Story Identification: Novel in which the dead are terraformed to create a satellite near stranded spaceship

Question: I remember that there was a stranded spacecraft and several splinter groups made up from its survivors/desendants set up camps nearby, one of which was a "Planet" built up by using deceased crewmembers. It was a short novel, 180-200 pages. I read it in the 80's. The opposing factions of the living had to work together to repair the main spacecraft to escape whereever it was they had been stranded.  Edit- IIRC, Gravity played a major factor in the tale.
Comment: would you say it was short enough to be a 'novelette'?
Comment: I had some of the details wrong, but @Frock is correct.
Comment: It still baffles me as to why you guys mark older questions as duplicates of newer questions. "Because I liked the newer questions answers better" is lame. The question you closed this one to is a duplicate... of a 2011 question, the 2011 question should be open and both mine and January's questions should be closed as duplicates of it. That would be logical and not hand wavy. Are you making things up as you go along? Saying it doesn't make any difference is true in a way, but if it doesn't really matter anyway, why not use math instead of your general opinion?
Comment: That  being said, it's still a great site, but sometimes it's a little subjective in it's reasoning.
Answer: This is "Raft" by Stephen Baxter.

The novel is an elaborated version of his 1989 short story of the same title, Raft. The story follows a group of humans who have accidentally entered an alternate universe where the gravitational force is far stronger than our own, a "billion" times as strong. Planets do not exist, as they would immediately collapse under their own gravity; stars are only a mile across and have extremely brief life-spans, becoming cooled kernels a hundred yards wide with a surface gravity of five g. Human bodies possess a "respectable" gravity field in and of themselves. "Gravitic chemistry" also exists, where gravity is the dominant force on an atomic scale.
Comment: Thank you. I was wracking my brain, thinking it was a Niven tale.
Comment: You're welcome. This book left me with mental scars (the food and drink)


Monitor network activity of TeamViewer connected computer on another computer connected to different network

Question: I have a computer(1) which is connected via TeamViewer to another computer(2), in another network. My question is, is it possible to somehow monitor (1)'s network activity on (2)?
Answer: It's not possible literally - without somehow forcing all traffic for computer(1) through computer(2) - but doing this using TeamViewer would be very inefficient.
You can of course install network monitoring tool on computer(1) and view it's output through the TeamViewer connection...
The only activity related to computer(1) you can monitor on computer(2) are packets directed from computer(1) to computer(2).
The TeamViewer software creates VPN (Virtual Private Network) to which both of the computers are connected. However other traffic is never routed through this virtual network - as there is no reason for it.


Charger with long usb cable

Question: I have ASUS ZENFONE 2 with model no ASUS_Z00LD and type ZE550KL.
I need a adapter and charging cable of at least 2 metre length.
Google is not showing relevant results.
 How do I get one?
Comment: I don't think that you'll get genuine cables with that length.
Comment: Long cables if not properly chosen can end up with slow charging. See this https://android.stackexchange.com/a/134970/131553
Comment: You don't need a charger with cable, you need an compatible USB charger and a long cable with thick copper cables inside. Buy them individually or use an existing charger.
Answer: If you cannot find a reference to one on the Asus website, then Asus does not make one. Also, longer cables cause loss of current and hence your phone will charge slower.
Most companies these days don't even sell their chargers and cables in open market. They are only bundled with the products and available via authorized service points. So, if you have an Asus point nearby, go check in there.

Charger with long usb cable


Can all surfaces be turned inside out?

Question: I saw this YouTube video claiming that spheres, double torues, triple toruses, etc. can all be turned inside out, but what about other surfaces? Are there any surfaces that can't be turned inside out?
Comment: You may find [this](https://math.stackexchange.com/questions/2755/why-can-you-turn-clothing-right-side-out) question and answer useful or interesting.
Comment: https://math.stackexchange.com/questions/499963/smooth-torus-eversion
Answer: In mathematical terms, your question may be restated as "does every closed orientable manifold of dimension two admit an orientation reversing diffeomorphism?" As noted by others, the question does not make sense for non orientable surfaces, and so we have to limit ourselves to orientable spaces.
A key phrase here is the classification of surfaces, which puts surfaces into three categories: the sphere, tori with several holes (surfaces of genus $g$), and several copies of the projective plane glued together. It can be shown that any closed $2$-manifold must be of this type. So in short yes, since the orientable surfaces are precisely the tori with several holes, all orientable surfaces admit an orientation reversing diffeomorphism.
It should be noted that the answer is negative for higher dimensional orientable spaces. For example, even dimensional complex projective spaces do not admit orientation reversing diffeomorphisms.
Edit: I am limiting myself here to closed orientable surfaces. Non-closed surfaces are not as nice and I'm not sure there's a clear answer, perhaps someone else can fill in those details.
Comment: To me "can be turned inside out" suggests something much stronger than the existence of an orientation-reversing diffeomorphism - indeed, it's obvious that the antipodal map of the sphere reverses orientation, but the sphere eversion theorem was a great surprise.
Comment: Well, it's about being able to smoothly deform the standard embedding to one with the same image, but the orientation reversed. This is formalized by requiring the two embeddings to be homotopic through immersions. Given that the OP linked a video specifically talking about Smale's result, I don't think orientation-preserving diffeomorphisms alone answer the question.
Comment: Interesting. How does one formalize the idea in general?
Comment: The sphere eversion theorem seems to be a bit more general than just the claim that I can be turned inside out. To me it seems to be saying that it can be turned inside out, regardless of how you embed it. But I assume the OP cares only about the standard embedding
Answer: A Klein bottle is a surface with no inside and no outside. So in that case I don't think it would make any sense to talk about turning it inside out.
Answer: For the class of surfaces called non-orientable, there's no such thing as inside or out.
This class includes the famous Moebius Strip and Klein Bottle, for instance.
Comment: Ok, but what about surfaces that do have an inside?
Comment: This question deserves a better answer than this.
Comment: I agree, @mjd. If I have time later I'll expand, in the meantime why don't you give it a shot?

Can all surfaces be turned inside out?


what is the cross section of an elevator and trailing edge flap?

Question: Is the cross section of both a Trailing edge flap and elevator an aerofoil please or, like i've shwon in in image below? I tried to find a side view of an elevator and TE deflected to see this for myself, but couldnt find one
Comment: What do you think this image represents if it is NOT an airfoil with deflected trailing edge?  I'm just not understanding your confusion here.  If you have done enough research to locate an image like what you posted, it would seem that you would understand what it represents from the context where it first appeared.
Comment: I can't help but notice that in the past few days you asked several questions about basic aeronautical and aerodynamics concepts. I'd suggest you to read a good book about those concepts instead: getting a lot of answers from random guys on the internet is definitely not the best way to learn this kind of subject. ["Aircraft performance and design" by Anderson](https://archive.org/details/AircraftPerformanceAndDesignByJohnD.AndersonJr.) is a classic.
Comment: Hi Sophit, thanks for the book. I swear I did do research into this question, but just haven't been able to find anything.
Comment: I generated that image in cad Michael- I just wanted to know whether the cross section of an elevator and flap is an Aerofoil or like I've done
Comment: What you have done is an airfoil, with a hinged trailing edge.  (roughly...)  Is that what you were trying to create?
Answer: Many elevators have airfoil shapes.
The precise way you've drawn the flap is not physically possible.  It is drawn as a shear of the trailing edge.  That would involve deforming materials.
Instead, a control surface has a hinge and there is a rigid body rotation about a single axis.  This usually means that the front of a control surface is an arc about the rotation axis.

On small general aviation aircraft, it is not uncommon for the elevator to be made out of welded metal tubing and covered with fabric.  In this case, the elevator (and its control surface) will be flat plates with circular leading and trailing edges.

In general, to prevent control surface flutter, control surfaces need to be balanced (mass) around their hinge.  In addition, it is often beneficial to add some sort of aerodynamic balance in front of the hinge.  This is an extension to the surface that reduces the force required to deflect the surface.
Comment: Hi Rob, can I ask for the book you got those nice pictures from please?
Comment: No book, just a random website.  I did a google search for control surface hinge or something like that.


Loading screen for TTImageView

Question: I have a table with images that are loaded from the web. I'd like to have an animated loading screen while it's loading.
I tried (successfully) to use a UIImageView and use the animation property. I want the loading animation to be synced however. What would be the cleanest way to do this?
I tried to use NSTimer. I would use NSDate to get miliseconds = m. Then (m * 500) % 4 to get 4 frames per 2 seconds. I wasn't able to get it to work. I also feel it's a bit messy to have 10 to 20 timers going on at the same time. One thing I was thinking is to have a singleton that has a NSMutableArray to which you can add a selector that updates the appropriate image. But it's still quite messy. Any ideas?
Answer: I suggest you check out MBProgressHUD:
More info:
http://macindie.com/2011/01/mbprogresshud-when-you-simply-have-to-make-users-wait/

Loading screen for TTImageView


How to update all dependencies to a specific version

Question: I'm trying to upgrade a project from Angular 6 to 7. There are a massive amount of dependencies that also need to be upgraded, but all I can find are tutorials to upgrade everything to the latest version (which would be v8)--not to a specific version. What is the proper procedure for this?
Answer: ng update @angular/cli @angular/core

This command will update your project to latest version of angular. but if you want to upgrade to specific version then you have to add @version in dependency as below
ng update @firstname.lastname@example.com @email@example.com

Answer: Angular has Upgrade page. Which will tell you how to upgrade angular related stuff


Can the AMPscript DatePart(D1, S1) isolate AM or PM?

