see http://askubuntu.com/questions/795617/how-to-find-more-suitable-drivers/795637
Comment: @edwinksl yes. Definitely.
Answer: You usually do not need any additional drivers, Ubuntu is able to handle most common devices out of the box. This is unless you experience any problems like a not properly working wireless network.
In some cases, you might want to replace the default open source drivers with the proprietary ones provided by the device manufacturer for better performance or support of special features though. This usually applies to graphics cards, mainly nVidia and AMD ones.
You check whether there are additional proprietary drivers available for your specific system by opening the System Settings and clicking on Software & Updates. Navigate to the Additional drivers tab. It takes a while to scan your device and will then offer you a list of devices for which you may chose one of multiple drivers.
Answer: Most of the time, there's no need to install additional drivers. The main three exceptions to this are:-

GPU - nVidia and AMD have their own drivers providing accelerated 3D capabilities.
Wifi - Some Wireless chipset drivers aren't installed by default.
Printers - Many printer drivers will be auto detected and installed, but some require drivers from the manufacturer website.
Comment: Yes Initially I faced a problem while wanting to connect to a Wifi.


SQL query a new thread in vBulletin

Question: How to make a query to the database(mysql) to create a thread?
I need to create a thread from a non-registered user, if not, then from the present ..
Simply query the database with the subject "Test", the text "test text" and any nickname
Sorry for bad english, thank you!
Answer: If you have access to the vBulletin code-base, I'd use their datamanagers.  Otherwise, it gets very messy as there is lots of other data to update after posting.  At its very core, you'd want to insert data into the post table, and the thread table.  I'd recommend looking at the structure of those tables and going from there.

SQL query a new thread in vBulletin