16" Pop-up Spray Heads

Question: Are 16 " high pop-up spray heads available? I have a 12" high pop-up spray head positioned 3' from a rose bush. It sprays forefully into the small rose bush (15" - 18" high). I prefer not to move the head, the spray covers the rest of the plants in the mulched bed. What I would like to do is leave the head in that location and simply change the 12" pop-up spray head to a 16" (or higher if available) thereby raising the spray height so it doesn't spray forcefully into the small rose bush.
Answer: There is no such thing as a 16" pop-up that I have run across in the irrigation world.  Or perhaps I should say, none of the major US manufacturers make such a beast.  Rainbird makes a 6" extension (part # 1800-ext) that can be screwed onto the pop-up below the nozzle.  These stick up above the ground are are quiet fragile because of the fine threads.  The flip side is you can screw several together and they even work on Toro heads.  They probably fit most of the the other companies as well, but I mostly have experience with Toro and Rainbird.
You could also swap ALL the heads in that zone to a stream spray. I prefer the Hunter MP stream spray to the Rainbird but there's really no basis behind it.  They work better in larger areas so if the beds are small I'd go with@stormy's suggestions.  The nice thing about stream sprays is they are designed to shoot thought the plant.
Answer: I would shorten the head instead of raising it.  Please send a bit more information on your head/nozzle or look up Rain Bird.  These guys I trusted.
Plants like to be washed off by free water.  I can understand getting the roses wet is not good for roses and would hold too much water for too long and in the sun could decimate flowers.  Water ONLY in the morning never at night. If you are watering a little every day we need to talk.
If you lowered your popup, the water would spray the branches down lower and be able to assure water to that shrub.  Higher would mean that shrub, rose would be missed...not mist, grins...and all the other shrubs would get watered missing your rose? the spray would have more chance to evaporate, less water to the soil.
The sprays should over lap, that was how they were designed.  Have you tried turning off that head?  If you did, the pressure of the other heads will rise a bit and if the coverage is good chances are good that your rose is getting watered that is what I would do.
I've never tried making a head into a drip.  Didn't have this option back in the day...think about making that head into a drip...even better.  I want to see what happens to the pressure of the other heads. Check out the link I am sending.  I would also call Rain Bird and talk directly with them.  Lots of better designs to be had today that I don't know about.
Segway:
If you are watering correctly you should only be using 1" of water on your landscape per week.  This takes a bit of time to train your plants but saves mucho bucks on your water bill and makes your plants drought proof, you lawn drought proof. Most people water every day and that is a waste and unhealthy for your plants.  If you haven't done the kitty cat can test or tuna fish can test let us know and we can direct you.
I know this wasn't part of your question, but if you are worried about a rose bush (yay) I would imagine you might care about your water bill.  And I want to find out how well this 'drip' head works!
from riser to drip connection Rain Bird
Comment: Shortening the height of the pop-up will mean nearly all of the spray will impact the rose bush leaving little to no spray left for the rest of the plants in the mulch bed.
Comment: Going to a 16" or higher pop-up spray head gets me spray above the rose bush, giving me coverage of not only the rose bush but all the other plants in the mulch bed. Coverage from the spray head is relatively uniform from the head out to the limits of the coverage resulting in coverage from the rose bush out to the rest of the plants in the mulch bed. I repeat, are 16" or higher pop-up spray heads available?
Comment: I asked for a picture at the very least.  My ideas were based on...what little I could discern.  Most heads, as I tried to communicate are placed to cover ie)15' diameters with 1/3 overlap.  By turning this one head off, for instance, if that would cause a major hole in the watering I would be concerned about the design of your system.  One irrigation head too high will cause an artificial hole right below it depending on soil and timer.  My advice to you is not that of a retail sales clerk.  I tried to give you a far bigger picture.  Call Rain Bird, I am sure there are ways to 'stack' heads.
Comment: Yes, there are 16" risers.  Standardized parts to make what ever height you want or need.  Home Depot; up to 24"!  Adapters and reducers and pvc plumbing stuff with which you can do what ever you think best.

16" Pop-up Spray Heads


Prove that given any five integers, there will be three for which the sum of the squares of those integers is divisible by 3.

Question: Basically the question is asking us to prove that given any integers $$x_1,x_2,x_3,x_4,x_5$$ Prove that 3 of the integers from the set above, suppose $$x_a,x_b,x_c$$ satisfy this equation: $$x_a^2 + x_b^2 + x_c^2 = 3k$$ So I know I am suppose to use the pigeon hole principle to prove this. I know that if I have 5 pigeons and 2 holes then 1 hole will have 3 pigeons. But what I am confused about is how do you define the hole? Do I just say that the container has a property such that if 3 integers are in it then those 3 integers squared sum up to a multiple of 3?
Comment: Here's a horrible solution, that a computer would find, that actually works: start with the polynomial $\prod_{1\le i n^2$ objects into $n$ boxes then some box has $> n $ objects. Here $\,n = 2\,$ is the number of values taken by $x^2\pmod{\!3},\,$ viz $\,0,1\ \ $
Answer: Any square integer must be congruent to either 0 or 1 mod 3. So for each of the 5 squares, we put it into hole 0 if it is congruent to 0 and into hole 1 if it is congruent to 1. Then take three squares from the hole with at least 3 squares and add them together. You will get either: $0+0+0\equiv 0$ or $1+1+1\equiv0$ mod 3.
Comment: Interesting note:  You don't even need to square the integers.  The statement "Of five integers, three of them will add to a number divisible by 3" is also true by a slightly longer argument.
Comment: That's also the reason that any set of 5 cards in the board game Risk contains a cashable set. Given two cards of one kind and two cards of another, the 5th card has to either complete a 3-of-a-kind or complete the set-of-all-3. (Call the three kinds 0, 1, and 2, and you can see that the sum of a cashable set is always divisible by 3.)
Answer: The remainder of every integer in dividing by $3$ is either $0$,$1$,or $2$.
Thus the remainder of a square in dividing by $3$ is either $0$ or $1$.
Now we have $5$ perfect squares that means a set of $5$ remainders each of which is either a $0$ or a $1$.
The Pigeon hole principle says there are at least three of the same kind in the set of remainders.
Well, we either have $1+1+1$ or $0+0+0$ in our sum of the squares and in either case the sum is divisible by $3$
Answer: Any integer is of one of the following forms:

$3k + 0$ (these are the multiples of 3)
$3k + 1$
$3k + 2$

where $k$ is an integer.

If we square these, we get

$9k^2$
$9k^2 + 6k + 1$
$9k^2 + 12k + 4$

If we then look at the remainders of these when divided by $3$, because $9$, $6$, and $12$ are all divisible by $3$, we see that

$9k^2 \equiv 0 \pmod 3$
$9k^2 + 6k + 1 \equiv 1 \pmod 3$
$9k^2 + 12k + 4 \equiv 1 \pmod 3$

So any squared integer is equivalent to $0$ or $1$, modulo $3$.
These will be our two pigeon holes.

Applying the pigeonhole principle to the squares of our 5 integers, we see that either at least 3 have remainder $0$, or at least 3 have remainder $1$. Let's call these 3 integers $x_1$, $x_2$, and $x_3$.
In the former case, $x_i^2 \equiv 0 \pmod 3$ and so the sum of these $x_1^2 + x_2^2 + x_3^2 \equiv 0 + 0 + 0 \pmod 3 \equiv 0 \pmod 3$
In the latter case, $x_i^2 \equiv 1 \pmod 3$ and so the sum of these $x_1^2 + x_2^2 + x_3^2 \equiv 1 + 1 + 1 \pmod 3 \equiv 0 \pmod 3$
QED
Answer: Any integer is in one of 3 sets:

multiples of 3
integers of the form $3k+1$ where $k$ is an integer
integers of the form $3k+2$ where $k$ is an integer

These are the congruency classes, modulo 3. Think of these as your pigeonholes.
Of the 5 integers $x_i^2$, if any 3 of them are all in the same congruency class, the sum of those 3 integers is divisible by 3.
If any 3 of them are 1 in each of the 3 congruency classes, their sum is divisible by 3.
Otherwise, your given integers are in at most 2 congruency classes, with at most 2 in any congruency class. This means you have at most $2\cdot2=4$ integers. But you have five. Contradiction. This proves your result.
Alternatively: you have 5 integers and 3 pigeonholes to put them in, and you may not put more than 2 integers into the same hole. Two each in 2 holes is 4. Thus you must use all 3 holes. And the sum of 3 integers, one in each hole, is divisible by 3.
In fact it proves a stronger result because it works for any 5 integers. You don't need to know that no integer's square is congruent to 2.
Answer: Let's look at any $3$ of them,say $a,b,c$ among $a,b,c,d,e$. You must have $2$ cases: $a^2 = 0, b^2=1, c^2=0$ or $a^2=0, b^2=1,c^2=1$ for the worst scenario. For the last $2$ numbers $d,e$, if at least one, say $d^2 = 0$, you're done. If not $d^2= e^2 = 1$, then $b^2+d^2+e^2 = 0$, all mod $3$. And you are done.
Answer: Basic pigeon hole.  If all integers fall into either type $A$ or type $B$ and you have $n$ integers.  Then at least $\lceil \frac n2 \rceil$ will be of the same type.
I hope you can convince yourself of that on your own.
...
Let $x_i = 3*M_i + r_i$ where $r_i = 0, 1,$ or $-1$.  All numbers will be one of these three options.
Then $x_i^2 = 9*M_i^2 + 6*M_i*r_i + r_i^2$.  Let $V_i = 3*M_i^2 + 2*M_i*r_i$ so $x_i^2 = 3V_i + r_i^2$ where $r_i^2 = 0$ or $1$.  All numbers will be one of these $2$ options.
Let all integers, $x_i$ where $r_i^2 = 0$ by of type $A$ and let all integers, $x_j$ where $r_j^2 =1$ by of type $B$.
So if you have $5$ integers and each is of type $A$ or type $B$ then by pigeon hole you must have at least $3$ of same type.
So suppose $x_a, x_b, x_c$ are three that are of one of these two types.
If the three are of the type where $A$ where $r_i^2 = 0$ then you will $x_a^2 + x_b^2 + x_c^2 = 3V_a + 0 + 3V_b + 0 + 3V_c + 0$.  And that is divisible by $3$.
If the three are of the type $B$ where $r_i^2 = 1$ then you will have $x_a^2 + x_b^2 + x_c^2 = 3V_a + 1 + 3V_b+1 + 3V_c + 1 = 3V_a + 3V_b + 3V_c + 3$ which is divisible by $3$.
So you will always have at least three integers whose sums of squares is divisible by $3$.

