Will install Watch App called with bad bundle identifier '(null)'

Question: When I use xcode 7 beta 5 and wanna to run a simple demo on watch simulator. It prompts this "Will install Watch App called with bad bundle identifier '(null)'". I cannot find it anywhere. Does anyone know this?
Comment: Tab you scheme->Edit Scheme->Build->+
Add you app, watch app and watch extension there. I think it will be fine.
Comment: The final scheme should be something like this:
https://drive.google.com/a/umn.edu/file/d/0B_N0iePPjbEjWXh1TDYyU0NwWEk/view?usp=sharing
Comment: After add iOS target to Build target. The problem solved.
Comment: I have the same problem for Xcode7 beta5.I choose the watchKit App for the build target but nothing help.
Comment: Thank you, @Michael. I had the similar problem. Your advice helped me.
Answer: The problem comes from the fact that the iOS app is not compiled when Xcode tries to launch the Apple Watch App + Extension.
In order to solve this problem, as said in the comments of the question, add the iOS App to the Build Target (edit scheme, select the Build entry, and add the iOS target).
Answer: I had the same issue and solved the problem by creating a new scheme with the correct target.
It worked without doing anything more.


Count of Lines within a Range

Question: I'm trying to do a count of all the values (numeric) in the third column of a file that fall within a specific range of numbers. I've found the min and max but have no idea how to do the count now. I've tried egrep, grep, awk, and more but am still confused. I'm very new to UNIX/Bash and would really appreciate any help. Thanks so much!
Comment: It will be better if you edit your question with sample input file and required output, so someone could help you. Now is unclear what you are trying to achieve.
Answer: I interpret your question that you want to sum up only those numbers in column 3 that are within some numeric range. Try (for sample range [9-12]):
<code>awk '$3>=9 && $3<=12 {s+=$3} END {print s+0}' the_file
</code>

Count of Lines within a Range


Percona db Replication Issue

Question: One master Server
3 slaves
Master Server version: 5.5.24-55-log
1st slave Server version: 5.5.24-55
2nd Slave Server version: 5.5.24-55
3rd slave Server version: 5.5.25a-27.1
On the first two slaves,the following type of statements get replicated properly
insert into table1 (select * from table 2)
insert into db2.table1(select * from table2)
On slave 3 (with newer version of percona db), the statements seem to fail
all of the slaves have same my.cnf file with only server_id different.
could this be a bug in the new version of the software.
I have tried uninstalling the slave and then resyncing it using latest data from the master.
Any clues?
Answer: Found the Issue
1. The timezone on the slave was different to all other machines
2. this differnce in time ,caused some of the queries to not work properly as the queries were using the mysql NOW function

Percona db Replication Issue


Trane furnace pilot wont stay lit

Question: I have a 1983 Trane gas furnace, Model BLU108E936B1, the pilot light went out, I could get it to relight but wont stay on> Changed the thermocouple, same results, Pilot light doesn't look right as I recall before, the flame doesn't seem to come up as high as before to hit the thermocouple correctly. I tried different positions for the flame to hit thermocouple but still same results, Pilot wont stay lit.
Comment: How long did you keep your finger on the light pilot button?  Some pilots take a good minute, or even two or three, before they stay lit.  (It can feel like a long time to lie in an uncomfortable position with your finger on the light pilot button.)
Comment: NYC thanks for the reply. I had the button down a long time. Furnace been working fine, noticed getting cold, checked and pilot wasn't lit. Tried many times, it would lite, Burner come on and pilot goes out
Answer: I would still not trust the thermocouple. I encourage you to just take the new thermocouple back out, and re-install it. I had this exact same problem and unfortunately paid a contractor to come out and do just that, and somehow it fixed it. I guess the things are just finicky.
There should also be a way to adjust the pilot light's flame, typically a screw.
Comment: Thanks for the replies. It ended up being my outside gas meter was sticking not letting the gas supply get to my furnace all the time, that's why it would work sometimes and then shut down again. Gas company came out and replaced the meter.

Trane furnace pilot wont stay lit


adjectives before and after nouns: "My white computer" vs. "My computer is white"

Question: what is the difference between these 2 sentences in meaning and when adjective comes after the noun like in these sentences?

My white computer
My computer is white

PS: I am not an advanced student so please try to explain using simple words
Comment: You're thinking about it wrong if you call this "after the noun". If it's before the noun, it's part of the noun phrase. But it's after **the auxiliary verb *be*** that matters here. That makesit  part of the verb phrase, which happens to come after the noun phrase. A modifier that appears **after** the noun it modifies, but is still a part of the noun phrase, is "in the picture" in_The man in the picture is dead._ The adjective _dead_ doesn't modify anything here; it's a predicate adjective and it requires _be_ to carry the tense, just like a predicate noun (or nominal) does.
Answer: There is a nice overview of the various ways adjectives and nouns can work together in English here.
As to your specific example, you might find these portions of the cited page especially helpful:

When the information contained in an adjective is not the main focus
  of a statement, then the adjective is usually placed before the noun
  in the attributive position.
However, when the main focus of a statement is to give the information
  contained in an adjective, the adjective is usually placed after the
  verb in the predicative position, compare:
He handed me a bucket of hot water. (attributive position) I put my
  hand in the bucket, the water was very hot. (predicative position,
  emphasising hot.)

and

There are some adjectives which can only be used before a noun, in the attributive position. For instance, we talk about the main problem but cannot say, the problem was main.
Adjectives which occur only in the attributive position are generally
  those which identify something as being of a particular type. For
  instance, we can talk about a financial decision where financial
  distinguishes this from other types of decision, e.g.: medical,
  political. This group of adjectives are often referred to as
  classifying adjectives, and rarely occur in the predicative position
  unless we specifically want to emphasise a contrast, e.g.:
a chemical reaction not, e.g.: a reaction which was/is chemical the
  phonetic alphabet not, e.g.: the alphabet is phonetic It was an indoor
  pool. not, e.g.: The pool was indoor

To look at your specific question about the computer:
Your first example, "the white computer," seems to be an instance of a "classifying adjective," as discussed in the second block above:  that is, an adjective used to distinguish the white computer from the black one, the gray one, etc.  So you would use "white computer" as with "financial decision" in the text above, because you want to specify that you mean the white computer, not the black one or the gray one.
But if you wanted to emphasize the whiteness not just as a classifier but as the most important piece of information, you might say "the computer is white."  For example, if someone asked you "Is your computer black?" you would say, "No, it is white."
And if you were using an adjective that provided some additional information about the noun which was not so important either to classify or to emphasize, you might put the adjective before the noun, but probably preceded by "a" or "an" rather than "the," e.g., "I think there is still an old computer in the attic."
Note that there are other special instances to keep in mind, at least some of which are discussed at the linked page.
Answer: In the first sentence, "white" is used as a modifier (adjective modifier). In the second sentence, it is used as a subject complement.
From the sources/links:
A modifier is a word, phrase, or clause which functions as an adjective or an adverb to describe a word or make its meaning more specific.
A subject complement is the adjective, noun, or pronoun that follows a linking verb. The following verbs are true linking verbs: any form of the verb be [am, is, are, was, were, has been, are being, might have been, etc.], become, and seem. These true linking verbs are always linking verbs.
Comment: _Become_ and _seem_ are not linking verbs. They can appear in many constructions that _be_ appears in, but they have totally different grammar, and usually some meaning, whereas _be_ has no meaning at all.
Answer: Shin's answer says it all.
Another reference is here from About Education which says
The adjectives can be written in two ways.