Question: I see here that S1 = The part of the date to retrieve. Valid values include year (Y), month (M), monthname, day (D), hour (H), and minute (MI). I don't see a script to isolate the part of the datestamp which would indicate AM/PM. Is there one?
Comment: In my testing, I actually don't think we allow that...I am looking for a workaround.
Answer: I don't believe there is such a function.  The reason being that AM/PM data is not stored in the date; the date is stored in 24h format and AM/PM would need to be calculated.  A possible workaround: if you need to just display it nicely on a landing page, then you could format it client side using something like date.js.  Otherwise you could use SSJS and use a function to do it like the following, only modifying it to run server side:
function formatAMPM(date) {
  var hours = date.getHours();
  var minutes = date.getMinutes();
  var ampm = hours >= 12 ? 'pm' : 'am';
  hours = hours % 12;
  hours = hours ? hours : 12; // the hour '0' should be '12'
  minutes = minutes < 10 ? '0'+minutes : minutes;
  var strTime = hours + ':' + minutes + ' ' + ampm;
  return strTime;
}
(Taken from
https://stackoverflow.com/questions/8888491/how-do-you-display-javascript-datetime-in-12-hour-am-pm-format)
Comment: I believe that is true of a unix datestamp but it appears that the AMPscript datestamp does have a built-in AMPM indication and is not a 24 hour time. I'm not sure of that but someone who knows may clear that up for us.
Answer: The suggestion below is certainly valid and may have benefits over my own workaround but I figured out a fairly easy "AMPscript only" solution. I used concat to set the AMPM value in the datestamp and it works but, the challenge is getting it to set a DatePart for the form that sets the events time as there is no method in datepart specific to the AMPM appendage.
So what I did is created a separate field in the data extension which ALSO holds the AM/PM setting of the record. When we update a record, it now uses the @ampm variable from the dropdown menu both to set the value in the concatenated datestamp and ALSO to set the AMPM value in the specific data extension column which only holds that information.
Now when the landing page reads the data extension it sets the dropdown based on the ampm column, and if that is changed and submitted it will update both that field AND the datestamp. An extra field to mimic data which otherwise can't be isolated. Simple and effective.
Answer: I haven't validated this, but could you use the FormatDate() function?
<code>FormatDate([attribute/variable], 'tt')
</code>
I think this should return AM or PM.


WebSharing Enable in mac 10.8

Question: In mac 10.6.8 systempreference->sharing->WebSharing is there but mac 10.8 websharing not in sharing folder how can i add and enable websharing in systempreference panel.
Answer: I have used this on a few Macs running OSX 10.8:
http://amz.clickontyler.com/WebSharing.zip
It creates a PrefPane in System Preferences, with two toggles:
- web on/off
- php disabled/enabled
On one of the Macs it didn't work at first. I uninstalled and re-installed it.
It can be uninstalled by right-clicking on the PrefPane, and selecting "Remove Preference Pane". Or by removing it from YourUserName/Library/PreferencePanes/ or from /Library/PreferencePanes, depending how you installed it.
On re-install, it worked, but I think it doesn't 'keep track' of the service if for instance, you just kill the httpd process, or stop it through Activity Monitor. I don't think WebSharing PrefPane knows. It has to be re-toggled.
Comment: I'm not sure I would be downloading a ZIP file from an essentially anonymous source. Or, is there something I don't know about 'clickontyler'?
Answer: I'm also not sure, if it's an good idea to use WebShare PrefPane from ClickOnTylor...
It asks for the user password after toggle, but toggles also if you escape the input of the password.
Yesterday I switched WebSharing off (checked by Safari localhost). Today I have seen WebSharing PrefPane says still "off". So I removed it from SystemControl. Then I realized, that Safari localhost still answers "It works".
In conclusion: using WebSharing PrefPane without having knowledge on backgrounds is not a good idea, if you know the background I feel you don't need WebSharing PrefPane.

WebSharing Enable in mac 10.8


Why did prices of Treasury securities go up when US lost its AAA credit rating in 2011?

Question: When the credit rating of a fixed-income security is cut, this means the security has higher default risk. What follows is that the price will go down. However, the opposite happened in 2011 to US Treasury securities. Why did Treasury securities go up when US lost its AAA credit rating in 2011?
Comment: Can you be more clear on what you mean by 'went up' in this case? What exactly went up? Based on the data I can see, everything is still as it should be.
Answer: According to the United States Treasury:

The price and interest rate of a bond are determined at auction.

The Treasury doesn't choose interest rates. Treasury Bonds, Notes, and Bills are auctioned off with Primary Dealers being the main bidders. Primary Dealers are required to bid at Treasury auctions. The auctions take place on a yield basis with the lowest yields being the winning bids.
Only S&P downgraded Treasuries and they still had a very high rating; the other rating agencies did not lower their rating.
Interest rates were falling sharply fell during the period when S&P lowered its rating (8/5/11), with 30 year rates falling by over 100 basis points1.
Long story short the effects of government intervention and a weak economy over-shadowed any small effect that the rating downgrade from one rating agency might have had.
1. from 4.5% to below 3.5%
Answer: The short version of your answer is that bonds from the US Treasury are sold with a fixed interest rate that is determined by the issuer at the time of auction. If this (the quoted interest rate) is 'what went up', then it went up simply because the Treasury decided to issue securities at a new rate.
What matters to investors at the end of the day for bonds is 'yield'. This is the effective interest rate received by an investor who purchases securities at auction. This is the number to watch if you're trying to see the impact of a market-shaking announcement like the time when the US' rating was downgraded.
Based on what I can see by comparing Aug 1, 2011 and Aug 8, 2011 on this handy chart from the Treasury, YIELDS went down after the announcement was made. (Wikipedia says downgrade happened Aug 5, 2011.) That seems counterintuitive, as the logic you mentioned above means that this should be a more risky asset with the lower credit rating, and investors would want more yield for the higher risk.
If that's what you're really trying to get at, then you need to look at what else was going on in the world at the same time. This article from BusinessWeek hints that the bottom was really falling out of European bond markets about the same time. So even though the US Treasury was being downgraded, everywhere else was so much worse that the US--even at a higher risk level--was seen to be less risky and so investors piled their money into US debt.
Comment: @dcaswell nothing is wrong with this answer or my previous answer. Bonds are a function of the *COUPON RATE*, which I'm referring to here as the item set by the Treasury, as well as the discount rate, and the price paid for the security. From the price a yield can be imputed. So, based on your linked explanation off newyorkfed.org, please feel free to go back a read it for any mention of the coupon rate. You'll see it is missing. That rate is set by the Treasury at its leisure, and investors use their personal or institutional discount rates to bid. Winning bidder's sets the 'rate' or yield.
Comment: If you're trying to delineate the difference between a Treasury Bond vs a Treasury Bill, be my guest. All that OP mentioned when the question was asked is "why did prices of securities go up". While we're being perfectly technical... a "Treasury Bill" is simply a Bond with a Coupon Rate of 0. So the money returned to the investor will be one lump sum at the end of a time period.
Comment: The United States thinks that interest rates are set at auction: http://www.treasurydirect.gov/indiv/research/indepth/tbonds/res_tbond_rates.htm If they're wrong please contact them directly, I don't think they read these comments.
Answer: The phrase I'm hearing a lot from financial pundits talking about U.S. creditworthiness is that the U.S. is "the best looking horse in the glue factory". The U.S. Government has historically been the safest port in a storm from an investment perspective. As such, it has typically enjoyed very low interest rates, based on high demands for its perceived low risk.
Now, even when that reputation is being sorely tested by Congressional brinkmanship, investors are looking around, at a stagnant to still-recessing Euro Zone, an unstable Middle East, a cooling China, Japan still in the same position it's been in since the 90s, and returning to the United States' debt as being the best option in a less-than-ideal global market. We may be starting to look like a bad option compared to our position 10 or 20 years ago, but other options are still so much worse that even the downgrade from AAA to AA+ was shrugged off by the marketplace at large.
The only effect seen was in the most conservative of wealth-retention funds, the ones you're typically urged to move your retirement fund toward when you hit retirement age, in order to protect the nest egg while compensating for inflation. Firms offering these funds have their own bylaws concerning what's acceptable for monies invested in them, and a few did in fact reduce their holdings of T-debt or divest altogether as a result of the S&P downgrade, because their bylaws said that the fund had to be rated AAA by all of the Big Three ratings agencies. But, the resulting divestiture was a drop in the ocean compared to Chinese, Japanese and European investors clamoring for safe government debt, especially now that it was clear the U.S. would, in fact, make good on this debt. As such, the U.S. 10-year T-note remains the benchmark for effectively zero-risk investment in the global marketplace.
This position is about to be tested again; about a week from tomorrow, the Treasury predicts that the U.S. will max out its credit card (the self-imposed "debt limit" that Congress allows itself to accrue) on October 17, and there is virtually no movement by either party of government towards a resolution of the government shutdown, much less the debt ceiling. Beyond October 17, it's anyone's guess as to how far the daily incoming revenue stream of taxes, fees, fines, loan payments, recovered interest etc will keep up with the partially-furloughed government's various obligated payments falling due. Some estimates I've heard from financial pundits have said the government could continue to honor all its debts for up to a week after hitting the debt ceiling.
Beyond that, Obama will have to pick and choose what bills get paid. Whether he can legally do that is an open question; no President has ever had to pick and choose, and Obama is currently bound by conflicting laws, so he'll have to break one of them either by ignoring the debt limit and ordering the Treasury to make payments to all debts, or by staying under the debt limit and thereby choosing which debts don't get paid based on his political ideology instead of Congress' mandate. Now, Congress may try to enact legislation putting themselves in charge over choosing what obligations get paid, but such legislation requires either the President's signature (not a chance in hell) or a supermajority veto override (extremely unlikely, but possible if the President indicates he'll act in a way that the overwhelming majority of constituents would not like, such as suspending SS/Medicare/Medicaid, or suspending duty pay or supply shipments to active military).


Difference between Fock space and Hilbert Space

Question: I am beginner in QFT. I would like to know why there is a need of constructing Fock space for a  $N$-particle system? Why can't we represent this many body system just as the tensor product of Hilbert space itself? In short what is the difference between a Fock space and a tensor product of Hilbert space $H_n$?
Comment: The tensor product represents specifically $n$ particles, while the Fock space can represent any number of particles.
Comment: You can do that, but then you need to manually make sure you are working with wavefunctions that have the correct symmetry properties under particle permutations (symmetric/anti-symmetric for bosons/fermions). By using the Fock space constrution, particle statistics are automatically implemented.