Prove that given any ﬁve integers, there will be three for which the sum of the squares of those integers is divisible by 3.


Python progress bar for PyGithub clone function

Question: How can I see the progress of a cloning process? tqdm module does not work for single line statements. Is there a git argument that I should add? Any references would help. Thanks.
import git

#clone to local system
git.Repo.clone_from(repo_url,path, branch='master')

Answer: The GitPython source code includes:
def clone_from(cls, url, to_path, progress=None, env=None, multi_options=None, **kwargs):

with progress defined in git.remote.Remote.push
:param progress:
    Can take one of many value types:
        * None to discard progress information
        * A function (callable) that is called with the progress information.
          Signature: ``progress(op_code, cur_count, max_count=None, message='')``.
        * An instance of a class derived from ``git.RemoteProgress`` that
          overrides the ``update()`` function.

You can see an example of a progress function here or here.


Should we assume both processes are getting same CPU clock while we solve SYNCHRONIZATION problems in uniprocessor system?

Question: In synchronization, when one process is in a critical section & another is busy waiting,  both are using CPU. But in a uni processor system, in the same clock both cant get the CPU. So there must be a scheduling algorithm for them. Should we consider these while solving synchronization problem or should we think both are doing their work on the same clock while we solve problems in synchronization?
Answer: It is very common to run processes on an operating system with a preemptive scheduler. The scheduler can switch between processes at any time: it is unpredictable when the operating system will switch from one process to another.
Unless otherwise specified, this is the model we use when discussing synchronization problems: there may be a switch between processes at any time. This means that in many cases there is no difference between the uniprocessor case and the multiprocessor case: the same execution sequences are possible in both. The operating system effectively pretends that there's one CPU per process.
The switches can even happen in the middle of a high-level instruction. For example, if you write a simple assignment in a high-level language
x := y;

this could translate to multiple machine instructions such as
copy top half from x to y
[possible switch]
copy bottom half from x to y

or
load x to register r1
[possible switch]
store y from register r1

This is why it's important to know which operations are atomic even in the uniprocessor case.
When you consider synchronization between kernel threads, and you get down to the level of machine instructions, there are things that are not possible in a uniprocessor case, because the kernel decides when a context switch is possible. But to exclude these impossible sequences, you need to know both how the machine instructions work and how the kernel works. If you don't know that then you can't exclude any interleaving of the execution.
Comment: @AhwanMishra I think the most useful mental model is that the processes are running on separate CPUs, but they are only progressing one at a time. It's hard to reason about things changing at the same time (but of course sometimes you need to).
Comment: "The switches can even happen in the middle of a high-level instruction"

Thank you. Point.
I am asking about the simple problems with lock variable, interested variable, Peterson's solution etc & problems related to this.

Not in practically implemented way but when logically asked to verify mutual exclusion, progress, bounded waiting are satisfied or not.
While solving the problems related to this, while analysing the problems should I consider both processes are getting CPU at the same instance?  @Giles sir


error on assigning an event to multiple objects with excel vba

Question: I followed all the advice I found here to automatically change the "change" function of comboboxes.
All works fine, the code does not produce any error, until I want to change the combobox value on the excel sheet : the macro is not launched.
My code is :
In the class file (class : COptions)
Option Explicit

    Public WithEvents lOptions As MSForms.ComboBox

    Private Sub lOptions_Change()
    MsgBox "hello "
    End Sub

In the module file
Sub macrotest()

Dim j As String
Dim tObject
Set tObject = Sheets("test").OLEObjects.Add(ClassType:="Forms.ComboBox.1", _
                Link:=False, _
                DisplayAsIcon:=False, _
                Left:=50, Top:=80, _
                Width:=100, _
                Height:=15)
            tObject.Name = "Combobox32"
            tObject.Object.Font.Size = 8
            tObject.Object.BackColor = vbWhite
            tObject.Object.AddItem "blub1"
            tObject.Object.AddItem "blub2"
            'MsgBox "tObject " & tObject.Name

Dim Obj As OLEObject
Dim Cl As COptions
    Set Cl = Nothing
    Set Collect = New Collection '(previously declared as global variable)

    For Each Obj In Sheets("test").OLEObjects
        If TypeOf Obj.Object Is MSForms.ComboBox Then
            MsgBox Obj.Name 'check if we enter in the loop : always successfull
            Set Cl = New COptions
            Set Cl.lOptions = Obj.Object
            Collect.Add Cl
                    End If
    Next Obj
    MsgBox "Collect  " & Collect.Count ' which result is 1

End Sub

So everything works fine, but back on the Excel worksheet, when I change the combobox value, nothing happens.
By the way, I don't really understand the way this code works.
The new object of the defined class (here : Cl) is created and modified. But the combobox, which is the target of the change, where is it modified? Why is it that by changing the new object Cl, it is the target object ComboBox that it is supposed to change ?
I have no idea of what is happening as I did not find this error on the web.
What should I do to fix this problem?
Answer: There's a problem with creating OLEObjects and hooking them up to events. Unfortunately, you have to let the procedure that creates the object terminate, then run a procedure that hooks up the event. You can use Application.OnTime to run the 'hook up' procedure right after the 'create' procedure.  Like this.
Public Collect As Collection

Sub macrotest()

Dim j As String
Dim tObject
Set tObject = Sheets("test").OLEObjects.Add(ClassType:="Forms.ComboBox.1", _
                Link:=False, _
                DisplayAsIcon:=False, _
                Left:=50, Top:=80, _
                Width:=100, _
                Height:=15)
            tObject.Name = "Combobox32"
            tObject.Object.Font.Size = 8
            tObject.Object.BackColor = vbWhite
            tObject.Object.AddItem "blub1"
            tObject.Object.AddItem "blub2"
            'MsgBox "tObject " & tObject.Name

    Application.OnTime Now, "LinkupCombos"

End Sub

Sub LinkupCombos()

Dim Obj As OLEObject
Dim Cl As COptions
    Set Cl = Nothing
    Set Collect = New Collection '(previously declared as global variable)

    For Each Obj In Sheets("test").OLEObjects
        If TypeOf Obj.Object Is MSForms.ComboBox Then
            MsgBox Obj.Name 'check if we enter in the loop : always successfull
            Set Cl = New COptions
            Set Cl.lOptions = Obj.Object
            Collect.Add Cl
                    End If
    Next Obj
    MsgBox "Collect  " & Collect.Count ' which result is 1

End Sub


Is there any way I can rotate an armor stand?

Question: I'm making a pose emporium, and I'm making a crawling animation. Is there any way I can make an armor stand look like it's crawling? It needs to be a /summon command, too.
Answer: This video goes into explicit detail about how the armor stands work in minecraft, including how to /summon, edit with /entitydata, create custom poses and static artworks.
For your specific needs (look like it crawling) you can use commands to set the angle of the head (Head), arms (LeftArm and RightArm), body (Body), and legs (LeftLeg and RightLeg).
/entitydata @e[type=minecraft=ArmorStand]{Pose:{Head:[~f,~f,~f]}{RightArm:[~f,~f,~f]}{Body:[~f,~f,~f]}{LeftLeg:[~f,~f,~f]}}

Note: the ~f relates to the 3 degrees of rotation - x, y, and z; from 180 to -180.
For example, if I wanted to tilt the head forward by 20 degrees, I would use the command
/entitydata @e[type=minecraft=ArmorStand]{Pose:{Head:[20f,0f,0f]}}

Comment: This tool should help posing armor stand. https://haselkern.github.io/Minecraft-ArmorStand/
Comment: I try that but it says this to me in red Usage entity dataTag I dont know what to do.
Answer: This is /entitydata command, that means that you change a entity. You must first place the armor stand. Or change the command to /summon ArmorStand ~ ~ ~ {Pose:{Head:[20f,0f,0f]}}.


Mixing African cichlids with goldfish

Question: I have goldfish in a tank. I added cichlids 3 weeks after. They died over the weekend. I don't know if it was the heater I have in there or I could have overfed. My question is what do I do to next time keep my cichlids alive the next time and should i do something to the tank before I put new ones in? By the way goldfish are still living.
Comment: How will the goldfish create bacteria? What's the size of the tank? Did you cycle it before? Please add these details to your question.
Comment: For the record, since the question has been re-opened, I still believe there isn't enough information in the question to be answered. See: [What to include in questions about fish?](http://meta.pets.stackexchange.com/a/1908/481)
Comment: Part of the answer is probably here: http://pets.stackexchange.com/questions/215/how-does-one-effectively-cycle-an-aquarium, Although there isn't enough information in the question to really tell what the problem truly is.
Comment: What do you mean by "cichlids" ? Africans want hard alkaline water, south Americans generally want soft acidic water. What water do you have.?
Comment: Good to know, thanks! We are trying to reduce the number of tanks and thought the goldfish might like it in the tank with the one cichlid that's left. It's already chasing around one one the goldfish. Guess we'll move them back.
Answer: Goldfish are in the carp family and are coldwater fish, they thrive in temperatures from 15 - 25 °C.
Goldfish handle water temperatures above 25 °C poorly, so they are not a good fit for aquariums at all. For goldfish to really thrive, a pond is the best.
Goldfish are seen as dirty fish as they produce more waste than many other types of fish, so they need a larger amount of water than other fish.
Cichlids are tropical fish and they thrive at temperatures from 24 - 30 °C so they are ideal aquarium fish. The difference in optimal temperature for cichlids versus goldfish makes the two types of fish incompatible so you can not expect these two types of fish to live in the same tank.
Please do not mix tropical fish with cold water fish, it is not possible to fulfil the needs of these two species in the same tank.
Answer: I would have no way to know if your heater was the problem as you asked because you never told us the temperature of the tank. My tank is at 24 - 27 °C (75 - 80 °F) it fluctuates with the temperature swings in my house, but it also has a heater. I have 2 goldfish in there along with my new cichlid, 10 minnows (hopefully will become cichlid food when cichlid gets larger, I bought too many and can't catch them), 4 zebra danios, 1 gold danio, 2 giant danios, some ghost shrimp which I think the cichlid ate and 1 map turtle as well.
All these fish (besides the newest only cichlid) have survived with the turtle for a few months now. The cichlid seems to be doing fine. My plan is to make my turtle tank more of a cichlid and turtle tank without all these smaller fish. My turtle caught some of the minnows but now rarely chases them because he thinks he can't get them and would rather beg for food.
Besides all those minnows I don't have that many other fish, only the 5 danios and the 2 giant danios. I plan on relocating the goldfish as they get larger into a pond my neighbor has with other goldfish and koi in.
My advice is to keep your water very clean. I have to do so many water changes and also have 2 filters running in there, but still do biweekly water changes, and every other day or so I do waste vacuuming.
Answer: I have goldfish and African Cichlids living together in perfect harmony.  It is amazing how some of them always swim together. That said, it is not something a beginner should do, unless you are fine with killing perfectly healthy animals.  Of you introduce the two completely different species together in the right environment, then it is easy.  If not, they will compete to survive and the similar comes cichlids will always win. You must have the right water, which means correct Ph, Kh, NO, temp and flow.  If you don't understand that, then do Not try to mix goldfish with Cichlids.
Answer: I have a large parrot cichlid fish *6" living with 3 huge goldfish and 2 koi fish.  They are all healthy and have been living together for 3 years now with absolutely no problems and no aggression. So , I would suggest you look into what your water temperature was.  The goldfish are hardy. They can deal with the warmer temperature. The cichlids need extra filtration to be used, double what your tank requires because the goldfish produce a lot of ammonia. Was your tank cycled?
Comment: Welcome to StackExchange Pets! Please take the [tour] and have a look at the [help]. StackExchange is a Q&A site where every post must answer the question asked by the first poster, which is *"what do I do to next time keep my cichlids alive?"*. Unfortunately your post doesn't answer this question at all. You have the chance to [edit] your post to actually answer the question, otherwise it will be deleted.
Answer: It is better not to put goldfish with cichlids, cichlids are much more aggressive than goldfish. Also, they live in different temperatures, goldfish need temperatures of less than 22 °C (72 °F) and cichlids of more than 24 °C (75 °F).
Comment: While this is good advice, it doesn't really answer the question that was asked.

