Preventing alternator draining car battery

Question: Just purchased 12V alternator to put on my '26 model T ford.  Instructions said without wiring through switch the alternator will slowly discharge the battery when not running.  Never encountered this before.  Alternator is only rated at 35A.  If I put a 40V,10A diode in series with the output will this keep the battery from discharging and will the diode handle that output.  (I've never seen one of these charge more than 17-20 Amps and then only briefly.)
Comment: Is this an Alternator or a Generator? For a 1926 Model T Ford... Is the smaller terminal labelled "F" ? A picture would help.
Answer: An alternator already contains diodes before the output terminal that will prevent reverse current flow, in most automobiles the alternator output is wired directly to the battery.
The risk of slow discharge is the alternator input. This line often includes the "check alternator" lamp in series, is is this connection that will slowly discharge your battery if left on with the motor stopped. Only a small switch is required, as the current in this line is no more than is required to light the warning lamp.
If your alternator kit includes an external voltage regulator, it is the input to the voltage regulator that should be switched. But most alternators have the voltage regulator built in.
Answer: A diode will stop reverse current flow.
A well heatsunk 10A diode MAY survive. I'd recommend a 20A diode or 2 x 10A in parallel OR a MOSFET wired to act as diode - ask if interested.
A diode will drop about 1V so at say 15A it dissipates 15W.
That's equivalent to a resistor of R = V/I = 1V/15A =~ 6- milliOhms, so a MOSFET with around say 10 milliOhms om resistance will dissipate far less energy. (FET at 10 milliOhms. Power = I^2.R = 15^2/0.010 = 2.25W.
It seems unlikely than an alternator would do what you say. A standard 12V alternator has diodes in it as of right as it is an AC machines with conversion to DC using diodes. An olde school generator with a commutator has no explicit reverse current blocking path so MAY discharge a battery. Usually the good olde days mechanical regulator handled this with a contact that was open when not charging. Supply model and brand for a better comment on your new fangled gear.

Using MOSFETS as blocking diodes.

A MOSFET may be connected in a manner that allows it to act as a diode.
It is connected so that when votage is connected in the desired "forward" direction, current flows through the drain-source "body diode" PLUS the gate source junction is biased on so the FET conducts. When polarity is reverse the body diode blocks and the FET turns off.QED.
Here is a webpage covering Using MOSFETs as blocking diodes. They provide practical advice as well as the theoretical basis. Very importantly, the FET gate-source junction must NEVER be subjected to > Vgsmax - often 20 to 24 V but sometimes as low as 10V.
From that page:
The alternator is in the position shown as a battery in these diagrams.
Note that in each case the polarity of the drain-source connection is the opposite of what is used in practice. (I've used several hundred thousand examples of this circuit - it works :-)).
If a PFET is used it is placed in the alternator positive lead.

If an NFET is used it is placed in the alternator negative lead.

As noted above - the gate voltage must ALWAYS be "in spec" - this should need as little as a resistor or two and a zener diode and maybe a small capacitor.
Comment: 2 x 10A in parallel...you sure about that?  Didn't think the diodes would share very well but have never tried it.  You can get diodes larger than 20 A.  Like VS-100BGQ100 -  schottky rectifier.  100 A
Comment: @RobertEndl More horsepower ! :-) - a single 20A diode is better. If using two diodes then to assist current sharing a small resistance can be included in series with each diode - and by simply having a short length of non shared wire per diode you'll probably get enough to balance. Devices within batches are usually "reasonably well" matched. At 1A you only need 0.01 Ohm to get 0.1V drop and that is probably enough to balance approximately matched diodes..


Why isn't Taggart protected by Double Jeopardy?

Question: At the beginning of Broken City, Billy Taggart is charged with murder but then walks. At the end of the film, it seems that he still has to face his crimes. Why isn't he protected by the Double Jeopardy clause in the U.S. Constitution? Does he actually not have to face his crimes at the end?
Comment: Was he actually acquired, or was he just dismissed.  Was this actually at a trail, or just during the arraignment.  I am not a lawyer, but it seems like this would be dependant on the specific details of exactly what happened.  Jeopardy doesn't attach as soon as you step into the courtoom.
Answer: This is a mistake in the movie. Taggart is charged with the crime of murder, and it is determined during the trial that he was acting in self defense. This is an acquittal, and because of that double jeopardy would apply, and he would not be able to be charged again for the same crime, even if he stood in the courtroom and confessed to it.
Currently this concept is recognized and enforced by a vast majority of countries in the world. It's easier to list the ones that don't recognize it than the ones that do. If a trial reaches either an acquittal or a conviction, then double jeopardy attaches.


What is the most efficient way to destroy the universe?

Question: Don't worry... I won't actually do it, just would like to know how.
Comment: Honestly, I don't think this question is well-defined enough. If you're really interested in destroying the universe, a better question would be to think of a way to do it and then ask if it's possible, and if not (which is likely to be the case), _why_ not. That's where the physics really comes in.
Comment: @Matt: the problem is that you saved a terrible question with an interesting answer.
Comment: Multivac says: INSUFFICIENT DATA FOR MEANINGFUL ANSWER
Comment: Just wait until LHC starts running at 14TeV: then you'll find all about the destruction of the universe in your local newspapers :-)
Comment: @weiqure: energy isn't really conserved in general. Rather, it's a consequence of certain simplifications (assumption of time-translational symmetry of the spacetime), so this requires stationarity of space-time, which isn't consistent with expansion of the universe we are observing. Actually, in general theory of relativity it's hard to even reasonably define the concept of gravitational energy.
Comment: I'd tell you, but then you might stop me.
Comment: Eliminate the observer (when he/she's not looking).
Comment: Depending on the definition, this is impossible, see [Conservartion of Energy](http://en.wikipedia.org/wiki/Conservation_of_energy).
Comment: efficient wrt time or energy ?
Comment: Voted to close ...
Comment: I don't agree that the question should be closed. Perhaps it should have been rephrased as "are there physical processes that could destroy the universe," which is what I tried to answer below, and which I think is a perfectly reasonable and interesting question.
Comment: Isn't it already destroyed? Or, at least be destroying? And your question seems to accelerate this process.
Comment: This question has no "right answer", so making it CW.
Comment: There are only a couple of useful answers to this question right now (_maybe_ three), and other than those, it's just generating a lot of noise. So I think it's time for this one to be closed.
Comment: @AbdullahJibaly - I created an account here just to upvote your Multivac comment.
Answer: The physical process that might best be described as "destroying the universe" would be vacuum decay. Our entire universe might be in a metastable state, much like a supercooled liquid, and at some point quantum or thermal fluctuations could send some region of the universe into a lower ground state. If the region that tunnels to this ground state is large enough, it will expand at the speed of light, swallowing up the rest of the universe and converting it all to the lower state. This type of vacuum decay, in theories involving gravity, was calculated in a famous paper by Coleman and de Luccia. Anyone with the relevant background knowledge should read the paper, which like much of Coleman's work is beautifully clear and comprehensible. One passage in the paper is particularly famous (though it arguably shouldn't be taken too seriously now, given some of the assumptions it involves, including that our vacuum has exactly zero cosmological constant):

"The possibility that we are living in a false vacuum has never been a cheering one to contemplate. Vacuum decay is the ultimate ecological catastrophe; in the new vacuum there are new constants of nature; after vacuum decay, not only is life as we know it impossible, so is chemistry as we know it. However, one could always draw stoic comfort from the possibility that perhaps in the course of time the new vacuum would sustain, if not life as we know it, at least some structures capable of knowing joy. This possibility has now been eliminated."— Sidney Coleman

If we live in a metastable vacuum (and, due to the observed positive cosmological constant, most physicists working on high-energy physics, cosmology, or gravity believe that we must, though there might be some unknown loopholes), then the universe will eventually decay. Luckily, the production of critical bubbles is quite rare, allowing us the time we needed to evolve and live in this metastable universe before the inevitable catastrophe. [Edited for clarification due to Marek's comment: it's only "inevitable" if our universe really is metastable, which despite strong suggestive arguments we don't definitively know.] You would have to wait around for billions of years to witness the end of the universe. If you're more ambitious (let's hope not), you could try to cause the decay by producing a region of the true vacuum, thus catalyzing the process instead of letting it happen naturally. A number of crackpots have tried to start a panic over accelerator experiments by suggesting that they can do this. However, higher-energy collisions happen in nature, and we're still here, so this is nothing to worry about. (There are more quantitative versions of this argument, of course. The risk really is effectively zero.)
The vacuum decay processes I've mentioned don't necessarily "destroy" the universe, they just radically alter it by leaving it in a completely different state. There is one type of vacuum decay, discovered by Witten and known as the bubble of nothing instability, which is more radical and leaves behind nothing, not even a new vacuum state.
Comment: Very nice answer. Just perhaps it would be correct to explicitly state that this isn't a prediction based on an accepted physical theory. I.e. this is all based on some hypotheses and not much different from when I tell you that universe will be destroyed by flying spaghetti monster but you would have to wait for it for billions of years. That is, of course, unless you tried to catalyze the process by producing large amount of ketchup :-)
Comment: The one part of this that isn't known is whether we really live in a metastable state or not. The Coleman-de Luccia calculation of how the vacuum could decay is based entirely on accepted physical theory (quantum field theory and general relativity). We even *almost* know that we live in a metastable state: lower vacua can be calculated entirely from known physics (http://arxiv.org/abs/hep-th/0703067), provided neutrinos are Majorana and there are no new unknown very light fermions. There are many other convincing but not rigorous theoretical arguments that our vacuum is metastable.
Comment: I'd read about Coleman's vacuum decay before, but never heard about Witten's bubble of nothing.
Comment: This bubble nucleation process is not something you can induce particularly.  It seems as uncontrollable as radioactive decay.  To be honest I am amazed at the large + scores given for this question and its answers, when the whole question is frankly silly.
Comment: (To further clarify, the paper I just linked argues for the existence of lower-dimensional vacua than ours, and the physics that would connect us to such vacua is not precisely Coleman-de Luccia. If we discover supersymmetry at the LHC, other arguments will make it extremely likely that there are four-dimensional supersymmetric vacua that we could tunnel to in the CdL manner.)
Comment: ... and Guth went ahead and applied this idea to cosmology discovering inflation along the way. @Matt - Is that a correct reading of history - barring the contributions of Vilenkin, Starobinsky and others to inflationary theory?
Comment: I'm not an expert on the detailed early history of inflation, but yes, Guth's "old inflation" idea involved tunneling out of a false vacuum.
Comment: @Matt--yes, great answer. I linked the Coleman paper in another question.+1
Answer: Kill all the turtles on which it rests.
Comment: One should not take this advice too literally - otherwise, inflector will have a really bad day ;)
Comment: Yes, I do have a certain fondness for Turtles ;)
Answer: We are only humans. We don't know how to destroy the universe.
Answer: You can't. Anything you do will only have an effect that effects an area that expands (at most) at the speed of light, so it only effects at most a sphere of radius $c t$ after time $t$. Anything else would violate the no-signalling principle which appears fundamental in physics. This means that the photon that just bounced off you into space will outrun the edge of any such an attempt to destroy the universe.
Answer: Find antiuniverse somewhere and annihilate it with what we have here.
Black holes does not work as they evaporate when growing.
Comment: they _evaporate_?
Comment: Yes, http://en.wikipedia.org/wiki/Hawking_radiation
Answer: I think that only an Universe can destroy an Universe (there's a lot of energy implied in doing so). If there is enough mass in our Universe, maybe its end could be a Big Crunch.
Answer: At CERN's website, there was - for the time being - a page (which I cannot find now, someone please help?) about how the LHC could possibly "destroy the earth, the solar system or the whole universe altogether" with possible speculations.
These included creating black holes, strange matter that is more stable than the regular one, and a bunch of other ideas which I don't remember. All of this of course rather bogus, because such collisions occur naturally in cosmic radiation at sufficient frequency.
Comment: http://public.web.cern.ch/public/en/lhc/safety-en.html
Answer: Inverse the forces in nature is the fastest way to destroy it.