Also note that in a field theory your Hilbert space is not just the space of $N$ particles, but a direct sum over all possible $N$ as number of particles can dynamically fluctuate.
Comment: Trying to make sure the wavefunctions are symmetric/anti-symmetric while particle number can change is complicated without the Fock space.
Answer: A Fock space is just one special construction of a Hilbert space. The basic idea is that the Fock space allows you to superpose tensor products of distinct degree. In other words, it allows you to make sense of expressions of the form $$|a\rangle+|b\rangle\otimes |c\rangle.$$
where $|a\rangle,|b\rangle,|c\rangle$ are one-particle states. From the quantum mechanical point of view, if ${\cal H}_0$ is the "one-particle Hilbert space", representing the states of a single particle, then the states of a collection of $N$ particles of this kind, with this $N$ fixed, form a subspace of the tensor product of ${\cal H}_0$ with itself $N$ times:  ${\cal H}_0\otimes\cdots \otimes {\cal{H}}_0$.
The Fock space allows you to superpose such states and hence allows you to have a state on which for every $N\in \mathbb{N}$ you have probabilities for the number of particles being $N$: speak differently, you are allowed to describe states on which the very number of particles is uncertain and becomes an observable with probabilities and mean values as any other observable.
A very transparent example where this would be necessary is in relativity theory. The relation $E = mc^2$ implies that given enough energy particles can be created and that particles can be destroyed. This makes relativistic quantum mechanics with fixed number of particles problematic and the Fock space picture helps quite a lot.
So the construction is to simply form the direct sum of all symmetric or skew-symmetric tensor powers of ${\cal H}_0$. This yields either the bosonic or fermionic Fock space: $${\cal F}_\pm ({\cal H}_0)= \bigoplus_{n=0}^\infty (\cal H_0)^{\pm \otimes n}$$
where $({\cal H}_0)^{\pm \otimes n}$ means in my notation to take the tensor product of ${\cal H}_0$ with itself $n$ times and symmetrize for $+$ or anti-symmetrize for $-$.
To answer your question the distinction between the Fock space and a tensor product of Hilbert spaces is simply that the Fock space is a direct sum of infinitely many tensor products of one Hilbert space with itself.
Comment: Thanks for your answer. If one wants to go from Fock space to Hilbert space, for eg, (assume a system with indistinguishable bosons) can I write |2,0> in Fock space as |LL> in Hilbert space? As a follow-up, how does one write |1,1>? As |LR> + |RL> in Hilbert space?
Comment: I'm not sure I understand your question. A Fock space is a kind of Hilbert space, so I'm not sure what "go from Fock space to Hilbert space" means. Could you clarify?
Comment: Thanks. I just mean from the occupation number representation to particle state representation... So for example |2,0> tells me that there are 2 particles in the left mode. So if I write the wavefunction of the 2 particles as a tensor product, I get |L>|L>. I just want to know if I am reasoning correctly being intuitive, and whether there is a rigorous way to show this transformation in terms of annihilation and creation operators.


Is there any way to preserve roasted coffee beans?

Question: I know different people try different things to preserve roasted coffee beans, including freezing them or vacuum sealing them. But do any of these actually work? I have a very rare and expensive coffee bean that I'd like to take out once a month or so on special occasions, and I'm trying to see if there's anyway to do this without buying the coffee new every time.
Answer: Coffee beans, once roasted, are perishable; they don't "keep". Within roughly five days of roasting staleness is detectable (taste/quality is adversely affected). There is one way to preserve freshness: consume freshly roasted beans within roughly a week. Don't freeze; beans absorb moisture and lose flavour— ick. Vacuum packs aren't the answer, either. To remove all gases from packaging would require a system using pressure, 29" Hg, that no one, not even coffee giants, can afford. The best practice is to just buy beans (roasted on the day you purchase, ideally) in quantities you'll use within a week to 10 days.
Comment: The best way to preserve them is to grind them, brew them, and carry them around in your stomach.
Comment: Yes, brilliant advice.
Comment: The air in a freezer circulates from all over the fridge and freezer, so unless the package is 100% air tight, it's going to pick up flavors from all the foods, as well.
Answer: What I usually do is to place the degased beans (30hours after roasting) in a nitrogen atmosphere.
I did a couple of experiments to check whether this is working, namely mass-spectrometry on the brewed coffee. Although this does not directly link to the taste, it confirms my theory that the nitrogen atmosphere conserves the solubles in the coffee for a longer period of time.
In a good atmosphere (>0.1ppm H20 and >0.1ppm O2) and no ambient light, the flavor, in my opinion, can be conserved for up to six months.
The problem with vacuum is that you actually extract part of the flavor by helping the beans to degas further.
Comment: Hi I'm new to this and I found this answer of your's interesting. Are you saying that you don't vacuum but that you replace the oxygen with nitrogen? Also, can you explain for me the problem with vacuum because several containers use this as their unique selling points, thanks.
Answer: Right after the coffee is roasted, you should not consume it right away but degas it for one or two days. Degassing improves the flavor for a while, say up to ten days, then the overall quality of the bean began to get worse. There is nothing you can do to reverse it, as coffee is alive. However, you may slow it down by using vacuum packs or freezers.
I have just edited and added the "storage" tag. There are many discussions under this tag on how to store green beans, roasted beans and ground beans. Please take a look.
Comment: I would only add that to freeze, you should make sure to keep humidity out (by keeping in vacuum or at least in a container with a one-way valve).
Answer: I am a coffee roaster. The coffee industry has played a shell game with us when it comes to the question of preservation and freshness. They have led us to believe that it has to do with the off-gassing. It absolutely does not. There are lipids and other such oils and fatty compounds in the coffee. These are what go stale. These can be preserved by freezing the coffee in air tight containers. Technical specifics can be found in Michael Sivetz's book "Coffee Technology". Freezing/unfreezing/re-freezing isn't a good technique. If you can manage - break up your supply into the amounts you'd normally use and store them like that individually...in the freezer. Small glass jars that seal air tight work perfect.
Answer: I was able to get some non-freshly roasted beans from Germany one time. Sold to me for cheap because it wasn't freshly roasted. I kept it since October 2015, and just last week (June 2016) I was still drinking some of it. It's flatter, but the acidity is still there. (Owing to the fact that those were some rather high-level green beans). It was just in the same bag it came with, and some loose plastic clip to keep it closed.
It took me so long to finish it because i'm always preoccupied cupping and road-testing beans that I roast for my kiosk business. (The irony of being a coffee business!)
In fact, in an Intelligentsia video/speaking occasion somewhere, they mentioned how when they cupped some old and new coffees side by side, the 6-month old roasted still scored better, and it's really just evidence of the excellent quality of green coffee.
Coffee is a weird product in that it never actually befits "special occassions". For special occassions, you bring out wine, beer, cocktails. The best and absolutely superwordly experiences of drinking high quality coffee are those nights when you come home tired from work, and find a sliver of excitement in a cup of fruit-bursting pure joy COFFEE.
Answer: In a previous similar question I posted this picture of a method I've been using for a couple of months now.

I place my freshly roasted beans into an empty wine bottle and then vacuum pump it for storage. The special rubber stoppers have a one-way valve in them which allows air to be removed and held under a partial vacuum.  The advantage of this method is two fold.  First, the container is as full of beans as I can get it which minimizes the space available for air (oxygen is the bad guy).  After pumping out the air with the little hand pump, it creates a partial vacuum which extracts additional oxygen from the bottle but also promotes the accelerated off-gassing of carbon dioxide.  I know the beans are emitting CO2 because for the first day or two I can continue to pump out gas from the bottle.  After that, the bottle holds a vacuum indefinitely.
I've stored freshly roasted beans like this for at least a couple of weeks with no noticeable loss of flavor.  After I open the bottle and begin to use the beans, I can re-seal it; although the more space there is in the bottle, the more oxygen will remain in the bottle even after I pump it out.  After using a couple of days worth, I more often transfer it to a zip lock baggie that I can roll up and extract air from.
Longer storage than a couple of weeks I can't comment on because I don't roast coffee that far in advance.  I prefer my coffee as freshly roasted as possible.
Comment: It would be interesting to compare partial vacuum vs. a simple sealed bottle, over 4 weeks, using a triangle test. I'll bet people can't taste the difference.
Comment: @Jerry101 after 4 weeks I don't think it would make any difference.  The CO2 would be long gone in either case.  I want my coffee drinkable within a week.  This method makes that possible.
Comment: Ah. It'd be useful to test short intervals. I tested one coffee stored in the freezer vs. cabinet overnight and over 4 weeks and longer, Trader Joe's Kenya, but it's fair to figure that coffee was already a week after roast when purchased.


Ceiling fan/light support hook?

Question: just tonight we upgraded our ceiling fan to a ceiling fan/light so can finally have good room-fill in our living-room. However just now (like 2 hours after install) I realized I may have forgotten to install the suport hook so it is only being held up with the 3 screws and the hinge hook on the outside. How critical is it that I pull the screws out and attach that hook if I did in fact forget it?
Answer: Quite critical -- an improperly installed fan is a trap waiting to fall on an unsuspecting occupant's head!  I'd fix it straight away (and double check to make sure you didn't damage the parts that are currently holding the ceiling fan up, too)!
Comment: K wanted to be sure. I didn't know if the hook was just to hold it while you are hooking up the wires. It seems like it'd be pretty slack one fully installed so wanted to be sure. I'm not even sure of it's purpose if I'm mistaken about it.
Comment: once fully installed*
Comment: I agree with ThreePhaseEle the hook is a safety in case the screws fail. I have seen fans take out sliding glass doors, sheet rock and even a China hutch. Luckily no people were injured in any of the failures. +

Ceiling fan/light support hook?


How big does a landmass have to be in order for biota to not undergo island dwarfism or gigantism?

Question: Somebody asked it here, and the answer was basically "there's no specific size". Still, I'd like to ask if there's an average size to it. Would a Greenland-sized landmass cause elephants to evolve into smaller sizes? (On a side note, were there mammoths in Greenland?)
Comment: Please don't add extraneous material to your posts, instead if you have questions about site etiquette please use the [meta] site. However, if you are posting using two separate accounts, you may find this information on [merging accounts](https://biology.stackexchange.com/help/merging-accounts) to be of interest.
Answer: I don't know the answer properly, so I welcome other input.
You can probably work this out more or less empirically. Going through the (possibly incomplete??) lists of island gigantics and insular dwarfs you can see a list of which islands they have been found on. Also ignoring the dinosaurs, as we don't properly know the size of islands in those cases
The largest listed is Madagascar and it's about 1/4 (actually 0.275) the size of Greenland at about 587,041 km2 / 226,658 mi2 . It may be that this is about the limit.
Note that this answer relies entirely on the current sizes of the islands, it does NOT take into account previous changes in land area from such things as sea levels raising/lowering. I am almost certain that there will be more to it.
Comment: Thanks, but Borneo is larger than Madagascar and its native subspecies of Asian elephant is slightly smaller than the others.
Comment: @LordNobody - It wasn't on the list of animals with dwarfism on Wikipedia hence my "(possibly incomplete??)" phrase.
Comment: Okay, sorry to miss that.