Mixing African cichlids with goldfish


On a resume, should I italicize the name of a magazine when I'm referring to it *as* an employer?

Question: In an earlier version of this question, I confused the issue by using the word company instead of employer. Strictly speaking, the magazine is not a company, but I was considered an employee of the magazine, not the publishing house that owned it. I'm not italicizing my other employers. Before I had this job, however, I worked as a freelancer at a variety of magazines, and I list a few examples in italics as part of the description of my stint as a freelancer.
Comment: You are free to do as you please. As a writer, you should know that. And as a good writer, you would go with a choice that is pleasing to your readers as well.
Answer: If you are looking for work in publishing, your resume should follow the style used by others in the profession.
The Wikipedia biography of Anna Wintour has a nice set of examples, but the staff biography pages of any major publisher should do just as well.
Answer: Resumes are special bodies of writing, and hence exempt from many of the style rules we associate with proper writing.  Therefore, it is unlikely that anyone would criticize your decision to italicize or not italicize the name of a magazine.  It's more important that you maintain a consistent style throughout the document. Inconsistency is a much greater transgression than a style choice about italics.
That said, I personally, would choose to follow the same citation rules as a bibliography for many of the same reasons. Presumably, a prospective employer will be seeking out your work, and the information contained in that bibliography would allow them to easily find an example of your work.  Most style manuals call for italicization of the magazine name in a citation.
If your work is not of a creative nature, the point is moot. Do as you please.


Securing OpenLDAP on Debian Buster

Question: would this still be the way of securing an OpenLDAP server on Debian 9 (Stretch) and 10 (Buster). See Section 18.104.22.168. Securing LDAP Data Exchanges. Unfortunately the Debian manual seems to always be a few distros behind. Although its a home network, I'm still no keen on having passwords traveling in clear between hosts.
Answer: Yes. Always use TLS to secure data transmitted and let the client authenticate the server to which it sends credentials.
Yes. The section Securing LDAP Data Exchanges seems to be sufficient to properly configure TLS. You should consider to automate things especially for certificate and key renewal.
Comment: Thanks for your reply Michael. I guess my question was whether the above guide was applicable to Debian Buster? Apologies for not wording the question correctly.
Comment: Edit my answer.

Securing OpenLDAP on Debian Buster


Are there linux distros running Unity by default, besides Ubuntu?

Question: I read that OpenSuse ported Ubuntu's Unity desktop and made a repository, also available in Fedora and Arch. I was wondering if, besides Ubuntu, any other distro (or spin) is using Unity as default.
Answer: Well you just answered yourself. Yes OpenSuse, Fedora and Arch have a repo for Unity. In the Ubuntu ecosystem, all direct Ubuntu based distros (Lubuntu, Xubuntu, Kubuntu...) have Unity in the package manager, so you can install it if you want to change from the default this distros carry.
Outside of the Ubuntu world (In other distros not based on Ubuntu directly) we can see the following:
Arch Linux offers Unity and Unity 2D for low end systems.
Fedora and OpenSuse do offer Unity, but this need to be installed from a repository.
Other distros like Frugalware and Leeenux have or had Unity in some version or another and at some point in their development.
The small amount of distros offering Unity as an alternative is because:

Unity is/was still under heavy development so the decision was on hold.
Unity uses Compiz which some distros do not want
Unity has compatibility problems with Gnome libraries
Unity is a radical change.

Of course, there are many benefits of using Unity, and most of this points in later versions were fixed, but depending on the distro (Is it orientes towards and old linux user, is it for low end systems...) they would use or not use Unity.
I myself, can't really go back to another since Unity really covers everything I do in a strange way that after using it for a week had/needed to stay with it.

Linked Questions:

Do any Ubuntu-based distributions ship with Unity?
https://askubuntu.com/questions/71345/have-any-other-distributions-packaged-unity
Comment: Thanks for your time, @LuisAlvarado. This is a very complete and justified answer *regarding* Unity as (meta)package. However, I was curious about another distro or spin offering Unity as default desktop — for instance, a rolling release...


Are there Warrant Officers in Starfleet?

Question: Does this rank even exist, or if it does is it utilized? I've often wondered as it would seem quite applicable in many scenarios. I know that on occasion the non-commissioned ranks have been somewhat obscured for various personnel.
Comment: I was going to add a Star Trek tag, but wasn't 100% sure that's what you were asking. You might add another tag to clarify your question.
Answer: Chief O'Brien is referred to as a Warrant Officer in many scripts, though I do not believe the term was ever appied to him onscreen. Here is an admittedly not-very-good source on the subject; I can't seem to find the source they used on their forum, so I suspect it may be a book, rather than an online source. Memory Alpha does not include Warrant Officers in its list of Starfleet ranks, but Memory Beta, which includes information in all Star Trek media, including non-canon novels and comics, states that Warrant Officers exist in Starfleet.
Comment: It is les that it is incomplete, and more that canon sources are inconsistent. There is no definitive mention of Warrant Officers existing during any *Star Trek* television program or film. There are scripts where the term is used, but that's as close as *Star Trek gets to a definitive answer.
Comment: +1. Yeah I've looked Memory Alpha, and there you can see the ranks. But it seems incomplete, especially considering the references in the show itself.
Comment: Yeah, there is conflicting information on that. From TNG, my impression (and what I saw of the rank pips) is that he was either an Ensign or Lieutenant. However, in the episode "Family", he was referred to as a Chief Petty Officer. However, in DS9, it sounded like either Chief Petty Officer or Chief Warrant Officer.
Comment: Let's not [get into Miles O'Brien's incomprehensible Starfleet career](http://scifi.stackexchange.com/questions/60540/why-did-obrien-start-out-as-a-transporter-chief-in-tng).
Comment: I know this is old, but I've been trying to verify the claim that O'Brien was called a warrant officer in DS9 scripts. I can't find any source on that, yet this seems to be a really prevalent claim whenever the topic of O'Brien's rank comes up. Do you have evidence for this?
Answer: "Warrant Officer" isn't a Starfleet rank.
The confusion seems to lie in the fact that the (canon) Star Trek Encyclopedia and (now non-canon) TNG Officer's Manual both have written references for a 'Warrant Officer' rank, despite it not being used in the shows or in any of the show scripts.

Star Trek Encylopedia

Star Trek TNG Officer's Manual
This use appears to be a typographical error that should read "Chief Petty Officer" and stands firmly at odds with the ranks laid out (in consultation with both the Studio and Gene Roddenberry) by Robert Fletcher, Senior Costume Designer for the first four Star Trek films and Costume Consultant on TNG, DS9 and Voyager.
These costume notes form the basis for all subsequent representations of Starfleet rank in the subsequent films and TV series and represent the "word of god" on the issue. Specifically, there is "no warrant rank".
Comment: Where can these emblems be seen in canon?
Comment: @ellesedil -http://www.empireonline.com/images/uploaded/star-trek-the-wrath-of-khan-uniforms.jpg
Comment: Ah, TOS. Right. Are they ever used in the later shows?
Comment: @ellesedil - I don't think so. They were superseded by the pips and bars.
Answer: What is a Warrant Officer
There are three basic kinds of Warrant Officer in the world. All of them are more specialized in their duty than the Commissioned Officers, but with more authority than NCOs usually have.
The actual Warrant was a document issued by other than the Commissioning authority. Which was, in the UK, the Crown, and in the US, the Congress. Warrants in the UK were issued by Captains and by the Admiralty; in the US, by the President, the Admiralty, and by Captains. (It's worth noting as well, until the US CW, all the US "admiralty" were captains...)
UK & Commonwealth Model
Senior members of the Other Ranks, depending on specific service, above Colour Sergeant or Chief Petty Officer.
Note that while some US Warrant officers are promoted from the senior non-commissioned officers, they do not serve as senior NCO's, and still don't qualify.
US & Soviet Model
Professional individuals in specific fields with Officer rank but not full officer training. The Soviet and Russian Praporshik and the US Army Aviation Warrant Officers are of this model.
16th-19th Century US & UK model
In UK and US navies, Captains were commissioned by the Crown or Congress, and given somewhat extensive authority. That Authority included the authority to hire and warrant officers of the ship.  These were specialists in charge of departments - The Quartermaster, the Sailmaster, the Botswain, the Gunner, the Carpenter, the Surgeon, and the Engineer. They held the same authority aboard as a lieutenant did, but unlike the lieutenants, they did not have authority off-ship. Later, they were issued by central Warranting boards at the admiralty, and became proper ranks. The term Master was used for many of these, such as Master of Guns, Master Engineer, and Master of Sail...
(The Petty Officers being addressed as Mates are due to their having been assigned to one of the above departments. So, a A Gunner's Mate was a petty officer assigned to assist the Gunner.)
Warrants could also be issued by captains or commodores to field promote Masters to Lieutenants. This is a form of Brevet promotion. Again, it carried weight aboard ship and/or in squadron only.
What We See On Screen In Trek
We see senior non-coms - specifically, Senior Chief Petty Officer Miles O'Brien. If the Fleet uses the UK model, yes, then, we have a warrant officer in the UK model. This is unlikely, tho', as we see Paramount fixated upon the US model in terms, titles, and progressions. Besides, he'd have been "Charge" or "Buffer", not "Chief", in that model.
We see provisional officers in duty positions on Voyager. Lieutennat Torres, Ensign Seska, and several others amongst the Maquis are given provisional rank, and it's issued by the Captain. This is the 18th Centry style of Warrant Officer.
We also see one "doesn't fit cleanly anywhere" rank insignia...

