The science behind an invisible wall of pain

Question: In this concept, a person is confined by a precisely-defined invisible barrier that causes extreme pain when any part of them crosses it.  It affects only them, thus the source of the pain must be within them, but triggered externally.  I'm thinking something like nano-sized GPS receivers (either organic/chemical or mechanical) that have been put into their body and have dispersed to all of their nerve receptors.  When any part of their body crosses the threshhold of the GPS coordinates, the receivers do something to excite the relevant nerve receptors to an excruciating degree.  I'd be curious to hear plausible ideas about nano/biological/biochemical systems that could produce spatially-determined effects within the human body.
Comment: If you really want this to be precisely defined so that a single body part crossing the threshold will trigger pain, you'll need something more local than GPS. Even the most accurate GPS available doesn't come near to providing accuracy down to a few inches.
Comment: If you cannot rely on GPS signal, perhaps you can use proprioception. Transport the prisoner to the center of the designated location, then prime and implant the nanobots/anthrobots, which spread all over and can tell how much the prisoner moved. Move more than the specified parameters and prisoner gets punished.
Comment: Steven Gould describes a mechanism for this in _Reflex_. Wikipedia provides details (that completely spoil the book).
Comment: As a suggestion, why not simply two laser 'walls' after each other? If the laser is interrupted, the receiver will not see the laser and instruct the pain. With two laser 'walls' after each other you can also pretty accurately see if they returned or exited, to either keep the pain or turn it off again.
Comment: "*precisely-defined invisible barrier*" - how precise does it need to be? Does it surround them, to keep them contained? Or is it meant to keep them out of an area? How large is that area?
Answer: Ferrite nanocrystals dispersed in one's body, and a microwave source can do what you are looking for.
When the subject gets outside of the shadow area for the microwave source, the ferrite will start absorbing the microwave and convert them to heat, with related discomfort/pain.
Comment: Ambiguous syntax, @DKNguyen - do you mean the crystals, or the person so afflicted?  The former, maybe.  The latter, unlikely, though you could probably make them suffer and die.
Comment: This might work without ferrite, just use microwaves of frequencies that heat water, but control the barrier so it won't hit the person enclosed with rebounds off its surroundings.
Comment: Could you hold them in an area via magnetic field?
Comment: Could you hold the ferrite nanocrystals airborne in an defined area via a magnetic field?
Comment: A low tech version of the same idea is a collar made of a conductive material shaped in a way to maximize microwave reception. More than pain it will cause burns but the effect might be equally deterrent.
Comment: Can you do it without microwaves?  Solely by the interaction with the satellite GPS systems, so it doesn't require any other equipment?  The nano-receiver, based on location data, triggers an impulse, perhaps biochemical, in conjunction with an organic nano-computer, to produce pain to the nerve receptors?
Comment: @GeneTerry The process L.Dutch describes doesn't need GPS, just the ferrite crystals, a local microwave source and something to provide a shadow within it. Getting GPS involved is an unnecessary expense, especially since it probably isn't accurate enough for what you want
Comment: @DKNguyen No, not by a static magnetic field.
Answer: You can buy these things from Amazon. They are usually meant for pets. I find this to be a kind of animal cruelty, but if you apply it to a human, it might be something more humane than prison.
With pets, you use a set of transmitters to make an invisible fence. When the critter crosses them, their collar will give them a little jolt. With humans, all you need is to adapt the collar.
If you want something really fancy and you like DYI, you can instead take an electronic tag - the kind worn by people under house arrest - and combine it with a tazer. If you want to be cruel, you can make an implant, kinda like the internal part of a pacemaker.
Heck, I'm even gonna prototype one now and make a Kickstarter to sell it.
Comment: Many hospitals have something similar for babies. Except the baby only has the tag anklet, not the shock collar, of course. If a baby is kidnapped from the hospital, the hospital security and police are immediately warned. Of course the "invisible wall" is only defined by the range of the transmitters. I think the important point in your answer is that there are two distinct parts to the technology: the electronic tag to detect that the individual is on the wrong side of the "wall", and the punishment device. The OP is free to adapt both parts separately to best fit with their story.
Answer: Camera and Laser
The invisible wall is defined via software. There is a camera with depth perception. Any part of the prisoner's body that touches the wall (as seen by the camera) is shot by the laser, which will hurt. The laser can even be outside the visible light spectrum. The software will not aim the laser at non-prisoners.
Answer: I don't think nanotech is necessarily required when you could just put a chip in the pain center of the brain. From there, you could remotely activate it to cause the sensation of pain, modulate exactly how painful it is, and prevent it being solved by anaesthetics or narcotics. And since you already have a chip inside the brain, you could also add the failsafe option of inducing a seizure or unconsciousness remotely.
As far as the granularity of the zone is concerned: if you just want it to be "when crossing X point" then you could have the equivalent of an RFID chip or some sort of GPS signal and give it a bounding zone. I prefer the latter because then you could also set up a failsafe where if the GPS signal isn't detected for X period of time it starts inflicting pain, which would prevent blocking the signal with a tinfoil hat or what not.
If you want more granularity, a few well-placed sensors will allow an excellent amount of coverage. Placing relay sensors in the T1/L4 vertebrae, elbows, hands, knees, and feet would be very effective in preventing any part of the body being extended past the zone without the need for more comprehensive solutions. At that point, what could possibly get out of the zone? At most, some fingers or toes, and at that point just increase the size of the bounding box by six inches (and honestly another two feet just for good measure) and you're set.
This system could actually be relatively cost-effective, all things considered. The brain chip is obviously the main expense, but that's just a GPS/RFID chip and a simple way to stimulate the brain. Have a surgeon or robot install it and you're away. Then 11 relay chips that are just RFID/connect to the brain chip somehow, and RFID is cheap enough even with today's technology. Have a nurse or another robot install those (which are even easier to install), and that's that. Plus, this allows for easy removal of the system if the prisoner is released or if the plot demands it.
Answer: If you can put implants in the target's body, and those implants either

have long-lived batteries (weeks-months with current tech, dependent on the size of the battery pack)
draw energy parasitically from the target's system (moderate-future tech, maybe 20-50 years?)
and the implants are large enough to have a GPS transceiver (think cell phone, though phones are dominated by the size & weight of the screen + battery),

then you can do pretty much anything you want to the target. <10 mA across the appropriate nerves could probably cause excruciating pain and/or let you manipulate the target like a puppet... depending on how good your surgical procedures are. Pain & spasms are going to be easier to do than fine motor control. No hardware required other than the implants and the existing GPS network.
If you can't put an implant in your target, you could ward specific areas with directed energy weapons and put facial recognition or other sensors in the area whose access you want to control. Turn on the system only when the target approaches. Of course, those systems may be vulnerable to both false-positives and false-negatives, and creative targets might try to cross at the same time as someone you don't want to fry.
More exotic, target-specific wards / pain-walls might become available further in the future by having swarms of nanites that look for genetic markers and restrict themselves to particular areas. They'd effectively be infecting your target if small enough to enter the body unnoticed, or infesting / attacking the target if a bit larger. But they could presumably induce all the pain & control options for implants above.
Comment: Great ideas.  Thanks.
Answer: We can kind of do this today with millimeter waves. This operates on a principle similar to a microwave oven, set to use a wavelength that completely and fully activates the pain receptors of any skin they hit, forcing a complete flight response. You do NOT want to be there.

For the first millisecond, it just felt like the skin was warming up. Then it got warmer and warmer and you felt like it was on fire. ... As soon as you're away from that beam your skin returns to normal and there is no pain.

This has four major drawbacks based on the question, but I list it here because I feel like it's the most "sci-fi" solution, and depending on the exact details of the story it might still work:

They don't discriminate against the prisoner. You may be able to work around this if you can allow visitors and jailers to wear special clothes, or have other protections, especially if its something like fibers woven into normal-looking items so the prisoner might not perceive they're doing anything special. Combine this with things like disabling parts of an emitter array as people approach.
You can't put them everywhere. The barrier is only going to be so thick, and once through it the prisoner is completely free. You'd need to fill a fairly thick area to be effective.
They won't protect against something like tunneling. Even a piece of cardboard is enough to totally block the effect based on current capability. For a science fiction story, you might get by saying the captors use a different band or type of radiation that can penetrate solid materials to a much greater depth.
It can actually cause burning if the exposure lasts too long.
Comment: This was my first thought, but it's indiscriminate, so it doesn't fill the requirement of the field affecting only him.
Comment: @AosSidhe Correct, though I do address that weakness.
Answer: Against my better judgment, I'm going to give you a tech that isn't here yet.
Nanobots, not even smart ones.
They spread to predetermined places where nerve traverses, sit dormant absorbing your body's energy and filling some kind with small capacitor, then when they detect your coordinates are outside boundaries, they release small pulses that would cause pain, discomfort and uncontrollable spasms, maybe even death, if you feel like it*.
In reality, this would require a ammount of energy a single nanobot probably can't generate/contain


Scenes of helicopter

Question: Hi everyone,
I'm looking for scenes of helicopter on animated movie or movie.
I would try the synthesis of this. So I need to impregnate the sounds with several scenes, several views, several sounds .....
Any exemples? Tips?
Thanks for your help
Answer: The one that immediately spring to mind is Apocalypse Now.  Walter Murch used helicpotor recordings, but also synthesised elements of helicopter sound. He then mixed between the acoustic and synthesised sounds, particularly in the dream like sequences.  IMO worth a look and evaluation.
http://www.salon.com/2000/04/27/murch/
Answer: Hi lili
Sounds for a cool job, helicopters makes fun.
As bit depth said before, try to separate blades from engine. If you need fx for the blades, use a kind of pitched down sword-swishes or whooshes. Try to experiment with the pitch to find something who works. Also helicopters makes some great noise if they are in distant and there is only the low swapping sounds from the blades. Similar than: https://www.soundeffects.ch/soundeffectstracksheet.php?prodid=90026
More helicopter sounds you can find: https://www.soundeffects.ch/soundeffects/sound-effects-categories/sound-effects-helicopter.php
If you need helicopter sounds, I can make you a package up from $50 to $...
As an inspiration, the 80 tv series Airwolve came in my mind
Best
Guido
Answer: Sorry for the short answer, but perspective is key, here.
Try to get many different perspectives so that the camera cuts are made more interesting and sonically different so that it doesn't sound like a plopped long helicopter sound was thrown in.
Good examples of wonderful helicopter design:
Black Hawk Down - cliche good helicopter movie
A good day to Die Hard (most recent movie - not sure if that is the "official" title or not)
Mission Impossible 1 (helicopter and train scene at the end)
Day After Tomorrow (helicopter crash scene, which also on the DVD has a special feature with a breakdown of the stems)
Answer: Hello,
Thanks for all. Your examples are great. So I found what I wanted. Many scenes with different views and sounds.
That's true that for a good chase with helicopter, we have to have sounds very differents to each plans.
So I have the intention to use synthetic sounds and real sounds, as Apocalypse now.
Thanks for your help
Lili
Ps: sorry for my bad english
Answer: To get the sense of movement from the helicopter (if you are using synthesized sounds, they will probably start out feeling motionless) adding doppler effects can be really fun!  There are various plugins that can do this including at least one for free:
http://www.vst4free.com/free_vst.php?plugin=ADopplerEn&id=517
I have heard helicopter sounds made from a noise source and an automated filter producing that distinctive envelope...not as realistic an effect on its own but can be cool sounding.