Make "Weak force" strong
Make "Strong force" weak

First one will increase radiation and will decay matter to energy instantaneously and second one will explode atom nucleus.
Comment: This makes no sense. What does it mean to make the "strong force weak"? There are different mechanisms that give rise to either force and you can't simply invert their relative strengths at every point in space.
Comment: does it matter? the question was a joke, hence all answers are the same... no need to get technical...
Answer: Dear Splashhit,
the easiest way to destroy the Universe is to continue to drive cars for years.
Whether you do it or not, the global mean temperature will increase from 15 °C to 16 °C or so in a century. When the temperature of the materials and organisms increases by as much as one Celsius degree, they will - according to the IPCC - transform into a deadly plasma that will kill all living life forms and evaporate all stars, ending with a complete cataclysm where the vacuum itself (scared by watching the horror on its most important planet) is eaten by nothingness. If you've ever experienced the staggering heat of 16 °C, you must know what terrible thing I am talking about. It's worse than hell.
Just kidding. There is obviously no threat whatsoever that would be linked to "climate change" as this meaningless tautology is often called. The IPCC is not destroying the Universe but it is surely destroying the ability of the people to think rationally about very basic things - and it is trying to destroy the world economy, too.
Cheers
LM
Answer: Find a logical inconsistency and use it to prove that the universe does not exist.
You could kill all observers, that would make the existence of the universe an unprovable proposition.
Alternately you can just wait for the Big Crunch.
Comment: Or simply refuse to accept the axioms of logic. Then you can insist whatever you want is true.


How to link paragraphs in essays and articles?

Question: All I can find online is cohesion and coherence for paragraphs. But in a essay how can I link all the paragraphs. Any good methods for the university level.
It would be great if I can find an annotated example essay for understanding this.
Comment: What field? I found the my papers for Political Science linked better than Economics, which linked better than Biomedical Science.
Comment: Hi Oncidium, welcome to writing.se! Take the [tour] and visit the [help] for more information.
Answer: In academic and persuasive writing, what you're referring to are often called segues or transitions. They are not used solely to link paragraphs, but any shift in ideas, even within a single paragraph. This is a pretty helpful summary of what transitions are and how they're typically used.
How I've used transitions in the past is reserving the last sentence of each content paragraph for setting up my next bit of evidence or argument. The ideas in your paragraphs do not have to be closely related for this to work, you can use the contrast of the ideas as your segue, or use a third concept to bridge the gap between them, so long as that third thing is previously established in your paper and previously linked to one of the two ideas you're trying to connect in your transition.
Lastly, coherence can be derived simply by organizing the paper so that arguments "flow" more naturally, with earlier ideas laying the foundation for later ones. This is something you can work out while writing, but it's often easier to do after finishing a rough draft.


Media Module Bulk Upload for Image Field

Question: Using Media 7.x-2.x-version I am trying to use the integrated Bulk Upload Module. I have activated Media Bulk Upload sub module as part of Media. Now if I use a image field with media selector I can still upload only one image at a time. Only if I go to "file/add" I have the multiple file upload option. Is this by design or is there a possibilty to use multiple file upload directly when adding content via Image field.
Answer: I'm also faced the same issue. But after applying this patch (check your media module version) it works great.
Answer: Go to Content types -> Manage fields and edit the image field. select "Number of values" as "unlimited" and save. This allows you to add multiple files.
Comment: Yes I know about the unlimited number of values and have set the field like this, but unfortunately it is not possible to bulk upload more than one image at a time, while the same is possible via "file/add". This means I can attach multiple images but need to upload each one separately while I was hoping to be able to bulk upload them.
Answer: I could not find a solution to conveniently bulk upload a number of images directly in a node with the Media Bulk Upload feature. Media Bulk Upload allows me to bulk upload images to the files library (add/files). But if I want to include them in a multiple value image field in a node, I have to add each image separately from the Media library.
So I ended up using Block Upload module. I create the node first without images and then I bulk upload as many images as I like in one step to the image field with the Block Upload module. That's really a great time saver.
Actually there is a issue with the bulk upload form of the module, but the issue can be fixed easily, look here


Can small-caps be automated for abbreviations and acronyms?

Question: Is there a way to force LaTeX to automatically use small-caps for abbreviations and acronyms (or more specifically, strings of two or more uppercase letters)?
Answer: You might want to take a look at the glossaries package.
\usepackage[acronym,smallcaps]{glossaries}
\newacronym{WHO}{WHO}{World Health Organisation}
The \gls{WHO} recommends...

Comment: This would be useful if I were writing an extensive informative paper, but I am more interested in an application for novels. In other words, I would like to see the small-caps styling applied to words such as "AM" and "PM" (where it doesn't necessarily make sense to put such words in a glossary context).
Comment: Wouldnt it be much easier to just do this in the texteditor with find/replace with ? The list of abbreviations used in a novel won't be very big. If you use a texteditor that supports Perl style regex, you can even do this in one go with a simple command.
Comment: @squidbear: I would write with lowercase and periods: a.m. and p.m. Why should they be (small)capitalized when none of the other latin abbreviations are?
Answer: I think it's difficult to implement such macros. However, we can do it with help from some preprocess. It easy to write a script to do this. For example, an one-line script of sed:
sed -e "s/\(\s\)\([A-Z]\+\)\([^A-Z]\)/\1\\\textsc{\2}\3/g" foo.tex

You may modify it as your wish.
On windows platform sed have to be installed manually, from GNUWin32 or MingW. Just write a batch file and configure the editor to call it.
Comment: I thought of doing something similar to that; however, I want to keep this type of styling separate from the content, if at all possible.
Comment: @squidbear: But this way you *can* keep styling separate from content. Your content is in `foo.tex`; this is the master file that you edit. Your styling is in a script. Your makefile (or whatever you use to produce the final PDF document) first invokes the script to produce `bar.tex` from `foo.tex`, and after that it runs pdflatex, etc., on `bar.tex`. File `bar.tex` is just a temporary file that you can delete after compilation.
Comment: A slightly less complicated implementation of that `sed` command is as follows: `sed -E -e "s/([A-Z][A-Z]+)/\\\textsc{\\\MakeLowercase{\1}}/g" foo.tex`. It doesn't do any front/back of word checking, but it does incorporate the use of `\MakeLowercase` to format the small-caps words properly when wrapped in the `\textsc` command.
Answer: If you don't need all of the power of the glossaries package, you could use the acronym package instead. The main idea remains the same. If you want LaTeX to do something with particular types of elements, you must create a markup for them.  So if you want to do this within LaTeX itself, (which IMO is preferable) then you will need to explicily mark the relevant elements every time you use them.  (This also has the advantage that if you decide later that they shouldn't be in small caps, one change will change them all.)  Here's a solution to your problem using the acronym package.
\documentclass{article}
\usepackage{acronym}
\renewcommand*{\acsfont}[1]{\textsc{\MakeLowercase{#1}}}
\newacro{AM}{}
\newacro{PM}{}
\acused{AM}\acused{PM}

\begin{document}

At 3:00~\ac{PM} John went out.  He didn't return until 2:00~\ac{AM}.
\end{document}

(Note that since textsc{AM} is indistinguishable from AM, we need to change your existing uppercase acronyms to lowercase before making them small caps. This is what the \acsfont macro is doing.)
Answer: I've been thinking about this myself, as I will need it soon.
For you, Wouldnt it be much easier to just do this in the texteditor with find x/replace function (\textsc{x})? The list of abbreviations used in a novel won't be very big.
If you use a texteditor that supports Perl style regex or simpler regex, you can even replace all wanted abbreviations in one single run.


Are there downsides to not caring for my Pokemon after a battle?