On Mr. Kosinski, we have a 2 rectangle pattern. In silver. One bright & shiny, one dark and matte finished. That sure says "Not a line Officer" to me.
Given that we see Staff Officers in standard uniform with standard pips... The implication is that he's either a Warrant Officer, a provisional officer, or an enlisted man below the rank of Chief Petty Officer. (We see Chief O'Brien in disks through TNG, so we know CPO's wear disks in that era.)
Futher, Mr. Kosinski is called "Mister Kosinski" consistently. This is the normal mode of address for both 19th Century warrants and for current US Naval and Coast Guard Warrant Officers.
Evidence in Licensed Properties
FASA, in their Star Trek Roleplaying Game, included two grades of Warrant Officers. They did not include them for the Movie Era.
Neither Decipher nor Last Unicorn included them.
Some of the fiction uses them, as noted on memory Beta.
Bottom Line
It's likely that they do, as best evidenced by both Voyager and Kosinski, but the term itself has not been used in on-screen canon.
Comment: This is a really well thought out answer, and incredibly informative! It used to be that I thought Kosinski was a WO too. But according to William Ware Theiss, a single black pip was used to denote Chief Warrant Officers (http://www.startrekpropauthority.com/2008/05/bill-theiss-lost-interview-rare.html?m=1). We can see Miss Gladstone, late series O'Brien, and I think one or two other characters wearing it. This lines up with concept art for VOY's provisional rank pips, as it lists a single black stripe as CWO. Kosinski appeared before the first single black pip though, so who knows!


How to get MODIS data with 3 band and step to change hdf file to colored map?

Question: I just convert hdf file to tiff with MRT but my result is grayscale map. How to get MODIS data with 3 band and step to change hdf file to colored map?
Answer: I think you can't get it. Because MODIS gives a some product(LST,NDVI.EVI..etc).The products have been produced by using multi-spectral bands ,but output is one layer.you want at least three bands to colour composite.I think you want to visualize some area as a colour map.Please use multi-spectral bands products of that area(LANDSAT,MODIS..)


How safe is luks?

Question: I constantly think about encryption, and how safe it might be. The general information I have tends to be secured by passwords that range in the hundreds with random key combinations in between random words and such. That's just for the general stuff, the more sensitive stuff is secured with keyfile's.
How safe would luks (Linux Unified Key Setup) be against government investigation. Lets say I'm in the US, or another country and the government decides to confiscate my drives. I read about the powerful computers the government buys. I just imagine throwing my drive in one of these and brute forcing the partitions. Imagining how long it would take. I know key-file's are more secure against such attacks. I imagine getting a key-file on a small partitioned USB and putting it in a live rasberry pi to carry around and have a push button to activate a crypto-graphically secure wipe/overwrite of the key file if I feel its in danger of being taken. How safe would you say Luks is against such an attack? 8192kB is the Max Keyfile size, I dont like this.
I use dd if=/dev/urandom of=/key bs=8192KB count=1 to generate keyfiles. What are your honest thoughts about the security of this kind of encryption against government or powerful computers?
Any true crypt alternatives that offer ultra encryption like true crypt could? I'm a tor/tails user, a Faraday cage enthusiast and a blanket wielding password typer. Thank you for your thoughts.
Comment: https://askubuntu.com/questions/97196/how-secure-is-an-encrypted-luks-filesystem
Answer: You may want to investigate how some common encryption schemes like AES work, keys are actually 16 to 64 bytes (maybe 256 or 512?). Having a 10 billion byte passphrase won't really add anything except confusion for you.
Also consider that if a government is investigating you, they could search every device & drive you have anywhere (house, car, work, buried in yard, swallowed, etc), a keyfile would probably help them a lot.
I haven't read anything about Luks being less secure than pgp/gpg, and it has thwarted a few government investigations.
I believe several governments and large corporations use & trust  Linux and LUKS, so if it's good enough for them...
Answer: alternative to old truecrypt is Veracrypt. Supposedly continuing where truecrypt left off. As Veracrypt can encrypt folders, you can have a LUKS volume with a Veracryt container with your photos of the president's wife naked, and they probably won't get to them. However, since the government pays Intel for backdoors into your PC with the firmware chips, who knows, it may store your passwords there?

How safe is luks?


Pronunciation of 개 versus 게

Question: Is there a difference between the pronunciation of 개 (dog) versus 게 (crab)?  Or do you just have to use context to know which one is being spoken about?
Comment: 야, 게 먹으러 갈까? (Hey, why don't we go grab some "crabs?") / 뭐? 개를 먹자고? (What? Did you just say "dogs?") / 아니, 게 말야. 아이 말고 어이. (No, I mean crabs; Eo-i one, not A-i.)
Comment: There's a very very small difference in pronunciation between 개 and 게. But you just have to use context.
Comment: ㅔ sounds [e] and ㅐ sounds [ae]. However, phonetic values of those two vowels are getting less distinguishable in these days.
Answer: In theory (the "Standard" Korean language), there's a difference.  In practice, there isn't.
On the other hand, if there's no context (e.g., "개/게 먹으러 갈까?", where both interpretation would make sense), since people "know" that they should sound different, they may exaggerate the difference to disambiguate. Then the vowel in 개 would move closer to ㅏ (somewhat similar to American English "cat"), and the vowel in 게 would move closer to ㅣ with more flattened lips.
Or they could just "spell it out": "아이" (ㅐ) or "어이" (ㅔ).
So if you can't hear the difference in a casual conversation, don't worry: it's perfectly normal.
Comment: There's definitely a difference in pronunciation of '개'  vs '게'.
Answer: Yes. 개 is pronounced by wider opened mouth than 게 is.

Pronunciation of 개 versus 게


Launching Google Maps with "My Location" as the starting point label

Question: i use the following code to launch Google Maps to show step by step navigation from my current location to a specific location:
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:[NSString stringWithFormat:@"comgooglemaps://?daddr=%f,%f&saddr=%f,%f",destLocation.coordinate.latitude, destLocation.coordinate.longitude,_currentLocation.coordinate.latitude,_currentLocation.coordinate.longitude]];

however, when Google Maps app opens, it displays for example "Howard Street" as the starting point label, which is correct, but how can I let Google Maps app displays "My Location" label instead of the street name label as the starting point ?
p.s. the user can display "My Location" label if he/she taps on the coordinates, then choose "My Location" as the starting point from inside Google Maps, but I want this behavior to be done on behalf of the user.
Answer: from Google Maps SDK, if I didn't provide the source coordinates, Google Maps will automatically display "My Location" as the starting point label.


Just driving around

Question: I drove in a straight line for 10km in one direction then 20km in another direction and then 30km in another direction. Assume the Earth is flat. The three directions are not necessarily distinct from each other and may be at any angle (not just cardinal). What is the most likely (in mode) straight-line distance from my final location to my starting point? Bonus: what about most likely distance in expectation?
Answer: Here is my approach as the answer as

 40

Here is the first condition where we drive in a straight line for 10 km and then another direction for 20 km. (|AB|=10)

The red lines are just examples among infinitively possible conditions on the the circle where you can go from;
where |BC| and  |BD| are equal to 20 whereas |AB| is equal to 10.
we can formulate the distance from C and D to A, to find the distance for the first condition by using simple geometric rules;

 $\sqrt{a^2+b^2+2\cdot a\cdot b\cdot \cos {\measuredangle }}$

which is the formula if you know two lengths and the angle in between them to find the opposite length, so with the values we have it will be;

 $|CA|=\sqrt{10^2+20^2+2\cdot 10\cdot 20\cdot \cos {\measuredangle_1 }}$

where $\measuredangle_1$ changes from 0 to 180 or 360 (from 180 to 360 would be symmetric so it is not important)
and $\measuredangle_1$ is then angle between |BC| and |BA|.
Since we move 30km more, it makes everything more complicated;

so after defining C point where is just a point over 20km circle, we need to make another circle with the radius of 30km and statistically we need to have that circle for every point on 20km circle which makes the things a bit harder.
So the problem becomes all lengths over 30km circle to the A, such as |DA| and |EA|. But how can we formulate this?
To do that, let's draw something like below;

We know how to calculate |CA| already, but we need to find |EA| to solve the original problem as below just like  what we did for the previous case;

 $|EA|=\sqrt{|CA|^2+30^2+2\cdot |CA|\cdot 30\cdot \cos {\measuredangle_2 }}$

where $\measuredangle_2$ changes from 0 to 360.
so the problem becomes something like this;

 What is the most frequent length |EA| where $\measuredangle_2$ changes from 0 to 360 and $\measuredangle_1$ changes from 0 to 180

where the formula is

 $|EA|=\sqrt{1400+400\cdot \cos {\measuredangle_1 }+60\cdot \sqrt{500+400\cdot \cos {\measuredangle_1 }}\cdot \cos {\measuredangle_2 }}$

to do that, I simply used excel and python code to solve it and the result becomes;

 $40$

and expected value (python code) which is the average of all possible conditions is around

 $34.4$

and here is the graphical representation of the $|EA|$

where x and z axes are angles, y axis is $|EA|$.
Comment: Well done! This is correct. I really like the diagrams, especially the 3D one. Do you have an intuitive explanation as to why the expected mode comes out to be a nice round number?
Answer: The following is no mathematical solution, but a visualization with a lot of random angles:

 The top graph shows 100'000 endpoints of the sum of 3 straight lines (10,20,30 km) having 3 random angles (0-360°). The angles are equally distributed between 0° and 360°.

 The bottom graph shows a histogram of the distances from the origin put into bins having a width of 0.1.

So, the most likely straight-line distance from the origin seems to be:

 ~40 km
Comment: Very nice plots. Thank you!
Comment: @Oray right, for the distance it doesn't matter, but for the absolute position (first plot) it matters.
Comment: why 3 angles? the first angle does not matter.

Just driving around


Why won't my iPad backup?