Scenes of helicopter


Set RTS on Close - option not found

Question: I'm trying to enable the "Set RTS On Close" option.  This is supposed to be located in:
 Device manager -> Ports -> USB to Serial Comm Port -> Properties -> Port Settings -> Advanced
The "advanced" screen on mine however gives no such option.  I have tried this on 3 PCs; two running Windows 7 and one on Windows 8. But they all display the same thing. See screenshot: http://tinypic.com/r/2uzt09f/8

There are also several other "Miscellaneous Options" that don't appear (but appear for other people).  I suspect these options are controlled by the driver.  The driver is "Prolific" and used for an Arduino chip.  It installs automatically when the USB is plugged in.  Perhaps if I could force it to use a different driver that might fix it but I don't know which one.
EDIT: Does no one else have this problem? The only other person I could find with this problem was in a forum posted here but he didn't really get any answers http://diydrones.com/forum/topics/stopped-on-unknown-problem
Answer: This option is available when you install the FTDI driver instead of the Prolific one. use this page http://www.ftdichip.com/Drivers/VCP.htm to find the suitable driver (not executable but rather the inf file)

Set RTS on Close - option not found


What is this plant with white bracts around the inflorescence?

Question: Does anyone know the name of this plant? I live in North Georgia.
Comment: Guessing the actual inflorescence + bracts are less than 3" across.
Comment: That looks remarkably like a member of the Monarda genus, very similar colouring and leaf shape to Monarda Clinopodia but the petals are so small that it makes me second guess. Do you have any other images, particularly with more mature flower heads?
Comment: This looks like two flowers...?  Please send more pictures.
Comment: Please send more information; opposite leaves? Shrub/small tree? Size of flower, is this one or two flowers? Is this a true photo? Please let us know...
Answer: That looks like Short Toothed Mountain Mint, Pycnanthemum muticum.
Comment: Can you tell us more why you think it is this plant? Similar pictures or references?
Answer: Could be Whorled mountain mint or Pycnanthemum verticillatum. I looked it up on the inaturilist database. This is what i found:
also known as the Hairy Mountain Mint is easy to grow from seed and easy to care for once established.  It is clump-forming and can spread by rhizomes readily so is not the best native plant for small areas but roots can be easily cut back once a year to prevent spreading. The maximum height of 3' will be in average soils and full sun.  1-2' is more likely in drier soils and part shade.  The small white to lavender flowers have subtle purple spots and are packed with nectar inviting all kinds of bees, wasps, flies, beetles, moths and butterflies. It indeed is one of THE natives to have to attract pollinators.
Mammals, small and large, will not bother this plant due to its strong mint smell.  A simple walk-by and brush up against this plant will yield that familar mint fragrance. The leaves and stems are more hairy than other Pycnanthemum species, giving it its Common Name, Hairy Mountain Mint.  It is also referred to as Whorled Mountain Mint.


Next and Previous button for looping scrollView

Question: I have a UIScroll view that scrolls between 4 different XIBs. I would like to disable the ability of scrolling by touching the scroll view. There are two buttons at the bottom of my app that I would like to scroll forward and back in a loop. The ViewController is forced to be in landscape orientation, and the scroll view dimensions are 568w x 217h.
Here is an image of the layout: Click Here
Answer: What you are tying to do is called "paging", and in my opinion a scroll view in not the best way to do so... here is a great project that looks like what you need:
https://github.com/caesarcat/InfinitePagingView
Hope this helps


Drywall Gap Too Big To Tape

Question: I am wondering if this gap is too big to tape and mud over.  The house is over 100 years old and the walls are not quite straight to say the least.  The opposite wall is relatively square btw.  It gap is about an inch at the top and tapers to nothing.
Comment: Wait...you're *leaving* the pink tile?
Comment: Its actually white - poor lighting
Answer: I think I'd lay in some half-inch filler and nail on a corner bead, 1/8" from the tile. You'll need to trim the one flange to less than the depth of the gap. Skim the bead out 8-12". This will leave you with a very nice, straight edge that you can caulk or grout the tile to without adding a clumsy visual transition.
Comment: Sorry I meant use a corner bead that is not nailed in place but embedded in joint compound
Comment: I would do similar but use a mud on corner bead
Answer: I'd lay some sort of filler strip that's the same thickness as the drywall and then put some sort of decorative strip on the unfinished edge of the tile.  Even small piece of PVC quarter-round (or similar) would be an improvement.
One option to fill it is to cut one or more strips of drywall that you can get in there.  It doesn't need to be perfect, just bring the gaps down to what you can fill with joint-compound.
Answer: Any decorative molding can be used to cover the gap.

Drywall Gap Too Big To Tape


Slice/Cut/Divide an artwork and paste them in different artboards (Illustrator)

Question: I have an vector Logo file. I need to increase its size to 10m x 10m. Printer can only take upto  1.3m x 2.5m , so he asked me to slice/cut/divide/tile(I dunno the exact word for it) the entire file into small boxes of 1m x 2m. Therefore total 50 files. He will print all those 50 files and paste it together to make the logo.
Can anyone please tell me how to slice/cut/divide/tile the entire artwork into small box and paste them in different,here 50, artboards?
Thank you
Answer: When printing from Illustrator, you don't need to do that. Just select "Tile Full Pages" in scaling and Illustrator will do that for you:

If you can't print from Illustrator, try printing to postscript file or PDF.
Comment: Thank you Lukigi for your reply. The problem is, i cant print directly from illustrator. There is a ripping software for that.
Btw how to increase the size to 10m x 10m, i guess maximum artboard size is around ~600 cm right?


When to use the word perceive

Question: When I was reading about the meanings of the word perceive, I found that it is used in different ways. For example, sometimes it could mean understand but in other contexts it could mean realize, so I am a little confused because I do not know if it is exactly interchangeable with the words understand and realize or not.
Comment: It's closely related to the verb *see*. *I see you* has a wide range of meanings, for example. *I see you* could mean I can perceive (hah!) you with my eyes, or I visit you, or I understand you (though normally, that would be just *I see* or *I (can) see what you're trying to say*), among other things.
Answer: Perceive refers to the capacity of perception through your senses. You can perceive something through one or more of your senses, that is seeing, smelling, touching, hearing or tasting.
But to perceive something doesn't necessarily imply that you understand or realize it:

I can perceive something in the sky but I can't realize what it is.

However, there are instances when you may assimilate the perception to an understanding, for example definition #2 from American Heritage Dictinary of the English Language:

To achieve understanding of; apprehend: Einstein perceived that energy and matter are equivalent.

When to use the word perceive


Whats the best practice when using Amazon Redshift as a cache

Question: I have tested Amazon Redshift as a cache. So I save data by a key. But with the time the cache becomes slower and slower. Once I do a VACCUM on the database it get backs to the speed. But should i run VACCUM continuously in the database ?.  Or is there a better way of using redshift tables for continuous reads, writes and deletes.
Answer: I would not recommend using redshift as a cache. Have you considered Redis?
Redshift saves all data to disk in 1MB blocks, in an order established by your sortkey, and distributed between nodes based on your distkey. When ever you create, update, delete you are appending data to the last blocks of the database. These blocks that hold all the new changes are not sorted until you vaccume the database.
Hence, when you use redshift as a cache you are very quickly fragmenting your data, making your queries slow.
Answer: Certainly a BIG NO for using redshift as cache.
Unless, by cache you meant storing pre-computed aggregates.


What is the direction of Induced Current in the given loop?

Question:
My attempt-
Now since the charged particle is moving it induces a magnetic field in the vicinity of the loop. So as per Lenz's Law there would be an emf induced in the loop so current would be induced having clockwise direction. But the book says the answer is option (2)
I'm not able to understand this. I would like to know where I went wrong and the correct answer.
Comment: Hint: figuring out induced current. directionality requires an analysis in three dimensions.
Answer: Imagine the wire is infinitely long, at first. In that context it's easy to see that when the particle is far, far away from the loop, it will have practically no influence over it (i.e. the magnetic field induced by the movement of that charged particle, which is infinitely far away from the loop, wouldn't induce any current on it).
The same reasoning would work the other way around: when the particle is moving near the loop, the induced magnetic field will induce a current on the loop.
So whether the wire is infinite or not, the result is the same: as the particle approaches the loop, the influence over it increases; when it moves away from it, it decreases.
This leads to two cases:

When the particle moves from $A$ to the center of the wire, the magnetic field is increasing. By the right-hand rule, on the surface of the loop the magnetic field will have a direction towards you (going out of the paper). As it is increasing, by Lenz's law a current opposed to this change has to appear: the current in the loop is clockwise.
When the particle moves away from the loop (towards $B$), the magnetic field is decreasing. The direction is still the same (the particle keeps moving in the same direction). But now, by Lenz's law, the current on the loop must be counterclockwise.