Before a noun  In the end of the sentence using a stative verb

Two examples given there are -

He's an interesting person OR  Jane is very tired.


How do I open this plastic surface-mounted fixture?

Question: A bulb in bathroom has burnt out, and upon trying to change my bulb I've been met with a wall mount that is a bit poorly fit, and seemingly immovable. It doesn't seem to rotate, push up, or have any gap to wedge a screwdriver into and pry open. Pulling down seems to pull the whole light fixture down, but if I have to do that I'll call the landlord so I don't get blamed if I mess it up.
Comment: FYI, a "flush-mount" anything results in a fixture that's level with the mounting surface _on top_, not attached to it and protruding. Ignore what marketing departments say. They're wrong.
Answer: See the little tab in the picture? There should be one on the other side too. Bend  them outward and the dome should drop down.
Comment: I just had another try but no such luck so far - it seems like that tab is part of the white plastic at the top and doesn't want to move in any direction. I get the feeling that the bottom part might even be glued on - maybe because the mechanism had broken? I tried some WD40 and wedging a pliers in the gap for leverage but didn't have any success there either.


Adding click event to KMLLayer Placemarks and Markers

Question: How do i attach an onclick event to Placemarks specified in the KML file. Can event listeners be added to both google maps and google earth plugin?
How would I go about this?
Answer: In the Google Earth plugin...
google.earth.fetchKml(ge, href, function(kmlObject) {});
google.earth.addEventListener(kmlObject, 'click', function(event) {
    event.preventDefault();
    var kmlPlacemark = event.getTarget();
    alert(kmlPlacemark.getName());
});

In Google Maps API
var ctaLayer = new google.maps.KmlLayer('http://www.****.com/index.kml');
ctaLayer.setMap(map);
google.maps.event.addListener(ctaLayer, 'click', function(kmlEvent) {
    var text = kmlEvent.featureData.description;
    alert(text);
});

Answer: Seemingly the onlick event is wrapped up when the kml loads (GMaps v3, kml with Placemarks) Any Placemark references to "BallonStyle" bundled in the same kml file causes these to replace the default popup - and you can achieve a lot with them.
These are the kml elements supported by Gmaps v3 http://code.google.com/apis/kml/documentation/kmlelementsinmaps.html
If your question is how to intercept that onlick event, then I am sorry I do not know how you can achieve that.


How do I seek advice for the following question?

Question: My question was closed as a duplicate and I was told that it's too personalized to be a helpful question to the community. Where can I find an answer to my question? Does it not belong on SE at all? If so, that is fine, just want to be clear/
Is it possible to overcome poor undergrad performance with a masters at a much lower ranked institution?
Answer: The trick to getting duplicate questions reopened (in my opinion) is to edit away all the detail that might obscure the fundamental difference between your question and the existing questions. Otherwise, it can come across as "I know my situation is really similar to existing questions, but I just want highly individualized advice" (which is off-topic per the help center - see "Can I ask about my specific situation"). What you really want to convey is "Here is a general question that may help many others, that isn't addressed by the current questions and answers on this site."
So, if you believe that answers to existing questions on the site do not apply to your situation, you should edit your question to focus on what is different about your situation, and to reflect what you've learned from reading related questions. Then, it might be reopened.
This means not just adding a paragraph to the end explaining why you believe your question is different, but really editing the entire question to focus on the part of your situation that is different and remove the part that is already addressed in existing answers.
If your question did remain open in its current state, you would probably just get more answers telling you what you already know (that recent performance counts more than past performance), because the title and most of the body of your post is about that issue.
My suggestion would be to rewrite your question as follows:

I have browsed extensively on academia.se and generally understand from similar questions (e.g. Doing bad in undergraduate but good in a masters program and How does the admissions process work for Ph.D. programs in the US, particularly for weak or borderline students?) that Ph.D. admissions committees care most about an applicant's most recent performance.
Is this still true even if the poor undergraduate grades were at a highly ranked university, and the good masters grades were at a much less competitive program?
I am interested in applying to top statistics PhD programs, but I have very poor undergraduate grades (2.8 GPA, 3.3 major GPA in math/stats) from a top 15 department. My grades in the masters program are good (>3.9 GPA), but at a state university that is not so highly ranked.
If the grades from the less competitive masters aren't enough to overcome the poor undergraduate grades, is the quality of my masters thesis likely to help me secure admissions to a top PhD program?

This version is concise, still captures the essence of your situation (I think), but distills it in a way that makes it helpful to others as well. It also emphasizes that you have a real, new, question and you're not just looking for more reassurance that recent performance matters more than youthful mistakes.
The question title "Another poor undergrad grades strong MS grades applying to phd next year question" suggests that even you think it is a duplicate of existing questions. Perhaps an edit to the title is in order, too. How about:

Is it possible to overcome poor undergrad performance with a masters at a much lower ranked institution?

Note that these edits will automatically push the question into a review queue where users of the site can vote to reopen. (You're probably familiar with this if you're an avid user of other SE sites.)
Comment: Nice explanation, but I'm not sure even the proposed edits will be enough to get the question reopened, since I still don't understand how we could say anything in answer other than "Maybe, it depends."
Comment: thanks your edits are clear and concise, I will change it in that manner.
Comment: @jakebeal I am hoping some people will have more insight into this situation. For example one user already said that he does see this happening in my current situation.


Can you start a bounty on a question that already has an accepted answer?