Question: I always get notifications that my iPad "hasn't been backed up in X weeks. Backups occur when the iPad is locked, connected to WiFi and charging." I feel that this must occur all the time, but the iPad still does not back up. Is there a certain amount of time the iPad must be in that state before a backup is completed, or something?
Answer: Make sure that iCloud backup is turned on.
(Settings -> tap on your name at top -> tap on iCloud -> tap on iCloud backup -> turn on.
iPad will now automatically back up daily when the screen is locked, wifi is on, and iPad plugged into power.
You can also backup manually from this screen by tapping backup now to iCloud.
If you don't have enough storage available on iCloud you will get an error message.
You can also backup to a computer by connecting through usb, then "trusting" the iPad (find the iPad in Finder) then the option to backup to computer will become available. Or use iTunes.

Why won’t my iPad backup?


Lost password/the user "Sara" doesn't exist

Question: I just downloaded Ubuntu 13.0 and was setting it up, and making sure that I got everything just right. And then when the log in screen I realized I forgot my password. I then rebooted and clicked left shift at the boot screen, typed in the commands and typed in "passwd sara" ( as my username is sara) But it said the user "sara" doesn't exist. I was really confused, because I just created it few seconds ago, so I went back to the login screen and it said "sara" as my login name. So, how am I supposed to change my lost password if it says my user doesn't exist?
Answer: If you didn't set a root password yet (most likely not), then the way I would do it is boot back to the install CD/USB drive that you installed from, then mount the / (root) partition and change the password.

Boot the live CD/USB drive
Mount the / (root) partition, this can be done a number of ways but clicking on the drive Launcher is probably the easiest.
Now you have your computer's hard drive mounted, now its time to change root to that drive (this essentially will convert the commands you type next to apply towards your install, not the live boot)

First, open a terminal, using the search is easy enough
Then figure out where your drive is mounted, it will most likely be under /media/ubuntu/
cd /media/ubuntu/[your drive here]
sudo chroot .
You now have chrooted into your local install

Change your password

sudo passwd sara

You should now have your password set and you can reboot your computer without the live CD/USB drive and be able to login with the recently set password.


Are gift cards considered currency or an object?

Question: In the eyes of the IRS, are gift cards viewed as an object or as currency?  Like if I were to accept gift cards as payment for items I sell in an online store, am I accepting dollars or am I trading property with my customers?  Do they differentiate between a physical gift card and a 'virtual gift card', as in an identification code that operates exactly like a gift card, minus the physical plastic card with a magnetic strip.
Comment: Ok.  Your current question still talks about *accepting* gift cards instead of *selling* them.
Comment: In what legal context do you think it might make a difference?  And why would the SEC have anything do with your online store?
Comment: Note that those "major retailers" usually tell people not to pay third parties in gift cards, e.g. https://security.target.com/fraud.  And the FTC would call you a "scammer" and "not a real business": https://www.consumer.ftc.gov/articles/gift-card-scams.  However, they don't say whether any specific law is actually violated by accepting gift cards as payment.
Comment: @NateEldredge Oops I rewrote my question and forgot to take that out.  The 'property' I want to accept from customers is cryptocurrency.  I know the SEC regulates cryptocurrency exchanges where they exchange crypto for USD.  The big question I'm leading up to is if me trading the dollar value represented on my gift cards for customer's crypto could be considered a currency exchange.
Comment: @NateEldredge I mispoke again... The 3rd party business's do have a gift card reseller program where I hold an account with them and they issue cards in bulk to me.  And to get the account I have to submit an application and be manually approved.  So that's explicit approval to distribute their gift cards.
Answer: In the eyes of the IRS, income is income
It doesn't matter if that income is in the form of dollars, or gift cards, or red kidney beans, so long as you pay the correct tax on the income the IRS is happy.
Answer: A gift card, physical or virtual, is evidence of a debt owed by the store (or possibly a third party backer) to the cardholder.n many ways it is similar to an IOU, except that many IOUs are negotiable instruments, while most (if not all) gift cards are not; and most IOUs are transferable, while a significant number of gift cards are no validly transferable.
Comment: I wish that any downvoters would leave a comment indicting what they think is wrong with this answer. In the absence of a comment, I cannot improve the answer, others cannot use the reasons to write better answers, and readers have no idea why someone objects to the answer. Such a downvote seems pointless.


Having trouble starting a bounty

Question: I am a relatively new user, with 114 reputation points. I'd like to start a bounty on this question, but I'm not seeing any link. Any ideas?
Comment: It should be possible, since you only need 75 rep for that. I see the corresponding link...
Answer: It seems you've already found the answer to your question but for completeness, the bounty option is just below the comments on the main question and above the "Answers" text. It can only be started after a question has been posted for at least 2 days.
For more information, see the Bounty help page.

Having trouble starting a bounty


Clear Workbox's Registry constant

Question: In workbox, Listing of workflow items can be customized using Registry.SetString("/Current_User/Workflow/FilterOption"). but how to clear this filteroption & rollback to default. currently while testing i'm using powershell console or codebehind to do this everytime but wondering whether it can be doable through clearing cache in 'admin/cache.aspx'. Any input on this ?
Answer: When you use Registry.SetString(key,value) or any other Registry.Set* you're setting in fact this value on user profile:
Sitecore.Context.User.Profile[key] = value;

Clearing the cache will not help you here. Even if you clear the value in cache, it will still be set on the profile and loaded from there if needed.

EDIT
I've written a blog post describing how you can work with Sitecore Registry and with simple Sitecore Registry Editor application.
Comment: Cache is only another layer for caching so you don't need to get the value from the profile itself. You can add simple aspx page which will contains buttons for clearing what you need if you want to use something less hardcore than ps scripts ;)
Comment: thanks for the reply, i'm currently using powershell console to do this like [Sitecore.Web.UI.HtmlControls.Registry]::SetString("/Current_User/Workflow/TemplateFilter",'')   and finding appropriate way to clear them while showing demo to clients :)
Comment: So you're not clearing the cache. You're clearing the registry value using code.
Comment: yes, believing clearing cache can clear the value & rollback to default entry. but this didnt workout. so using console to reset value :(

Clear Workbox's Registry constant


Are Photoshop skills needed for a Graphic Illustrator?

Question: I am a student who is going for internship soon. However, I am not sure what I would want to do. I'm slightly better at Photoshop than Illustrator. However, there are only 2 jobs available for me. They are Graphic illustrator and Photography. I want to become a Advertiser when I am older however I am confused on which one to take.
Comment: You really should learn both since you get both with the adobe suite.
Comment: @Scott you're right, it was wrong, I think I've fixed it.
Comment: @WELZ good edit :)
Answer: You will be best served over the life of your career by knowing both Photoshop and Illustrator.
For immediate needs, generally Photoshop knowledge can be slightly more useful out of the gate. But you won't go wrong by learning either.
And be aware, merely because an employment position is listed as "Photography" or "Illustration" that does not mean the other application won't be used.
Comment: Hi may i know what do you mean by 'photoshop knowledge can be slightly more useful out of the gate'? Thank you.
Comment: The request to edit raster images is often more common than the creation/editing of vector content. Therefore it's more common to need Photoshop knowledge when you are starting out.
Answer: It would serve you best to read the full job description and talk to both employers to make sure your skills would be the best fit.
Photoshop is probably the easiest of the programs to use, but it would be best especially in the illustrator position to know how to use Illustrator. Personally,  out of InDesign, Illustrator and Photoshop, I actually use Photoshop the least, not that it's not important.
Each program has its qualities, but I mainly use Photoshop specifically for picture editing or anything that is rasterized. Illustrating in Photoshop can create massive files which can be a problem when trying to transfer files or when there's limited memory available.
My suggestion would be for you to go through illustrator tutorials. There are numerous sites and videos to help you with the basics and build up from there. My favorite (though it does cost something) is Lynda.com.
Comment: Sara, your reference to Lynda.com is a good one. Our local library has an arrangement which allows patrons to the library to have free access to many Lynda.com resources. That makes your suggestion all the more valuable.


Connecting edges with eachother to extend a bevel

Question: so i am modeling a 3D "dollar bil" and i am having an issue, i want to bevel the sides of the bil so it becomes round, but the bevel only moves until an edge(see 2nd picture) so i think i need to combine or connect the 2 edges (the orange and white edge need to becone one) but i don't know how, i hope you can help.
Comment: As well as @Gordon Brinkmann's answer, it looks from your second image as if you may need to apply the scale to your object so that the bevel is symmetrical round the corner.. - In Object mode, CTRL-A > apply Scale.
Comment: @JohnEason Yes, I guess you're right. If the scale was correct the beveling would look different. I just focused on the problem of joining the edges, but for a good bevel the scale should be applied, too.
Answer: Just go into Vertex Select mode, select the vertex which splits the edge and hit Ctrl+X to dissolve the vertex.
Or press X and in the popup menu choose Dissolve Vertices.
Just a sidenote, apart from the split edge it looks like the object bevels unevenly on both sides, so as @JohnEason mentions in his comment it is probably needed that you apply the scale on your object with Ctrl+A > Apply > Scale.
Comment: This worked Thanks!
Comment: @RyanvanVuure You're welcome. You might consider to accept this answer then.


PHP file_exists() returning false on some files

Question: I'm having a strange problem with the file_exists() PHP function on a Linux server.
When using file_exists to check the image is on the server before editing it, it will sometimes fail for no apparent reason. File paths are absolute and I've checked them through ssh they are 100% at the specified path.
The images that fail file_exists() will still display in the browser. The code doesn't make a difference a basic var_dump(file_exists('/home/user/path/image.jpg')); will return false.
The file permissions/ownerships are exactly the same on all images and parent directories. Safe mode is off. There are no PHP errors. I'm stumped now and not sure what to look for.
Here is how the images are on the server:
/home/user/public_html/images/location/1.jpg -- will work
/home/user/public_html/images/location2/1.jpg -- won't work
/home/user/public_html/images/location2/2.jpg -- will work

I have root access to the server so if anyone has any ideas I will happily try them out.
Thanks in advance for your advice, let me know if you need extra info.
EDIT:
To answer the questions in the comments below.

Yes the images are there, it's definitely not caching.
Safe mode is off (I already mentioned this in my post).
Paths are not symlinks but direct links to the files location on the server.
Phoenix, it is consistent. The working files will always work and vice versa. The names are 1.jpg, 1.thumb.jpg, etc. so it's not a problem with strange characters or spaces.