Notice that the direction of the magnetic field is the same in both cases. It is its derivative that changes the sign, leading to the change in the direction of the current on the loop.
Answer: To determine the direction of induced current :

Decide the direction of external Magnetic field
Determine whether flux is increasing or decreasing as you are causing any movement.
If flux increases, current induces in a direction such that its induced magnetic field opposes the external field and vice versa.
Hope This Helps.
Vote me if you were satisfied...!!


How to Enable XA Oracle 11g

Question: We recently moved to Oracle 11g from MSSQL and am completely new to this. Can someone tell me how to enable XA transactions on Oracle? From what I gathered, I think I need to run initjvm.sql and initxa.sql but I am not entirely sure. Is there someway of doing this through the Enterprise manager? Also, what is the XA driver class called? Is that oracle.jdbc.xa.client.OracleXADatasource?
Answer: Read this official Oracle Article:
https://community.oracle.com/thread/920935
And this:
http://www.orafaq.com/wiki/XA_FAQ
Also. You have to execute $ORACLE_HOME/rdbms/admin/xaview.sql as sysdba to have XA releated views created.
Perhaps, Metalink note : Required Grants For Retail Integration Bus Distributed XA Transaction-467466.1 Would help.

How to Enable XA Oracle 11g


How did ancient civilizations obtain the information to create the star map?

Question: The star map found in all those ancient civilizations pointing to the Engineer outpost - do we know anything about how the ancients obtained the information needed to create the star map?  It has to have been relayed fairly concurrently with when the paintings/carvings were done, since stars change position quickly (at least when you think in time scales spanning back to the engineer pan-sperming earth hundreds of millions of years ago)...
Comment: @aslum You're right, but further evidence of them being recent is that the map reflects continental drift on Earth.
Comment: Just how quickly do you think stars change positions? Moving a thousand kilometers per hour is nothing when the distances are in the hundreds of light-years.
Comment: @aslum - just clarified that -- i guess what i mean is that the the clues to the star positions can't have been left at the same time as the original engineer disintegrated himself at the start of the movie -- that would have been far too early to predict the positions of those stars by the time that civilized humanoids evolved.. so, I mean quickly in a geologic/galactic time scale
Answer: All of the Earth civilizations who were privy to the Engineer's star system maps would have been given that information, by the Engineers in the worst case scenario, 30,000 years ago. In stellar terms, those stars would have barely moved at all in relationship to the Earth. And seeing that they are created as ART, there would have been obvious differences that would be compensated for using technology once the right stars were found.
There is, of course, some stellar drift on their part and ours, but 30,000 years is insignificant on a galactic scale for those stars to have drifted beyond our ability to identify them, particularly in relationship to each other.
Stellar movement is incredibly slow given the distances between stars; it takes an estimated 215-250 million years for the galaxy to rotate just once.
Comment: the engineers seem to be depicted in the paintings/carvings with the stars - so it is possible that they visited the ancient civilisations at some point


Putting points within an institution on a map

Question: I have a map drawn in coreldraw for points and locations within a large institution and I want to put it on google maps so that users within the institution can be able to search and locate points from where they are. Any idea on how I can go about this will be appreciated.
Answer: Google Maps has an upload a floor plan page, though it's up to Google whether they accept your map addition. You might also be interested to check out OpenStreetMap, which is gathering the data but hasn't got it publicly visible yet.


I need data backup and all metadata backup of salesforce org including Managed package

Question: I need data backup and all metadata backup of salesforce org including Managed package.
I need all components including managed package such as cloud sense .Please suggest
Comment: One option you can consider is to use clone sandbox option and create a cloned sandbox from the backup sandbox.
Answer: There are a number of vendors on the AppExchange that will happily sell you a solution to do this.
Full-scale data and metadata backup is not a built-in capability of Salesforce. If you'd like to do it yourself, you would be looking at combining the native Weekly Data Export feature with a regular process to extract all of the metadata from your org using, most likely, an IDE or a Metadata API client like Salesforce DX or the Force.com CLI.
Even using a purpose-built tool, backup and recovery is never a simple push-button operation, and backups lose a lot of their value if you do not have a detailed and rehearsed incident recovery plan in place.
Answer: To backup all metadata from a Salesforce Org, you may also explore this: https://github.com/itlibrary/salesforce-metadata-backup
Make sure you list all the desired metadata types in build.properties. Many of them are already mentioned there for easy reference.


Does increasing the resistance in a branch of a parallel circuit decrease the overall current?

Question:
In the above question, why does R3 increase? If R2 increases, wouldn't the parallel combination's resistance increase? If so, wouldn't the circuit have less current? Then why would the voltage across R3 increase?
Comment: Is there a source connected to this resistor network? If not, the answer is [c].
Answer: When "the circuit has less current", then there will be a smaller voltage drop across R1. It's (a little bit) harder to calculate the currents in the individual branches R2-4, but you don't have to. If the sum of the voltage across R1 + R2-4 is constant (that is not explicitly stated, but I will assume you have a constant voltage source across the network), then lower current through R1 means lower voltage drop there, and more voltage across the parallel network.
Comment: Why does having less current in the circuit only give a smaller voltage drop in R1 but not the parallel network? Why would the voltage across the parallel network increase?
Comment: The sum of the voltages across R1 and R2-4 must be constant (if the entire network is fed by a constant voltage source).
Answer: The voltage drop across the parallel combination is equal to-
$ V - current*(R_1)$
where $V$ is the voltage across the terminals of the battery.
This is so as the sum of the voltage drops across $R_1$ and the parallel combination is equal to $V$.
Hence if current decreases, voltage across the combination increases as $V$ and $R_1$ are constant.
Answer: The voltage on all resistors in a parallel circuit is the same, so that means that the voltages on resistors $R_2,R_3,R_4$ in this example will always be the same. Since voltage is: $$U=I*R$$
this means that if we increase resistance value of element $R_2$, the voltage $U_2$ on that element will also increase, and since the voltages on all resistors in a parallel circuit are the same : $$U_2=U_3=U_4$$
that means that the voltage on $R_3$ will also increase.
Comment: R1 is in series with R2, R3 and R4. Even if all the resistors were parallel the potential across each resistor would remain the same (equal to the batterys voltage) even when the resistance of any resistors is increased. Increasing R2  will lower the current, nothing will happen to the potential across the resistors. I apologize for being rude, but your answer is wrong.
Comment: @Mitchell I didn't see that R1 is in series with the others I'll edit that. How is it wrong? When you increase resistance the voltage also increases (unless you have constant voltage) and since R2 is parallel to R3 since voltage on R2 is increased voltage on R3 will increase as well.
Comment: The battery is the same. Recall, when you calculate the current in a circuit you first calculate the equivalent resistance. When all the resistors are parallel, the potential drop across each resistor will be the same no matter what. But on increasing the resistance of a resistor the equivalent resistance will increase, which will only effect the current. The potential drop before increasing the resistance will be equal to the one after increasing (or decreasing) it.
Comment: @Mitchell  I agree with what you said but it's only valid for a constant voltage and I don't see anywhere in the problem OP wrote that the voltage in this problem is constant.
Comment: In such questions, voltage is always assumed to be constant (unless stated).
Answer: By increasing $R_2$, you increase equivalent resistance of the three parallel resistors, say $R_{eq}$.
Consequently the current in the circuit decreases $I=\frac{V}{R_{1}+R_{eq}}$.
Before establishing relations to solve such type of questions always determine the parameter that remains constant. In this case, the voltage drop across the battery (or simply the battery's voltage) remains constant.
$V= constant$,
The voltage across $R_3$ will be,
$V_3=\frac{V}{R_{1}+R_{eq}}. R_{eq}$.
On simplifying,
$V_3=\frac{V}{\frac{R_1}{R_{eq}}+1}$,
From this relation you can see that on increasing the value of $R_2$ (or $R_{eq}$) the voltage drop across $R_3$ (or $R_2$ or $R_4$) increases.
Answer: From an intuitive point of view, electricity will take the path of least resistance. When you increase the resistance on R2, current will be shunted away from this path to the other parallel branches. Current through R3 and R4 will increase, and since their resistance hasn't changed, the voltage increases as well.
Comment: According to your answer what will happen to the voltage across $R_2$ ? However, when you increase $R_2$ the overall current in the circuit decreases. Then how will the current through $R_3$ increase, if the total current is decreasing ?


Why is water's IR spectra indistinguishable from the IR spectra of a solution of glucose in water?

Question: Anhydrous glucose has an absorption spectra (glucose IR spectra) that is quite different from the spectra of water (Liq. water absorption spectra). However, when a solution of glucose is prepared in water, the absorption spectra is almost indistinguishable from the absorption spectra of water alone. Is this because glucose forms additional bonds when in water? Pointers to links that explain this in detail is also appreciated. Most links I searched on Google just stated this as an observation without explaining the underlying reason.
Comment: In order to answer accurately more details would be needed on exactly how the spectra were taken, the concentration of the glucose solution and so on. // The gist of the problem is signal to noise. There is a lot of water and little glucose. So you have to detect a relatively small glucose signal in a large water signal.
Comment: Hi and welcome to chemistry.stackexchange.com. Feel free to take a [tour] of the site. Visit the [help] to learn more about how it works. As Max said, this question would greatly benefit from an IR spectrum of the actual *solution.*
Comment: @MaxW I am referring to the plots in this [link](http://www.andor.com/learning-academy/spectral-response-of-glucose-spectral-response-within-optical-window-of-tissue). So if I am getting this right, we would need large amount of glucose in water to be able to see peaks from glucose? At 4.4mol/lt, the difference in absorption spectra is very little.
Comment: The article is doing in-vivo monitoring, so you can't just dissolve more glucose. So yes, there is a poor S/N ratio.
Comment: Thanks! Is there a website that holds data for uv-visible-IR absorption spectrum of common chemicals? The NIST database lists only the IR spectrum.
Comment: Why use IR? Its not even quantitative. I would suggest polarimetry as is typically used for measuring glucose content and is quantitative.
Answer: I see the spectra in the following way:

The sample and measurement: glucose in water and IR absorption measurement

Considering free glucose molecule, we should expect the vibrations from $C-H$, $O-H$, $C-O$ and $C-C$ bonds and other associated vibrations.
The approximate vibrational frequencies are :
a) $C-H$ = ~2800 - 3300 $cm^{-1}$ (stretching)
b) $O-H$ = ~3800 - 3200 $cm^{-1}$ (stretching)
c) $C-O$ = ~1200 - 1030 $cm^{-1}$ (stretching)
d) $C-C$ =  usually not good for interpretation
e) $C-H$, $CH_{2}$ and $O-H$ bend(in plane) = 1500-1200 $cm^{-1}$
and now considering water,
the $O-H$ stretching band  spectrally overlaps with the bands of glucose (~3750 - 3200). The combination band (~2300) and scissor mode (~1600) are also relatively broad and strong. Due to this spectral overlap and also larger infrared  absorption cross-section of water, glucose is not clearly identifiable in solution.