Question: Can you start a bounty on a question that already has an accepted answer, if you feel that your answer to the question is better than the one that was accepted?
Comment: @user58319 Yes, but when the best answer is *your own* answer, then why set a bounty? That's the question I meant, following from your post.
Comment: Of course you can!
Comment: I'm not sure why you would want to, though. Could you expand your question to include your reasoning?
Comment: @AndrewLeach Some common reasons: to reward a user who posted an excellent answer (usually either the top-voted answer, the accepted answer, or the answer which is both, think eg of tchrist-style answers), to reward a user who posted an excellent answer which did not get the recognition you think it deserves (usually *not* the top answer or accepted answer), or to encourage renewed engagement with a question that everyone else considers settled (that is, *none* of the current answers completely satisfy you).
Comment: Related question, [Can I award a bounty to an answer given *before* the bounty? AND Can I divide a bounty between two or more answers?](http://meta.english.stackexchange.com/questions/4048/can-i-award-a-bounty-to-an-answer-given-before-the-bounty-and-can-i-divide-a).
Comment: I mean especially when an 'old' and settled question does not satisfy you at all. ('Roundabouts and swings' on ELU, for example)
Comment: @user58319 Yes, that is one of the primary uses of bounties.
Answer: Yes, you can. Do note that the minimum bounty will be 100 reputation points (since you've already posted an answer to the question) and you can never award the bounty to your own answer.
Everything you want to know should be covered by the FAQ entry How does the bounty system work? on Meta Stack Exchange.
Comment: If I understand the OP correctly, in some sense the answer is then 'no', because they want to know if their -own- answer can get the bounty and if they themselves start the bounty, they can't then award it to themselves.


phone gap in blackberry

Question: I am using the phonegap in my blackberry application.I need to get the button clicked and go to the next form.please tell me for that i need to use the phone.js or to create my own javascript file.
Answer: You need to use a javascript framework to make your life easy :)
Try http://jquerymobile.com/ that works very good in BB OS v5+, Android, Iphone and so on.
Good Luck!

phone gap in blackberry


How to arrange web application docker containers in production stage

Question: I'm approaching to the Linux Container world by looking at one of maybe the most famous and used containers manager that is Docker. I have quite clear the advantages of using Docker at the development stage. Fast and easy creation of image including any sort of application (database, server, etc...) but I haven't clear yet the advantages in production. I mean let's assume two have three different instance running on AWS running docker. In one instance I decide to run a web server container (nodejs), in the second one a database container (mongodb) and the last one a cache container (redis). All these ones running in their own container running in one separate instance. The deployment is fast and easy but how many others containers can I run in the other instance and which one? I don't mean to say the maximum number of containers. I know that it depends from the memory. I mean which other kinds of containers could have the reason to running in one of these three instance? For example I would add in the future nginx. In which of this one should I place it? Should I take another aws ec2 instance?
Answer: As you said, it will depend on your resource requirements which containers you place together. However, AWS offers container service (in Preview) that allows running docker containers and comes with a scheduler that can decide where to put things. Maybe this would be an option?
From http://aws.amazon.com/ecs/details/:

Amazon EC2 Container Service comes with a default scheduler that
  schedules containers to help find the optimal instance placement based
  on your resource needs (e.g., CPU or RAM) and availability
  requirements. The EC2 Container Service APIs also provide you with
  complete cluster state information, allowing you to write your own
  scheduler or integrate existing 3rd party schedulers if you choose.


How does electromagnetic news travells?

Question: A charge particle is moving at constant velocity and an another charge particle is placed at some distance.we know that the charge particle will experince force due to some earlier position of charge particle because electromagnetic news travels at a finite velocity which is speed of light but how does this electromagnetic news travels as the charge particle is moving with constant velocity there will be no electromagnetic wave??
Answer: The electromagnetic field travels out with the speed of light. The electromagnetic "wave", or "radiation", is only the part of the electromagnetic field that attenuates its amplitude according to the 1/r rule. Besides this part, the other part, which attenuates its amplitude according to the 1/r^2 rule, also travels out with the speed of light.

How does electromagnetic news travells?


why nobody uses matlab

Question: I wonder why most people now don't use matlab. I guess the reason is matlab is not free, so companies don't want to use it, then interviewees don't use it, then schools don't encourage it, then nobody ends up using it.
But I like it, compared to C++, Python, for it's convenient to plot figures without needing to import any libraries or header files, let alone those powerful ODE solvers.
I might be wrong on any of the above points, as I'm not most familiar with other languages. Any comments?
Answer: Most people are using Python or R for data-science, I like Python more because python have enormous amount of libraries for datascience related tasks (for data-analysis, plotting, out of the box machine-learning & deep learning algorithms) and huge open source community to support/help.
You can read more about individual language capabilities everything can be done using any of these languages (Python/R/Matlab) it's just the matter of perspective.
Comment: Matlab has its embedded machine learning toolbox too
Answer: I beg to differ. I've seen a multitude of researchers using MatLab in their respective research initiatives. MatLab, as many will soon point out, is closed source. In addition to its code proprietary legalities, it has a hefty price tag. Almost all educational institutions, in the US for example, that are ranked as "Highest Research Activity" and "Higher Research Activity" universities by Carnegie Classification of Institutions of Higher Education will typically have bulk licensing. This means that their professors, masters(thesis), and doctoral students will have MatLab availability(at their request) from their local office of  information technology (OIT) in their respective universities(typically the College of Engineering at a university)
At a personal level, you may buy MatLab, but you are likely to migrate to R and Python soon. This unfortunate and monetary painful process is due to the widespread adoption and development of Python libraries and R packages specifically for data science research and analytics.
The short answer after this lengthy response comes down to MatLab's adoption and its upfront cost. With Python and R, you can be learning and producing in a shorted period of time. Plus, it's free.

why nobody uses matlab


Can I use Sum of squares in R for variable significance instead of p-values?

Question: I have a data with 20k samples. It includes 6 categorical and 2 continuous variables. When I performed multiple linear regression and ANOVA to test the variables significance, it shows p-values 1e-16 for all variables. I suppose it is because of data size and has to do something with power. However, I am quite sure that 2 varables are not important for the regression at all. Could I use sum of squares as a quatitative measure of significance instead of p-values or something else?
I can also reduce the size of data, but how much? What is an optimal size which I should use?
Comment: Not a programming question - try stats.stackexchange for statistics questions. I would recommend looking at (standardized) effect sizes to determine non-statistical significance. You could also use regularization techniques such as LASSO.
Comment: There are a lot of ways to do variable selection; see [Chapter 6 of ISLR](http://www-bcf.usc.edu/~gareth/ISL/ISLR%20Sixth%20Printing.pdf). Most methods depend on a quantity like AIC or BIC rather than RSS directly.
Comment: It sounds like you're interested not in statistical significance but in whether the effect size is of practical importance. Do you have some prior idea of what size of coefficients (whether raw or standardized in some way, whichever makes sense for your problem) would be worth bothering about?
Comment: I'm not sure how you would use Sum of Squares as a variable-level metric - maybe fit a model with and without the variable and compare? And come up with some way to decide whether the difference matters or not? I wouldn't recommend it...
Comment: Generally speaking, more data is better.  This is the idea behind much of statistics such as LLN, CLT, etc....  There is, therefore, no optimal size of data.  That said, you'll want to use an information criterion (AIC, BIC, etc...) for model selection.  Try a bunch of different specification (i.e. specification with different co-variates) and pick the one with the smallest information criterion.  Using RSS for model selection will not work.  RSS will always favor more variables to less, because each additional variable will provide additional, but potentially really small, helpful info.
Comment: (cont) information criterion, in contrast, penalize the introduction of each additional variable and therefore pick the model which explains the LHS variable the best with the least amount of parameters.  Additionally, you can use a LASSO for model selection.  Run the LASSO with all your data.  Those variables shrunk to zero should be omitted from your OLS regression.  However, be wary of shrinkage estimates such as LASSO, if your goal is parameter estimation.  Shrinkage estimators generate bias coefficients and therefore should really only be used for forecasting (or model selection).
Answer: If you do an ANOVA, you can see the sum of squared variance explained by each variable. This will help you judge how much explanatory power is added.
Here's some sample R code:
<code>tmp <- data.frame(a = rnorm(100), b = rnorm(100))
tmp$c = tmp$a + 3*tmp$b + rnorm(100)
anova(lm(c ~ a + b, tmp))
</code>
Alternatively you can look at the R-squared of regression models with and without the relevant variables, and take the difference. This tells you how much extra explanatory work the variables are doing. I think the two approaches are almost identical.
Answer: The suggestions to use penalization or variable selection are off the mark in this low-dimensional setting.  Overfitting is not an issue here.  The partial sum of squares for each variable can easily be turned into a semipartial $R^2$ to measure the predictive discrimination of each predictor.  Related measures are discussed here.