[root@server ~]# ls -l /home/user/public_html/images/Hawkhurst/
total 92
-rwxr-xr-x  1 user user 24501 Aug 11  2009 1.jpg
-rwxr-xr-x  1 user user  1672 Aug 11  2009 1.thumb.jpg
-rwxr-xr-x  1 user user 14983 Aug 11  2009 2.jpg
-rwxr-xr-x  1 user user  1370 Aug 11  2009 2.thumb.jpg
-rwxr-xr-x  1 user user 17238 Aug 11  2009 3.jpg
-rwxr-xr-x  1 user user  1453 Aug 11  2009 3.thumb.jpg
-rwxr-xr-x  1 user user 14168 Aug 11  2009 4.jpg
-rwxr-xr-x  1 user user  1464 Aug 11  2009 4.thumb.jpg
[root@server ~]#

I have tried with permissions 777 and 755 which make no difference. For example in this folder, 1 and 2 may work whilst 3 & 4 don't...
I ran a quick test to see what apache/php runs as and they do run as nobody, but this does not explain why some images work and some don't with the exact same permissions.
EDIT 2: Problem solved. Can't believe how stupid it was, some of the filenames which were called from a database had spaces at the end... Whoever made the original script didn't run any sort of cleaning up before saving them.
Comment: `This function will return FALSE for symlinks pointing to non-existing files.`
Comment: Is the file actually there? You maybe seeing images due to caching.
Comment: Do you have safe_mode enabled?
Comment: A couple of questions:  In your example, does the file that doesn't show as existing always not show every time the script is run or is it an intermittent issue?  What is an example of an actual file name of a file that doesn't work?
Comment: Thanks @ben, that actually really helped me (I had to same stupid problem!). I blame php.
Answer: Try running ls -l /home/user/public_html/images/location/ and add the output to your question.
This is most likely a permission problem. PHP probably does not have read-access to the file.
Comment: If you're running PHP on Apache HTTPd web server, please note that generally apache is running as `daemon` user. Check whether that particular user has required permissions.
Answer: After a lot of searches on the web, I found the solution myself. Hope it will be helpful for other people:
Ensure that the User and Group that are configured in your apache httpd.conf are the same like the apache group and user.
Answer: Perhaps, in a name of the file there is a whitespace symbol. It's important.
Answer: I also had problems with getting the right result.
It turns out that it for me was a permission problem located on the folder.
You got to make sure that folders have the eXecute permission for the Apache-user.
To fix it I just did this on my linux-box:
chmod g+x csv_files
Kind regards
Ivan


Ubuntu 10 or 11 installation on MacMini Server 5,3

Question: I have the latest MacMini Server with the i7 Quad core running OSX lion server.
Has anyone had any luck getting Ubuntu 10 or 11 to run on the latest MacMini's? (5,3)
Answer: I haven't actually gotten around to installing, but I booted from an 11.10 USB flash drive that I made. Most hardware was supported, from the HDMI out to ethernet.
I didn't actually install because I was unable to get WiFi and sound to work. If you are planning to use the machine as a true and pure server, it should be fine (especially headless).
Note: on Mini 5,3 i7 2.0 GHz quad with 16GB RAM


exception occurs during uninstalling msi

Question: I installed my web application via an msi. When I try to unistall the application via add/remove programmes an exception occurs during the uninstall and the uninstall never completes. Is there any way I can get my application uninstalled or work around for this?
Comment: Do you not have any more information than that? Details of the exception might help, or did anything appear in your event log? What is the application, I'm guessing it is something you've developed yourself?
Comment: This is the exception information, it is an application I developed myself: Error 1001. Error 1001. An exception occurred while uninstalling. This exception will be ignored and the uninstall will continue. However, the application might not be fully uninstalled after the uninstall is complete. --> Could not find file 'app_offline_template.htm'.
Answer: Does your setup have any custom actions? If you specified to check error code this could trigger rollback of both install and uninstall.
Does the uninstall actually complete, or does it roll back leaving the application still installed?
In cases where an uninstall fails for a product that is in the wild, the solution is normally to develop a minor update for the MSI and deliver it as a patch. A minor update actually changes the cached installation database on the system and hence you are able to fix any errors in the uninstall sequence. Then you run the normal uninstall sequence afterwards. This is as opposed to a major upgrade which is essentially an uninstall of the existing product and a reinstall. Creating such a patch is quite a bit of work, and fairly complicated. If the application isn't "in the wild" I normally end up zapping the installation using MsiZap.exe from the MSI SDK and then resolve the errors in the MSI before testing again.
Answer: Best way would be to use the MSIZAP.exe tool to remove the Installer entries for the MSI package and then use Orca or MSIVAL to validate your MSI. It seems as if your MSI contains ICE validation errors that will need to be resolved.


500 Server Error now occurring on existing Google App Engine site

Question: I have an existing GAE application that I've been running for months at www.sachinrekhi.com that just started returning the following 500 Server Error. I've changed nothing on the application (haven't done a deployment in 56 days). I checked the logs and there are no recent Errors in the logs to help get to the root cause. The App Engine status page seems to suggest everything is currently up, so doesn't seem to be an overall GAE issue.
There appear to be 0 running instances of the application. But even after I hit the site, a running instance doesn't seem to be automatically added. However, I'm below the rate limits for today, so I don't understand why an instance wouldn't automatically start.
How can I get to the bottom of the issue?

Error: Server Error
The server encountered an error and could not complete your request.
  If the problem persists, please report your problem and mention this error message and the >query that caused it.
Answer: I have the same issue. There are 2 others who reported this
https://groups.google.com/forum/#!topic/google-appengine/g1VinggHeqU
https://groups.google.com/forum/#!topic/google-appengine/4f9mcNiErnM
Takashi from Google responded to the second report.
Update:
At 16:37 PM Pacific my instances started back up, so far so good.
Answer: More information on this issue can be found at http://code.google.com/status/appengine/detail/serving/2013/01/03#ae-trust-detail-helloworld-get-latency.


Restore database - maintenance plan task

Question: I need to schedule a task that restores a database once a week from a backup. I have setup maintenance plans for backing up databases (Management > Maintenance Plans) but cannot find out how to make a restore task - does this need to be an Execute T-SQL Statement Task, or is there a Toolbox item for it?
Comment: What is the purpose behind this?  Is this for a "cold backup" that needs to be up to date?  Or a test machine that you want to restore from the same backup each time?
Comment: Oh, interesting.  Stanley seems to be thinking along the lines of regular restores for a training environment, Jon seems to be thinking along the lines of DR, and I'm thinking along the lines of dev/stage refresh.  I'm curious to see which one of us guessed your business requirements correctly.  :)
Comment: There is a production database which will be restored into a test environment each week. I also have a Logging database which only has 5 tables but grows at 10-15GB/week. The logging database is being archived away weekly and  then restored over from an empty database. Thanks for the answers!
Answer: There is no 'Restore DB Task' in the maintenance plan. You will have to use the Execute T-SQL Statement Task. In that task, add a restore script in your T-SQL statement. Simple example:
RESTORE DATABASE YourDBName FROM DISK = 'D:\DBbackups\YourDB.BAK'
WITH REPLACE
GO

Then create a schedule for weekly execution. Hope this is what the business requires, as you are overwriting a DB.
Answer: Like Jon said, there's nothing in the maintenance plans that does this.
I'm assuming that you're looking to copy the current state of a database for staging or development environments, not looking for something like log shipping.  If so, you could do something like this in task scheduler with batch and t-sql:
ECHO ON

set backupscript=c:\path\backup.sql
set restorescript=c:\path\restore.sql

set backupstore=\\server\share
set restorestore=\\server\share

set backupserver=server\inst
set restoreserver=server\inst

sqlcmd -E -S%backupserver% -i "%backupscript%"
copy "%backupstore%\*" %restorestore%
sqlcmd -E -S%restoreserver% -i "%restorescript%"

Answer: There isn't anything built into the Maintenance Plans that does this.
However, Transaction Log Shipping is built-in/supported and provides a way to keep a copy of a database in two places. It was built with disaster recovery in mind, but there's no reason why you couldn't leverage that for your purposes (aside from the requirements and limitations inherent with using Log Shipping to start with). It might even be more efficient than doing a full restore every week.
If Log Shipping is unsuitable, you'll either need to find someone else's solution, or roll your own. You could also look at built-in solutions like Replication (Snapshot Replication in particular), but that may be overly complicated for your needs.


How to make a frame out of edges

Question: So I have this shape that I want to turn into a sign.I want to make a black frame around this on these selected edges using materials.How can I make the edges look like an actual frame in object mode?
Answer:
Extrude the polygon to create some depth for the sign.
Inset the polygon to create the width of your frame.
Extrude the polygon inwards to create the inside faces of the frame.
Assign materials in the Properties panel.
Answer: If you want to add the frame only using materials, then you'll need to apply an image texture to the material. For that you'll probably want to unwrap your model first in order to be able to better place the image and match it to the shape of the object.
Having said that, it might be easier/better to model the frame with some faces. for example, you could dissolve the four faces you have and then inset the one face you'll end up with after dissolving. Then you can select the outer faces for the frame and assign a different material to those faces.

How to make a frame out of edges


I'm plumbing up a tiny house and the homeowner bought a gravity flush RV toilet, does it need a ptrap under it?

Question: Thanks in advance for your assistance! So I've never installed an RV style toilet, and I can see that when you push the pedal it's a straight shot down the drain, and I don't know if it holds water in there until it's flushed like a standard house toilet. Do I need to install a ptrap under the floor for it, because I'm thinking that it doesn't possess the 'ptrap effect' that a house toilet does. Help!
Comment: I'm voting to close this question because this is not a DIY project, but a contractor doing work for a client.
Answer: No, an RV toilet does not use a trap. The valve in the bottom of its bowl serves the same purpose (that of blocking sewer odors from rising up out of the waste plumbing/tank).
Note, however, that you need to be using the right kind of toilet. If your tiny house is a glam RV -- it's mobile and waste from the toilet will drop directly into a holding tank -- then an RV-type toilet is appropriate. On the other hand, if this is just a very small building but it is connected to municipal or private sewer, or to a septic system, then a flush-type toilet should be used. I would expect the volume of water used in an RV toilet may be inadequate to move solid waste through a plumbing system properly.


Missing Audio despite wave form being present

Question: After recording audio via a mic, some of the audio won't play in sections, despite the audio being visible. If the audio wave form was missing in parts I'd assume its a faulty mic or cable, but the wave form is visible right through the recording. Using a Universal Audio 8xP interface with Logic Pro X and all other audio is working. Any ideas
Answer: try importing the audio into another DAW or audio player and do some elimination testing.