Instrument and spectral quality : For obtaining a high resolution spectra with good s/n ratio the instrument should be good (FT-IR) and long exposure is needed.
The spectra shown by @user1155386 has the $x-axis$ as nanometers (not wavenumbers  ! ), indicating that the spectral resolution is low. It is noisy showing that exposure time can be improved (the exposure time shown there is only 10 milliseconds).

However, still it would be difficult (but not impossible) to differentiate glucose solution and water. The main hurdle would be get a good spectra and the reason 1. mentioned above.
Additionally, I should mention Raman spectroscopy is better for aqueous solution measurements.
Answer: Like @MaxW said, in this case it is probably a problem with the SNR ratio of the glucose to water. Of course there could be some differences in a solid state spectra to a spectra of a liquid. This could be caused by interactions with the solvent.
An additional database for IR-spectra (and more) is SDBS. There are more databases like reaxys, but it is not for free. Maybe you university or library owns an account.
Answer: Take a good spectrum (not too high resolution, more than a few scans if your spectrometer is not in top shape) of your solution, and an evenly good spectrum of pure water, and subtract the two from each other. The glucose spectrum (i guess looking quite different from the spectrum of the solid) should appear as plain as day.
Try to scale the relative intensity of the two spectra so as to minimise the residual difference. The absolute intensity signal intensity in IR spectrometers tends to drift quite heavily (compared to the very small signal difference you want to observe) on a timescale of minutes.


More info for autocomplete choices?

Question: When I have an entity reference field with an autocomplete widget, is there a way to add a field to the info that appears in the autocomplete choices? Seems like the default field is Title, but this in my case might be ambiguous.
Answer: An easier solution is to modify the 'label callback' property of the node entity.
<code>function mymodule_entity_info_alter(&$entity_info) {
    $entity_info['node']['label callback'] = '_mymodule_label_callback_set';
}

function _mymodule_label_callback_set($entity, $entity_type){
    if($entity_type == 'node' && $entity->type == 'my_node_type'){
        //Compute new label here
       $label = 'test';
       return $label;
    }
}
</code>
Comment: This code appears to change the label everywhere that it appears, not just in the autocomplete.
Comment: You could add more logic so that it only fires on certain URLs, like backend edit forms.
Comment: Forgot to add, the callback override would be set permanently, but you could grab/copy the default label code from the entity to populate it otherwise.
Comment: Great solution - It may not give uber context (as it only has type & entity not where it's being rendered) but it's reliable
Answer: You must create a selection entityreference plugin.
In you can see an exemple in selection directory of plugin directory of entityreference module.
Comment: I am flagging this answer as accepted, since it hint at the right, clean direction, however if you care to provide more instructions on how to write a minimal sufficient code for such a plugin, I would be extremely grateful. I am not an advanced programmer and it's difficult for me to say what methods must be implemented to get it done. I'm acting on nodes which have a `subtitle` field, and I want the ajax to display "Title - subtitle (nid)" instead of "Title (nid)". Thank you.
Comment: More info on entityreference plugins: http://drupal.org/node/1962284
Comment: Also see my anwser on http://drupal.stackexchange.com/a/82665/526
Answer: For the non-coder solution that only affects the field:
What you could do is create an entity reference list from a view and populate your widget with the view.
Create a new view
Untick Create a block and Create a page
Then click continue and edit.
That should get you to the master view.
Click Add to add a new display and choose entity reference.
Give your display a easily recognisable name.
Add your fields/ filters etc and order them as required.
I usually change the items to display under pager to display all items, but I'm not sure how required this is.
Under the Format heading beside Format, click settings and set your field(s) that are to be searched when auto-completing.
Under the Format heading beside Show, click settings and set your fields to be inline.
Save your view.
Now head over to edit your entity reference field.
Assuming you already have your field pretty much set up the only bit you might need to change is under:
Entity selection mode
Choose: "Views: Filter by an entity reference view"
Assuming your field reference target type and view list match up you should get a dropdown appearing under "View used to select the entities" with your newly created view listed in there. Choose it and save.
Now all going well when you add a new entity your field reference will contain a list of entities based on your view.
Answer: You can create a "Reference" display on a view which you can use. If you created this, go back to your autocomplete field and select the created reference display. But with this, you only alter the text which is displayed in the autocomplete box. The search still goes on the node title.
Comment: Actually, using a simple module, I created Live Preview display view, hoping that it will be used by Entity Live Preview module. Unfortunately I cannot get it to work. Altering the text would be just fine, I need to append just two more fields to suggestions. Care to give more instructions, please?
Comment: Do you work with Drupal 6 or 7?
Comment: It's version D7

More info for autocomplete choices?


What handles the event of changing the email you're looking at in outlook?

Question: I have a custom toolbar that I want to toggle the visibility for based on some criteria about the current email being viewed in the active inspector. I need to check for this each time the user changes which email he/she is looking at. I'm very new to coding add-ins, but I imagine the code would look something like this:
<code>Sub EmailBeingViewed_Change(object, args) Handles 'Whatever-the-event-is-called
    Dim OpenEmail As Outlook.MailItem = CType(object, Outlook.MailItem)
    If OpenEmail.Body 'Contains thing I care about' _
    Then
        MyToolbar.Visible = True
    End If
End Sub
</code>
Any help would be appreciated.
Answer: Use Explorer.SelectionChange event.


Is it possible to find who has built an exe file?

Question: Having an exe file at hand, is it possible to find any information about the person who has compiled it? More specifically, does delphi compiler include its own licence information or OS user or even some hardware IDs in the executable?
Comment: Answer to question is no
Answer: As far as I know the only information that delphi compiler includes in compiled executables are compiler version, SKU edition (Comunity edition, Proffessional, Enterprise, Architect) and whether it is registred or not.
As far as I know it does not include specific licence information like licence owner.
So if as a developper you want such information included in your executable you either need to fill up Version Info fields apropriately or use some tool for digitally signing your executable in which case the information from digital certificate like certificate owner will be included.
Comment: Is there any documentation on the information you say it is storing (SKU etc.)? Where and in which format does it store it?
Comment: @dummzeuch I would expect that this is not officially documented, at least the implementation and format details, since the primary purpose, one would assume, would be for Emba to retain the ability to inspect suspect published commercial software for licence compliance.
Comment: There is no official documentation for retrieving of this information available. Maybe just for compiler version. The reason for this is that if people would generally know of where such information is stored in executable they could then modify executable in a way to hide the fact that they might for instance be using pirated copy of Delphi for compiling of those executables.


Continuous change in Sphinx Config File

Question: I am working on one project in which i have one Sphinx Config File.There are main four parts of Sphinx(source,index,indexer,searchd).In config file there is only one indexer and one searchd but source and index are multiple.Now i am starting searchd service over this config file.When new source and index added in config file, i notify searchd service with --rotate option in indexing to inform that new index is added over this service.But now suppose i am delete some source and index from config file.At that time i have to restart the searchd service to inform that particular index is no more in use.Is there any direct way to do this without restarting searchd service?
Answer: you may want to use
<code>  kill -HUP `cat /path/to/sphinx.pid`
</code>
to tell Sphinx to reload current config

Continuous change in Sphinx Config File


What are the differences between "Deva", "Bhagavan", and "Ishvara"?

Question: All that I know is that "Deva"/"Devi" refers to individual Gods and Goddesses, but we also use the term "Ishvara" and "Bhagavan". Aren't these two terms just synonyms for "Deva"/Devi"?
Comment: Bhagavan simply means one who is lord of divisions in space and time, as Bhag means 'division' & Van means 'with', hence upanishads mention 'ekoham bahusyam'- 'I am one, let me be many' as desire for split of one Supersoul into many souls. Bhag is also root of Bhagya or 'luck' which means fate of an individual soul and PIE english word like 'Bag'. Ishvara means Ishan+Vara which means First(Ishan) https://en.wikipedia.org/wiki/Purusha or the Godhead Brahman.Deva/Devi are part of 33 koti gods https://www.sacred-texts.com/hin/sbe15/sbe15072.htm and root of words like 'Diva/Day' means enlightened.
Answer: Bhagavan and Ishvara are simply Brahman as viewed by Jiva. There is no difference between Bhagavan and Ishvara and both may be conceived as epithets for the Supreme.
The issue of Devatas is complicated. There are different types of Devatas.

There are three aspects ... The three main .. deities - the Trinity
consisting of Brahma, Vishnu and Siva - along wth their consorts, form
the first aspect. Here all the .. deities are considered to be
different facets of God, the Supreme (Isvara). The minor deities like
Ganesa and Kumara, form the second aspect. Though these deities also
are sometime described as the facets of God the Supreme [Isvara],
their position is usually inferior to that of the Trinity. They
represent limited manifestations of the Supreme God. The Lokapalas
(protectors of the world), also called Dikpalas (protectors of the
cardinal directions) like Indra, Varuna, Agni and others, comprise the
third aspect. They are actually offices of power in the cosmic scheme
of creation and human beings who have acquired extraordinary religious
merit necessary for getting these places, will occupy them in each
cycle of creation. Then there are any number of village deities and
demigods who can be regarded as very limited manifestations of the
Supreme God or as forces of nature deified or as human beings who by
virtue of some special merit and power are elevated to godhood in
course of time, after their death.