Can a workflow start a console app in SharePoint?

Question: I would just like to know, if it is possible to start a console app from a workflow in SharePoint?
Answer: Well i don't think this is a good idea. You are asking to start a exe from workflow. This is against security.
This questions has been asked earlier with a nice answer.
Have a look at it.
Click here
However you could start a PowerShell Script using workflow and in that PowerShell script you can call your Console app.
Comment: Hi Varun, Thanks for the quick reply, and the good answer was clutching at straws. Will mark as answered as soon as i can. Thank again.


grails plugin for eclipse and netbeans 6.1

Question: Has anyone been successful in getting the grails plugin for eclipse to work? How about grails plugin with netbeans?
Answer: If you use the NetBeans 6.5 Beta you'll see the Grails functionality is promising, but still buggy(minor).  The good thing is in 6.5 Groovy and Grails support is standard, you don't have to install the plugins.
Answer: Unfortunately, there hasn't been much progress on the Eclipse plugin for Grails, we have started using IntelliJ IDEA for Grails development, the JetGroovy plugin is excellent and keeps getting better!
Answer: Netbeans 6.5 is pretty good for Grails and allows for debugging, though the code completion is just barely there.
Answer: Well, here's a quick update.  The Eclipse plugin works, and has refactoring support.  But, for some reason I can't get it to recognize the Grails plugins in the Eclipse project.
It's starting to come along though.
Comment: Grails support in STS (an Eclipse Distro for working with Spring and Groovy) is becoming mature.  Are you using the Grails-Eclipse tooling?

More here:
http://www.grails.org/STS+Integration
Answer: I haven't had any problems getting the Eclipse grails plugin "to work" insofar as it's installed and providing all the features advertised. The problem is that this set of features is minimal, and light years behind IntelliJ. I understand that switching from a free IDE to a commercial IDE isn't at all possible, but if it is, do it! Although Netbeans is better than Eclipse, it's still quite a distance behind IntelliJ.
Answer: Just for future documentation:
Netbeans 6.8 is available with a very nice Grails/Groovy Plugin that works like a charme.
Additionally you can use a new Code Coverage Plugin.
Really nice build.
Link:
Netbeans Homepage
But you have to keep in mind that Grails now belongs to Spring Source. Spring Source is known for developing their own Tool Suite based on Eclipse. Maybe we will see a better grails plugin implementation for Eclipse.


Hide or Delete the User Home Folder in Windows Explorer Navigation Pane

Question: I am using Windows 7.  I don't like the User Home Folder in the Windows Explorer navigation pane.  In fact, I don't like the folder itself.  I never use it, per se, and it comes up sometimes as an irritant, just to let me know it's still there.  Instead, I use Explorer to go directly to the folder I need (e.g., Computer > D: > Workspace).  Can/should I delete the home folder or, if not, can I at least prevent it from appearing in the WinEx navigation pane?
Comment: When I click on Desktop in WinEx, I see "Ray" listed as a System Folder.  Not sure if that's germane.  I do have "Delete" as a context menu option there; just not sure if using that option would make life unbearably interesting.
Answer: You can use Windows 7 Navigation Pane Customizer a freeware by door2windows for enabling/disabling anything on that navigation pane.
Comment: I tried it.  It doesn't seem to be working for this.  It worked for some of the other folders, though.
Comment: info: freeware. **download link seems dead**. supposedly updated to x64. moderate reviews.
Answer: I also think it's extremely annoying the way W7 Explorer displays the folders you don't really use.  Here's one way to get rid of the user folder:  Menu -> Tools -> Folder options, in Navigation pane (on first tab, called General), uncheck both boxes. Then go to View tab, Apply to Folders.

(image source)
You can right click in the Navigation pane under Libraries to that type of  folder you don't use, but this didn't work for the user folder.
On my wish list for Navigation pane, when you click on a folder to display it's sub-folders, the folder you clicked should move automatically to the top of the Nav pane, or at least move up near the top, so you could see the sub-folders without having to scroll down all the time.   I thought it used to do that, with XP.
Comment: Not an answer as you need "Expand to current folder" if you're ever navigating to a parent folder.
Comment: OH OK, I found how to set W7 Explorer so it does show all the subfolders without scrolling. Just check the second box in Tools-Folder options - Navigation pane.  Uncheck only the first box to avoid the automatic display of user folder.
Answer: Why not redirect the home folder to where you want it to be?  right click on My Documents, select Properties, select Location tab, type in the new location and click Move.  Say yes when it asks to merge.
Comment: Sorry.  In the navigation pane in Windows Explorer, I see Desktop at the top.  Below it, I see five first-level subfolders:  Ray, Computer, Network, Control Panel, and Recycle Bin.  I don't want the Ray folder to be visible, and I don't want it to be the subfolder that is opened when I start a new session of Windows Explorer.
Comment: I've already done that.  Maybe I did it in a different way.  That hasn't prevented the User Home Folder from appearing in the WinEx navigation pane.  When new WinEx instances open, they do open in the desired folder -- but as a subfolder under the User Home Folder, which I don't want.
Comment: You keep using User Home folder - which isn't Win7 terminology.  Do you mean Documents and under that is My Documents?


Managing 80 ~ 90 accelerometers with Arduino

Question: If one were to want to keep track of data from 80 - 90 accelerometers using arduino, what would be the best way to go about this challenge?
Comment: Please specify what data rate do you need, distance between accelerometers, are you open to using more than one arduino?
Answer: 1) Use the I2C address select inputs as an "enable".  If you run out of I/Os before running out of bus time, drive the enables from an I/O expandander. If your accelerometers are SPI, drive or use the expander to drive the chip selects.
2) Use a tree of slave MCUs (Arduino or otherwise) reading a number of accelerometers, extracting and batching the useful data, and reporting only that upstream to a master.  Probably use whichever of I2C or SPI your accelerometers are not using (SPI can be much faster, so hopefully that).
Some accelerometer / gyro parts have an on-board processor which you may be able to program to do some of the data extraction for you.
You could also consider using an FPGA to collect the data.  A commonly available one with enough I/O pins to have a dedicated connection to each accelerometer (and so read them all in parallel) would probably also have the internal resources to implement an Arduino-class soft core processor, if not better.


Read content of file in ksh and split it by ','

Question: My file.txt contains the following content:-
./raw_input/0009/img.raw,./raw_input/0009/calib.raw

Answer: If your ksh is ksh93 or mksh, you could read the first line into an array with:
IFS=, read -rA array < file.txt

Also works in zsh or yash. For some reason, bash, years later, chose to use -a instead of -A for that.
ksh93 can also do CSV parsing with -S (handling quotes and values spanning several lines):
IFS=, read -rSA array < file.txt

For instance, with a file.txt containing:
"foo  bar",,"blah""blah
blah"

That gives:
$ typeset -p array
typeset -a array=('foo  bar' '' $'blah"blah\nblah')

To split the whole file on commas, you can use split+glob (done implicitly upon unquoted $(<file)) with glob disabled:
set -o noglob
IFS=,
array=( $(<file.txt) )

Or for compatibility with ksh88 / pdksh:
set -o noglob
IFS=,
set -A array -- $(<file.txt)

Beware $(<...) also strips trailing newline characters.
Also note that if the file ends in a , (and that also applies with read above even with -S, except with zsh) that doesn't create an extra trailing empty element (, is treated as delimiter, not separator, despite what the S in $IFS might suggest).
Comment: Thank you, for sharing this!


If you were able to get rid of Hydrogen from a weather balloon as it were rising and expanding would the weather balloon rise further than usual?

Question: I know that the weather balloon will eventually be stopped because of the atmosphere no longer being buoyant but would the balloon be able to go farther than it regularly would?
Comment: See also [EarthScience.SE] Stack Exchange.
Answer: Weather ballons are normally designed to burst at some chosen altitude so they descend and the equipment they carry can be retrieved. If the ballon doesn't burst then yes it will go higher, though as you say there is a limit. The limit is somewhere around 50km.
Comment: Most burst long before they reach 50 km.
Comment: @gerrit: yes, I think 20km is a more typical maximum height


Can a short-circuited heat bed be salvaged?