Solutions for Finding Position and Heading in a Multi-Level House

Question: I was wondering if you could reccomend possible solutions for locating a robot within a multilevel house.  What seems obvious to me is that need an altitude sensor to derive the story the robot, and a compass sensor to derive the heading.  However I was wondering what I could use to locate the robots xy position in the house.  If this requirement is unclear, imagine that I have to map a dot representing my robot position to an image of the current floor from the top.
My original idea was to use GPS, however as I need submeter accuracy that would be incredibly expensive.  I also considered Monti-Carlo localization, however that requires no obstruction between sonar sensors and walls.  It is also a significant task programically.  I had an idea to place 3 wireless beacons of some sort on the vertexes of an equilateral triangle surrounding the house, then triangulate my position using distance from each beacon.  However, I have no idea how I would go about this hardware-wise.  Do any of these ideas seem viable, and if so do you have suggestions on how to implement them? Otherwise, can you reccomend an easier or cheaper alternative?  My platform is essentially an arduino hooked up to sensors and motor drivers connected to java on a laptop over serial.  Thanks.
Answer: GPS won't give you the accuracy you are looking for. Outdoors it's good for around 1-3 m, indoors if you get a signal at all the multipath will increase your error. There are better GPS technologies out there such as RTK and PPP but their performance degrades significantly when the view of the sky is obstructed.
If you don't have line of sight to the landmarks, your options are a bit more limited.
RF trilateration is a good direction to investigate; there's a lot of interesting research these days into using COTS wifi access points for this purpose. You'll have to read some fairly recent research papers to find an algorithm.
This is actually a pretty difficult problem that you are trying to solve. To make it easier, I would suggest making the problem simpler. Try using a large number of artificial landmarks that are identifiable (such as QR codes or April tags), and use the landmark IDs to indicate the floor of the house you are on. (You can color code them by floor, for example.) From there you can implement a basic SLAM algorithm to find your position. It will be even easier if you map out the locations of the landmarks in advance, because then instead of SLAM you can just do triangulation.
Comment: Yeah, unfortunately QR codes are not an option as all electronics for the house need to be hidden.  Do you think I could do the same thing with IR leds?
Comment: Essentially, you need to get angle, distance, and id to at least 4-5 landmarks to calculate your position. There are a number of technologies that can achieve this. IR LEDs can be difficult because sunlight will wash them out, the landmarks will require batteries, and any data encoding you do over IR will be complicated if the robot is moving while localizing.


Outward opening bedroom door without a lock

Question: I rent a room in a private home and cannot change the doorknob, but I would like to be able to secure my room from others staying in the home. Is there a way to secure an outward opening interior door that does not have a lock?
Answer: I would search Amazon for "portable door locks" and add a long-shackle padlock to this type of device

You need the padlock because the majority is accessible from the outside. The whole thing will obviously be visible and not resistant to detrmined attack.
The lower photo shows how it locks into the door frame, preventing the door opening in its usual direction.
This works because an inward-opening door that an occupant wants to secure while asleep is essentially the same case as an outward opening door you want secured when you are elsewhere. The added padlock prevents passers opening the lock.
Comment: This is an IPX factor not a home improvement one, I think as soon as they see you fixing to deploy that gadget, they will cave on letting you just change the doorknob.  Doorknob is an easy swap, most use the exact same form factor, 4 screws and done.
Comment: Thanks, RedGrittyBrick.  I had not thought of portable locks.
Answer: Make a request to the home owner / lease holder (who ever it is that you rent from) - that you be allowed to put your own door knob with Lock on the door - they can keep their matching door knob somewhere else in the house. Generally two screws accomplish the change out. YOU SHOULD BE THE ONE TO DO IT and NO KEYS to anyone else.
This is a fair and reasonable request and I think it is a small thing since you are paying the rent for the room. If the owner will not allow this you should look for another room elsewhere to rent - something is probably not right.
I would also look for something like an iSmart alarm so you know if by some means anyone has entered the room or opened the exterior window while you were not home.
Further when renting such a room as this with access for whomever - check for hidden devices and cameras. I assume the room also has it's own full bath.
Of course if you are intent on staying there regardless of what the owner says about changing the door to a lockable door knob - get yourself an iSmart Alarm so you can see when and how many times entry is being made and ask for what purpose?
Comment: Thanks, Ken.  Access to my room by others when I am away is needed because the internet/phone/tv equipment is in my room.  I will use your suggestion about the iSmart Alarm System so I know when someone is in there and what they are doing though.


My iPhone 5 synced contacts from my wife's iPhone 5

Question: My iPhone 5 (iOS 6.1.2) synced contacts from my wife's iPhone 5 (iOS 7.0.2) and changed many of them (changed names to contacts with similar numbers). She uses my Apple ID, but contacts transfer from her phone to mine. Does anyone know why does it syncs contacts?
Answer: If you use the same Apple ID for iCloud on both devices then it will sync data like contacts between the two. I would suggest you sign out of iCloud on your device and create a new Apple ID for yourself.
Comment: she's not logged-in in icloud, anyway in that case my contacts should be transferred to her phone, not hers to mine
Comment: @user61956 Do you both sync to iTunes using the same computer or have the same email address which might sync contacts?
Comment: no, we use different mails and computers
Comment: @user61956 In that case I would restore from a backup to get your contacts back and create a new Apple ID for the rest of your phone separate from the one you use with iTunes/AppStore.
Answer: Suggesion 1:
Pardon me for being slightly out of context here, but I'd suggest creating a new Apple ID for her anyway. Apple now has Family Sharing feature, which would allow you to share media and purchases if you need. Though its available in only iOS 8+ (you'll have to upgrade of course) I recently got to upgrade my personal iPhone 4s to iOS 8 and I think its really useful in sorting out such situations with family and kids.
Suggestion 2:
I have switched off contacts sync with iTunes completely. Leaving iCloud to be only way the contacts sync, hence reducing the confusion and ambiguity.


How do I breathe with my diaphragm while running?

Question: I've heard that breathing with the diaphragm is the "proper" way to breathe. How can I make sure I breathe with my diaphragm while running?
Answer: Runner's World has got this completely covered here. The gist of it: Run until you're breathing hard, then put one hand on your belly and one on your chest, and breathe so the bottom hand moves and the top hand doesn't. I also found two of their three exercises helpful: the "Hundred", where you lie on your back with legs raised slightly and pump your arms with each breath, and the chest expansion, where you inhale while sweeping your arms overhead.


UIGestureRecognizer with a touch moving off UIView

Question: I have a UILongPressGestureREcognizer with a minimum press length of 0 seconds. On UIGestureRecognizerStateStart I alter the UIView. On UIGestureRecognizerStateEnded, I run the code for what ever the press is suppose to do.
-(IBAction)longPressDetected:(UILongPressGestureRecognizer *)recognizer {
    static NSTimer *timer = nil;

    if (recognizer.state == UIGestureRecognizerStateBegan) {
        // alter look of UIView
    }
    else if (recognizer.state == UIGestureRecognizerStateEnded) {
        // do something
        // change look back to original state
    }
}

I am running into an issue where if the touch starts on the UIView and if the touch is dragged outside of the UIView and is lifted, the UIGestureRecognizerStateEnded still fires.
I need to be able to handle a touch inside the UIView, the user drag outside of the UIView and to cancel it.
I know a UIButton can do it, but it does not fulfill all the needs I have.
How can I cancel a touch if the touch is dragged outside of the UIView?
Answer: Add checking of touch location. This method can be heplfull.

- (CGPoint)locationInView:(UIView *)view


Why no big and slow flywheels for utility-scale energy storage?

Question: The flywheel research I see usually focuses on small, high-speed (thousands of RPM) flywheels, often with an emphasis on transportation-related applications. The largest rotating building in the world weighs 500,000 kg. According to my calculations, that mass rotating at 60 RPM would have a KE of several hundred kWh. Is that correct? If so, why are there no big and slow flywheels for utility-scale energy storage? What am I missing?
Comment: The KE of a rotating object depends on its moment of inertia, not just its mass. A large rotating ring will have far more KE than a narrow cylinder of the same mass rotating about its axis, for example. It's impossible to say how much KE is in a rotating building from just its mass and angular velocity, you'd also need to know its size, shape, and mass distribution (all of which contribute to the moment of inertia).
Comment: I calculated that if your "*several hundred kWh*" was 500kWh, a cylinder with a radius of 19.1m would be required. Integration or a table is required to calculate internal stress from centripetal forces here. I was lazy so this https://www.engineeringtoolbox.com/stress-rotation-disc-ring-body-d_1752.html gave me 38.6Mpa if the material were steel. 250Mpa is listed as the yield strength of mild steel. The height if the cylinder was calculated to be...5.4 cm. so that is what the kind of device you are talking about would look like.
Comment: Because there are easier ways of producing "several hundred kWh".
Comment: @DKNguyen that's good information, thanks! I was looking at concrete, and calculating that a cylinder with radius approx. 10m and height 13m and rotating at 120 RPM would have a mass of 10,000,000 kg and a KE of approx. 10 MWh. No idea if that is structurally possible with concrete.
Comment: They would be a very large waste of capital.
Comment: Storing the energy is only part of the problem. You have to get the energy into the thing, and back out again. Both are lossy. So storage systems are defined primarily by the length of time the energy must be stored, and the power that has to be taken in and given up. By the time a big flywheel would make sense, you are better off pumping water up a hill and storing it in a lake. Also, compute the Coriolis forces involved, unless you plan to install it at the North Pole. Compare a modern train running in a circle at 250 km/h with one running up and down a steep hillside with regeneration.
Comment: @PhilLoden Concrete is strong in compression and weak in tensile. Spinning things experience centripetal force with is tensile. That's why concrete has steel rebar put into it.
Comment: I feel like this question should be, why don't we generate energy from things that are rotating already anyways?
Answer: What you are missing is that it is cheaper to increase the storage capacity of a flywheel by increasing its rotating speed than it is by making the flywheel bigger. This is the reason why (proposed) kinetic energy storage flywheels rotate at speeds high enough to generate stresses that are almost but not quite big enough to make the flywheel tear itself to pieces.
Comment: That reasoning seems to line up with my math in the comments.
Answer: IMHO another you are missing is the practicalities of size and friction.
A 500000 kg disc is bound to be big and it  needs special considerations for support, transportation, installation etc, thus making it impractical.
Additionally any practical application will have coulomb friction associated with it. However the thing is that coulomb friction is proportional to the weight. Thus increasing the weight increases the friction and the losses.