What is the difference between a composite data type and a data structure?

Question: I read that a character array in C is a composite data type because it is a sequence of characters, but then in Java a String is a class and Wikipedia says that a class is data structure, I am confused.
Answer: "Data structure" is a very general term of theoretical computer science.  Any technique for the organization of machine-manipulable data can be thought of as a data structure.  Even a single machine integer is a data structure, because there's more than one way that the bits could be interpreted.  Most often, though "data structure" is used to refer to the organization applied to a large collection of data: for instance, a binary tree, a hash table, a flat array, or a linked list.  And usually when people talk about data structures they do it in generic terms, not specific to a particular programming language.
"Composite data type" is a term-of-art of C and related languages, meaning "any language data type that isn't a machine number", more or less.  Composite data types are data structures, but not all data structures are composite data types -- machine numbers are too simple to be composite data types, and a complex data structure is likely to be built out of several composite data types.
"Class" is a term-of-art of object-oriented programming languages, referring to a data type that defines not only data but "methods" for manipulating the data.  In C++, all class types are composite data types, but not all composite data types are class types (the others are "plain old data", or "POD", types).
"String" is the generic term for a data structure that holds a sequence of small machine integers that somehow represent text.  Just about every programming language has some notion of a string, but no two of them are the same.  Strings are by definition data structures.  In the C family, strings are always composite data types, because a single machine integer is not big enough for more than a few characters.  In object-oriented programming languages, strings are usually, but not always, class types.
I hope this at least advances you to a more sophisticated level of confusion.
Answer: a datatype is any thing you can make a variable out of.
a member is a variable.
a method is a function.
a base type has no members and no methods in it.
a struct is composed of combinations of base types and other structures.
a class is a struct that includes methods as well as members.
an array is an array of any datatype, either of base types, structs, or classes.
Answer: Well, I'd say "composite data type" and "data structure" are pretty much the same thing: a piece of data with distinguishable parts, as opposed to simple or elementary data types like char or byte which are not made up of smaller data types.
Answer: Every Data Type is a Data Structure but nor every data structure is a data type.
A data type is an entity that can hold data.
A data type of the simplest form is a primitive data type.
A more complex data type made up of primitive data types is a composite data type
A Data structure becomes different from a data type when it hold Relationships between the entities stored, along with the entities.
here the entities are the data types. but the data types together with the relationships form the data structure.
Answer: Composite types are derived from more than one primitive type (chars, ints, boolean, etc). This can be done in a number of ways. The ways they are combined are called data structures.
Therefore, your character array in C is a composite data type and a data structure. In general, to make your life and the lives around you easier, you can see a data structure as a generic term.


Identifying the font that inspired the Pierre Balmain fashion house logo

Question: I am trying to figure out what font inspired this old Pierre Balmain logo and I'm having trouble finding this font. Can anyone help?
Answer: The group name for this type of fonts can be called and googled as "engraved".
Studying the font in question I have found that font is very similar to Smaragd designed by wife of Hermann Zapf - Gudrun Zapf-von Hesse in 1953 and in book by Zapf named as Emerald font.
Both designers updated their fonts after 1957 when phototypesetting was introduced and old versions of their fonts became deprecated.
Pierre Balmain opened his fashion house in 1945 (first collection) and probably the logo was inspired by the old version of the Smaragd font which had M letter other than in newest version.
Considering aforementioned fact, we can assume that the font in logo was inspired by older (and probably depricated) version of Smaragd font, this is why we cannot find the exact match in our databases.
smaragd
Comment: The free font is indeed a ripoff of an Adobe/Linotype font. It still has the copyright information in the TTF file!
Comment: When a 'free font' site lists a font with the same name and apparently letter design as a commercial font, odds are it may be a rip-off. It's not necessarily a rip-off, but it's probably best to link to the commercial version: http://www.myfonts.com/fonts/linotype/smaragd/
Comment: Also, while this is certainly 'in the ballpark' there are many differences (Apex of the A, the flared stems, the thick/thin contrast). Odds are the original logo was custom lettering.
Comment: @AndrewLeach good catch! I'll update the answer to link to the original Linotype typeface.


Can I remove bluestone pavers embedded in mortar

Question: Can I remove bluestone pavers embedded in mortar and reuse them?   A house with a bluestone foyer is being demolished and I would like to salvage the pavers and reuse them in my new home.
Comment: How thick is the stone? Mud set stone is usually 3/4" thick. Thinset stone is usually 3/8" thick. No matter how thick, it starts with cutting out the joints. Knowing how thick will help know how easy it will be.
Comment: We had a bluestone patio installed, and a few stones needed to be redone (the grade wasn't right).   The masons cut the grout lines and popped them up with a chisel.  Some of them broke, which wasn't a problem since we have irregular sizes.
Answer: You can always try.  You will need to break some of the grout away so you can see the base where the paver and the mortar meet.  Then using a floor chisel (3 inch wide blade cold chisel) set between the paver and the mortar, see if you can pop the paver up.  If the paver is not well bonded to the mortar, they will pop up.  If they are well bonded, they will just snap when the one side is getting lifted.
Answer: If you can get power (the place being demolished or a generator) your best bet in just getting them out would be a circular saw with a Diamond Tipped blade or a few Black Fiber blades (they wear down pretty quick but are cheap). Of course, don't cut the Bluestone cut the mortar around them.
Then, you can soak & chisel on them at home. I don't really suggest it since I haven't done it, but if the mortar isn't budging & you've already snapped one or lost corners. If they fit in your freezer I knew some salvagers that swore by it to free brick, marble & tile inlays. Perform at your own risk.
Answer: I think it's going to depend on whether they are actually embedded in mortar or just glued down with mortar in-between. I don't see this working. I think they'll break but you'd have to try it with some flat bars to see. Either it's going to work or it isn't. No special trick I can think of to keep them from breaking.
Comment: The only thought I've got would be to extract them with mortar attached and chip it away from underneath. If it works for fossils...?