Question: I was working on my printer when something metallic came into contact with the pcb. I smelled smoke and quickly unplugged the printer. Anyway, this is the result and, of course, the heat bed won't heat.
Can this be salvaged or should I toss it and buy a new one?

update the heat bed was not hot at the time. I had the heat bed unscrewed from the chassis but had forgotten to unplug the printer. I am not exactly sure how it shorted but I think it shorted between the power lead connection and the thermistor.
Comment: Worth noting here that all heaters in a 3D printer are always energized with positive voltage. The ground side is what is switched. So shorting any heater element to ground will cause current to flow, whether or not it's "on."
Comment: Hello @zkent, I noticed your question has been up for a while now. Have any of the answers below been able to solve your question? If so, would you mind accepting the appropriate answer. If not, what is missing so that we may help you further? Also, if you have figured it out on your own, you can always answer and accept your own solution. Thank you.
Comment: FYI I have already ordered a new one for $20 but I still want to see if I can fix this one for the experience.
Comment: @RyanCarlyle what is the difference as it's in fact a resistor? According to my knowledge it doesn't matter if you change polarity (checked on Mk2 HB - as same as in the case). The only difference is that LED is lit or not.
Comment: @darthpixel Doesn't make any functional difference in normal use whether V+ or GND is switched. But it's a big safety difference. The entire heatbed circuit is always energized with respect to ground, so any short to ground at any time with the system powered will cause Bad Things. If you switched V+ instead, the heatbed would be safely grounded and inert when not actively being heated by the controller.
Comment: @RyanCarlyle I still don't get how it influence on the case of fixing HB. The problem is not how to do it according to all possible standards but to recognize if it can be fixed (make to heat again). Nevertheless I still suppose there are 2 heaters with common pin1. This asumption is made on the table all HB has painted with (which i linked in my answer). (take a look on my [edit2])
Comment: @darthpixel Oh, sorry for the confusion, I wasn't trying to say anything about your proposed fix. Just commenting on the question -- the fact that the heatbed was "off" doesn't mean it's de-energized. It's an important safety note for people when working on the printer, cleaning build plates, etc.
Comment: This sounds like the precursor to settings ones house on fire ...
Answer: What happend was short circuit of course. There is no doubt you overheated HB so copper detached from HB base plate. Because you wrote it doesn't work it means copper tracks are broken.
There is very low chance to fix it. I mean it - near to zero.
What you could do is:

Detach HB from arduino
Find a place where track is broken (which needs to uncover it from protective layer)
Connect it with a wire

Unfortunately even if you do it and your HB will work (electrically) your fixed HB which won't be flat anymore.
So definitely it's to be thrown away.
[edit]
I just realised you have double power HB, which means your HB has 2 heaters... which gives a bit hope.
take a look here

here is schematics which could give you an idea
You could check if your second heater works ok
If yes then you are salvaged! :)
[edit2]
I really suppose the schematics of HB is more or less like this

So if H1 is broken there is a chance to use H2 connecting pins respectively
Comment: It will still be flat after the repair if you remount it with the heating tracks on the bottom.  That will also help spread out any localized heat difference from a bypassed section.
Comment: Isn't that track only for the sensor in the middle?  On the other side of the pcb, at the end of those tracks is the thermistor.
Comment: @zkent My understanding of this circuit is that there are 2 heaters. #1 between pin 1 and 2 and second between pin 1 and 3. It means pin 1 is common. One of these heaters is broken so try to use second pair. (pairs are 1-2, 1-3)
Answer: Yes, it should be possible to fix, although you might choose to replace anyway on the basis that the repaired bed might give you concerns about how long it will be before your repair fails.
You will need to carefully remove the protective layer to expose the heating element (assuming you can identify where it is likely to have broken). Then carefully solder across the break (maybe with a short fragment of wire).
After making the repair, you should cover the exposed track. This provides both electrical and thermal insulation. In the absence of any suitable high-temperature paintable covering, you could try using kapton tape.


Why is there a vent on the ductwork coming right from the furnace?

Question: Why is there a vent on the ductwork coming right from the furnace? I have a typical furnace for a 1400sqft house in Michigan. I also have central air which runs through the same duct work. There is a separate room in the basement for the furnace, hot water tank and workshop area. No one ever spends much time in that room if any. Should I leave the vent open for both heat and air conditioning or should it be open for one/closed for the other? Please let me know. Thank you
Comment: if it's an intake, leave it open. if it's indeed a vent, and un-used, close up that waste asap
Comment: It's not an intake, it's blowing out hot air right now because I'm using it for my boots and gloves dryer lol the reason I ask though is because how close it is in the start off the duct work. As well I have done little research and it sounds like you don't want to close of to many vents depending on your system because closing off to many will cause to much back pressure or something.
Comment: So it's a vent to condition the space--heat in winter and a/c in summer--and it has an adjustable damper on it so you can control how much air comes out.
Comment: if you have several closed off, you can adjust the fan speed to reduce pressure. many of those $99 "fall specials" from HVAC companies include adjustments along with the safety inspection.
Answer: Furnace installers and/or home owners will put a register in the duct work to provide some heat in the winter to that area. The number of these supply registers is determined by the typical use and desired temperature of this area. I recommend that all basements should have at least 2 supply registers and 1 return register in the basement/equipment area just to keep that area slightly warm and the air fresh. If you are going to finish that area to be used as living space, then more supply and returns will be needed. Also you may want to close the supply registers in the summer when using the A/C since cold air is heavy and will move to the lowest level in the house. Keeping the register you originally inquired about either open or closed would be your choice.
Comment: It's there to help prevent anything that shouldn't freeze from freezing. In many homes it's the only heat supply in an unfinished basement. Use it as appropriate.
Comment: Any chance that register is there to help prevent pipes from freezing?
Comment: Works very nicely in an otherwise unheated basement.
Answer: D George-unless you're talking about an all electric building NEVER place a return air grill/vent in an equipment room. I say never because most people (even contractors) fall woefully short of understanding barometric pressure issues. Frequently a return in the equipment room of fossil fuel appliances is enough to overcome the natural or assisted draft of a fossil fuel system. This can easily result in the byproducts of combustion, including deadly carbon monoxide being drawn back into the occupied space with catastrophic results. GAMA and National Fuel Gas codes have very strict and sometimes complex rules for doing so. Since we don't know the competency of the homeowner or technicians we must rely on municipal inspectors to verify the safety of it. Unfortunately, many of them also lack understanding of these codes and their application. Better off just not doing it-unless there is verification the system will work under all circumstances.
Comment: Sidenote: while this doesn't apply to the OP's situation of a *supply* vent (vs a return) in the furnace room, the language being referred to can be found in IFGC 618.6 with the prohibition on returns in the furnace room being a new addition there in the 2021 code cycle


Start a dead battery car with a power/USB charger

Question: today my car couldn't start beacuse of dead battery. The battery is not old, I simply left my dash cam attached for a few days without using the car...
I'm alone at home and my car is in a difficult position to place another car beside and charge the battery through the wires...
I have not external battery charger or anything to charge the battery with.
This is an annoying sitiuation. So I got an idea (for future similar events): basically, all you need to charge the battery is something that can provide a tension greater than 12v, with a good amperage, for a while and attach it to the battery, wait and start the car. I saw people using laptop charger, AA batteries, etc.
I was wondering if I could do this using a power bank, or even a mobile charger. My phone can handle 12v and the output of the charger is 12v 1,5A, quite high. My power bank is 5v 2.1A instead. By having a USB transformer I could attach it into the power bank and have something like 15V 0,7A... Is this possibile? Could this give the car battery enough juice to start? How long would it take to recharge the battery enogh to start the car? Which is the best voltage to charge the battery? Where can I find a USB 5V to xV transformer?
Thank you and sorry for my bad English
Comment: 15V at 0.7A would work, but would take several days to fully charge a car battery. What is a "USB transformer" and how would you get 15V out of it?
Comment: USB supplies put out 5vdc, so a transformer will not work. You need to re-think this from a different angle, and that is buying a off-the-shelf battery charger. Your thinking in terms of USB, which has maybe 1% of the power you need.
Comment: Take a look at your insurance policy. More than likely it has a "road assistance" provision which will provide someone to jump-start your car if the battery has gone dead.
Comment: The guy I saw was using 12 AA batteries (about 18V) with an amperage going from 2.2A to about 1.4. So it was about 40w and the battery charged in 10 minutes enoght to set the engine on (I don't qant to charge the battery at 100% of course). If my power bank can provide 10w, then, if I can manager to get a voltage higher than 12v, I should ne abile to charge the var enough to start in about 40 minutes, am I wrong?
Comment: [$35 on Amazon Prime, saves you the trouble of having to reinvent any wheels.](https://www.amazon.com/Compact-DBPOWER-8000mAh-Portable-Flashlight/dp/B013UJ2JCE/ref=pd_sim_sbs_263_5?ie=UTF8&dpID=41nLstYVtuL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&psc=1&refRID=7Z5AHV8D5MYM179243PR)
Comment: Wow: [$19.99 on Amazon.  Prices keep dropping!](http://amzn.to/2nGgzUG) (but currently it's only 4, stars and the one Jason links to is 4.5 stars...)
Answer: Any car jump starter device will do, such as http://www.walmart.com/ip/Schumacher-Instant-Power-500-Peak-Amp-Jump-Starter/13005748

Cheaper, simpler, and more reliable than playing with stuff you find around the house.
Comment: Ask a simple question, get a simple answer. :) my thoughts exactly.
Comment: Lousy answer.  Why lug around this 10 lb device when you can get one that's 1/4 the size and 1/10th the weight and even costs less and works as quickly?  See Jason's or my answer...
Comment: Yep. A "lousy answer", but timely. I'm pretty sure the OP has started his car by now.
Comment: Yep, but the main goal of SE is to have the best answers most accessible to lots of people.  Not to answer one-offs.
Comment: This doesn't answer the question.
Answer: First of all, I realize your goal is to charge the car battery, but note that the typical approach is to just start the car (you need to output a few hundred amps for a short amount of time to start a car). Secondly, assuming your alternator functions properly, you don't need to charge the car battery, you just need to get the engine started. The alternator will take over from there and charge the car battery back up.
Anyways, I know this doesn't directly answer your question of how to build your own, but there are dozens of products like this that already exist, are small enough to fit in your pocket, have a USB port for charging devices as well as cables for jump starting a car, and charge in just a couple of hours, e.g.:

The one pictured above cost $40 USD, is a 8000mAh power pack with a USB output port for charging devices, a USB and barrel input port for charging itself,  a jump starter output with 300A crank current (you can do about 10-ish starts with it when it's at full charge), and it fits in my pocket. I own this one it's great (I don't want to turn this into an ad though so I'm not going to mention the product name, but these are easy to find).
So you might want to consider an existing product.
Also, depending on the type of vehicle you have and the terrain around you, you might just be able to push start it, too.
Comment: I'm a newbie here so my votes don't count yet, but this is by far the best answer.   I have a similar device (different brand and it works great.)  Is it not OK to post an amazon link?  You mention not wanting to turn this into an ad, so I won't either.
Comment: Well, the current top-voted answer has a link to an utterly obsolete product at walmart, so it seems links are OK.  I have one of these: http://amzn.to/2le9uec works great but there are competitive products for half the price now - $39 !
Comment: @MatthewElvey It's totally OK to post an Amazon link. Me not posting them is just personal preference, and isn't really related to this site. My picture already has some free advertising in it but I prefer not to further that by making it easier to buy. Also there may be better products out there, I don't want it to look like I'm implying that only one product is  suited (esp. if it's actually a crappy product and I just didn't realize it). Plus, like you noticed, the products can become obsolete. In this answer I only wanted to say that products like this *exist*.
Comment: @MatthewElvey Btw, since we've broken the seal on Amazon links (lol), I also have one of https://www.amazon.com/gp/product/B01D42TYFC, which is a bit pricier, but is 18000mAh with a 600A crank output, and also has a variable voltage generic DC output, and charges the *hell* out of my cell phone, the USB ports have an ungodly max output current. The one in my picture, though, is cool because it fits in my pocket.
Answer: Three things:

The currents involved will need thicker gauge cables or they will melt.
For about the same cost of tinkering with all this stuff, buy yourself a battery charger. If you don't have an electrical socket near where you usually park, either get a proper extension cord or learn how to disconnect and remove a car battery, charge it in your home.
Since you say your dashcam is what killed your battery, you may want to change the power wiring of your dashcam. Right now, it sounds like it is getting power directly from the battery, instead use power wires that are only on when the ignition key is at the "accessories" or the "on" position. The radio, cigarette lighter and heater fan use such connections.
Comment: Not all lighter sockets do.  For example in my ford transit the lighter socket is always on (so I've added a double socket+USB switched by a relay run off the radio power line).
Answer: In theory something like this might work but we are talking charging times in days not hours. Go buy yourself a cheap battery charger. If you really insist on trying it you are looking for a 5-14V dc-dc converter.
Answer: Basically, a power bank is designed for low power applications and a car battery would fall into high power category. So you would be using the power bank for something that it is not intended for. I would definitely not recommend it.
Getting into the technical aspects of it:
First thing you would want to consider is the Ah ratings of your power bank and car battery. Typically, a mobile phone power bank(assuming a very powerful one) would have charge rating of approximately 10,000 mAh(that is 10Ah). A car battery generally has a charge rating of approx. 70 Ah. Even under ideal conditions and loss free energy transfer, you would need 7 such power banks to charge the car battery. You need not completely charge the car battery to start the car. So, let's say you try to charge the battery to 50% of it's capacity. This would still need 3.5 times the charge content of your power bank.
Let's assume you have 4 such power banks. Now the charge problem is solved(ideally!!). But, the critical factor here is whether your power bank can supply power at the required power rating. You have stated that your mobile power bank has 5v 2.1 A rating.
So it's maximum output power rating is 5 X 2.1 = 10.5 W.
Generally a car battery would require a charging current of atleast 1A at a volatge higher than it's terminal voltage. Car batteries are generally charged at a voltage of approx. 13.5v. So, the power required to charge the battery is
13.5 x 1 = 13.5 W (ideally).
Therefore, your power bank will not be able to charge the battery even under ideal conditions since power ratings do not match. In real time, charging circuitry would involve lots of power dissipation which makes things even worse. I would not recommend this!
Comment: Thank you for tour answer. I don't want to charge the battery at 100%, not even 50%. Just the minimum to get the engine start (which I suppose it's not that high). I saw a guy which with 12 AA batteries gets the engine on after 10 minutes of charging. That's about 18v at 2,2 to 1,4A for 10 minutes (che showed alla the infos about the charging)... Why would you say that the battery requires 1A to charge? With 0,7A wouldn't it simply charge slower? What about the wall USB charger which outputs 12v 1,5A (18w). Would it be able to charge the battery? Thank you
Answer: Such a product already exists and is available, at least in the UK.
http://www.argos.co.uk/static/Product/partNumber/1985289.htm
Answer: No, your normal cell phone charger (wall wart) won't put out nearly enough current to jump start a car, even if it puts out 2.1A at 5v or 1.5A at 12v (that would be one weird cell phone!!! I bet you're misreading the specs.)  But one of jumbo-sized cell phone power banks can put out enough current to start a car- which is why some come with the adapter to make this possible.  If you tried to run enough current to start the car through a cigarette lighter, you'd likely blow a fuse -  (or worse melt a wire and possibly start a fire) so the devices that work via the lighter port instead need to slowly feed enough charge to the battery 'till it has enough to start the car.
What you want is what Jason C provided in his existing answer (we could combine answers...)
I have one of these: http://amzn.to/2le9uec works great but there are competitive products for half the price now - $39 !
This one is $19.99 on Amazon.  Prices keep dropping! (but currently it's only 4, stars and the one Jason links to is 4.5 stars...)
Answer: This is going to go against a bunch of other things on here.
Batteries do regenerate some current by chemical reaction if you have an engine that has a low compression start cycle AKA not high performance you may be able to let the battery sit disconnected for about five or six hours and try to start the vehicle with your headlights off. You disconnect the battery so that parasitic drains don't hurt your chances this will help if your battery is weak and not completely dead. If your battery is old you may not be able to do this. I have successfully done this on the road. Also if you have a manual transmission you can pop start the car scents that will let you cycle the starter and get the engine turning but that also will not work if your car battery is completely dead.


Component of one signal along the another

Question: Whenever we need to find component of one signal along another signal we can do so by the help of dot product. I want to as if this method is valid for all kind of signals. Are there any restrictions upon either of the signals?
Comment: I think bubble might have *convolution* confused with *correlation*, which can be interpreted as an inner-product operator on two equal-length vectors. The inner product can be used to calculate the projection of one vector onto another, which might be what is being asked about.
Comment: >"Whenever we need to find component of one signal along another signal we can do so by the help of convolution."  If you would explain just a little bit what you mean by "component of one signal along another signal", and how you believe convolution is used to find the answer, it would help people in formulating an answer.  Also, what _kinds_ of restrictions are you concerned that your signals might not meet? Physically generated? finite duration? finite bandwidth?
Comment: Indeed, it looks like the OP asks about correlation since the above definition matches somewhat definition of an inner product.
Comment: @Jason thanks!! Corrected the question. Please once again consider this question. Sorry for the grand error.
Answer: Generally speaking, about the only restriction that the signals need satisfy is that they have finite energy or power.  Since you mention vectors by which is presumably meant $N$-tuples of real or complex numbers and dot products, the restriction is the trivial one that each component of the $N$-tuple has finite value.
Practically, there are several issues that you need to think about depending
on what you are trying to do.  Obviously
$$\langle \mathbf x, \mathbf y \rangle = \sum_{n=1}^N x[n](y[n])^*$$
is the dot product but how accurate a measure it is of the inner product
$$\langle x(t), y(t) \rangle = \int_{-\infty}^{\infty} x(t)(y(t))^* \mathrm dt$$
of the continuous-time signals $x(t)$ and $y(t)$ from which these samples
came depends on whether the signals were filtered before sampling, the
sampling rate, whether the samples span the entire time interval where
the signals are nonzero, whether windowing was applied to the samples, etc.
You might be interested in the cross-correlation function $R_{x,y}(\cdot)$
instead of just the inner product (which is $R_{x,y}(0)$) in which case
FFTs might be used and you have to make sure that the signals are properly
zero-padded so that you get the right answers. Finally, we began with
the "trivial" restriction that each component is finite which always holds
in practice, but if the components are large in magnitude, you need to worry
about  the possibility of overflow in the inner product computation.
So, as you can see,
in theory, theory and practice are the same, but in practice, they are
different.
Comment: Thanks for your time Dilip. So it seems that inner product will give me the desired information as long as the signals are finite. I could not understand what you meant by cross-correlation. Can you elaborate further ? Or point to some link ?
Comment: $$R_{x,y}(\tau)=\int_{-\infty}^{\infty} x(t)(y(t-\tau))*\mathrm dt$$ measures how well $x(t)$ is aligned with a delayed version of $y(t)$. It might be that for any number of reasons, $x(t)$ and $y(t)$ are misaligned in time by $\tau$, and so $x(t)$ has a larger projection on $y(t-\tau)$ than on $y(t)$. If you find $R_{x,y}(\tau)$ for all $\tau$, you can determine the best fit. It is easier to calculate _all_ of $R_{x,y}$ instead of one point at a time if you use FFT; same reason that entire convolution $x*y$ is easier than to do it for one sample of $x*y$ at a time: $O(N\log N)$ vs $O(N^2)$.


Is it possible to use an app to disable the power button from switching the phone off?

Question: Is it possible to have an android application such that if the user starts it the phone will not switch off by pressing the side button? It means the only means to switch off it will be remove the battery, and taking all sort of permission from user is not an issue here.
Comment: https://play.google.com/store/apps/details?id=com.nezdroid.lockscreenprotector
Is for you, I think it is ok, but need to use .
Answer: No, it's not possible. The functionality to turn off the device if the power button is held down is at a very low level of the system, so that even if Android gets into some broken state, the user can still switch the device off to prevent it overheating. This is especially important on devices without a removable battery!
Only replacing the kernel with a custom-built one can disable the power button completely. This may or may not be possible depending on what device you're targeting and whether all the drivers and kernel source for that device are available.
Answer: It is possible to disable or even change what hardware keys do even without an app.
In my case I just commented out (added a # at beginning of) the lines starting with POWER in the /system/usr/keylayout/Generic.kl  file
(with root and rw access to /system . To access /system as rw just use this command: mount -o remount,rw /system)
and rebooted the device. After this my physical power button doesn't work anymore. I tested this more by making my physical home button type the letter a in the same way.
(You can get an idea what changes can be made by reading that file. MEDIA_PLAY , CAMERA , CALL , CONTACTS , BRIGTHESS and more are all there. I suppose that in the same way it is possible to change what virtual keys (like virtual keyboard keys) do).


