How does a smart bulb work? There is a type of bulb in the market nowadays that detects load-shedding! I mean it keeps lighting after load-shedding. But my curiosity is if I turn off the switch of the bulb, it might have detected that load-shedding has occurred, but it doesn't! How does exactly it detects electricity outage!  I want to know the electrical working behind it.  [EDITED]  Here is a video of that product (not exactly mine, but similar)   I'm from Bangladesh, yep here load-shedding means turning off in a grid for a short period of time.   My Building has no special electrical connection.
Doubt on Rechargable LED Emergency bulb I have recently seen a  and I  was wondering how it is working.  In the event of a power failure, the LED bulb will turn ON automatically. That is, when the switch is ON and mains power goes off the bulb will detect that and turn ON. If the switch is OFF bulb will not turn ON. When mains are ON and the switch is ON the bulb will start recharging again.  It is just like a normal bulb. See the   My question is, how the bulb will detect the event of mains failure? Can somebody give me a hint on this?
Is it possible to get a list of most recently installed packages? Could not make temporary scratch layer permanent I want to make a temporary scratch layer permanent but it shows  Could not make temporary scratch layer permanent. Error: Creation of field addr:street_1 failed (OGR error: Can't create field addr_str_4 in Shape DBF file, reason unknown.) How can I fix this error?  This is my attribute table. How to find number of prime numbers between two integers I have two integers, x and y so that x &lt; y. How many prime numbers are there between x and y (exclusive). Is there a formula or algorithm to compute? Uniform distribution on the surface of unit sphere Best way to follow a log and execute a command when some text appears in the log I know that the gravitational interaction of antimatter is expected to be the same as normal matter.  But my question is, has it ever been experimentally validated?  I think it would not be a trivial experiment, because electromagnetic effects have to be eliminated, so neutral particles would be needed. Maybe diamagnetically trapped antihidrogen atoms could be examined as to which direction they fall? I'm trying to make a logo that will be on the header of a website. What I'd like to achieve, and the reason I'm using Blender, is the projected shadows on the background looking perfectly real (as opposed to doing a drop-shadow in Photoshop).  The only thing is, the background has to be transparent because the website might use different background colors / gradients that make it impossible to match with the exported 3D background.  I made this dummy file (not the real logo... duh!):    If I use the file as is, the grey borders of the image will be impossible to match with the website's background color.  Here what I want:    So obviously, I tried masking the plane, which made the shadows disappear. I tried having a plane set to glass, which didn't work either.  And I looked around for a similar question, but didn't find one.   I am not trying to render , or a . I've seen  which has a very difficult solution to this problem, and  that is very similar but in Blender Internal.  is similar too but has never been solved. I'm only a beginner at Compositor, and I'm trying to learn more any chance I get, so any solution in Compositor is welcome if detailed enough. Although if there's a simpler or faster way, it's welcome too!  .blend file: How come such different methods result in the same number, $e$? I guess the proof of the identity $$ \sum_{n = 0}^{\infty} \frac{1}{n!} \equiv \lim_{x \to \infty} \left(1 + \frac{1}{x}\right)^x $$ explains the connection between such different calculations. How is it done? How to change user in WinSCP? I'm using WinSCP to access Unix computers. How can I change user after I have logged into a Unix server using WinSCP?  E.g. I have personal account in Unix computer A. I can log into this computer using PuTTY and then change user to root user  $sudo /usr/bin/su - rootuser   How can I do the same thing using WinSCP? I don't know the password for rootuser. What is a single word for a person who, as a habit, exaggerates a lot when relating information?   So for example, they relate something that happened but exaggerate so much that they are including clear falsehood and they are well known for doing that. Suppose that $f : \mathbb{C} \to \mathbb{C}$ is entire. Let $\Omega = \{ z : \frac{1}{2} &lt; |z| &lt; 2\}$. Furthermore, suppose that $ \mathcal{F} = \{f(kz) : k \in \mathbb{C}\}$ is a normal family of analytic functions defined on $\Omega$; the family $\mathcal{F}$ is normal on $\Omega$ iff each sequence from $\mathcal{F}$ has a subsequence converging uniformly on compact subsets of $\Omega$. Prove that $f$ is a polynomial.  I'm studying for my qualifying exam in complex analysis, and this question appears on an old exam. Usually, when I want to show that some entire $f$ is a polynomial, I just try to show that there exists some $N$ so that $f^{(k)}(0) = 0$, all $k \ge N$, but I'm having trouble getting that strategy to work here. I've been looking at the sequence $f(\frac{z}{n})$ trying to make something work, but have not had any success.   I would prefer to receive a hint or two, and then I'll try to post my own solution. Thanks in advance! Sometimes it's hard to search for older versions of macOS &amp; OS X  on the App Store.  This is an attempt to provide the canonical QA for this issue, as per the Meta QA -  I expect it to be modified over time to hopefully become a complete information resource.  How can I get any older version of a Mac OS to be able to run as a VM, or to reinstall on my Mac? How do JavaScript closures work? Why is integration so much harder than differentiation? identity element of $(D_n ,\gcd)$ Fine, the 's math  did in the old pop-up. That makes sense. But this is just silly. Why do I need to be notified that a post I downvoted got deleted?    (The title links next to the red -1s were removed from the screenshot by me. They're present in the real pop-up.)  So I can break out a bottle of the '82 Rothschild? It's especially pointless because there's  that caused the change.  Please don't display the Rep Signal when the change is only due to someone else's deleted posts. Making an elastic waistband on clothing? Layover at Dusseldorf and Frankfurt, category A or B visa? I am a Indian citizen in the United States on a F-1 visa.  For the summer break, I am traveling (round-trip) from Chicago to New Delhi via Dusseldorf-Frankfurt by Lufthansa airlines. My onward Journey would be on July - 8 and return Journey on Aug - 11.  My layover will be of 1 hour 10 mins in Frankfurt and 3 hours in Dusseldorf.  I would like to know if I require Category A or Category B Visa. If not, what type of visa do I require for the Schengen visa for my transit. How I can apply for the same?  I tried to find slots in German consulate but all slots are full before my departure date. If I don't get the Schengen visa, I cannot travel and will loose all the fare (since my ticket is a non-refundable ticket). Is there any other way I can tackle this situation. Installed Ubuntu alongside Windows 8, and W8 won't boot anymore I'm new to field extensions and I can neither see why or how to prove this statement.  If I'm not mistaken, to construct a splitting field, you construct rupture fields one after the other, using that the $8$ element field is the splitting field of $X^8-X$ over $\mathbb F_2$, since $2$ is the only prime divisor of 8.  Over $\mathbb F_2$ $X^8-X$ has two roots : $0$ and $1$. Therefore $X^8-X=X(X-1)(1+X+...+X^6)$. The last factor, call it $P$, has no roots. So let $\alpha$ be a root in some extension $\mathbb F_2(\alpha)$ of $\mathbb F_2$.  We now have $P=(X-\alpha)(X^5+\alpha X^4+...+\alpha^4X+\alpha^5)$.  I suspect $\alpha$ might not be the way to go and if so, my second plan would be to reduce $P$. I don't know how to do this but assuming it to be done, hence having $P=P_1...P_n$, I could start using $P_1$'s rupture field, and then my best guess is that if $\mathbb F_2[X]/(P_1)$ is not sufficient, I re-reduce $P$ over this new field and consider the rupture field of one of the factors, and so on.  Now assuming I wasn't given the statement itself, is it elementary to construct the $8$ element field using $\mathbb F_2$ ?