What game(s) does Michael play in Mind Field S2E4?

Question: I've been binge watching the Mind Field Youtube series from VSauce because it's free until the end of the year, and in Season 2, Episode 4, "Your Brain on Tech", Michael plays a space game, and maybe some other games as well since I'm not sure if all the shots are from the same games. They look interesting, and I was wondering what games he's playing. The video in question is

, and the gameplay segments can be found at 2:05, 3:17 and 12:07.
Comment: Since it's a 27min video, you should add some timestamps or update the URL to start playing at the part of the video
Comment: @Wondercricket Added some timestamps.
Answer: Other answers are close, but lack a primary source.  Michael Stevens (vsauce) himself responded in this Reddit thread, saying:

The footage on the screens is from a game called Star Citizen. However, FUN FACT: that footage is just placed on top of the screens in post. I was actually playing League of Legends, but in the end, LoL wouldn't give us permission to show their game or mention its name. Which game you play doesn't matter, though. It's been found that any 3D game can lead to noticeable results -- but not 2D games like platformers.
LoL was recommended by the researchers at UC Irvine. They've found that 2D platform games lead to a lower effect, but this is still a really new area of study. There's a lot more to test, experiment with, and learn.
Answer: It looks like he's playing Everspace 2
Answer: There's bits of various different game trailers and stock footage in there that the producers used to artificically replace the actual game he was playing. In actual fact, he was playing League of Legends, but they had to remove that footage for legal reasons. I noticed that this was one of the trailers used, but there are others.


Practice program for home

Question: My work make me stay on a desk along time and that make me usually very lazy ,
so is there any recommended practice program to do it at home ?
Comment: What do you mean by "Practice Program"?
Comment: Different people like different things. Most people i know enjoy relatively short workouts (under 1 hour) that make you sweat and hurt and mostly train your abs - most people think that's what a good workout is. Others are obsessed with effectiveness and efficiency and do 5 heavy sets if squads and then take a 5 minute break because study x. Others enjoy activities that they see some deeper meaning in like team sports, variations of rock climbing or such. Some people are competitive, some are not. Is there any best way? Ask a powerlifter or a tennis enthusiast - completely different answers
Answer: If you have no weights and are just wanting to stay healthy at home without going to the gym I recommend doing the basic pushups, situps, burpees, mountain climbers and star jumps.
Simple exercises like these done correctly do a degree of intensity can be very good to get your heart pumping and to incorporate your recommended 30 minutes a day of exercise.

Practice program for home


Service feedback fail issue on Mobile app

Question: I'm now on the process of developing a Mobilepush app SDK and still on the step of testing, there's a issue regarding Opt-out method. We keep failing to receive a push message because the system automatically opts out even though we basically did not try 'opt out' in the app. It keeps give us 'Service feedback' fail message, but we don't know what exactly went wrong in this case.
As far as I know, APNs system provides at least one feedback a day, but when it fails to meet the feedback,it handles it by 'Service feedback' error.The error generally happens when users try to delete app or literally try to opt out, but it isn't the case.
Can anyone share the case why, or when this error happened? It would be okay if it's not a first hand account, anyting would be a huge help.
Answer: 99.999% of the time this is a certificate issue for iOS or a mismatch between your license key and sender ID for Android.
Open a support case.
Comment: Thanks for your help :)
Comment: Did this solve it?


what is d-sub connector metal shield made of?

Question: I want to solder a ground wire to the d-sub connector's metal shield( the bright color metal part of the connector), using tin-lead solder 60-40. I just wonder what kind of metal it is. I searched the web and couldn't find the answer.
This kind of connectors
Comment: It's whatever metal the manufacturer of that particular connector decided to use. There is no definitive generic answer other than "Read the datasheet".
Comment: use some sandpaper and the conductive glue sold at radio shack; works with all metals
Comment: Just get a big solder gun or iron and try it!  (near the edges, you don't want the plastic to melt.)
Answer: Finding the datasheet or mechanical drawing of your part would be the best way of getting the answer.
Taking one connector at random on digi-key, http://www.assmann-wsw.com/fileadmin/datasheets/ASS_4884_CO.pdf you can find that the shell is SPCC. So soft steel. Not so fun to solder on.
Some (most?) shells are plated though, with copper, tin and/or nickel, which are much nicer to solder on.
The other factor is that the shell is basically a HUGE heat sink (in terms of soldering electronic components) so you might have a hard time getting it hot enough to have a good solder join.
Good luck.
Answer: It is commonly nickel-plated steel.
Soldering to this requires an immersion flash-gold plating process, which is probably beyond your means.
Otherwise,  HCl acid with ZCl and NH4Cl  and cleaners with toxic fumes when soldering is also not recommended.
The recommended solution is to use a thin ring-term. lug on outside screw connection to chassis ground and crimp wire connection to lug.
One example might be to terminate  a shield at one source only to circuit 0V to prevent ground fault currents yet provide 0V coupling to reduce noise.  The shield area has a 1/4 wavelength of several GHz so it practically won't see any egress in normal applications but ingress might only come from arc welders nearby or more likely ESD discharge. In which case I would prefer 10kV insulation over a low impedance current path for ESD to go around a plastic shell screws with heat shrink. But you may have different requirements. Others might terminate to pin 7 ground, but then ESD tests to shell may induce  a false start bit. This may be irrelevant to you but are real issues for commercial equipment.
Comment: Huh, I've never had a problem soldering to DB9 connectors, nor to nickle plated brass stand-offs.  I wouldn't think the steel underneath made much of a difference.  Then again with the right flux I solder to stainless steel and Al.
Comment: Even with standard rosin flux, nickel solders fine. The trick is to get it hot enough, which can be a problem with a fine-tip soldering iron, given the large size of the body.
Comment: Does it pass the 5lb pull test? or is it just tacked on, solderability is defined by this adhesion test.
Comment: @TonyStewart.EEsince'75 - Oh, tacked on for sure. But keep in mind the difference between military and hobbyist solder philosopy: hobbyist assumes solder has infinite strength, military assumes zero strength. I go with military, so any joint made by laying a wire on a surface and soldering should be assumed to fail under mechanical load. It's still useful, sometimes.
Answer: They tend to be steel, sometimes plated with nickel. I have also seen some that are die cast zinc or nickel, too. The actual manufacturer will generally give you this information in their datasheets.
Answer: In general, the d-sub connector housing material is SPCC, but there are also some SUS301 and SUS304 stainless steel.