Hindu Gods and Goddesses by Swami Harshananda
I present an analogy which will clarify what has been described above.

Do you know what I mean? Think of Brahman, Existence-Knowledge-Bliss
Absolute, as a shoreless ocean. Through the cooling influence as it
were, of the bhakta's love, the water has frozen at places into blocks
of ice. In other words, God now and then assumes various forms for His
lovers and reveals Himself to them as a Person. But with the rising of
the sun of knowledge, the blocks of ice melt. Then one doesn't feel
any more that God is a Person, nor does one see God's forms.

The Gospel of Sri Ramakrishna, Chapter 6, The Master with the Brahmo Devotees (I)
Sri Ramakrishna is using the analogy of an ocean to describe Brahman. Brahman when thought of as Sat Chit Ananda may be thought of as an ocean of existence itself, consciousness itself, love itself. In this ocean are floating iceberg like structures which may be thought of as frozen consciousnesses. Brahma, Vishnu and Siva and their consorts may be thought of as comprising the largest icebergs with maximum power. Ganesha and Kumara may be thought of as smaller icebergs with more restricted powers. Then comes the even less powerful deities like Indra and village deities. Finally those who follow Advaita Vedanta consider jivas also as simply small bubbles in this ocean of Brahman.
Comment: Thank you. This was a very helpful answer.
Comment: While this is a nice answer, and the second quote illustrates a wonderful metaphor, it doesn't really answer how the terms are used differently, who is more likely to use one term over another, or any other reason that jiva have created these three words to refer to the same concept.
Answer: The words 'Devta', 'Bhagwan' and 'ishwara' can all refer to 'God' in General. However, looking deeply their meanings will drastically vary according to context. (See the links)
I would like to give a example,

गजाननं भूतगणादिसेवितं कपित्थजंबूफलसारभक्षितम् । उमासुतं शोकविनाशकारणं नमामि विघ्नेश्वरपादपङ्कजम् ॥

विघ्नेश्वर (Vighnēśvara): Vighna = problems and Īśvara= master or controller
Thus then, Vighnēśvara = the master or controller of all obstacles.
(Source)
From viniyog of Aditya Hridyam,

आदित्यह्रदयभूतो भगवान् ब्रह्मा देवता

Here,
भगवान् (Bhagavaan)= principle or eternal God. देवता (Devta)= deity
So the complete meaning comes out as,
"The deity (of aditya Hridyam) is the principal and eternal god within the Heart of Aditya".


Any presentations or people who'd be worth contacting at Where 2.0?

Question: I'm attending Where 2.0 next week on behalf of GIS.SE, and will write up my experiences to share with others here -- perhaps some material worthwhile for the blog idea floating around. Are there any people or talks that you'd like to hear about in particular? The schedule includes most of the talks, and I've gone through the attendee directory picking out a few folks who I think would be interested to hear about our community. I'm open to suggestions, and if you're also attending please let me know!
Answer: Of general interest to the community might be

Visualizing Data with Maps, Nathaniel Vaughn Kelso (The Washington Post) Th 3:30pm.  He claims to show "the best ways to map and visualize data."  I guess we all need to know what they are :-).
Geo-Analytics Tutorial, Peter Skomoroch 2:35pm Tuesday.  "Learn about the newest geo-analytic tools and services."  Who can resist?
Living Maps – Making Collective Geographic Information a Reality, Jack Dangermond (ESRI) 11:10am Wednesday.  A grand scheme "to integrate everything that moves on the planet into a geospatial framework."  Ignore him at your peril: he's still in charge of the 800-pound gorilla.

Of course schedule conflicts might preclude attending these, but thanks for reaching out!
Answer: Consider attending Max Odgen's presentation.  Tim O'Reilly presented a keynote at the Esri Dev Summit where he highlighted  Code For America - regretfully, I didn't have time to attend their workshop.
I suspect they do more than just code.  Still, CFA should explicitly mention that it's often a good idea to define at least a few requirements before writing code.
I gotta admit, though, coding is more fun.  There are probably a lot more people volunteering to code than to write requirements.
Maybe CFA coders could direct the City Managers to GIS.SE.  The City Manager's staff would ask questions, the community would answer, then the coder could glean requirements from the resulting threads.
From the "what we do":

Working with city managers, we help to
  identify projects that can benefit
  from web-based solutions.


Is it possible to transfer minecraft worlds across devices?

Question: I have many worlds on the Xbox edition of Minecraft (Bedrock platform) but I recently bought the Switch version for portability. Is there anyway I can transfer my worlds between devices?
Answer: I've actually done this a few times - taken a copy of a world from my Xbox One so that I could play it on my Windows 10 PC (the concept is the same) - but there are a couple of prerequisites:

You'll need an active subscription, whether paid or free trial (see bullet points), to Minecraft Realms/Realms Plus.

Realms/Realms Plus is basically a private, invite-only Minecraft server hosted by Mojang/Microsoft.
If you've never availed yourself of the free 30-day Realms trial offered by Mojang, you can use that to complete the upgrade/migration process no additional cost. Simply register for your trial and then cancel the subscription before the end of the 30 days to avoid being charged. During that 30 days, you'll be able to follow the instructions below as many times as you want/are able to migrate several worlds for free.

Your original world must be from *Minecraft Bedrock Edition *

"Minecraft Xbox One Edition" is not the same thing as Bedrock Edition. The latter (on the Xbox One) is simply called "Minecraft" without any qualifiers.
If you're world is from Xbox One Edition, you'll need to migrate it to Bedrock Edition before it can be played cross-platform (see below if this is the case).

You can only have one of your worlds active on your realm at a time (unless you pay for more than one subscription).

Using a pre-existing world on your realm
Once you have a Realms/Realms Plus subscription, you can choose any of your worlds from your Xbox One (Bedrock Edition) to use on the Realm by doing the following:

Launch Minecraft (Bedrock Edition) on your Xbox One and click "Play".
You'll see a section at the top for "Realms", and your realm from your subscription should appear there. If you don't yet have a Realms/Realms Plus subscription, (I'm pretty sure) you will have the option to create one in step #5 below.

Find the world you want to be able to play cross-platform (on your Switch, Windows 10, Pocket Edition, etc.) and click the pencil icon to the right of that world. You should see the following:

Click the "Play on Realm" button.
You'll be prompted to select a Realm Server. If you've already got a Realms/Realms Plus subscription, simply select your realm from the top of the list. If you don't, (I'm pretty sure) you should be able to "add" a subscription from here by clicking the "Add a [X] player Realm" button of your choice.

You'll be prompted to confirm the replacement of any existing world that has been created for your realm before continuing. Simply click Confirm, and the necessary files will be uploaded to your realm to make available for anyone to whom you've given access.

Now, at this point, you can do a couple of different things. You can either leave this world on your realm so that it can be played by anyone you've invited at any time. All changes from any players will be persistent and show up for everyone else anytime they log in. A realm is, by definition, invite-only, so only those people to whom you've given explicit permission to join will be able to access it, so you don't necessarily have to worry about random "griefers".
Your other option is to download the world to your new device to play it locally. Of course, this means that any changes you make in the local copy will need to be re-uploaded if you want them available on other devices. However, this can be a useful tool for creating copies of your realm world for testing out certain builds and such (if that's something you're in to).
To download the world from your realm for local play, simply click the pencil icon next to your realm on the world selection screen and you'll see an option to "Download World". The game will process the game information and make a local copy of the realm world, which will show up in your main worlds list.

Migrating a world from Xbox One Edition to Bedrock Edition
If you are wanting to play an older world from the Xbox One Edition of Minecraft on your realm, you'll need to follow these additional steps to migrate/convert that world to the Bedrock Edition format:

Launch Minecraft (Bedrock Edition) on your Xbox One and click "Play".
Scroll down to the bottom of the worlds list and select "Sync Old Worlds". This will add a section below the main worlds list titled "Old Worlds", which should contain any worlds created in the console-specific version of the game.
Find the world you want to convert to a Bedrock Edition world and select it. Minecraft will run through some processes to complete the conversion and add it to the top of your main worlds list.
Scroll back up to the top and select the "new" world to play it on Bedrock Edition.

Final Thoughts
If you're starting with a world from an even "older" generation (e.g., Xbox 360 Edition), it becomes a bit more complicated as those worlds cannot be directly migrated to Bedrock Edition. Worlds from the Xbox 360 Edition will first need to be converted to the Xbox One Edition before they can be moved to Bedrock Edition.
More information on migrating worlds from various console-specific editions to Bedrock Edition can be found in the official Minecraft Help Center. See the section titled Minecraft on Consoles for details.
Lastly, just for the sake of completeness, for anyone who's wanting to copy a Bedrock Edition world from one PC to another, you can simply transfer the MCWORLD file between the two computers using USB, DropBox, Google Drive, etc. You'll need to copy/export your world, then transfer the MCWORLD to your storage medium for retrieval on your other device.

RELATED
I found another, similar question here (How to share worlds between platforms with Minecraft Better Together) that offers some possible alternatives to using Realms, but I've not tried these other methods and can't speak to their functionality or reliability.
Comment: I know I'm not supposed to use comments at StackExchange to say thanks. But - the details you've provided here have been extremely helpful to me today, and I don't feel the upvote I've given is enough. So - thank you!
Comment: ***Unrelated side note:*** I've actually used the XB1 migration method to create custom [superflat/flat](https://minecraft.gamepedia.com/Superflat) worlds for Bedrock Edition. Since there is no interface for customizing flat worlds in BE, I created the world in the "*Xbox One Edition*", customized the world settings (biome, layers, etc.), entered/saved the world, then converted the world to Bedrock Edition using the steps above. This provides me with a great place for testing out building ideas and such.
Answer: The previous answers do provide one possible solution, however, if you are on a mobile device or a computer, you can also access the world files directly, copy them to a media transfer device, and transfer them that way. This is similar to the way uploading/downloading maps works for adventure and puzzle maps (which is another option you have to transfer your worlds). I'm not sure if either of these methods work for xbox, switch, or playstation, as I've not attempted to transfer any worlds that way.
This is especially useful if you play a world with a friend, and your friend wants to have a copy of the world for themself, or if you wish to backup a world in case it gets deleted or otherwise lost.
Comment: I can say that I've yet to see a way of directly accessing the Minecraft world files on an Xbox One to do as you suggest. Although to be fair, once I started using Realms to access my world from just about anywhere, I pretty much stopped looking for other ways to make it happen.
Answer: You can put the world on a realm on the device that has the world (your Xbox) then download the world from the realm on a different device (your switch). Assuming you're using the same account on all devices.