I have two switches for one light. One is a dimmer switch and other is single pole switch

Question: Dimmer operates light but if the single pole is off the dimmer switch doesn't operate. The problem is the single pole light switch has only one black and white wire connected inside. No other wires in box.
The dimmer has two wires in box. Two blacks connected to switch and two whites married. Is this fixable without running any other wires through wall?
Comment: Chris, Welcome to the site. It is not very clear in your question what your goal is. When  you say "Is this fixable" you should state what you really are meaning to achieve.
Comment: I understand how, from your perspective, this setup seems like surely it must be just like every other wiring setup any of us have ever seen, so no need to explain the lay of the land.  However, actually your setup is very weird. We need all the details.
Comment: Can you post photos of the insides of all boxes involved, including the box for the light itself?
Comment: Also, what does this light serve? Some lighting outlets are required by Code to be able to be controlled from multiple locations...
Comment: I am attempting to replace my dimmer with a wifi dimmer. The new dimmer requires a neutral wire hookup. The two "white wires" that are marred together I assumed were the neutral wires however upon checking for the hot wire or line wire, i found that one of those white wires is the line wire. I am assuming that it goes to the light since the other switch only contains one 14/2 wire which are connected to the single pole switch. And in the light, the white wire is marred to the wire that goes to the single pole switch. This single poke switch has to be in the on position for the dimmer to work
Comment: The line wire is going to the single pole switch before it goes to the dimmer no? Then it has to go to the light. I have seen my fair share of wiring issues but this takes the cake for me
Comment: @Chris -- we really need photos of the insides of the boxes to resolve this....
Answer: You need smart switches. Period.
A smart switch can handle this problem easily. Anything else will require busting up drywall and laying new cable - possibly /4 cable to the switch loop owing to needing to support both a 3-way and provide neutral. Let's sidestep that, eh?
Why would anyone wire it this way? My guess is, the now-dimmer location started out only as a place to tap power for the light, and the switch loop was meant to be the only switch.
Use a smart switch with smart 3-way capability and wireless remote
You put the smart (dimmer) switch at the current dimmer location (with neutral). The line up to the lamp becomes switched-hot and neutral.  That means the switch loop to the other switch is pretty useless.  That is why you need a wireless battery powered remote which matches to the smart switch. Generally these look exactly like wall switches or dimmers, but can be mounted to the wall with sticky tape.
Selecting particular models is off-topic here, so I leave it to you to find an a) smart b) dimmer that c) accepts wireless remote and d) talks to whatever WiFi scheme you are interested in.  Don't buy mail order; make sure the part that touches mains power has a UL listing, CSA, ETL or other NTRL.  CE is not one, and is the mark of cheap Cheese junk that you are not allowed to use in mains wiring.  CCC, FCC and RoHS are also used to fool you.
Or, use a smart module in the lamp box
In this case, you can use the wiring in and out of the lamp as always-hot and neutral.  That can power any wired smart switch of your choice coughInsteoncough, provided the switches can communicate with the module via powerline or wireless signaling,
Answer: So, you appear to have a "switch loop" on the single pole switch, which was fine years ago and is grandfathered, but is not current code.
That appears to be in series with your dimmer switch, from your description of the behavior.
If you want either switch to control the light (known as "3-way" switching) you will need additional wires (or more likely new cables, unless you happen to have conduit) run to support that function. You'll also have to make sure that both locations have neutral in the box for meeting the updated codes, since you will be modifying the wiring.


Can a developer use someone else's product name as an Open Source project name?

Question: Suppose that an open source developer wants to use the product name ninjago owed by Lego for the name of an Open Source project. Is it allowed to base the project name on Lego brand? Also can the developer  create a unique logo for this open source  project that will look kind of similar or has some kind of reference to Lego product? Or is even a name protected?
Comment: Even if you aren't infringing on the trademark, you're pretty likely to eventually get a cease and desist letter. Lego has lawyers, you don't. At least in Germany, Lego is known for aggressive trademark enforcement.
Answer: united-states
Trademark law varies somewhat from country to country, and the set of protected trademarks varies a lot from one country to another. In this answer I shall consider primarily US law, although I will try to make the answer as wide ranging as I can.
What trademark law protects is the identification of a source of goods or services, and the associated reputation an good will. By using a trademark that is identical to or confusingly similar to an exiting mark, one may be relying to some extent on the reputation of the existing brand. Unless done with permission, this is unfair, and is generally not allowed.
However, the protection of a trademark is normally limited to a product or service of the same kind as the existing mark. So suppose one firm registered "GreenCall" as the name of a smartphone service. Another firm wanting to use "Greencall" as the name of a wine would probably not be infringing on the first firm's trademark, and could not be successfully sued. (They might well be sued, however, and need to spend significant money defending their mark.)
In some countries, only registered trademarks get any protection. In others, such as the US, use of a mark without registration will provide some protection, but not as much as registration does.
In the US at least,a well-known or "famous" mark gets addition protection, even outside the category where it has been registered and used. What counts as "famous" is ultimately a decision fo the US Patent and Trademark office (USPTO) to make.
A toy line set in a fantasy world would seem like a rather different category than an open-source project, unless the project was a game with similar elements. The farther and more obviously different the project might be from the toy line, the less likely the use of the same name would be to be held a trademark infringement.
Since the Lego mark is used not only on toys, but on a successful TV series, a movie, a video game, and a theme park, it might be held to be a "well-known" mark, and be protected even in categories it is not used in.
Actually the project being an open-source one would make no significant difference here. Open source project and commercial products follow the same trademark rules.
However, even if the category is different enough that the use of the same name is ultimately held not to be trademark infringement, it is not unlikely that the trademark owner would take legal action, and the developer or development group would need to spend money on legal fees at n early stage of the project. It might be wiser to choose a more clearly distinctive name. It might also be wise to consult a lawyer with trademark expertise.
As to the logo, if the logo in some way "looks similar" to an existing logo, it might be held to be a derivative work, and thus a copyright infringement. This is a highly fact-dependent judgement call.
Comment: @jcubic If the name "thanos" is protected as a trademark (which not all character names are) and if a developer uses it to identify a product (or service) in a way which could reasonably be confused with the protected use, or which could be taken to falsely imply sponsorship. approval or endorsement by the trademark holder, that would be infringement and the holder could sue and perhaps win. However a software product is in a significantly different category from a comic character, so it might not be infringement unless the mark is "famous".  The copyright issue for a logo is as above.
Comment: @jcubic  even a lawyer cannot give final assurance. the only way to be **sure** is to use the mark and be sued.  Then, once any appeals are resolved, one can be sure what the law is on that issue. But a good lawyer should be able to give more assurance than any other means. Looking for quite similar cases in existing case law can often give reasonable assurance, But the facts will almost always be somewhat different, which could lead to a different outcome in court.
Comment: I want to add additional question. I planed to create a project named after Thanos (Marvel character owned by Disney), not exactly Thanos but using his glove as logo and name that word play related to Thanos. And when doing research found a lot of project that use Thanos like this one https://github.com/shril/thanosdb . Is something like this an issue and projects like this should worry about being sued.
Comment: And another question, if it's unclear/fuzzy is the "contact a lawyer" the only option to be sure?


Help needed understanding atmospheric tank vent physics principals

Question: I try not to be a complete moron but am not an engineer so please bear with me. I have this LP record ultrasonic cleaner system that uses a solution stored in a "tank" which is a simple water container and can't stand much pressure (atmospheric tank). The ultrasonic cleaner is open to the air during operation; a pump moves the solution in and out of the tank through a filter; the sequence of operation is controlled by microprocessor. The solution is distilled water/Methanol/Isopropyl alcool plus a few drops of wetting agent that is heated to 43°C for cleaning. Methanol and especially 99% Isopropyl are not cheap so I would like to have an intervention-free system to reduce evaporation of the solution while not having to open/close a lid during solution transfers and cool down after a cleaning session.
In a previous post I learned about storage tank "conservation vents" used in the industry which control vacuum or pressure build-up. I figured I could rig something similar with both pressure/vacuum proportional reliefs but agree this all seems overkill as was mentionned in replies. As was suggested and as I read more on storage tank operating principles, turns out an adequately sized vent might fit the bill. I have started reading API 2000 standard but I don't have a copy of the Crane TP-410 reference used in the industry.
From what I understand, in my situation the vent has a compressible flow and the pressure drop associated with a vent in this mode is proportional to the flow pressure, the Darcy friction factor (which takes into account the inner surfaces roughness of the vent piping), the pipe length, and inversely proportional to the piping inner diameter and the operating pressure. There is also a minor loss (K) factor added that accounts for vent entry, valves, bends etc... So a gooseneck vent with two right angle bends has a higher pressure drop than a straight pipe vent (eh... dah!)
Do I understand correctly the mecanism and the following conclusions:

If the pressure drop through a vent is equal to the vapor pressure of the solution at storage temperature then there would be no evaporation at that temp? E.g. the solution reaches an equilibrium with the outside air pressure at some point.

Conversely, when the solution is back into the tank after cleaning a record, there will be evaporation since the solution temperature after the process is much higher (about 37°C) and so is it's vapor pressure, until the solution cools down and the vapor pressure equalizes with the vent's pressure drop. I calculated the solution's vapor pressure (Raoult's law) at that temp to be 7.1 kPa, slightly higher than water only (6.2).

During transfer operations, the pump will force more air flow through the vent, which will raise the pressure drop; at some point a dynamic equilibrium will be reached during transfer where the output of the pump will be reduced by the work needed to overcome the vent pressure drop.

Many small vent holes would allow more total air flow during transfer operations while reducing evaporation since each would have a higher pressure loss than a single vent of a cross-sectional area equivalent to the sum of the small holes'. Small holes are short in length (thickness of the cap material), but minor losses play a bigger role, each hole adding it's own entry point loss.

Or I am completely lost? Any insights appreciated!
At the moment I hesitate between a gooseneck vent made from of about 30 cm of 4mm I/D PVC tubing, or 7-10 1mm diameter holes through a 3mm cap thickness. I used the "empirical" formula from this site to evaluate pressure drop: https://www.engineeringtoolbox.com/pressure-drop-compressed-air-pipes-d_852.html but I'm not sure it applies; I'm still searching for a good calculator online, suggestions are more than welcome.
Many thanks.
-Joe
Comment: you could add an electric vent valve ... or a trap filled with distilled water
Answer: Pressure drop is nonzero only in case of some flow (for really small flow rates, it is proportional to the flow rate), so the equilibrium in your case would always involve some evaporation. What you need is a relief valve with a set pressure. This causes the valve to be closed until the difference between the inside and outside fluid pressures is greater than the set pressure.
For a proper choice of relief valve, you need 2 parameters:

the set pressure - when should the valve open (in case of storage tanks this can be chosen based on allowable pressures that the tank can safely withstand)
relieving capacity (how fast can the pressure difference be brought below the set pressure - this is also important, because in some cases, pressure buildup can be fast and a valve with small capacity would fail to relief it even when open)

The most basic relief valve designs are one way, but I think you would require two of these or a "two way relief valve", maybe one of these or something similar.