Botanicula- Sun Element Disc disappeared/did not register

Question: I found the room and acquired the sun disc, my last of the star, rain, sun and plant discs you need to talk to the pacman guy. I walked through the rope room and grabbed it, but now it's not showing in my inventory and I can't move on. Did this happen to anyone else? Game developers aware? I literally can't play anymore.
Comment: the same happened to me... seems like a bug.... unfortunately, cant play either.
Answer: This is a bug.
This is a new one, but similar ones have been reported in other questions and comments:

Animation keeps on repeating (How can I fix a terrible bug in the middle of Botanicula?)
Game is buggy in full screen (What do I do with this cone?)

and I personally have had similar but different unreported issues with the game playing automatically and having the animation repeat until the game was restarted. They are few and far between, but they happen.
Make sure to save often. There are six slots -- just enough to save at the end of each chapter.


Just Cause 2 lost game

Question: After 36 hours progress on Just Cause 2 - I got stuck, so I started a new game. It warned that this would overwrite autosave data but I went ahead and started a new game - does this mean I have totally lost the old game - all that 36 hours progress? Is there any way to bring that old game back - I mean surely the PS3 saves a certain amount of the progress somewhere? Please help!
Answer: Did the auto save function kick in during the "new game"? If so I'm afraid its lost.
The way saved games are handled in Just Cause 2 is that you are expected to save regularly to ensure progress isn't lost. The auto save only takes up one "slot" and is rewritten frequently.
It's actually more of a safety net against random deaths or errors than a long term way to save your game.
Answer: You should always save your game manually trough the menu, so whenever you start a new game and your auto-save file is overwritten, you will be able to load it back up using one of your 10(or so) custom save slots.
For those on the pc: The save files are located in your documents folder under the name 'square enix/just cause 2/', you might get previous versions back from there if windows automatically saves recent states of that folder.
Good luck re-doing stuff.
though 36 hours isn't much time lost relatively speaking, it took me about 60 hours of gameplay to finish ALL locations AND challenges.
Comment: I don't see how you could reasonably think that "36 hours isn't much time lost". That's a day and a half of playing the game straight, and longer than playing through an awful lot of other games. If I lost 36 hours of progress on a game I don't think I'd be redoing it.
Comment: note that I said it isn't much time lost RELATIVELY speaking. since going for the full completion takes about the double amount of time. You can compare it to school, it takes one year to finish a semester. If you fail and have to redo a year, a full year of work is actually lost so you'll have to redo it. But 1 year is once again, nothing compared to the full 4 semesters to finish the education. But it's totally up to you whether you actually find the will power to redo it.
Answer: I am afraid that there is not much that can be done.

Just Cause 2 lost game


How can I change the color of my prompt in zsh (different from normal text)?

Question: To recognize better the start and the end of output on a commandline, I want to change the color of my prompt, so that it is visibly different from the programs output. As I use zsh, can anyone give me a hint?
Answer: Put this in ~/.zshrc:
autoload -U colors && colors
PS1="%{$fg[red]%}%n%{$reset_color%}@%{$fg[blue]%}%m %{$fg[yellow]%}%~ %{$reset_color%}%% "

Supported Colors:
red, blue, green, cyan, yellow, magenta, black, & white (from this answer) although different computers may have different valid options.
Surround color codes (and any other non-printable chars) with %{....%}. This is for the text wrapping to work correctly.
Additionally, here is how you can get this to work with the directory-trimming from here.
PS1="%{$fg[red]%}%n%{$reset_color%}@%{$fg[blue]%}%m %{$fg[yellow]%}%(5~|%-1~/.../%3~|%4~) %{$reset_color%}%% "

Comment: the `%{...%}` means that the content will be interpreted as a literal escape sequence, so the cursor wont move while printing the sequence. If you dont use this, the color codes can actually move the cursor and produce undesired effects. This is documented in the `Visual Effects` section in [zshmisc man page](http://linux.die.net/man/1/zshmisc)
Comment: Agreed, by far the superior answer (luckily this answer was the third Google result ;)
Comment: not working for me. :(
`zsh: colors: function definition file not found`
Comment: do you mind explaining in detail what all the symbols in your prompt are doing or at least a link to a reference? e.g. what is are the `%` outside doing? Also what does things like `{$fg...}` etc do?

its difficult to understand your answer because it assumes to much knowledge of shells or zsh. Can you make it a little bit more self contained or link to references please?
Comment: Are you using ZSH4? I don't think it works on versions less than 4.3.11. If you have the latest version maybe it is not using the right files.
Comment: What are the valid color values?
Comment: As of Feb 2023, the macOS Ventura 13.1 Terminal has no response to the `%{$fg[red]%}%n` command for color change. I had to use `%F{red}%n` instead. Not sure why. It could be because of a version update.
Answer: Zsh comes with colored prompts builtin. Try
autoload -U promptinit && promptinit

and then prompt -l lists available prompts, -p fire previews the "fire" prompt, -s fire sets it.
When you are ready to add a prompt add something like this below the autoload line above:
prompt fade red

Comment: this sounded great but I don't like any of these options...
Comment: Is there a way to color all the themes? I like the walters prompt but would like it in red.
Answer: Here's an example of how to set a red prompt:
PS1=$'\e[0;31m$ \e[0m'

The magic is the \e[0;31m (turn on red foreground) and \e[0m (turn off character attributes). These are called escape sequences. Different escape sequences give you different results, from absolute cursor positioning, to color, to being able to change the title bar of your window, and so on.
For more on escape sequences, see the wikipedia entry on ANSI escape codes
Comment: Your answer is missing the `%{` and `%}` markers that identify the escape sequences.  Without these, `zsh` will count escape sequences as part of the display length of your prompt, and you'll end up with bizarre cursor positioning and line editor behavior on longer commands.  See `man zshmisc`, EXPANSION OF PROMPT SEQUENCES, Visual Effects.  Not all shells require you do this; Korn shell, for example, parses common escape sequences in the PS1 string (though it will display the aforementioned problem on sequences, usually unusual ones, that it doesn't identify correctly).
Comment: It is working, but the $ before the string make zshrc to glitch. The text is put on the left when I use tabulation. I prefer @Joe the Person answer
Comment: I am using PROMPT='[%!]' in my .zshrc. How can you color it? I run unsuccessfully PROMPT='\e[0;31m[%!] \e[0m' in my .zshrc.
Comment: @erikb85: why do you say it's wrong? Is there something I can do to make the answer better? For me, doing the above gives me a red dollar sign, so I don't understand why you think it's wrong.
Comment: I thought zsh didn't need crazy weird ANSI escape stuff...there must be a better answer...
Comment: I agree @Moebius I wanted this one to work it was clear and simple, but it completely messes up the tab on cd
Answer: The answer by Bryan Oakley above has a glitch as it has already been pointed out and the solution offered by Andrew Marshall though it does not carry the glitch, nevertheless it does not make it obvious for too much customization on the colors used.
As macOS Catalina asks for zsh to be the default shell from now on, I think several more people may want to customize their prompt and might be coming here for an answer. So, I thought I would try to give a broader summary and touch upon other very closely-related notions that allow more customization.
3-Digit Codes for Various Colors.
First of all, here we can find 3-digit codes for various colors: https://unix.stackexchange.com/a/124409/194343.
For example, 214 is some kind of orange color.
Foreground and Background.
The other key information is that for Foreground and bacKground colors one can define what they want with F and K respectively. Source is zsh manual on visual effects: http://zsh.sourceforge.net/Doc/Release/Prompt-Expansion.html#Visual-effects
So, for example, the following two commands
autoload -U colors && colors
export PS1="%F{214}%K{000}%m%F{015}%K{000}:%F{039}%K{000}%~%F{015}%K{000}\$ "