Unable to install Ubuntu on HP Pavilion DV6

Question: I tried installing Ubuntu 12.04 on my laptop (HP Pavilion DV6). Can you guys please tell me whether it is possible to install it or is 12.10 version of ubuntu compatible with it? I heard there problem is because of the graphics card.
Answer: You can install either Ubuntu 12.04 or 12.10 easily in your laptop and is compatible with it. The graphic card should not be the problem to install Ubuntu.


What is the point of borrowing on Defi

Question: In order to take out a loan on a Dapp you have to come with collateral. Whatever you cannot pay back on the loan,  you lose that amount in collateral and the interest accrued. That being the case what is the point for the average user to borrow on Defi? It seems only suited to traders to leverage their money. Is there another use case that anyone knows of?
Answer: I personally have many ideas. Some people need to borrow and that's OK. If I were to lend someone money though, I'd expect interest to be paid and the principal to slowly go down and usually, one would go through a bank with lawyers so it will be fairly costly for all this so there are minimums to reach before it becomes profitable to the Everyman. This clearly is an issue if we are to have safe, inclusive and decentralised finances.
Another reason is accessibility. Have you ever asked your bank how much it costs to use their API? Ring them, try it, their only line of questioning will be to ascertain how much they can get from you. With a smart contract, you could, depending on provider, interact with you SC at low cost or you can use your own node / code for free. Bet your bank won't do that.
To summarise, average user won't have immediate benefit other than reduced fees ( which add up quite quickly). So how is it going to change the world? It won't. The old world will simply die, as it does every generation, leaving behind a new people who are more technically knowledgeable and with that, these automated systems will allow users to interact with their finances.
This is obviously my own opinion with no historical backing (as there exists, none) and not everyone will agree. Heck, not sure if I do.So many moving cogs. But as I see it, right now, to the average person, I'd see more benefit in using fiat loans until a point where usage and value of crypto stabilises and only at that point in the not far away future, will it be globally beneficial.
Comment: Thanks for the thoughtful answer. I've been bouncing these ideas around in my own head too and I agree. These technologies are new and will eventually  be adopted by the masses and provide much greater efficiencies in financial markets, disintermediating great swaths of the economy. Let's see how long it takes!! I just don't see myself taking out a crypto loan on one of these dapps. I am happy to provide liquidity and make some interest, but I have no idea what I would do with a loan. Not interested in high stakes trading.
Answer: I recently borrowed some funds on Defi. The reason I borrowed was so I didn't have to sell my crpto. The collateral required was 4 times the loan. The loan was at 1% interest and my interest on the Defi token paid the 1% interest. I've paid back the loan and the only advantage I see is I didn't initially have to sell my crpto. But when I paid back the loan I had to sell crypto at a lower price because I needed to withdraw some funds permanently. The only way I will take another loan is if the collateral coin is in the initial stage of a bull run. Otherwise, it's best to just sell crypto for needed funds.

What is the point of borrowing on Defi


How to restart/reuse a recurring Task?

Question: I have a long-running Task that I've implemented using the Task Parallel Library.  When the Task starts, I grab snapshots of several input values and collections then perform various operations using that information.  If any of those values or collections change while the Task is running, I'd like to have the Task run again immediately upon completion.  Should I be creating a new Task or is there a way to reuse the existing Task?  What's the best way to start the second iteration?
Answer: Create a new task.
As http://msdn.microsoft.com/en-us/library/dd270682.aspx points out, trying to restart a running or completed Task is not supported. It is rarely a good idea to do something that normally throws an exception, and re-using a Task is one of those things.
Comment: How would you signal the need for the second task? Changes could occur while the original task is running or not until sometime after it has completed.
Comment: Based on that criteria, I think you would do fine with a single, non-terminating Task that polls the current state, and if the state changes, do your thing. The basic requirement here is that this happens asynchronously, to avoid blocking the main thread. You would need to place a flag of some sort to indicate to the Task that the application is closing and it should terminate.
Comment: A single, non-terminating Task is what I was thinking. I can use a CancellationToken to handle when the app is closing but I'm not sure what mechanism I should use to flag that I need the Task to execute my algorithms. If I use an AutoResetEvent, then I won't be able to cancel because the Task's thread will be suspended waiting for the event. On the other hand, I am reading that using SpinWait is very CPU intensive.
Comment: If I understand you correctly, you could use Sleep instead of SpinWait. You could poll every minute, second, etc. and sleep in between e.g. `while (continue()) if (ready()) do_whatever(); else sleep();`
Answer: You can't start again an existing Task. So you have two options:

Start a new Task. This is probably cleaner.
Run an loop in your Task that checks whether something changed since the last time and if it does, starts a new iteration.
Comment: Same question as above: How would you signal the need for the second task?
Comment: Hard to tell without knowing how do you determine that the second task is needed. If you want to restart even after it has completed, you might use events.
Answer: You could also refactor program logic to use function pointers (or delegates in VB.NET).

How to restart/reuse a recurring Task?


Mobile Broadband in Network Manager

Question: I am running Ubuntu 16.04 and using a mobile broadband Internet connection over a Nokia E51 cellphone. Now the phone died and I wanted to get another dumb phone (no smartphone!). But I don't know how to figure out what is needed in the phone to be working as a modem? Specifically I am looking at the Nokia 3310 3g.
Answer: First of all i'm not sure if nokia3310 3g can be used as a modem. And there are 3 ways to use it as a modem a. via usb cable, b. via wifi if the phone supports wifi hotspot, c. via bluetooth tethering if supported. The only way to use this phone as a modem is via usb cable as i'm not sure that supports wifi hotspot or bluetooth tethering.
You rather should check phone's manual or contact nokia.
But why don't you buy a usb mobile modem (3g/4g dongle) from your mobile provider?
It's the best solution especially now that 3g/ 4g speeds are sometimes faster than adsl.
Comment: Nokia 3310 3g is unfortunately not supporting tethering. The reason why I dont want a usb-dongle is that my (prepaid) contract includes 2GB of data, way more than I need, and I dont want a) a second SIM or b) another contract, since I only use the data very occasionally.
Workaround: Bought a secondhand Nokia C5.

Mobile Broadband in Network Manager


Multibit HD: how much fee for cheap way to transfer bitcoin to other wallet?

Question: I have 0.015161 BTC in my Multibit HD wallet and now I want to move them all to Electrum wallet. So, how much fee to set for this transaction as a cheap way?
And how long I must wait?
The default value I see in Multibit HD is 0.0005 BTC/kb
Comment: Use the sweep private key feature in electrum instead. Multibit hasn't been updated in years. You'll have trouble sending from it.
Answer: https://bitcoinfees.21.co can give you an estimate of transaction fees based on the current network activity. It's recommended rate at the moment is 0.0026 BTC/kB to have a good chance of being included in the next block, but this changes often. Lower fees will take longer to confirm typically, but it's hard to be sure how long. At the rate multibit suggests, the website estimates it will take 4-28 blocks to be included, it estimates it could take up to 6 hours in the worst case.
Answer: At the current fee average on Bitcoin network you can easily set 2 satoshis per byte as tx fee if you are not in rush to have you transaction confirmed in the first block after you submit it.
Graphical info here: https://bitinfocharts.com/comparison/bitcoin-transactionfees.html#3m


Given an initial orbit calculate the necessary maneuver impulse to obtain a required final eccentricity and semi-major axis

Question: The question is simple. Starting from an eccentric orbit I want to obtain a final orbit of which the final semi-major axis and the final eccentricity are known. You would have to determine the boost and the point in the orbit where it should be done to get these final conditions. That is, we have an a0 and an e0 and an af and an ef and I would like an algorithm that gives me the impulse and the point of the orbit where to do it.
Comment: What research have you already done ? Have you read [this](https://en.wikipedia.org/wiki/Hohmann_transfer_orbit) ? Are there no constraints on parameters other than semi major axis and eccentricity ?
Comment: The point of the orbit at which to do it is going to be the point where the two orbits intersect. Delta-V requirement will be the same at either one.  If the two orbits do not intersect, it will be impossible to do so with a single impulse in a Keplerian/Newtonian two-body situation.
Answer: As a comment suggested, you should do some research, but here are equations to help you.
First, given $a$, the velocity at any $r$ is calculated from the vis viva equation:
$v^2 = \mu (\frac 2r - \frac 1a)$
Then, calculate the parameter of the orbit (ok, if you are a math type, the semi-latus rectum): $p = a(1-e^2)$ and then the angular momentum $h= \sqrt{\mu p}$. This gives the transverse component of velocity by the definition $h = rv_t$. From the Pythagorean equation, the radial component of velocity can be found.
These equations should be known if you do celestial mechanics or astrodynamics.
So, you can calculate $v_t$ $v_r$ for both orbits then the delta velocity follows from change in each component.


Can the link to the Help section be restored?

Question: Since the new look of Biology SE there is no link from the main page to the Tour or the Help section. This is bad as it means that people who wish to cannot find the guidelines on asking (especially) and answering questions, and provides an excuse for those who wish to ignore or violate the SE model. How can this be restored?
Comment: low reputation users (I think <500) still have the help link in the top bar. And there is a help link in the site switcher for all users. Still, it's far less obvious for many users now, and there are a bunch of requests on Meta SE to change this in some way.
Answer: I noticed the same thing. It is not Bio alone, though. The top bar has been replaced SE-wide. There is still a link to the help center when you click on the hamburger on the top right of your screen.
To be changed, e.g. by placing a help link on the top bar, a Meta.SE question should be asked I guess. I don't think it'll be implemented anytime soon though.