In Photoshop, how do I take a grayscale image and transform it into shades of whatever color I want?

Question: In Photoshop, how do I take an image in shades of gray, and transform it into shades of whatever color I want? I don't know the term for it, if there's one, neither the property of the image I would be changing with this effect, but I think it's easy to understand.
Comment: It depends on the image and the coloring you want on it. If it's a black and white photo that you want to make into a colored photo, chances are that you need to use something like brush tool rather than just laying color over it semi randomly.
Comment: @Joonas, thanks for your reply. I needed this to ajust grayscale icons to match my application theme. I needed to transform them to a #336699 scale. nine9ths solution worked like a breeze.
Comment: As a semi-related note, from offset printing experience: if you are intending to print grayscale images using a spot color you need not do anything to the image. You can place a grayscale image in a layout program like InDesign or QuarkXPress and assign it one of the spot colors you are using at the press. It will be rendered in the chosen spot color on screen, but the image itself remains "grayscale". (Or "single channel".)
Answer: Make sure you're working with a Grayscale image and then go Image > Mode > Duotone, you'll bring up this dialog:

From there choose the colors you want to use by clicking on the color block. Adjust the mapping of gray to color by clicking on the curves (the block with the diagonal in it).
You can achieve different effects by adding multiple colors. For example, this image:

With this tritone:

Produces this image:
Comment: This is absolutely amazing! worked perfecly. I needed this to ajust grayscale icons I downloaded from iconfinder to my application. I needed them to follow the application theme. Thank you so much!
Comment: Photoshop will even remember the last Ink color I created to make my job even easier. Awesome.
Comment: You could also save a preset if you anticipate needing to do this on multiple occasions.
Answer: Gradient Map Adjustment Layers are awesome, precise and exactly what you're after.
Gradient Maps map the underlying image's brightness to a point on the gradient. This means you can choose exact colours for highlights, midtones and shadows.
There's a bit more info here:
https://graphicdesign.stackexchange.com/a/10789/3901


What's the easiest way to install multiple versions of IE and Firefox on the same (virtual) Windows machine?

Question: I could obviously have multiple VMs, but that would be highly inconvenient. Is there some easy way to have multiple versions of browsers installed simultaneously? It's mostly about IE and Firefox; other browsers are not popular enough to make testing with their old versions a terribly high priority.
Comment: Just care about IE7 & IE8, IE6 is dying rapidly (~9.6%) and things dont break in firefox much (its very forgiving).
Comment: Particular versions come and go (by the way ~9.6% doesn't really count as "dying", it counts as "very popular") - the problem stays. In a few years people will be saying "just care about IE11 & IE10, IE9 is dying rapidly" - and multiple versions will still be necessary to test with.
Answer: I have had luck with this:
http://spoon.net/browsers/
Launching a virtual browser takes a couple seconds to load, but less of a pain than multiple VM's.
Answer: Internet Explorer
Our team struggled with this some time ago, and we found that neither IETester nor Multiple IE provide a solution which you can rely on if you want to get the same results as native IE users.
The best solution is the native "virtual" one. Microsoft itself provides Virtual PC disk images for individual versions of IE (disregard the expiration date on their page, they should release new images once the current ones expire). Note that you can download Virtual PC from the Microsoft site for free (the page above contains a link), but for some reason they have a broken link there at the moment.
The only disadvantage of the above is that Microsoft does not provide an image for Windows XP SP2 with IE6 (the SP2 version of IE6 uses an older Javascript DLL, so it behaves slightly differently than the newer SP3 version).

Mozilla Firefox
You can test individual versions by using Portable Firefox from the PortableApps suite. The linked page offers the newest version, but it also contains links to older (legacy) versions at the bottom.
Please note that by default this won't allow you to run multiple versions of Firefox simultaneously. It's possible, but it requires some simple hacking:

download a portable version of FF from the site above, "install" it into a folder
go to {your FF vX.Y folder}\Other\Source, locate and copy a file called FirefoxPortable.ini
go back to {your FF vX.Y folder} and paste the file there
open the file in a text editor and change the following:

add -no-remote into AdditionalParameters
set AllowMultipleInstances to true

If you setup each version of Portable Firefox as shown above, you will be able to run individual versions simultaneously.

Please note: this is for development purposes only. If you use FF as your primary browser, include it in the "mix" only at your own risk. We're using it only for testing purposes ourselves, and even though we did not encounter any problems so far, I would not want you to lose/corrupt your primary FF profile.
Answer: IETester is an excellent choice for testing in IE5.5-8 without even bothering with virtual machines. There's also Multiple IE, but it's old and buggy.
No idea about Firefox, though.
Comment: IE instances in IETester behave significantly different than IE instances outside IETester. I don't know how common it is but I ran into it during the first 15 seconds of testing (http://bit.ly/bp8X3w), so it doesn't really work for me.
Answer: If you want to do it from a single VM image, just use snapshots.  VMware Workstation will handle this quite nicely.  Install your base OS with the lowest level IE you care about and take a snapshot.  Then install the next major version you care about and take another snapshot.  Rinse and repeat for however many versions or patch levels you care about.
Now all you have to do is revert to the particular snapshot that contains the browser version you care about.
Answer: Try http://utilu.com/IECollection/ for multiple IE browsers and http://utilu.com/UtiluMFC/ for multiple Firefox browsers.


Given an $m$ how to find $k$ such that $k m + 1$ is a perfect square

Question: Any way other than trying linearly for all values of $k$.
Answer: Note that $(m+2)m+1$ is a perfect square. But it is not necessarily the smallest perfect square of the required shape.
We can if $m\ge 3$ do it a little more cheaply with $(m-2)m+1$.
I assume $k=0$ is not allowed!
Comment: Feeling ashamed now. Why didn't this strike me?
Answer: If $km+1=n^2$ for some $n$ and $k=am+b$ for some $a,b\in\mathbb{Z}$, $0\le b<m$. Then
$$k=\frac{n^2-1}{m}=a^2m+2b+\frac{b^2-1}{m}$$
So we can know $k$ is integer if and only if $b^2\equiv 1 \pmod{m} $.
For example, if $b=\pm 1$ we get $k=a^2m\pm 2$ and $km+1=(am\pm1)^2$
Answer: There are infinite $k$ such that $km+1$ is a perfect square. One class of infinite solutions is given below.
For a given $m$, choose $k = a^2m + 2a$, i.e. $k = a(am+2)$ where $a \in \mathbb{Z}$. Hence, we get that $$km + 1 = (a^2m+2a)m + 1 = (am)^2 + 2(am) + 1 = (am+1)^2$$


Get title of current figure in MATLAB?

Question: I have a figure opened with a certain title.
How do I get the title string?
I have tried get(gcf) but I don't know how to navigate to the title.
I want to get the title of many figures, add some more characters to the string and write it back.
Answer: x=0:.1:3.14;
plot(sin(x))
title('Sin(x)')

%get the title
h=get(gca,'Title');
t=get(h,'String') %t is now 'Sin(x)'

%new title
new_t=strcat(t,' Sine function')
title(new_t)

Comment: You could make it into single line `t =get(get(gca,'Title'), 'String');`
Answer: Given a handle to a figure window, this shows how you can "get" and "set" the "title" of the figure.

Run the following lines of code and see for yourself. I used Matlab 2016a.
Here is a summary:
h = figure;
h.Children.Title.String = 'Your desired title';
disp(['Current Figure Title: ', h.Children.Title.String]);
figure(h);

Create a demo figure with title: 'Test Title-1'
h = figure;
title('Test Title-1');

Access the figure title through the handle: h
figTitle = h.Children.Title.String;
disp(['Current Figure Title: ',figTitle]);
figure(h);

Change the figure title to something new: 'Test Title-2'
h.Children.Title.String = 'Test Title-2';
disp(['New Figure Title:',h.Children.Title.String]);
figure(h);

Get title of current figure in MATLAB?


Swell spectrum and wind spectrum

Question: While modelling both wind waves and swell waves, whether we have to add both spectra or append wind spectra in swell spectra? Because swell spectra has high amplitude values but wind spectra has very less amplitude than swell. Kindly guide me to model both swell waves and wind waves.
Answer: Although it is unclear which model(s) you are using, mathematically speaking:
Assuming that wind sea and swell are uncorrelated, combined wind sea and swell (total sea) can be described by a double peak frequency spectrum
$$ S_{total}(\omega)=S_{ws}(\omega) + S_{swell}(\omega) $$
where $S_{ws}(\omega)$ is the wind sea spectrum and $S_{swell}(\omega)$ is the swell spectrum.
The spectral moments $m_{n}$ are additive
$$m_{n,total} = m_{n,ws} + m_{n,swell}$$
so e.g. combined significant wave height can be calculated as
$$H_{s,total} = \sqrt{H^{2}_{s,ws} + H^{2}_{s, swell}}$$
Comment: Thank you for your response...I meant like this only... I studied some literatures in that also they add wind spectrum and swell spectrum... But I have doubt in that... While adding swell spectrum has high amplitude values but wind spectrum has less amplitude values... Is it ok to add those two spectrums? Thanks in advance

Swell spectrum and wind spectrum


Why was an internal plug installed in a cleanout?

Question: The picture shows a 2" ABS cleanout with the cap removed. As shown, there is a white plastic internal plug, apparently glued in place so that I cannot use the cleanout. Why would the plumber have installed this white plastic internal plug? To use the cleanout (the kitchen sink drains slowly even after I cleaned out the traps on the sink side of the clean out) should I just gently punch a hole in the white plastic internal plug?
Answer: That's a temporary cap, or "test plug", installed for either pressure testing or debris prevention. You can just knock it out if you actually need to use the cleanout.
Obviously try to recover the parts so they don't become a problem downstream. The outer ring will stay in place as it's cemented in. Since there's no water flow through that section it's not an issue.
Comment: Thanks for these clarifications. I drilled a small hole through it, then inserted the bent arm of a hex key to try to pull it back out.  The plastic just cracked, but with pliers I was able to pull out the pieces.  This is one of those things that should be noted in a user manual for the homeowner.