present the hostname in orange with black background, followed by a colon in white with black background, followed by the current working directory in bright blue with black background, followed by the dollar sign in white with black background.
More related information is found below.
Prompt information on the right-hand side. For example, adding a timestamp. See https://superuser.com/a/1251045/290299. Of course, this can be color-coded, for example with some light blue/purple-ish color, like this:
RPROMPT="%F{111}%K{000}[%D{%f/%m/%y}|%@]"

Colors for ls. After reading the manual for ls, one for example can activate the colors for ls using the following two commands:
export CLICOLOR=1
export LSCOLORS=gafacadabaegedabagacad

Finally, as a last remark that I have not tested as I am happy with my configuration, another avenue might be for someone to install the port coreutils from MacPorts and then use gdircolors (source: https://unix.stackexchange.com/a/174596/194343). (I may edit this last part in the future as all the above are related pieces that make every-day life much more fun and easier to cope with.)
Comment: This is an immensely helpful answer. Thanks for putting this together.
Answer: I don't think the autoload -U colors && colors is needed anymore and one can simply do:
PS1="%{%F{red}%}%n%{%f%}@%{%F{blue}%}%m %{%F{yellow}%}%~ %{$%f%}%% "

to achieve the same result as FireDude's answer. See the ZSH documentation for more info.
Comment: Weird. Works for me on OS X & Ubuntu 10.04.
Comment: If you don't need `autoload -U colors`, that means that your distro already has it in some other zsh initialization file. You should still include it in scripts you intend to share with others.
Comment: FYI. I've just tried in Ubunutu 11.04 and colors didn't work for me without `autoload -U colors && colors`
Comment: @Andrew Marshall Yes, but it is more likely to work with `autoload` on.
Comment: @fireDude67 How to set `autoload on` ?
Comment: @balki autoload -U colors && colors
Comment: The `autoload` is not needed for me with Debian and `zsh 4.3.17 (i686-pc-linux-gnu)` - also check out the [documentation](http://zsh.sourceforge.net/Doc/Release/Prompt-Expansion.html#Visual-effects) mentioned above for some cool effects, for example `%K (%k)` for background color. Thanks for this, Mr. Marshall.
Comment: I needed the `autoload` in Crunchbang (essentially Debian) and `zsh 4.3.17 (x86_64-unknown-linux-gnu)`.
Answer: Try my favorite:
put in
~/.zshrc

this line:
PROMPT='%F{240}%n%F{red}@%F{green}%m:%F{141}%d$ %F{reset}'

don't forget
source ~/.zshrc

to test the changes
you can change the colors/color codes, of course :-)
Comment: Only this works for me, after try hundreds PS1's that they all not works
Answer: In order to not waste space in the terminal with special characters to pieces of information, you can differentiate information using multiple colors.
Eg. in order to get this desired effect:

You can do the following to your prompt:
PROMPT='%F{magenta}${PWD/#$HOME/~} %F{green}${vcs_info_msg_0_} %F{cyan}$%F{reset_color} '

The way it works is every time you set a color using $F{myColor} the color from that point onward will stick to that. It's important to add in %{reset_color} at the end so that the input text goes back to the original color (or you could set it to something else if you'd like).
Answer: Debian/Ubuntu/Raspberry Pi OS style bash prompt:
autoload -U colors && colors
PS1="%B%F{034}%n@%m%f%b:%B%F{019}%~ %#%f%b "

Not entirely sure if autoload -U colors && colors is necessary but I did need it when I was using $fg[...] instead of %F{...}.
In my example;

%F(%f) starts(stops) foreground color - I've used 256COLOR values but you could also use hex for example, I've used normal green %F{034} but %F{#00aa00} works too
%B(%b) starts(stops) bold
%n $USERNAME
%m short machine name
%~ logged in/working directory with ~ if in home directory
%# display % if normal user or # if su

Edit: Tested on macOS Big Sur, Monterey and Ventura. Unsure of earlier zsh versions but Ventura 13.0 is zsh 5.8.1 (x86_64-apple-darwin22.0)
Answer: I have found that, with zsh5 (the default one on Debian Jessie), all those solutions works:

$'\e[00m
$fg[white]
$fg{white}

Now, they have a problem: they will move the cursor, resulting in ugly decal when tabbing (for auto-completion). The solution is simply to surround the escape sequences with %{FOOBAR%}. Took me a while to figure this.
For 2nd and 3rd solutions loading colors module is mandatory.
To keep the 1st solution readable, just define variables for the colors you use.
Answer: To get a prompt with the color depending on the last command's exit status, you could use this:
PS1='%(?.%F{green}.%F{red})%n@%m:%~%# %f'

Just add this line to your ~/.zshrc.
The documentation lists possible placeholders.
Comment: `PS1='%(?.%F{green}.%F{red})%n@%m:%F{141}%d$ %F{reset}'` I went with this to add the PWD.
Answer: To complement all of the above answers another convenient trick is to place the coloured prompt settings into a zsh function. There you may define local variables to alias longer commands, e.g. rc=$reset_color or define your own colour variables. Don't forget to place it into your .zshrc file and call the function you have defined:
# Coloured prompt
autoload -U colors && colors
function myprompt {
  local rc=$reset_color
  export PS1="%F{cyan}%n%{$rc%}@%F{green}%m%{$rc%}:%F{magenta}%~%{$rc%}%# "
}
myprompt

Answer: man zshall and search for PROMPT EXPANSION
After reading the existing answers here, several of them are conflicting.  I've tried the various approaches on systems running zsh 4.2 and 5+ and found that the reason these answers are conflicting is that they do not say which version of ZSH they are targeted at.  Different versions use different syntax for this and some of them require various autoloads.
So, the best bet is probably to man zshall and search for PROMPT EXPANSION to find out all the rules for your particular installation of zsh.  Note in the comments, things like "I use Ubuntu 11.04 or 10.4 or OSX" Are not very meaningful as it's unclear which version of ZSH you are using.  Ubuntu 11.04 does not imply a newer version of ZSH than ubuntu 10.04.  There may be any number of reasons that an older version was installed.  For that matter a newer version of ZSH does not imply which syntax to use without knowing which version of ZSH it is.