Arguably same thing can be said of viscous damping and high rotation. The main difference that the conditions to mitigate the losses are simpler in the case of viscous damping. E.g. vacuum chambers can be considered. For coulomb friction of a 500000 disc my mind goes toward technologies which are either exotic (magnetic levitation) and/or not invented yet (anti grav).
Comment: The building I mentioned was using some kind of magnetic bearing, so I think you're right, something like maglev would be necessary.
Comment: @PhilLoden so how much power would your "maglev" bearing need?
Comment: Friction is proportional to weight, but so is inertia. F=umg and F=ma, so the deceleration due to friction is completely independent of the mass (for fixed m and g, a is proportional to u only). Two cars with the same tires and moving at the same speed have the same stopping distance regardless of their weight. A large flywheel is impractical, but not due to increased friction - friction slows a large flywheel at the *exact same rate* as a small one.
Comment: In a perfect (non deformable) world I would agree - although I would disagree with your example if you mean rolling resistance. However materials hit their limits as you increase the weight and deformations occur. At the end of the day, I haven't been able to put the same wheels on a loaded truck and a small passenger car and try to brake them from 50 mph and see if weight has a noticeable effect
Answer: Regarding energy storage, you really have to make a difference between power and energy.
For example, a laptop draws a few tens of watts peak, and a cordless drill draws several hundred of watts peak. So, from the same battery voltage, often around 18V, that's a few amps versus a few tens of amps.
Energy density is in Watt.hours/kilogram
Power density is in Watt/kilogram
You can also calculate it vs volume, vs cost, etc.
The laptop battery is optimized for maximum energy density so the laptop runs for a long time while reducing weight, at the expense of high power
density: these cells will only be able to deliver a few amps.
The cordless drill battery is optimized for the opposite requirements, which mean maximum power density at the expense of energy density.
The results are very different chemistries, different costs, etc. Other factors like lifetime, number of cycles, cost, etc, are of course important too.
Now if you want to do energy recovery on braking in a vehicle, then you need an energy storage that can charge at very high power. A 12 ton bus going at 50 km/h has a kinetic energy of about 1.2MJ. If it stops in 5 seconds then that's an average power of 240 kW, which is quite large.
If you want to store the kinetic energy of that bus to reuse it when it accelerates again, then you need a system which can both absorb and release 240kW.
Lithium batteries have gone a long way, and now the high power density ones would definitely be able to do that on discharge, but when carging, they tend to be able to safely take a much lower power.
So, if the bus was fully electric, a battery pack sized for powering the bus and accelerating it from a stop to its nominal speed in the desired time would not be able to recover the full energy on braking, because its allowed safe power is much lower than its safe discharging power. If the bus is not electric but instead hybrid, then the battery is much smaller, which is even worse for recovery.
This is why these systems tend to use supercapacitors, flywheels, or pressure tanks, which have the advantage of huge and equal power density both on charge and discharge, plus almost unlimited number of cycles.
Drawbacks of these systems are mainly very low energy density, high cost of stored energy, and energy loss for flywheels. That's not a problem for a kinetic energy recovery system, which only has to store enough energy for one acceleration, and only for the duration of a bus stop. But it means these could never be used as a main battery.
Basically, it's only for pulse power requirements.
So you will find flywheels in utilities, when there is a need for short-term pulse power, for example to react quickly in case of a sudden increase in power demand while the generators take a bit more time to react.
However, if you want to store energy from solar panels to use at night, it's not cost-effective. Concentrated solar plants just store the heat, which is cheap. Other systems just use batteries. A popular option is to run a hydroelectric dam in reverse to store energy by pumping the water up.


Is there any reward for protecting a follower until the end of the game?

Question: For example, Jaime is following me. But he's a bit weak and sometimes screws up my tactic since he always runs head-first towards the enemy. I wonder if there is any benefit/reward in trying to keep him and possibly other followers (characters that follow your group that you cannot control)? Do they have a specific purpose that is fulfilled later in the game? Do they affect the ending? In short: is there any point at all in trying to keep them alive?
Answer: Not aside from having them around for the climactic giant charlie-foxtrot battle.  (I had Puppy for that, and he contributed, but keeping Jaime alive through two Scorpitron encounters -- when any usage whatsoever of their close-range flamethrowers will instagib him -- seemed like more trouble than it could possibly be worth.)


staggering line paths evenly in illustrator

Question: Is there a way to offset the line path in illustrator? I want to evenly stagger the lines horizontally lines, I am trying to draw an escalator. I've tried offset path but it creates a stroke on the lines.
Comment: Did you try to use two separate steps and use the Blend tool to create the other steps? I think you're going the wrong way.
Answer: Option One: An Effect

Draw one path.

Select it and choose Effect > Distort & Transform > Transform from the menu.

Tweak the values there. (Note the settings in the screenshot below)

Then, if you need or want direct access to each iteration, choose Object > Expand Appearance from the menu and you will be left with a collection of individual paths.

Option Two: A Blend

Draw the first and last line

Select both and choose Object > Blend Make from the menu.
Then choose Object > Blend > Blend Options
Set the dropdown menu to Specified Steps and alter the number to your liking.

Again, if you need or want direct access to each iteration, choose Object > Expand Appearance from the menu and you will be left with a collection of individual paths.

Note that with a live Blend you can alter the position or size of one, or both, of the end paths to change the blend...

Most appearances can be created using the Effect, but the effect method is not directly editable the same as when using a blend.
Comment: Option three repeat last transfomation?
Comment: True Joojaa, but for me that's typically the least beneficial method if the above two work for a project.
Answer: This was not asked, but you can use a kind of engineering approach if you have a clear idea how the stairs are placed in relative of each other. 3D effect Extrude & Bevel makes a proper perspective view which at least can be used as a reference for the final drawing:

You can easily try different views, perspectives and even lights.
The stairs are here rectangles. It's inaccurate. See a more proper explanation here https://www.youtube.com/watch?v=1jfNIBtfWDY
An equally inaccurate side panel is inserted by drawing one with the Pen and by applying Pathfinder panel's Unite. The result got Effect > 3D > Extrude & Bevel.
A group can also be extruded as one if you want to keep the parts separate. The front-back layering order becomes critical if you extrude a group.
Making multipart assemblies of separately extruded parts is very difficult in Illustrator, use a proper CAD program for it. But extruding simple items can help substantially to find the right look.
The dialog can be reopened by double clicking in the Appearance panel. The effect can be fixed to a 2D drawing by applying Object > Expand Appearance.
Comment: +1...when you have a bit of the time,..please, can you see my recent question? Thank you very much.


No keyboard if I unplug the charger on my netbook

Question: when I unplug my netbook, I can use my keyboard.
I can write my password on login screen, but nothing on the softwares (firefox, mail etc...)
I must close and open the session for my keyboard is OK
I'm on eos 5.1 (Atom N450, 2gb of ram, model ACER D255)
Answer: This could be a USB power issue.
Depending on what kind of keyboard you have, it's possible that it's drawing more voltage than your Netbook can handle when not plugged in.
You might consider using a powered USB hub. I like the ones Plugable provides since they were recommended to me a while back as being unusual in that they provide really solid power (not always a given among hubs apparently.)
Comment: Hi, thank you for your answer, but, I don't use a USB keyboard, just the netbook's keyboard.
Comment: Oh wow sorry about that. I've never seen any Linux fail to detect / use an internal keyboard before!
Comment: I think it's a bug on eOS, to resolve it, I must reload session


Nodemcu powering with 5.2v and 2A?

Question: I bought a this voltage regulator . DC-DC 5v 8A voltage regulator. ıts supported 8-35V input voltage . And i want to use this with 12v power supply.
But i searched on the internet . Nodemcu max amp is 800mA. This device can provide 2A per usb output if i will plug the nodemcu with usb cable this what happen ? Does it burn ? How can i drop the amps ?  i want to use other 3 usb output with other devices sensors and screen .
Comment: the 8 A is the maximum current that can be supplied before the power supply shuts down, or the output voltage starts to drop .... it does not mean that 8 amps will be pushed through any load  ... the amount of current that 5 V can push through a load is dependent on the load resistance
Comment: @jsotola i understand thanks for your answer :)
Answer: Generally, we specify DC power supplies as constant voltage sources.  In order to do this, power supplies deliver more or less current as demanded by the load in an attempt to keep the voltage constant regardless of the load.
When a constant voltage DC power supply specifies a maximum current, it is saying the power supply can only maintain the specified voltage while the current demand is less than the specified maximum current.
To be clear, unless you need a constant current power supply, a power supply should be picked based on the required constant voltage.  And the capacity of that power supply, usually measured in Amps, should exceed the maximum combined current demand of all connected devices (loads).
Comment: usb output is 5.2V which is its ok . But now I have a prototype for my project . i plug nodemcu to pc usb port and its provide 500mAh and its ok . but i want to connect 5v 2A usb port . I dont have too much electrical knowledge  . I have difficulty about that. I just wonder nodemcu and other devices does it burn or not ?
Comment: USB ports are regulated to be 5 volts or very close to 5 volts.  You don't regulate both voltage and current.  It is one or the other.  Older USB ports are obliged to supply up to 500mA.  Newer USB ports can supply more.  But you only need to match voltages when talking about constant voltage power supplies.  You do not match the current values.  You only need to make sure you draw less current then the constant voltage power supply is rated for.
Comment: For example, it is fine if you plug in a USB keyboard which expects 5 volts and draws only 15mA.  As even the oldest USB computer ports supply 5 volts and have at least 500mA to offer.  See, 5 volts == 5 volts and 15mA is < 500mA.  So this should work fine.
Comment: Ok. I understand now. more clear in my mind. Thank you for explanation and fast reply :)
Answer: It will not burn.  The nodeMCU will only "pull" the amount of current (amps) it needs.
Comment: Thanks man .  I'm saying hypothetically. We will connect 5v 10A supply for nodemcu and nodemcu still pulls as much as it needs right ?
Comment: Yes, it will only pull as much as it needs no matter how many amps the supply is capable of.
Comment: Ok man thanks for your answer :)

Nodemcu powering with 5.2v and 2A?


Virtualbox, Win 7 host and Win 7 guest share folder

Question: I have Windows 7 as host and I am running VirtualBox with Windows 7 as guest. I have created share folder on my host but I do not know how to access it from guest. Any ideas?
Answer: Read about shared folders in VirtualBox here.

Fortunately a bit of searching yielded
  this article, which describes the
  problem nicely.  It turns out that
  there is a magic word you have to
  know, and that is the share name for
  the host OS:
<code>\\vboxsrv
</code>
Answer: (I ran into trouble too, the other answers did not help me, but I eventually found the solution which I am sharing with you)
In a nutshell it is:

On Host machine, share a folder under the name "share".
On guest machine, map it using "net use x:\vboxsrv\share"

More details on Shared Folders in VirtualBox
But, if it still fails, it is probably because Guest Additions are not installed.
On Guest machine, click in the menu: Devices > Install Guest Additions...
Navigate to the virtual CD-ROM just created, and install VBoxWindowsAdditions.exe
Comment: Thanks a bunch @Hugues, turned out indeed I hadn't set up the Guest Additions. After this it automatically set it up like Randolph mentioned