Question: After each battle in Pokemon sun and moon you get the opportunity to 'care' for your pokemon.
So far I can't tell if this makes any difference to just leaving them.
Are there any down sides to neglecting my pokemon.
Answer: No, there are no downsides, per se. There are just no upsides.
If you do choose to care for them, you will get more buffs as Pokemon have more Affection towards you. A full breakdown of these can be seen in this Q&A.
If you care for your Pokemon after battle, they will have a chance to do things like survive a hit that would have otherwise knocked them out, be more likely to get a critical hit, or dodge an attack. Thus, it's recommended to spend the ~30 seconds brushing your Pokemon after a battle if you receive the prompt.
Comment: Of course, stuffing them full of Rainbow Pokebeans has the same effect :-)
Answer: The after-battle treatment screen is actually Pokemon Refresh. Everything you can do in Refresh, you can do in that screen, with the addition that if your pokemon have taken a certain level of damage or have been hit with a status condition, you can clean them up, dry them off, apply medicine, ect. to give them additional affection.
In Refresh, caring for your pokemon increases its affection for you (note that this a different stat than friendship). A pokemon starts with 0 hearts of affection for you, and this can increase up to a maximum of 5, with each heart of affection after the first giving you additional buffs (such as additional experience, better critical hit ratio, a chance of a focus sash-like effect, ect). After maxing out a pokemon's affection, subsequent attempts to pet or feed the pokemon do not have any additional effect (besides looking adorable); this applies to the after-battle care tools as well. The only exception is the medicine (which looks like a pair of tweezers holding a cotton ball). If your pokemon has a status ailment that persists outside of battle, such as sleep, paralysis, or poison, using the medicine on the pokemon will remove that ailment, saving you money on full heals/antidotes/ect.
Also important to note; if you plan on playing in matches against human opponents or participating in the Battle Tower, note that you can't use the buffs from Refresh.
Answer: One downside, depending on how you look at it, is that certain pokemon like golbat, Type: Null, and Pichu can't evolve without having high friendship. Sure, there may be other ways to evolve them, like getting massages every once or a while, or putting on a soothe bell and leveling them up, but the most efficient way to evolve them is to just pet them once in a while or give them rainbow pokebeans.
Another downside is if your pokemon has a status problem and you dont cure it, you have to use one of your items. And that's wasteful, considering that curing them in Pokemon Refresh is free and doesnt use any of your items.


Programmatically redirect users to the default "access restricted"

Question: I would like to programmatically redirect my users to the default "access restricted" page. I know that I need a "RedirectResponse" object for a simple redirect, but how do I specify the default "access restricted" page here?
Comment: Usually, a "access restricted" page is produced by returning a 403 status code, not redirecting to another page. Did you try something like `return new Response('', Response::HTTP_FORBIDDEN);`
Answer: You can throw an exception at any point in your code:
403:
throw new \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException();

404:
throw new \Symfony\Component\HttpKernel\Exception\NotFoundHttpException();

The exception is then caught by DefaultExceptionHtmlSubscriber and a subrequest for /system/403 or /system/404 is returned, which you can configure in the basic site settings if you don't want to display a generic "access denied" or "not found" page.
Other options depend on where the code is placed:

Return a 403 or 404 response from a controller or a form

Set a response in an event if you are in an event subscriber.

What you should never do is to send a response directly. This doesn't stop the code and produces two responses, one you've sent and one returned by the Drupal kernel. This will result in unpredictable behavior.
Answer: This seems to be the right way:
    $response = new RedirectResponse('/system/403');
    $event->setResponse($response);

Answer: Build your redirect from the system's access denied route.
$url = Url::fromRoute('system.403');
$response = new RedirectResponse($url->toString());

This takes you to the Drupal standard access denied page. The route is defined in system.routing.yml in core.
The top answer will give you a broken looking browser based Access Denied, which may be what you're looking for. If you want your Drupal UI to show, use the above.
Answer: From a page, you can use:
return new \Symfony\Component\HttpFoundation\RedirectResponse(\Drupal::url('your.module.route.name'));

like : http://www.drupal8.ovh/en/tutoriels/88/page-redirection-on-drupal-8
Or from a from submit:
$form_state->setRedirect('your.module.route.name');

Then configure access permission of 'your.module.route.name'
If you dont know how to configure access permision, check:
http://www.drupal8.ovh/en/tutoriels/66/create-a-custom-permission-drupal-8
Comment: I have tried

        $response = new Response('', Response::HTTP_FORBIDDEN);
        $event->setResponse($response);

this shows only a white page to the user. That's too less information. I want to show the default "access denied" page from Drupal.


Soft Bricked Nexus 6P

Question: Back in 2015, I rooted my HTC One M7. It was an adventure; I messed up along the way, soft-bricking my phone. Eventually, though, I managed to get it working again. That was five years ago. So, I might as well have never tried to root a phone, because I've now soft bricked my Nexus 6P—and I don't know how to bring it back to working order. I seem to only ever know just enough to be dangerous.
On the Nexus 6P, the problem is that the phone hangs on the Google logo screen. However, I can boot into the bootloader and get into recovery. I've got TWRP 188.8.131.52 already flashed.
ADB does not recognize the device in the bootloader. It only recognizes the device when it is in TWRP. I am using PowerShell in Windows 10 as my terminal.
Everything went bad when tried to flash SuperSU-v2.82-201705271822. While I had done a factory reset before attempting this, the phone only reset to Android 8.1.0, the earliest build of which was 12-2018. Since the SuperSU I attempted to flash looks to have been from 05-2017 ... well ... my bad. Clearly. Rookie mistake.
This seems fixable, though. I just don't know how to fix it.
My error appears to have blitzed my OS entirely. In TWRP, if I look at the 'sdcard' partition, the only directory is TWRP. None of the Android file folders are there (Downloads, Pictures, etc.). Yet, at the level where 'sdcard' is listed, all the system directories seem to be intact.
Further, if I run 'adb shell su' in PowerShell, I get "su: not found", so my root attempt obviously failed.
In sum:

I have an unlocked bootloader
Device unrecognized by ADB except in TWRP recovery
I am not root
I seem to have no OS (but the directory structure above the 'sdcard' level seems intact)

I tried sideloading a factory *.zip from Google, but I can't do it from PowerShell with the phone unrecognized by ADB. I then tried using the TWRP ADB sideload option, but was told that my *.zip was invalid when I tried it (should I not have tried flashing the whole angler-[etc].zip?).
On XDA, I'm finding a lot of information, but it's not been helpful to me. This seems like a simple issue with a simple solution, but it's one of those "clear only if learned" scenarios, and I haven't learned.
As such, I just need some hand-holding for how to get back to a working OS. It seems that, for things being bad, they're not really that bad. If I just knew what to do and how to do it, I could get out of this pickle. If someone could teach me how to get out of this mess, I'd appreciate it.
Thanks.
Comment: Just to make it clear `adb` never works in bootloader mode. In bootloader mode only `fastboot` works (if the device supports fastboot)! https://android.stackexchange.com/a/221635/2241
Answer: I don't have a full answer for you Ican only help with the issue of your device not being recognized. But since I can't comment I will answer instead.
For your problem with your PC not recognizing your device. When your device is in fastboot mode, and connected to your PC. Goto device manager, there should be an item that matches your device that has a yellow mark showing it needs attention. Update the driver for that item and select the adb driver this should make your PC recognize your device.
This assumes you have the adb drivers installed on tour PC.

Soft Bricked Nexus 6P


Composting and/or using chopped blackberries

Question: I have wild blackberries in my garden that grow like crazy: They grow under the earth, over the earth with offshots - and possibly via seeds - I don't know, I just started gardening. I cut a lot of them and put them into a chipper. Can I put the chipped material (is it called mulch?) on a compost heap or will even the chipped blackberry material grow into blackberry bushes? If I cannot put the blackberry on the compost heap - what should I do with the material instead? One idea is to spread it out and have it dry by the sun. Not sure if that helps for killing the material and/or making the composting faster. Is there a smarter way to use the material.
Answer: They will stop growing when their connection to the roots in the ground is removed. If you chip them and compost them properly, you should be fine.
For eradication you've got 3 options that don't involve chemicals:

Complete removal of all below-ground roots and rhizomes - Since this is in a garden it might not be viable. Even if it is, you probably won't get them all the first time around, but it will be effective fairly quickly.
Vigilant removal of above ground material - the idea here is to remove the plant's ability to produce energy and feed the roots and rhizomes. Over time you will starve and kill the plant. This may be less disruptive to the garden, but if you leave too much above ground the blackberries may be able to produce enough energy to support expanded growth.
Comment: Yes to both of those. Even a inch of stem with a leaf bud and no roots will grow again if the conditions are right. Birds will eat the fruit and spread the seeds everywhere, each seed in its own little packet of "fertilizer".
Comment: Does the blackberry have seeds that might be still in the chopped material and grow? They do have fruits. Also: There is also root in the chopped material - might this grow again?
Comment: @alephzero: Then, how can I use the chipped material without fearing "death by blackberries" (meaning that I put the chipped material onto the compost or on my patch and then I have more blackberry bushes than before)?


Single switch controls GFCI outlet and lights

Question: My mother lives in a senior living apartment building.  The building and its wiring are at least 40 years old.  Her bathroom has one switch that controls both a GFCI outlet (top and bottom) and mirror lights.   Therefore, the night-light that is plugged into the GFCI outlet only works when the mirror lights are switched on. If the mirror lights are off, the night-light will not work.  How dumb!  I want the night-light to work even if the mirror lights are off.   The apartment "electrician" says the problem can't be fixed without ripping out walls.   Can that be true?   If not, how do I make changes to the GFCI and/or the switch so that a night light can be used as it was intended?  There are no other lights or outlets in the bathroom.
Comment: Can you post photos of the insides of the boxes involved?
Comment: Put the night light at the switch, if it has a neutral in there.
Comment: Yeah -- the hot feed's either at the switch (which means you can put the nightlight *there*), or at the receptacle with the switch on a loop (which makes constant powering the receptacle trivial), most likely.  (If it's at the light, then there's a /3 cable going down to either the receptacle or the switch, which means it boils down to one or the other of the above cases, anyway).
Answer: The apartment "electrician" is correct.
The feed for the receptacle is going through the switch. Probably so things don't get left on when someone has left the room. I agree it is not the way it should be but you can't change that.
You could replace the switch (or have the "electrician" replace it) with a lighted switch or a combination switch / receptacle like this and wire the receptacle always hot like it should be. (The lighted switch is lit when the switch is off.)
Either way you can have a night light.
Good luck and stay safe!
Answer: The only other thing you could do is add a new GFCI below the switch or use a combo GFCI/Switch just for the night light. Be sure and get permission from the house electrician or have him do it.