Using Skein as PRNG

Question: I have read that the Skein hash can be used for quite a few different functions, including a PRNG. Would using the 1024 Skein hash to return 16KB of data be appropriate for a PRNG? Or would it only be appropriate to use the 128 bytes of data as a PRNG?
Comment: Why did your question title indicate encryption?
Answer: The paper describing the Skein hash function does contain a short description in section 4.9 on how to use it as a PRNG (as otus and SEJPM pointed out). If you use that mode then Skein can be used as PRNG. If the security of Skein holds then you should be able to use it for very large amounts of output data, not just 16 KiB of output.
Note that Skein is "only" a final candidate to the SHA-3 hash competition and that it may not receive as much cryptanalysis as the final winner (Keccak). This is particularly the case for the additional modes such as the PRNG described in the paper. These seem included to show the flexibility of the hash construction based on a tweakable block cipher. No algebraic definition is provided, nor are test vectors. Using Skein as PRNG should be considered scientific research.
Alternatively you could use Skein-the-hash-function as input for a previously defined PRNG. In that case Skein could be input of the PRF construction or even replace the PRF construction of the PRNG.

Note that you should always consider how to seed the PRNG correctly. A PRNG does not magically add entropy to the seed; it's fully deterministic.

Using Skein as PRNG


HTC Evo 4g LTe Jellybean (JB) charge only

Question: I just flashed a new stock JB ROM from viper boy over at xda.
What happened to the Connect to PC in the settings window? I can see my HTC Evo 4g LTE as a disk drive and media exchange, but it has no option for charge only. What mode do I need to be in to run cmd commands on my JB phone? Every tutorial for cmd says charge only.
Comment: Just to confirm my understanding, you are saying that there is a cmd commnd to enable charging, and this is what you are looking for. Is that correct?
Answer: For starters, this shouldn't be here, this should have been asked at the XDA thread itself. With all the tweaks they make to their ROM, it would have been a good idea.
Second, with MTP, there is no need for Charge only. The SD card and Phone Storage is always available when you are connected. "Charge Only" was relevant when you were on ICS or GB and you had UMS (USB Mass Storage).
Answer: As it is two questions in one, you need two answers:

To run commands via ADB, you do not need to set that mode now - you just need to have USB debugging enabled, and the cmd commands will work.
Just remember that having USB debugging enabled could warrant a security risk as it may allow someone that has stolen your phone to access it's data without having to unlock it, but as you seem to have had it enabled previously, then I believe you should understand the risks.
Concerning the USB connection mode: In the old Android version, that mode caused issues (due to manufacturer modifications), since jellybean, Android uses MTP, so that option became redundant.
Comment: Thanks, great site and even better contributors.. Merry Christmas.


NLog does not write to file on Vista deployment

Question: I am using NLog for the first time on a project. I want to log to a file, so I added a target writing to fileName="${basedir}/logs/${shortdate}.log". This creates/appends log info to a file in MyApplicationFolder/Logs/2009-06-08.log.
Logging works fine on a Windows XP machine, in debug mode, and when I deploy using my msi installer.
However, when I deploy on a Vista machine, nothing gets logged to the file.
I tried to add a MessageBox target just to check whether the Vista deployment was talking to the NLog dll at all, or if there were issues with the config file - and this works, so I assume this has to do specifically with creating a folder and/or creating/writing to a file in C:/Program Files (x86).
Can anybody help me see what I am not doing right?
Answer: Vista uses Files System Virtualisation to protect some folders. So your logs have been writen, but silently to another folder.
Comment: Thank you, that does it. To summarize, the log file IS getting written, but instead of going to C:/Program Files (x86)/MyApplicationFolder/ , in Vista, it goes to C:/Users/JohnDoe/AppData/Local/VirtualStore/Program Files (x86)/ etc...


Freezing Ground Floor Flat

Question: Ground floor flat no insulation in floor. Draughts everywhere. Cold exterior walls. When raining or very cold the air in flat is icy cold even with heating on. Any suggestions. The kitchen floor is icy even through lino carpet tiles and rugs. Noticed skirting boards are icy cold too. I've tried carpet tiles in kitchen and when standing on them feels almost wet damp. Is there any insulation that covers concrete asphalt floor to improve it. I'm trying foam wall tiles to add a bit of insulation. It's council property.
Comment: Your question is too broad and you haven't provided enough information about the structure for good answers. Please see [ask] and take the [tour], then revise to be more specific and address just one issue.
Comment: If you owned out right and wanted to stay there, You would probably need to rip out everything(walls, ceiling and floor) and add insulation and sealing.  The job can be done in sections instead of everything at once.  Is your heating sized for area?  Too small heating capacity can leave you cold also since it won't keep up with the heat loss, but you will save money heating with better insulation than spending more money heating more.
Comment: Could you ask a friend or neighbour to take a look at the problem? If there is a leak, then you have to open the area around the sink in the floor a bit. If it is dry it can be glued again. For the wall is a insulation with Styrodur (from BASF) a option. The ground can be insulated too with Styrodur, but you have to add a layer of MDF boards and then a PVC flooring.
Answer: Draughts everywhere
That's where I would start. There are often, but not always, some quick fixes that can cut down significantly on heat loss:

Weatherstripping around doors, especially at the bottom.

Typically this takes the form of rubber/foam/plastic strips that are glued to the door frame and threshold. The catch is that you need to balance between too little - not effective - and too much - hard to open/close the door. If the door is hard to open/close then the weatherstripping won't last very long.

Weatherstripping around windows.

Add a dead-air layer inside each window.

This is typically using a plastic wrap that is stretched across the window with plastic pieces around the edges and use a heat gun (inexpensive substitute = hair dryer) to get it to stay. Something like this Frost King from Amazon:

Moving air takes away your heat/brings in the cold. Dead air is an insulator. Essentially you turn a single-pane window (or a leaky double-pane window) into a double-pane window. Not perfect, but can make a big difference.
Those are the easy things. If the easy things are not enough to solve the problem then you have to search more to figure out where there is heat loss and/or what can be done to improve your heating system.

Freezing Ground Floor Flat


Can stainless steel be used in continuous high temperature environment (500°C to 850°C)

Question: Can i use stainless steel as a furnace roof. Furnace temperature will be max upto 850°C. If so which ss grade will be the best in this situation. Thanks
Answer: Most grades of stainless steel can handle 850 degrees without problem. Even the cheap ones such as 304. Although at that temperature it will be glowing bright red. It will discolor and some degradation will occur over time. Especially if it is exposed to abrasive particulate exhaust, or if it's stressed due to thermal cycling. The solution for this is usually to make it thicker. No matter what you choose, though. It will not last forever.
316 SS is a good combination of quality and price.
For super high temp situations, 309s and 310s steel is usually used.
As a side note, chimney liners are stainless steel. 316 steel is usually used if higher temps are expected. 304 is used for cheap or wood only fires. They are designed to be able to withstand temperatures of over 1000 degrees peak, and both can run around 500 degrees for years with no issues.
Comment: I read that as "run for 500 years".
Comment: I added the word "degrees" after "500" for clarity.
Answer: Ignoring the fuel source for the furnace (such as vanadium in fuel oils causing rapid oxidation); What do you want the answer to be? For minimum stress as I expect a roof to be , ferritic like 430 or 446 should be lower cost. Otherwise any of the "18-8" types like 304 (HF as a casting) would be good. I would avoid 316 , 317 because of possible rapid oxidation in stagnant locations ( trapping of moly oxide).  The "best" of ordinary stainless are 309 and 310; they are the industry standard for furnace hardware. Nearly always as castings , HH and HK ( higher carbon types of 309 and 310). For hardware a supplier might even offer HH  at the same price as HF because it is so common. If you use any 300 series stainless that is not a casting, use H grade, higher carbon for better strength. L grades would be a mistake.


Beam with width tending to zero

Question: Suppose a cantilever beam (of rectangular cross-section) subjected to vertical transverse shear load at free end. If I consider any arbitrary cross-section then both bending and shear stress will be there, but now if replace this beam with another beam of same area but whose width is tending to zero and depth is very large then maximum bending stress will now be tending to zero because the section modulus will be very high and also the maximum shear stress will be same as in the previous case because Maximum shear stress = 1.5 * average shear stress and since area is not changing so maximum shear stress will not change.
So why we do not use such beam practically ?
Answer: The problem is that when you reduce the width but keep the area constant you are increasing one moment of area but you reduce the other.
Although there is a benefit in bending the same section with buckle (the term in structural engineering is lateral torsional buckling).

Figure: Lateral torsional buckling in a cantilever beam L. Dahmani, S. Drizi
If you try to using a sheet of metal on its side in place of a structural I Beam it will buckle under the load.
A way to maintain the stability of the column (if width/thickness cannot be increased) is to add lateral supports, but obviously that is not always convenient.