Base running in softball

Question: First base is occupied. Batter hits the ball and is thrown out at first (first). Does the runner have to be tagged at second or is it a force out.?
Answer: After the runner is thrown out at first, the runner who was on first is no longer forced anywhere.  He must be tagged.
There are two reasons why it is best to throw out the lead runner first:

If the runner is not forced at the next base, he must be tagged.  If you throw out the runner behind the lead runner, he is no longer forced to advance (he could return to the previous base), and you create extra work for yourself by having to tag him.
The lead runner is the closest runner to home plate - i.e. the closest to scoring.
Comment: @KKendall.  Sure.  But it's still not ideal.  Ideally, you have the 3-6-3 double play where the firstbasemen throws to the shortstop covering second, who in turn throws it back to first to get the runner there.  The fact that a firstbaseman would go to this length to ensure he gets the lead runner shows how important it is considered to preserve the force out.
Comment: I probably should have added the comment to the question, not this answer...
Comment: Just to add my 2 cents... This is a very common play in the MLB, when there is a runner on first and the ball is hit to the first baseman. If you look at the video in the link, Wilmer Flores tagged the runner as opposed to just touching second base: http://m.mlb.com/video/topic/6479266/v453814783/nymmia-campbell-begins-a-36-double-play
Comment: Yes I agree with you.

Base running in softball


closure of Context free grammer to homomorphism using PDA

Question: I was looking online, on sipser book, and on lecture notes and I can't find a proof to closure of context free languages to homomorphism that using PDA instead of CFG.
I'm not looking for a full and formal proof, I just want to understand the general idea.
Answer: The idea is to replace a single transition by a sequence of transitions.
Suppose for example that $h(\sigma) = \tau_1 \ldots \tau_\ell$, and consider a transition at state $p$ which replaces the symbol $A$ on the stack with the string $\alpha$, and moves to state $q$.
We replace this transition by a sequence of transitions $p \to s_1 \to \cdots \to s_{\ell-1} \to q$, which read the letters $\tau_1,\ldots,\ell$ in sequence; the states $s_1,\ldots,s_{\ell-1}$ are unique for handling this transition. The first transition $p \to s_1$ replaces $A$ with $\alpha$, and the rest don't change the stack.
Comment: So basically the idea is the same as the concept of proof that regular languages are closed under homomorphism?
And a little question, Do we add states between p and q and basically "force" the transition between the new states we add to be made only for the input letters that the homomorphism defines?
And in the transitions between p and q we only read from the input, without push / pop from the stack right?
Comment: Yes, the idea is very similar. There are some implementation details, which are better to work out on one's own; they depend to some extent on the exact PDA model, and also there are several different possible implementations.
Comment: thank you very much. I appreciate your help!!!


Where are the save files for the Steam edition of Assassins Creed II located?

Question: Where are the Assassins Creed II save files? I found a few locations in Google, but most of them do not exist on my system. I also found an article that Ubisoft patched AC2 to save locally. Are the save files for the Steam version located in the Steam cloud?
Answer: I finally found the folder:
[User HOME Directory]/AppData/Local/Ubisoft Game Launcher/<RANDOM NAME>/4

Answer: If you're looking for the Assassin's Creed 3 save files:
In Windows 7 x64 I found the save games (not the config files) under this folder:
%ProgramFiles(x86)%\Ubisoft\Ubisoft Game Launcher\savegames\{Unique Key}\54\

Where {Unique Key} is a personal ID for your UPlay account.
If you're on 32-bit Win 7 they're probably here:
%ProgramFiles%\Ubisoft\Ubisoft Game Launcher\savegames\{Unique Key}\54\

I'm using the Steam version.  I would think that other versions would be the same but I can't be sure on that.
Other UPlay games are in similar locations, with a different number at the end.  For example, I think Far Cry 3 is under 46 and Assassin's Creed Revelations is under 40.
Generally, saves in these locations should be synced via UPlay but I've had problems with that working before so it's good to know where these are and have a backup.
Answer: I could not find the folder spoken of in the accepted answer, with the Steam version of Assassins Creed II. However, it appears that Uplay stores save game data in the cloud as I was able to start where I left off on a different computer.
Answer: I found a "Saved Games" folder on this path:
%APPDATA%\Ubisoft\Assassin's Creed
also written like:
[DRIVE LETTER]:\Users\\[USERNAME]\AppData\Roaming\Ubisoft\Assassin's Creed.
Replace [DRIVE LETTER] with the drive you are using and [USERNAME] with your username.
By the way, I am using a windows 7 computer.


is it legal to be on a b1visa and work with clients in the USA but bill them from my home country?

Question: I have my own consulting company in Europe. Can I be on a b1 visa and work with  and get new clients in the USA and bill them from my home country? I will be in the USA for about  4 months per year.
Answer: B1 visas are complicated, ill defined animals but this is not allowed. In the normal course of events, this is clearly not allowed but there's a "B1 in lieu of H-1" (or H-3) scheme where it might be. But, in 9 FAM 402.2-5(F)  (U) Aliens Normally Classifiable H1 or H3

In order for an employer to be considered a 'foreign firm' the entity must have an office abroad and its payroll must be disbursed abroad

You do not have an office abroad, do you?
But also

the source of the employee's salary must be abroad;

Which I believe is not the case.
Finally, consulting a lawyer is advised.
Comment: Just to add that it probably *would* be legal to go to the US, solicit for customers, sign them up, and then return to your country, do the work there, and bill them. Soliciting for sales is allowed.
Comment: Since the question speaks of a "company" I suspect that there is a distinct legal entity involved and therefore both that there is an office abroad, even if it is just mellon face's residence, and that mellon face's income is foreign sourced. My question would be whether mellon face is properly considered to be "customarily employed" by that company.


Google Mail autocomplete contacts showing outdated address

Question: I have contacts who have changed their email addresses. Autocomplete in Google Mail still includes those addresses although I have deleted them from my contacts list. How can I delete those individual addresses?
Comment: Is this the same issue? [Remove email address from suggestions in To field on Gmail](https://webapps.stackexchange.com/q/18021/354)
Answer: It's included in the linked question, but make sure you go into contacts and search for the email address in question. We recently changed domain names at work, and I've been walking everyone through this process. The gotcha is usually that everyone in the directory (automatically created by Google) still gets listed in the 'Other Contacts' section of Contacts, because you've emailed (or received mail?) from them. So, there are literally hundreds of "contacts" with zero information on them.

Go to Contacts
Search for the email in question (in our case, for the @example.com domain)
Scroll down to "Other Contacts"
Select the top checkbox
Scroll down, and holding Shift, select the bottom box, which should result in all of them being selected.
Delete with extreme prejudice.
Then go into actual contacts and edit/update as needed (it sounds like you already did this step).
Answer: The problem I had with this is that there was no "Other Contacts" shown in my contact list so the problem email addresses didn't show up in a Search (or anywhere besides the auto-complete feature).  After a lot of trial and error, I realized that my "Other Contacts" group didn't show up because I had changed the Gmail Settings for "Create contacts for auto-complete:" to "I'll add contacts myself".  I couldn't see the auto-complete contacts anywhere, but the (incorrect) email addresses were still being shown when I started to type a name in the "To:" field of a new email.
To be able to delete (or correct) these incorrect auto-complete email addresses, I had to first change Gmail Settings for "Create contacts for auto-complete:" to "...add them to Other Contacts...".  Then my Other Contacts group started showing up again still filled with over 200 outdated email addresses, which I was then able to delete as normal.  After contacts were synced to my phone, the outdated email addresses were gone from the auto-complete feature there as well.
Once all the problem email addresses are deleted or corrected in "Other Contacts", you can change Settings for "Create contacts for auto-complete:" back to "I'll add contacts myself" again.  Of course the "Other Contacts" group will again disappear but remaining email addresses will still be used with auto-complete for any existing "Other Contacts" that you didn't delete.
Answer: Thanks for solving my problem!  I found that I didn't even have to change the Gmail Settings to see the 'other contacts' section.  It was rather laborious to delete all of them, but there's a fairly fast way to do it:

Hover over the contact name
Click on the vertical dots to the right ('more actions')
Press down arrow twice to highlight 'delete', press 'enter', then 'enter' again to confirm

Using the right hand on the mouse and the left hand on the keyboard, you can do it pretty quickly - about 3 seconds per deletion, once you get into the rhythm of it.  I deleted about 50 contacts in 10 minutes.
Answer: The easiest solution is to use Samsung Email app.  Next to every email address in the drop down list is an x.  To remove the address, click on the x.  This removes that address from Samsung Email app but not from Gmail.  I am disappointed that Gmail has not provided such a simple solution.  However, I am not surprised because Gmail is not user friendly.
Furthermore, the 'Gmail methods' would not remove all of the bad email addresses.  Some addresses I could only remove in the Samsung Email app.
I thought the option
 'Gmail/Setting/Create contacts for autocomplete/I'll add contacts myself'
 would let me start from scratch, but it does not.
And, what is the purpose of 'Other Contacts'. Also, with the 'g
Gmail methods', you will have to fix every Gmail account.
Comment: Welcome to [webapps.se]! Switching email providers isn't a viable option, I guess ...
Comment: I did not say change email providers. Samsung email is a email app that supports Gmail. When I want to send an email I will use Samsung email


What is the origin of the word "Nativity" as a title for Christ's Advent?

Question: I am interested in knowing when the term "Nativity" came into popular use for Christ's Advent and what are its origins.
Comment: General uses of "nativity" could be interesting, especially those biblical, as they set a pattern for "The Nativity." However, you are correct that I am most interested in how it became "The Nativity."
Comment: looking at https://books.google.com/ngrams/graph?content=nativity&case_insensitive=on&year_start=1500&year_end=2008&corpus=15&smoothing=7&share=&direct_url=t4%3B%2Cnativity%3B%2Cc0%3B%2Cs0%3B%3BNativity%3B%2Cc0%3B%3Bnativity%3B%2Cc0%3B%3BNATIVITY%3B%2Cc0 I'd say about 1625, but this is usage in books and its less than a tenth of a percent so it isn't exact
Comment: The phrase "nativity of Jesus" (with minor sp. variation) is attested in Middle English, but so is "nativity" with reference to the births of John the Baptist and Mary.  Am I correct in assuming that such details aren't relevant, since you are focusing here on when "the nativity," by itself, came to be understood as referring to the birth of Christ?
Answer: In Catholic culture it comes from the Latin.

"Festum Nativitatis Domini Nostri Jesu Christi"  (the Feast of the Nativity of Our Lord Jesus Christ) and the shorter form,  "Dies Natalis Domini"  (the Birthday of Our Lord).
From these Latin names most nations obtained their popular terms for the Christmas feast: "Il Natale" in Italy, "La Navidad" in Spain, "Natal" in Portugal, "Nadal" in southern France, "Nadolig" in Wales (and probably the Gaelic "Nollaig," as well). The Greek "Genethlia" means "Nativity," as do the names for Christmas in Hungarian ("Karacsony") and in most of the Slavic languages: "Boze Narodzenie" (God's Birth) in Polish; "Rozhdestvo Khrista" (Christ's Birth) in Russian and Ukrainian.
The French word Noel can be explained as either coming from the Latin "natalis" (birthday) or from the word "nowel" which means "news." In an old English Christmas verse the angel says:
I come from hevin to tell
   The best nowellis that ever befell.
It is possible that both explanations are right. "Noel" and "nowel" may be words of different origin that have become identical in meaning because they are pronounced the same. -  History & Origin: Feast of the Nativity

The year 336 seems to be the first recorded date of Christmas at Rome.

The Nativity stories of Matthew and Luke are prominent in the gospels and early Christian writers suggested various dates for the anniversary. The first recorded Christmas celebration was in Rome in 336. - Wikipedia

Etymologically the word nativity came into use in the 12th century:

nativity (n.) c. 1200, from Old French nativité "birth" (12c.), from Late Latin nativitatem (nominative nativitas) "birth," from Latin nativus "born, native" (see native (adj.)). Late Old English had nativiteð, from earlier Old French nativited.  - Dictionary.com, etymonline.com


Does a lady count as a Panim Chadashos?

Question: Even Ha'Ezer 62:7 says that in order to say Sheva Brachos at the meals that are made for the week after the wedding for the Chassan and Kallah there needs to be a Panim Chadashos (new face) present. Can a lady count as a Panim Chadashos or only a man?
Comment: http://www.haoros.com/Archive/index.asp?kovetz=913&cat=9&haoro=8
Comment: Its a machloket rishonim and achronim IIRC
Comment: I remember seeing somewhere a choshevh women can count.
Comment: Do the panim chadashos need to be counted as part of the minyan for sheva brachos?
Answer: Rabbi Mordechai Farkash (from Bellevue, Washington) suggests that this is dependant on the reason for the requirement of having a Panim Chadashos to be able to say Sheva Brochos. The Rambam (Hilchos Brochos 2:10) implies that when there is a new person present who has not yet heard the Sheva Brochos he becomes obligated to say them, which is why we can recite them again. However the Rosh (Kesuvos Siman 13) rules that even one who has already heard the brochas can be considered a Ponim Chadoshos if he did not participate in the eating at that time because his presence causes an increased level of joy. It would seem that the Rambam would require a male to be the Panim Chadoshos, because it must be someone who becomes obligated to recite the brochos himself. The Rosh on the other hand, would allow any one who brings additional joy - including a women - to bring the joy and thereby create a new obligation to say the brochos.
The Shulchan Aruch (EH 62:8) rules in accordance with the Rosh (that the requirement is because of joy), and it would therefore seem to follow that even a women could be counted. However, the Pischei Teshuva (:14) cites the Zechor Le'avraham that a women can not be considered the Ponim Chadashos. Rabbi Farkash concludes that common practise is not to use a women, and proposes that this may be due to issues of modesty.
Comment: Also, what is modest about not using a woman? I have been to multiple Sheva Brachos meals where I don't know who the Panim Chadashos are. In other words, it's not a very public, outward role. If the meal is such that women will be attending anyway, I'm not sure what is more or less modest about being the official Panim Chadashos. (I note that R Farkash himself doesn't seem convinced by his suggestion, noting that the matter requires further study.)
Comment: Why skip the Ritva and Chasam Sofer?
Comment: From the Aruch Hashulchan 62:23... It seems only men .

Does a lady count as a Panim Chadashos?


Partial Data Sandboxes - price?

Question: The new Partial Data Sandboxes sound extremely useful but to determine how useful they are I need to find out the price - anyone got any ideas?
Answer: To answer my own question - from the grapevine I'm hearing roughly 20% of annual license cost for a partial data sandbox, and roughly 30% for a full one.
Answer: As salesforce has a license based model, much depends on your total amount of licenses and feature setup. As sandboxes are a copy their price is in relation to your production contract.
You'll need to contact your official salesforce account executive for any pricing information.
Answer: This Sandbox type is available in Enterprise, Performance, and  Unlimited editions.It depends on licenses you are using. It is priced with your existing production. Contact Salesforce for any price information.
Answer: We are a pretty big SFDC UE customer.  Our use case was to copy over some selected custom object values that act as reference/configuration tables rather than going through data loader on each refresh.
This wasn't enough to justify accepting the SFDC quote of one partial data sandbox that was in Maserati-territory, price-wise.
Answer: Flosum has created a definitive guide on Salesforce sandboxes. It includes everything you wanted to know about Salesforce Sandboxes.
Comment: the link doesn't have a definite answer to the pricing of partial sandbox. thou it gives a consolidated view of sandboxes, it doesn't directly answer the question.
Comment: I voted up as slice 20 (not sure if this was updated since vote down) has a similar description as answered by codeulike

Partial Data Sandboxes - price?


Is there a possibility that the whole blockchain system will be DOWN?

Question: I want to know if there is a possibility that all of our hard-earned bitcoins will turn to dust if the Blockchain system will get shut down or stop. Is this possible? I really have a big question mark in my mind since Bitcoin is a digital thing.
Comment: Related: [If all block chain copies get deleted, what would happen?](http://bitcoin.stackexchange.com/q/30908/4975)
Answer: http://p2pfoundation.net/Blockchain

"The blockchain is nothing more than a long string of transactions,
  each of which refers to an earlier record in the chain. But Bitcoin
  users do not directly make the updates to the blockchain. In order to
  transfer coins to someone else, you have to create a request and
  broadcast it over the Bitcoin peer-to-peer network. After that, it's
  in the hands of the miners. They scoop up the requests and do a few
  checks to make sure that the signature is correct and that there are
  enough bitcoins to make the transaction; then they bundle the new
  records into a block and add it to the end of the blockchain."

I don't think that it will happen. As long as there is miners to "scoop" up the transactions, blockchain will still work as it should be. Miners will not stop since they are earning worth of bitcoins from transactions fees.
Answer: First, remember that everyone running a full node has a complete copy of the blockchain (minus some optional pruning).  Also, many who run full nodes have their own backup copies of this blockchain.  I, alone, have 3 up-to-date copies of the blockchain at my home.
Lets assume that somehow, for some reason, all full nodes in the world were simultaneously shut off.  At that point, the Bitcoin network would be off...but not dead.  At any point, these full nodes could switch back on one by one, and the network would continue with the exact same blockchain of transaction history that it had before.  The nodes would sync again, and the network would continue on as if nothing even happened.
Because of the decentralized, redundant nature of the Bitcoin network, this mass "switch off" has an extremely small probability of happening.  It would basically have to coincide with the entire internet getting switched off, and remember that the internet is also decentralized and redundant.
So yes, the Bitcoin network could, in theory, go down.  However, even if it did, the only way it could not be recovered is if the thousands of full nodes and their thousands of backups were also destroyed.  Anything is possible...but it's so unlikely that it's probably not worth worrying about.


Michigan's Pole Star

Question: Unfortunately, I'm not any good at figuring these things out myself so hope for help here. If the (true) north pole were over the Keweenaw Peninsula of Northern Michigan, what would the North Star be; a star, similar to Polaris that never sets? Or, what star would be directly overhead? I couldn't even pick out Venus or Mars in the night sky when I was younger and now, for personal reasons, I'm unable to go out and look. Any help would be incredibly appreciated. Thank you
Comment: Your question is not clear to me. Polaris is called the pole star because the axis of rotation of the earth points very close to its  direction. The star directly above you depends on the time. As earth spins in space the stars appear to move, so different stars appear to be above you at different times. These also change according to the seasons, as the earth moves around the sun.
Comment: Your answer isn't clear to me. I understand about the axis of rotation and so on. What if the axis of rotation changed, say, on 8/4/2017, making the UP of Michigan the North Pole. Were that to happen and the physical position of the Earth did NOT change; only the axis of rotation, how would I figure out what the new pole star would be? I'm not asking anyone to do the work for me. I'm asking how to figure it out. I want to do the research myself. However, should I be unable to, I am quite willing to give the person credit for the information I receive. Thank you.
Answer: It would depend on what time the Earth started to spin around Michigan. There is no way to answer this without saying what time, time of year, and which century (or at least millennium) it happens.
Edit: Hi Dayna. Thanks for the the time of year the Keweenaw Peninsula becomes the North Pole. One could be omniscient except for that and not know this. But we also still haven't ruled out a single star since your OP. With the time though we could tell you exactly what star. The decade is not important. What century or part of history it happens, yes but not the decade. (yes, astronomy is weird).
Comment: The UP being at about 47° latitude, your new north star would be some star currently in the ring at 47° declination.
Comment: Are all of you saying that there is no star over the UP of Michigan like there is over the North Pole? Let's say something changed on 8/4/2017 causing the UP to become the physical north pole with no physical change to the Earth, only the axis changing, etc. That's the question I'm asking. What star would always be in the sky over the UP like Polaris is always over the North Pole. Since Polaris is always over the North Pole for usually around 5000 years, I have difficulty understanding why one wouldn't be over every other area in the world within the same guidelines. Does the extra info help?
Comment: All locations on earth except the north and south pole get star trails. Which star i directly overhead depends on the time of day. http://apod.nasa.gov/apod/ap100711.html Click on the image to get the uncompressed view.
Comment: I appreciate the extra help, Stranger. I don't think I'm asking the question correctly, though. Thanks.
Comment: user6784: I still don't know the exact answer, but appreciate the information. I have accepted your answer with regards to my edit (and yours) Thanks much. (and, yes, astronomy is very confusing to me--love science, just not this part of it!)
Comment: The time of day the Earth started to spin around Michigan would also be important.