Figure: cross-section of wall loaded in compression
Comment: as per the figure, it is a C section and since the load is not passing through the shear centre, so that will lead to torsional buckling of member. But if I consider a rectangular section of large depth, then why does it buckle?
Comment: @Max I tried finding an image that is a flat sheet but I couldn't find one. I was hoping that would be suffient, but apparently it isn't. I updated the answer with an image of a the cross-section of a wall under compression. Hopefully it will be obvious that if a load is applied on a thin sheet of film is similar to (not identical) having *axial compression on a long and slender column*,
Comment: @Max continuing on from the previous comment, you could think of a flat piece of A4 paper as  rectangular section of large depth (if you orient it correctly). If you have that piece standing its not possible to carry much load without the paper collapsing under buckling.
Comment: yes the paper will collapse under buckling, so is it buckling because by making the width so small the other moment of interia is reduced significantly ? But I am not able to understand that the load which is applied is vertical so I have increased one moment of inertia significantly which has reduced bending stress, so how due to low value of other moment of inertia promotes buckling?
Comment: the minimum force required to cause buckling is proportional to $EI$. The formula is actually $P_{crit} = \frac{\pi}{(KL)^2} EI$. so different axis have different minimum loads. Obviously, buckling occurs when the lowest is reached.
Answer: You have a correct concept if there is no space limitation and side swing isn't a concern, but there is still a limit to the benefit of increasing beam depth without inducing the complexity in design.
We know that the beam theory applies to beams that possess linear-elastic behavior and the resulting plane section remains plane after loading, however, beyond a certain threshold "width-depth" ratio, and/or span-depth ratio, that usually identified as a "deep beam", the distribution of stress and strain across the depth are no longer linear, and the plane may no longer remain plane due to the increased influence of shear deformation (for the threshold, see the textbook by Timoshenko).
When you stretch the beam to a thin plate that has the same volume as the beam, do you expect them to behave the same? The answer is no. You can use beams made of cardboard to perform simple observation and verification.
ADD: As the beam gets deeper, the tendency of distortion (shape instability) increases, as the influence of shear deformation increases.
Comment: so such a beam will fail due to shear deformation? But the same shear stress was acting before in the normal case.
Comment: Yes, the deep beam is prone to shear failure. The shear distribution is no longer linear and tends to warp the cross-section. The warping phenomenon is kept in check by adding intermediate stiffeners for steel deep girder, and side face reinforcing steel for deep concrete girder. Another important phenomenon is the critical shear plane is much steeper than beams in the normal size range that usually fail in the 45 degrees pattern near the support.
Answer: Not all the beams are prismatic.
In places where changing the section geometry is meaningful and makes sense we certainly do that.
All the appropriate steel (or any material) structures take advantage of using the most effective profile as soon as they aren't typical beam and column grid work, like churches, auditoriums.

Bridges use tapered beams, trapezoid outriggers, and even cables if it makes sense.
Machinery and tools use the shapes that work best even if it seems a complex geometry, and unwieldy.

Beam with width tending to zero


Can I publish in English in Mexico?

Question: I'm writing a novel, my first ever, and I hope to finally finish the story and get it published. I live in Mexico, but I am writing in English.  Could I get the book published here, or would I have to approach a publishing company in an English-speaking country? I'm thinking maybe I can do it here because I live in Cancún and everyone here speaks English, but what if it weren't English? What if I wanted to publish a novel in, say, Romanian, or any other "uncommon" language?
Comment: I wouldn't say this amounts to a full answer, but Miami is generally seen as a big media city akin to L.A. and New York for Spanish Speaking Latin America, so it's possible that works in Spanish Language media available in Mexico was published in a Miami based publishing house.  That said, the reason for this is that the U.S. has some of the strongest protections for free speech and press in the world, so it's more stable business environment for publishers regardless of language of the intended audience.
Answer: Typically, it's difficult to publish in one country using the language of another.  Even in the U.S., where there is an ever-growing increase in Spanish-speaking persons, it's difficult to find a publisher for Spanish language books.
If you live in Mexico, reach out to U.S. (or even Canadian) publishing houses with your manuscript.  You're more likely to get a bite.  Then find an agent that can get it translated and published in Mexico in Spanish.
Answer: As I am not in mexico, I will look at this from a slightly more abstract position.
First to note In my hometown I only know of one publisher, but my dad retired from that after publishing only one book. Chances are that you will not find a publisher in your home town. Most of the ones I know of are based in New York.
Let's try another question, what are the most influential publishers where you live? the way to find out this is to just go to a bookstore, or library and find out who published the books that are locally available.
But what about the language issue? Well, in your case I would wander over to the english section of the bookstore/library. It gets harder if you can't buy books in the chosen language locally.
Answer: What you might be able to do locally, and this might be really fun -- would be to serialize your work in a local English newspaper or magazine.  Think of Dickens!
Comment: This does not address the core question of uncommon language.
Comment: @hildred, that part was already well answered.
Comment: but, not by you. If the question was how to publish locally your answer may make sense, but the question was how to publish in a language which your answer did not touch on (not that your answer could not be improved on by finding out if there are english language newspapers published locally or even recommended the OP do so) but as is this answer does not address the question.
Comment: @hildred, not sure if I understood you right, but I'll make a stab at a clarification.  I know Cancún, and I think the poster's chances of finding a English-language publication interested in a local author's book, stretched out for a chapter a day are reasonably good!  - - - With regard to other languages -- I doubt this would work in that city.
Answer: Yes, it is possible to get an English language book published in Mexico or any non-native language book published in foreign countries. I've listed two ways you could go below.
Find yourself a literary agent. A literary agent will handle all the work for you in reaching out to publishers and negotiating international rights. I did some googling and found this http://www.writersdigest.com/editor-blogs/guide-to-literary-agents/literary-fiction-agents but I'd suggest reaching out to some local writers groups in your area and see if you can find any connections through them or reading up on industry news through sources like http://www.publishersweekly.com/ and see if you can find new agents that are accepting submissions.
Submit your work directly to publishing houses, specifically ones that have Spanish language divisions. This is probably not going to be as successful as going through an agent as editors tend to prefer to deal with authors who have agents.

Can I publish in English in Mexico?


Internet connection using 2 modem at a time

Question: This may be a blunder question. But just for my curiosity Is it possible to use more tha one modem to connect to internet time,To increase speed . If yes How? If No why?
Answer: Your question results in answers more complex than you may imagine.
First off, there are many ways to do this, with different benefits and complexity. I don't know them all, but I am going to cover what I do know.
1) Load-balancing. Load balancing takes two connections, analyzes the connection quality per connection (as in typically per application connection) and chooses the best route between the two routes (two modems). This does not typically result in a doubling of bandwidth, it typically is better for redundancy (uptime) and best-routes. It can result in more available bandwidth for many different connections, say for lots of people, but does not combine bandwidth for single connections.
2) Connection Teaming/Bonding. Teaming/Bonding can be done many ways, but typically it requires identical modems, and identical routing/switching hardware on both your end and the ISP's end. Your ISP has to configure their router/switch to team/bond the connection in the same method you use (there are different protocols), and then so does yours. If this is done properly it should combine the bandwidth. Typically ISPs will charge extra for this service, and it's not going to come cheap. Not all teaming/bonding protocols include redundancy/fail-over built in, but consider that if your ISP goes down, so does your entire connection.
3) Multicasting. I'm not sure if it's possible but I've heard rumor that multicasting can be configured somehow to combine bandwidth. I have not seen a known good configuration just yet.
Load-balancing is the easiest to setup, typically should incur no cost from your ISP, and enables you to get connections from different ISPs.
Comment: Load balancing appears to ba good idea , Is their any guide for how to do it?  I am afraid cause problems due to frequent change ip address
Comment: Well first, you need to evaluate your hardware. If you are using a desktop pc (even a small form factor one), you will need one network card per internet connection, and at least one additional network card to route traffic to your local network. Assuming you are working with a pc or some form of computer with sufficient network cards, I recommend you use pfSense. It's a bit long winded, but their guide is at: http://doc.pfsense.org/index.php/Multi_WAN_/_Load_Balancing
Comment: If you are trying to use an integrate system, such as a Linksys router, dd-wrt may be able to do load-balancing, but I am not having any luck finding a guide for such.


12V Pump not working

Question: I have interfaced a 12 V pump and a 12 V fan to LPC2138, there are 3 5 V sensors interfaced, according to which the fan and pump function. The whole setup is in PCB. There is a ESP8266 module interfaced to controller. The decision to switch on or off these output devices (fan and pump) is given through the server end( WiFi connectivity). The problem that I am encountering is that whenever both the devices that is the fan and pump switch on together, the whole circuit either disconnects, or resets or the stops functioning normally (LCD displays vague values), what should I do??? Please help. The whole system is powered by a on board PCB voltage supply, where a 0-12V 1A transformer is used and voltage regulator ICs (plus design which includes rectifier, capacitors etc) are used to divert 12V, 3.3V and 5V dc supply voltages.
Answer: It sounds very likely that your power supply is not able to provide enough current for the fan and the pump while maintaining proper supply voltages for the computing parts of the design. It's as simple as that.
You haven't provided a schematic or links to the datasheets for your components so more detailed help is not possible.

12V Pump not working


Ember Addons and bower dependencies versioning

Question: (related, very similar, but not the same as this question, as my question is looking for the scenario where node_modules is lost and re-fetched through npm install and on the topic of keeping deps current in general.)
Let A be an addon in version a1, and let B be a bower dependency of that addon in version b1. The addon installs its bower package through the default blueprint like
afterInstall: function() {
    // b1 is the version.
    return this.addBowerPackageToProject('B', 'b1');
}

Now let C be an application consuming A. When A is installed using ember install A
The bower package is actually installed in C. Up to here, things are fine. Now A is updated to version a2, including B in version b2. In C,
rm -R node_modules
npm cache clean
npm install

(checking out C with no node_modules and running npm install will run into a similar problem if the bower.json is old)
will fetch A.a2.

Should A.a2's default blueprint run and cause C to install B.b2 as well? (this is the actual question asked here)

if the blueprint is run manually, B.b2 actually gets prompted for, that is, you get to see that the project has a bower conflict now and are asked how to resolve it.
I tried it out now, it doesn't work. If I specify a postinstall script for npm (ember g testaddon), it doesn't work either (because npm tries to install the packages in a different order and ember-cli isn't installed when the postinstall script runs).
What good is it to have blueprints propagate bower dependencies if one does have to check them manually anyway? Am I understanding this wrongly? Is this intended behaviour?
Answer: I totally agree. ember-cli currently does nothing on upgrade or uninstall of an npm package, and this is a problem for addons. Addons should be able to specify blueprints that run on version upgrade and uninstall. Alternatively, there should be an 'ember upgrade' and 'ember uninstall' commands that run such blueprints if available.
The addon could then in the upgrade blueprint cause C to install B.b2 if it is not already installed.
Anyone who would like to formally propose this, the way to do so is opening a pull request at https://github.com/ember-cli/rfcs