Michigan's Pole Star


how to set automatic git pull from bitbucket and complie project on ec2 instance create event with auto scaling

Question: I have just started reading about AWS services. I have a project where the backend is created with Spring-Boot, front-end is created with React and PostgreSQL is used as database. Both backend and frontend is different bitbucket repository. I want to use two different EC2 instance for front & back-end and RDS for PostgreSQL. Now I also want to use the autoscaling feature. The problem is how can I set the autoscaling feature in such a fashion where it automatically clone the app from bitbucket and then run a shell script file to compile and run the application.
Comment: This could be done with a [cloud init user data](https://cloudinit.readthedocs.io/en/latest/topics/format.html) section or with a systemd unit... as well as a cron job and many other ways. We would need more context on how you are deploying these instances. What process are you using to make the AMIs, what does the pipeline look like, what tools are you using?
Answer: You want to make use of user_data scripts.
It's basically a bootstrap shell script that gets executed on an instance during launch.
You can embed your app configuration script in there (either directly via bash, or have it call your configuration management software like Ansible or Chef).
Then, if you attach this script to a Launch Template or a Launch Configuration (which is an instance template required as part of an AWS ASG), it will be applied to the whole autoscaling group.
Then, when you have a scaling event, any new instances that come up in the ASG will run the script and deploy your code.
However, I would recommend you look into immutable infrastructure instead.  I.e. set up automation (i.e. via Packer) that builds your application code into your AMI, with user_data only used for actually starting the app.
Then, when you have a new build, have the same automation build a new AMI and replace your ASG (note you'll need to have your ASG created/deployed in a programmatic fashion.. I personally recommend Terraform).


Uk licence / no uk registered address

Question: Have uk driving licence  moving to france...when my house sold I wont have a uk address ..is my licence valid to drive on last known address? ..in the interim whilst I get new address ?
Answer: In principle, you just notify DVLC of your new address.  The fact that it is France is not a problem.  As the law stands at the moment, you can continue driving on your UK licence until it needs renewing (at which point you will have to replace it with a French one).
However unless you have been living under a rock for the last two years, you cannot have failed to notice that the UK is currently committed to leaving the EU on 29th March (although informed opinion appears to be that this might be pushed back by a few months).  Unless the UK leaves with a deal which involves a transition period (which is not looking particularly likely at the moment), your UK driving licence will cease to be valid when we leave.
UK government advice is that you should exchange your UK licence for a French one before 29th March.
Comment: Thankyou martin, however have spoken with dvla who clearly advise you cannot have foreign address registered against uk licence......  In the interim it poses a problem whilst in between addresses ?
Comment: @AudreySimmonds That cannot be right.  DVLA need to be able to contact you at your registered address.  If your registered address is not in UK, they can't.  What you cannot do is change your registered address online if you are not in the UK.  However, this is all irrelevant; you need to replace your UK driving licence as soon as you are resident in France.

Uk licence / no uk registered address


Would foil print get damaged if it stretches over the folds (edges) of the packaging?

Question: If you have a gold foil print crossing from one to another side of the box (a simple skincare packaging cardboard box -like in the example), is there any danger of the foil getting damaged when the cardboard is folded and bended on those edges?
Answer: Because the foil overlay is to be considered a distinct and separate layer to the packaging, it will have semi-independent characteristics of note.
The typical method of addressing this bending effect/problem is that the folded sections are embossed at the point of the bend. The foil has to "travel" a greater distance to cross the valley created.
Along with creating an easier folding location, the valley/embossing pre-stresses the foil and shortens the distance once the part is bent.

The top drawing shows a depressed/embossed section (not to scale) with a top dotted line representing the foil if it was not embossed. The length of the top dotted line is much less than the total of the two angled lines below it.
The bottom drawing shows that the panels can be folded to 90° while maintaining the same dimensions of the foil that crosses the valley, so to speak.
If you are having a product manufactured to your specifications, the vendor should have this knowledge and should have equipment designed to perform such actions.
Once the product is constructed, the edges will indeed be subject to wear and damage, but there's little that can be done from a design aspect to mitigate this aspect.
Comment: Thank you!  Do you think I should check with the manufacturer if they understand these principles or ask for this treatment?
If so, what should I ask them or what kind of note should I add to the design specs?
Comment: Your question here, posed to the manufacturer should generate a similar answer, perhaps more technically presented. Depending on the confidence you have with the vendor, you may not want to provide "leading" suggestions. Let them give you the answer, not the other way around!


What is the need for private IP addressing?

Question: I'm not able to get what a private IP address is, and why is it used?
Though I searched for it in Google, I'm not able to get it. Can anyone explain me with an example?
Comment: What do you mean by, "_I'm not able to get what a private IP..._?"
Comment: I'm not able to understand what and why a private IP is used for. @RonMaupin
Answer: Private IPv4 addresses allow you to run a network without applying for public IP addresses at your regional registry. Since IPv4 addresses have run out it's the only way to set up a new network or expand an existing one.
Private IPv6 addresses allow you to design your network in such a way that some entirely local services simply can't communicate with the outside world.
Answer: I think your questions can be answered by looking at the RFCs. RFC 1918, Address Allocation for Private Internets defines private IP addressing.
You can make up your own addressing from any of the private IP address ranges defined in Section 3:

Private Address Space

The Internet Assigned Numbers Authority (IANA) has reserved the
following three blocks of the IP address space for private internets:
<code> 10.0.0.0        -   10.255.255.255  (10/8 prefix)
 172.16.0.0      -   172.31.255.255  (172.16/12 prefix)
 192.168.0.0     -   192.168.255.255 (192.168/16 prefix)
</code>

Section 2 gives the reason for private IP addressing:

Motivation

With the proliferation of TCP/IP technology worldwide, including
outside the Internet itself, an increasing number of non-connected
enterprises use this technology and its addressing capabilities for
sole intra-enterprise communications, without any intention to ever
directly connect to other enterprises or the Internet itself.
The Internet has grown beyond anyone's expectations. Sustained
exponential growth continues to introduce new challenges.  One
challenge is a concern within the community that globally unique
address space will be exhausted. A separate and far more pressing
concern is that the amount of routing overhead will grow beyond the
capabilities of Internet Service Providers. Efforts are in progress
within the community to find long term solutions to both of these
problems. Meanwhile it is necessary to revisit address allocation
procedures, and their impact on the Internet routing system.
To contain growth of routing overhead, an Internet Provider obtains a
block of address space from an address registry, and then assigns to
its customers addresses from within that block based on each customer
requirement. The result of this process is that routes to many
customers will be aggregated together, and will appear to other
providers as a single route [RFC1518], [RFC1519].  In order for route
aggregation to be effective, Internet providers encourage customers
joining their network to use the provider's block, and thus renumber
their computers. Such encouragement may become a requirement in the
future.
With the current size of the Internet and its growth rate it is no
longer realistic to assume that by virtue of acquiring globally unique
IP addresses out of an Internet registry an organization that acquires
such addresses would have Internet-wide IP connectivity once the
organization gets connected to the Internet. To the contrary, it is
quite likely that when the organization would connect to the Internet
to achieve Internet-wide IP connectivity the organization would need
to change IP addresses (renumber) all of its public hosts (hosts that
require Internet-wide IP connectivity), regardless of whether the
addresses used by the organization initially were globally unique or
not.
It has been typical to assign globally unique addresses to all hosts
that use TCP/IP. In order to extend the life of the IPv4 address
space, address registries are requiring more justification than ever
before, making it harder for organizations to acquire additional
address space [RFC1466].
Hosts within enterprises that use IP can be partitioned into three
categories:
Category 1: hosts that do not require access to hosts in other
enterprises or the Internet at large; hosts within this category may
use IP addresses that are unambiguous within an enterprise, but may be
ambiguous between enterprises.
Category 2: hosts that need access to a limited set of outside
services (e.g., E-mail, FTP, netnews, remote login) which can be
handled by mediating gateways (e.g., application layer gateways). For
many hosts in this category an unrestricted external access (provided
via IP connectivity) may be unnecessary and even undesirable for
privacy/security reasons. Just like hosts within the first category,
such hosts may use IP addresses that are unambiguous within an
enterprise, but may be ambiguous between enterprises.
Category 3: hosts that need network layer access outside the
enterprise (provided via IP connectivity); hosts in the last category
require IP addresses that are globally unambiguous.
We will refer to the hosts in the first and second categories as
"private".  We will refer to the hosts in the third category as
"public".
Many applications require connectivity only within one enterprise and
do not need external (outside the enterprise) connectivity for the
majority of internal hosts. In larger enterprises it is often easy to
identify a substantial number of hosts using TCP/IP that do not need
network layer connectivity outside the enterprise.
Some examples, where external connectivity might not be required, are:

A large airport which has its arrival/departure displays individually    addressable via TCP/IP. It is very unlikely that these
displays need    to be directly accessible from other networks.

Large organizations like banks and retail chains are    switching to TCP/IP for their internal communication. Large    numbers of local
workstations like cash registers, money    machines, and equipment at
clerical positions rarely need    to have such connectivity.

For security reasons, many enterprises use application    layer gateways to connect their internal network to the    Internet.  The
internal network usually does not have    direct access to the
Internet, thus only one or more    gateways are visible from the
Internet. In this case, the    internal network can use non-unique IP
network numbers.

Interfaces of routers on an internal network usually do not    need to be directly accessible from outside the enterprise.

Basically, without private IP addressing, we would have run out of IPv4 addresses many years ago. There simply are not enough IPv4 addresses to for everyone to have a unique IPv4 address, which was the original premise of IP. To restore this premise and the end-to-end nature of IP, the IETF created IPv6.
Comment: Perfect ! Great information.
Answer: (note: this answer limits itself to IPv4, the IPv6 side of things is interesting but it's drifting a bit far from the question topic)
The original intent of private addresses was to allow people to run networks that didn't directly exchange packets with the global Internet without needing to assign global addresses to all machines on those networks. This saved addresses, and reduced the likelihood of inadvertant communication between those hosts and the outside works.
Later NAT came along. This allowed hosts with private addresses to make outgoing TCP/UDP connections to hosts on the public Internet. The NAT would replace the address and port used by the client with a globally reachable address and a suitable port (which may or may not be the same as the port the client originally used) and keep a mapping table so that replies could be translated.
Many companies found the advantages of running private IP addresses with NAT compelling. There was less possibility of inadvertantly exposing stuff to the whole world, no need to justify address usage, no need to pay per-address fees that some ISPs charged and for smaller companies no need to readdress their systems when changing ISP (for larger companies the final point was not an issue because they could get provider-independent address allocations).
In the home and mobile sectors too NAT became common. In the home case NAT became ubiquitous with the move from plain modems to "home routers". In the mobile case NAT was implemented at the ISP level.
So nowadays the vast majority of end-user systems use a private IP address behind a NAT.
Comment: So, the reasons for the creation of private addressing given in the RFC for private addressing do not meet your approval? As it says, the real motivation was the growth of the Internet routing table: "_A separate and far more pressing concern is that the amount of routing overhead will grow beyond the capabilities of Internet Service Providers._"


Why does my Finepix S2950 not show the image quality I expect?

Question: I am a little confused as to why my Finepix S2950 takes photos like it does. I seem to be able to take great Macro Shots, but not landscapes. I have noticed that if I zoom into a picture enough I can see that the individual pixels are all over the show. Compared with another image that a professional has taken and the difference is noticeable. Here is a part of one of my photos zoomed to 500%. I'm just a little confused as to whether my camera is performing normally or not. It wasn't exactly a cheap camera, but its not a DSLR. My pictures only ever seem to look good when I am zoomed out a bit. They don't look very nice at 100% real size. Not being able to post images is really irritating.
Comment: Could you post a 100% image?  When you're zoomed in as far as you are, it's hard to tell what is the image quality and what's the distortion introduced by zooming beyond the ability of the camera.
Comment: Something else to watch out for, which I didn't mention in my answer, is JPEG compression noise. Make sure you have the in-camera image quality settings set to their highest level. Some subjects (like landscapes) tend to be more susceptible to JPEG compression noise than others.
Comment: Zooming any picture to 500% is going to look bad no matter the camera
Comment: I bought this same camera and it is killing me. how do you get better image. what ISO setting should I use for normal day to day shooting?
Answer: A (simplified) Look at Camera Sensors
The sensor on your camera is 14 megapixels and 6.17x4.55 mm in size. By comparison, a Nikon D3100 (an entry-level DSLR) has a sensor that is also 14 megapixels, but its physical size is 23.1 x 15.4 mm.
Even more expensive DSLRs, known as "Full frame," have a sensor that is roughly the size of 35mm film (about 36 x 24 mm).
Why this matters:
Sensor size is important because it tells us something about pixel size. Think of each pixel on a sensor as a rain gauge, basically a small cup that catches water. Photons of light striking that pixel are like individual rain drops. When you take a picture, the camera opens the shutter and allows light (rain drops) to land on the sensor, falling on individual pixels (rain gauges). When the exposure is done, the camera closes the shutter and measures the figurative water level of each pixel, and from that information assembles an image.
Now, what would happen if we make the opening on a rain gauge bigger? Well, it would be able to collect water faster because it would collect more rain drops. That means you could leave it outside less time and collect the same amount of water. Or, conversely, you could collect more water in the same amount of time as you could with a smaller rain gauge.
Now back to cameras:
A camera with the same megapixel count (the same number of pixels) but with a larger sensor will collect more light per pixel than a camera with a smaller sensor. When you are dealing with the high shutter speeds that are typical for hand-held photography, the effect of catching or missing individual photons (raindrops) starts to matter. This effect presents itself visibly as "noise" in the image when viewed at 100%, as some nearby pixels catch more more photons than others (due to their random nature).
The larger the pixels, the less the random nature of light effects your image. You have actually observed this effect for yourself when you say that your pictures look good when you zoom out. By zooming out you are in effect blending nearby pixels together, creating  fewer but larger pixels.
The reality of the situation:
Most pictures, even those a professional has taken, are never viewed at 100%. Whether they are uploaded to the web or printed on a photo printer, almost all images undergo some amount of resizing, de-noising, and editing before you see them.
As you will often hear repeated on this site, the quality of a photograph ultimately has far more to do with the photographer than the camera, so you shouldn't worry if your images display some noise at 100%. If it really bothers you, there are some things that you can do to try to decrease the noise you see in your images:

Pay attention to the ISO your camera is using. This is related to how much light is hitting the sensor, and how much the camera has to scale the values it measures from each pixel to get a bright looking image.
Post-process your images with a noise-reduction filter.
Comment: Thankyou. I most often shoot at 64 or 100 ISO however. I will try noise reduction.


Circle/Rounded UIView Swift - not Square without corner radius

Question: I would like to have a "real" rounded UIView, to avoid to have a square view with corner radius applied.
Because I'm using gravity, and my circles are not well displayed because they cannot touch each other in the corner (the screen is from the "Debug View Hierarchy" button to see the screen in 3D :

My actual code for the rounded UIView :
 import Foundation
import UIKit
@IBDesignable class CircleView:UIView  {
    override init (frame : CGRect) {
        super.init(frame : frame)
        self.layer.cornerRadius = frame.width / 2
        self.clipsToBounds = true
        addBehavior()
    }
    convenience init () {
        self.init(frame:CGRect(x: 0, y: 0, width: 50   , height: 50))
        self.layer.cornerRadius = self.frame.width / 2
        self.clipsToBounds = true
    }
    required init(coder aDecoder: NSCoder) {
        fatalError("This class does not support NSCoding")
    }
    func addBehavior (){
        //print("Add all the behavior here")
    }
}

Thank you !!
Comment: did you try search google for uikit gravity circles' ? ;) < 30s and I found multiple hits
Answer:
I'm using gravity, and my circles are not well displayed because they cannot touch each other in the corner

So it has nothing to do with drawing: it has to do with how your views collide, i.e. where the dynamic animation system thinks their edges are. This problem is solved in iOS 9 by setting the view's collisionBoundsType to a circle.
Comment: ```override var collisionBoundsType: UIDynamicItemCollisionBoundsType {
        return .Ellipse
    }```fixes the problem in my circleView, thank you !
Answer: In your CircleView class, you can try use UIBezierPath(ovalInRect: rect) to get a real circle:
@IBDesignable class CircleView:UIView  {

override func drawRect(rect: CGRect) {

        let circlePath = UIBezierPath(ovalInRect: rect)
        let color = UIColor.orangeColor()
        color.set()
        circlePath.fill()
    }
}

Hope I understood correctly and it helped you :)


How is William Carlos Williams's affection expressed in "The Red Wheelbarrow"?

Question: In the poem "The Red Wheelbarrow" by William Carlos Williams, there is no specific mention of any person. However, he wrote that the poem "sprang from affection" for an old man named Marshall, to paraphrase. How does this affection for Marshall come through in the poem? Is it visible in the subtext of the poem?
Answer: The exact quote you're alluding to is presumably this one, cited at Wikipedia:

["The Red Wheelbarrow"] sprang from affection for an old Negro named Marshall. He had been a fisherman, caught porgies off Gloucester. He used to tell me how he had to work in the cold in freezing weather, standing ankle deep in cracked ice packing down the fish. He said he didn't feel cold. He never felt cold in his life until just recently. I liked that man, and his son Milton almost as much. In his back yard I saw the red wheelbarrow surrounded by the white chickens. I suppose my affection for the old man somehow got into the writing.

So how did that affection get into the writing? Where's the connection between the old Marshall and the poem? For reference, the full poem is only 16 words long and goes as follows:

so much depends
  upon
a red wheel
  barrow
glazed with rain
  water
beside the white
  chickens.

Maybe Williams was talking nonsense.
It's not unknown for authors, including poets, to just make stuff up when talking later on about the inspirations for their work. I found this article (mostly hidden behind a paywall, sorry - I'll include lengthy quotes here) which speculates that:

Williams' desire, late in his life, to say that his "affection for the old man somehow got into the writing" suggests his muse had trouble digesting Marshall and the black working-class experience he represents. Undoubtedly, Williams has a genuine affection for this man and sympathy for his plight that "somehow" get into the poem. But the question to ask is how they got there, because the poem, and Williams' lifelong relationship with it, would suggest that every effort was made to erase from the poem not only Marshall but, perhaps more importantly, Williams' feelings for him. [...]
As Williams sought different titles for the poem, little or no regard seems to be given to Marshall's role in the poem and even less to the black working-class experience he represents. Nonetheless, in so far as the title, "The Red Wheelbarrow," works to make the poem's "a red wheel / barrow" the wheelbarrow upon which so much depends, one could argue the definite article indicates its owner. In a certain way, it does, although the owner is usually read in terms of some abstraction—mankind, primitive man, rural life—not in terms of a historically specific individual. More than Marshall or these other owners, though, what the title's definite article indicates is Williams' ownership or authority, stating in effect: here is the red wheelbarrow I discovered and turned into "a red wheel / barrow." As Williams removes the poem from Spring and All and finds new contexts for it, he seeks to establish both his authority to speak for it, and, more importantly, its authority to speak for him. At some points in this process the emotional significance of Marshall all but disappears. At other points, however, Williams opens the poem up to the sort of symbolism and sentiment—those "extraneous comparisons, similes, [and] overweening autobiographies of the heart" that Zukofsky praised Williams for avoiding in Spring and All—that allow the figure of Marshall to appear.
(emphasis mine)

Let's be honest, there isn't really much room among those mere 16 words for "affection" or any other emotion to shine through very strongly.  This seems to be the best anyone's been able to come up with (from the same source as above):

Combined with the thematic and color associations Perloff draws out, perhaps one could see Williams' admiration for the red wheelbarrow's black owner as lifting the poem's technical virtuosity into a whole other realm of social commentary and irony. The comment that "so much depends / upon" the wheelbarrow could be an acknowledgement of the precarious nature of Marshall's life of manual labor. And the vibrant red of the wheelbarrow glazed with rainwater could embody Marshall's blood, sweat and tears, silently condemning "the white / chickens" beside it. However, if these feelings are in the poem, they can only begin to emerge with the discovery of Marshall thirty years later in William's account of the poem in his article for Holiday.
Comment: This poem seems to be a very clear direction to high school students: "You don't understand poetry. You will never know why we picked these particular 16 words for inclusion in your textbook, and any thought inspired will have more to do with us as editors than with anything Williams may have had in mind."
Answer: "The Red Wheelbarrow" presumably has some "hidden meaning".
Here is my own explication via transliteration:

so much depends upon
  a red wheel barrow
  glazed with rain water
  beside the white chickens.

I think it means:

so much depends upon
  ONE MAN
  AS the CORPOREALIZATION OF the MESSIAH
  therefore, SING, LET US REJOICE FOR the SON

Here's why. Using @ = aleph, KH = het, kh = khaf, 3 = aiyin, a: = vowel "aye"
                    and [T] for the ancient sound of the shin

wheelbarrow = KHaDoFeN < Aramaic KHaD = one + @oFeN = wheel.
red wheelbarrow = KHaDoFeN @aDoM
                           KHaD BeN-@aDaM = one + man/human/person
rain water = Ma:-GeSHeM. Glazed = Z'khookhi.
with rainwater glazed = B'Ma:GeSHeM Z' khookhi
                                  B'MaGSHiM MaSHiaKH = as [the] corporealization of + [the] Messiah
Beside the = 3aL YaD Ha-
                 3aL YaDa: Ha- = by means of, through; because of [this]
white chickens =  TaRNaGoLoT LaVaN
                       [T]aR NaGiLaT LaBeN = sing, let us rejoice + for [the] son

Did Williams do this with conscious intent?
Did Williams know enough Hebrew to implement this process?
If this poem were written by Lewis Carroll, I would say "yes". Carroll was fluent in all of the languages mentioned in The Hunting of the Snark.
Williams's mother was a Puerto Rican woman of French Basque and Dutch Jewish descent.
Perhaps he learned some Hebrew from his mother?
Perhaps he "engineered" this poem by doing the exact opposite of what I did?
Comment: I... *speak* Hebrew and I'm not sure what you're trying to say here. Can you please [edit] to clarify what exactly you're trying to say?


Content Porter Tool SQL Server/Oracle Issues?

Question: If the source CME is using SQL Server and the target SME is on Oracle, will I anticipate any issues migrating content from SQL server CME to Oracle CME via Content Porter?
Answer: I would not expect any issue because the Content Porter calls the Tridion Core Service API which is an abstract layer on top of the database.
However I did not try it myself so will let others detail their experiences.
Is this for a migration or do you have disparate systems in your DTAP setup? I would not recommend the latter.
Comment: Ok. Sorry late to respond to my own post. I didn't expect any issues either, however I have never been through an implementation of this kind before. This is simply for migration.
Answer: The problems you may spot are related to database and not to Tridion per se. Even more you might have problems migrating between the databases of the same type. For example: you may have different character set, this might result in some exotic characters being displayed differently or maximum name of an item be slightly shorter on one of the databases if use Chinese characters. But there should be no functional difference. If both databases are being setup according to Tridion installation manual, the only problem I foresee are slightly shorter item names on Oracle if use asian symbols
Comment: I concur on these, I never saw issues during the import (or export for that matter), but did see differences in the system afterwards (like the way a list is alphabetically ordered can be different on Oracle because there is a setting for it, although those differences you could also see on different MS SQL Server instances).
Comment: Appreciate the insight. My understanding was also that as long as you're using compatible version of Content Porter for both source & target systems. It doesn't matter with the backend.
Answer: Note that Content Porter is not intended for database migration purposes.
It doesn't port all data in the system, you loose version histories and you will hit size limitations if you try to export your entire CM system.
If you only want to port a limited number of items (and don't care about the functional limitations), there should be no issues with different DB types for the source and target systems.


Feature paging with ArcGIS map service vs feature service

Question: I'm about to implement an integration that involves reading all features from a layer on a municipal ArcGIS server.  There are at least two ways to go about this, including use of a Feature Service and a Map Service.  Are the solutions essentially equivalent?  In other words, can I use the Map Service to query and page through results in the same way, or in a way that is equally efficient and problem free, as I can using the Feature Service?  Both solutions appear to involve pulling IDs down and using offsets, there aren't for example 'next' and 'previous' links to utilize, from what I can see.  I am reading documentation on the Map Service presently and see ways forward, but want to see if anyone who has done this can answer this question and possibly provide other guidance as to whether I want to instead go with the Feature Service.
Answer: After implementing the solution: the MapService worked just fine; I was told since that the only reason to use the FeatureService instead is if I needed the ability to update data as well.


How to calculate displacement of the end effector by the yaw, pitch, and roll in the spherical joint?

Question: For planar robots, we can calculate how small changes in the angle of each joint corresponds to the displacement of the end effector, by constructing a jacobian consisting of cross products between the axis of rotation of each joint and difference between the position of each joint and the end joint. I tried to use the same logic for a spherical joint with 3dof by calculating three angles for each global axis of rotation, from the displacement of the end effector at each global axis. I then tried to construct a rotational matrix to correctly orient the joint from these three Euler angles. However, since rotations of each angle stack on top of each other in rotation matrices, this didn't work. Is there a practical way to construct a rotation matrix from these angles or is there a different solution to this problem?
Answer: Write the rotation matrix from the first coordinate system to the coordinate system moved by the first motor.  Four of the elements should include a cosine or sine of the first motor angle.  Then write the rotation matrix from that coordinate system to the coordinate system moved by the second motor.  Do this again for the third motor.
Multiply these three rotation matrixes together and you will get the rotation matrix for the 3 dof spherical joint.
Incidentally, you can easily write the individual 3x3 rotation matrices as follows:
The first column is composed of the direction cosines of the moving x axis relative to the fixed coordinate system; the second column is composed of the direction cosines of the moving y axis with respect to the fixed coordinate system; the third column is composed of the direction cosines of the moving z axis with respect to the fixed coordinate system.
Comment: Thanks for the reply! Sorry I'm new to this and also not very familiar with the terminology. I see the spherical joint as a gimbal. If I multiply by X, Y and Z rotation matrices in sequence, the next one in sequence is going to be influenced by the prior one. So I'm unable to see why this would work. I was contemplating about using angular velocity instead, and calculate the rotation matrix needed to orient the spherical joint, by stacking up quaternions constructed from small changes in angular velocities as related to the offset, that is the difference between the end effector and the target
Comment: My method assumes you have three actuators connected in serial (so the first motor rotates the other two motors and the second motor rotates the third.   To be spherical, the axes of all three must intersect.
Comment: Sorry, hit send too soon.  You can compute rotation matrices using quarternians as well but to me the simple, serial, individual rotation matrix method is the most intuitive.  Then you multiply those three 3x3's to get the thing you're going after with your quaternian approach.   The end result must be the same because both methods model the kinematics of motion of the same device.  Your choice.
Comment: This might help with terminology and notation:   https://robotics.stackexchange.com/q/8621/11125
Comment: I understand. Thank you!


Why does Paragus look younger in DBZ Legendary SSJ compared to DBS Broly

Question: Like if you watched the old Broly (the first one) He looked way younger, and in the DBS version he looks very old. So does that mean Goku, Vegeta, Gohan, Piccolo and Trunks minds where whipped clean?
Answer: https://www.polygon.com/2018/7/10/17550980/broly-canon-dragon-ball-super-z-movie-legendary-super-saiyan

Because of his limited appearances, fans have debated if Broly can be considered part of the larger Dragon Ball canon for years. But in a note on the Dragon Ball Super: Broly website, series creator Akira Toriyama said he worked to fit Broly into the Dragon Ball universe.

Hopefully that links confirms that Broly is canon now. The movie basically retcons Broly's origin. That's why his father looks older and different than in the DBZ Movie.
Comment: The only thing that confuses me. then why come out with the other 3 movies, The legendary super saiyan, bio Broly and Broly second coming. its like seeing Hitler in the Gogeta move (the first appearance of Gogeta in a movie)
Comment: Broly - Legendary Super Saiyan came out in 1993. That's over 20 years between that and DBS: Broly. Its safe to say that there's a newer generation of fans. And it might not be viable for fans to go back and watch the entire DBZ series and be confused when the story doesn't line up with the movies. I think only a handful of movies are actually canon to the series. If that makes sense? Hopefully?
Comment: Thanks, Im not that confused that much anymore, But like I said the movies are weird with "CANNON" And "NOT CANNON"
Comment: Agreed. I do respect the fact that they're trying to bring back old favorites to try and refresh the series again.
Answer: The Paragus from the old Broly movie is not canon while the Paragus from Dragon Ball Super Broly is. They are 2 separate characters and you shouldn't establish any form of relations between the two.
Answer: I think Toei wanted to distinguish between the canon and noncanon versions of Paragus so fans don't get confused when making fanart. As Gary said, you really shouldn't think of these two characters as existing in a uniform timeline and universe as one is canon and the other is noncanon to Dragon Ball.


How to verify if emails have been received through Google Apps?

Question: I am new to Google Apps. Our domain has MX records pointing to Google Apps but I have not been receiving some emails in Gmail sent from the server. Where do I check to see if the emails have been received? Is there a log record in Google Apps?
Answer: Super administrators of Google Apps for Work, for Education, for Government and Unlimited editions could use the Email Log. See https://support.google.com/a/answer/2604578?hl=en for further details.
By the other hand, the Google Apps Toolbox could be used to check several issues. See https://support.google.com/a/answer/2520136?hl=en.
On the end user side, users could use the following Gmail troubleshooter: An incoming message was delayed or hasn't arrived