Pass variable cart total to PayPal for Subscription (using Enhanced Recurring Payments w. Website Payments Standard)

Question: Summary: Trying to pass along a variable Monthly Subscription cost to PayPal based on user-selected options on a form I created. Working within Website Payments Standard with Enhanced Recurring Payment option, is this possible?
Details:
User visits "shop" page, which is a form with 4 line items, each line item consisting of 2-7 options, each option with an associated price.
For example, line item 1 is "size of business" with the options being:
a) 1-3 employees - $10
b) 4+ employees - $12.50
User goes through the list and chooses 1 option for each line item and some javascript calculates the total due on the fly.
Is it possible to pass this total to PayPal, not as a one-time cost, rather as the base cost for a monthly subscription?
Answer: Yes. Just change the value you're passing for a3, rather than amount.
Is there a problem you're running into?


Is there a device that converts any AC frequency to 60 hz?

Question: If I have something like a windmill generator that generates AC current, but at variable frequency, what device(s) would I need to convert that variable frequency into a constant 60hz frequency, so that the power can be used for net-metering?
Answer: As noted by several people AC->DC-> AC is the easiest way and would be the most normal.
But -
Cycloconverter - Olde tech system - something to think about for the more technically informed.
However, if your wind-turbine AC frequency is always high relative to AC you can get a moderately good result by using what is known as a cyclo-converter.
This is an option that I have not heard of being used in the domestic WT market and which is usually associated with high powers or Olde technology BUT
a Cycloconverter could be extremely easily implemented at good cost in the 100 Watt - 30 KW size range with modern electronics.
It is stated in a number of places on web that Honda use cycloconverters in some of their portable motor generator units. This is not certain but may well be true as this would allow them to use high frequencies with consequent reduced size magnetics and would also allow a degree of frequency stabilisation. I had noticed the very small size of their units wrt power levels and wondered what magic they had worked.
A cycloconverter takes the available waveforms and compares them to a reference desired output waveform. It then draws power from the waveform that is closest to what is required.
Waveform distortion obviously occurs but if the relative frequencies are high and multiple phases are available, quite modest output filtering may produce an acceptable result in many cases.
An advantage is the efficiency can be very high, as the "best" alternator phase is simply being switched to the output at any time and losses are mainly switch (typically MOSFET) dissipation losses plus switching losses. Switching losses are modest as even at 10:1 input to output frequency switching rate is only around a few kHz. (Multiple switchings per output cycle mean switching rate is > N x fout)
The diagram below shows basic operation with 3 phase in and 1 phase out. A major advantage is that because input and output float relative to each other, and given input phase can be instantly inverted in polarity relative to the output if requried. This significantly increases the number of waveform segments to choose from and thus the available spectral purity for a given input:output arrangement.
Multiple input phases are required to choose from - the more the better. As WT's often have 3 phase output and may have more this method may be a good match to the requirement. (The available number is effectively increased by polarity inversion - see below).

From here
Technical comment - not relevant for questioner:
This is very B.O.T.E. but seems OK -
Variable input frequency is easily handled with some effect on spectral purity. As long as rate of change of frequency is small compared to frequency this would not be a major problem. Typical loaded rotor inertias would usually make this not an issue. eg in the diagram above fin_3 phase is about 3 x Fout_1 phase. The shortest time period between switchings is about 10% of fin. The longest is about 25% Fin. If fout = 50 Hz then time period of longest segment ~~= 1/(50 x 3 x 10 ) =  < 1 mS. WT prop at say 3000 RPM = 50 RPS = 20 mS per rev = 20 times longest segment . Blade inertia needs to be such that blade speed does not change vastly over say 1 revolution. If WT rotation rate doubled in 1 second (wow) then speed would change by ~= 2%/revolution = OK.
Note that the above deals with frequency but not Voltage changes. In many cases an AC-DC-AC system will be preferred due to tye freedom i gives to alter bith frequency and voltage.
Wikipedia - cycloconverters
[Book, 1972, MIT pressThe theory and design of cycloconverters
About 20 page paper UoTK, Knoxville. About 2000 Cycloconverter tutorial
Images linked to pages. Many many many ...
Comment: Awesome Answer, I have lots to read about now, thanks so much.
Answer: You need to rectify the power to DC, then use an inverter to generate your 60Hz waveform.
Comment: @Madcow: I would be really really impressed if you can show me a AC to AC converter that is 98% efficient.
Comment: Is this very lossy?
Comment: It depends on how you implement it. Most cheap commercial inverters are around 80-90% I would guess, and the efficiency of the simplest diode bridges for rectification are very dependent on the current you draw. For a good implementation with active switching MOSFETs on both sides and a good controller, you could probably do the entire conversion 90-95% efficient.

@OlinLathrop. You're right, I was a bit quick there to ignore things that weren't the MOSFET's. Edited to a more reasonable figure..
Comment: @weezybizze as the input frequency is variable, I can't really see any other way of doing what you need (except for very silly things like rotary transformers...)
Answer: Aside from the standard rectifier + inverter solutions, and cycloconverters, there's also the less well-known matrix converter (these have a matrix of switches to connect any input to any output), which, like rectifier + inverter, uses power electronics to convert from one AC input to another, but without a DC link in the middle.
Answer: Convert the output of your AC windmill generator to DC.  Then feed the DC into a GRID-TIE inverter.
You can purchase a grid-tie inverter most anywhere that supplies solar panels and wind generators.
Another cheap source of grid-tie inverters is eBay.  I purchase several 250 watt units for less than $80US.  They come in much larger sizes also but I decided to break my large system into several smaller systems.  That way one single failure would not cause the entire system to fail.
From: https://en.wikipedia.org/wiki/Grid-tie_inverter
"A grid-tie inverter (GTI) or synchronous inverter is a special type of power inverter that converts direct current (DC) electricity into alternating current (AC) and feeds it into an existing electrical grid. GTIs are often used to convert direct current produced by many renewable energy sources, such as solar panels or small wind turbines, into the alternating current used to power homes and businesses."
N.B.: "Note to SYSOP" removed, such messages should go into Meta Electronics not into answers.


If a sector is projected to well in the future, does it make sense to invest in an ETF of that sector?

Question: For example solar energy and uranium seems to be projected to grow a lot in the future. Would it make sense to find index funds that track solar energy companies or uranium mining companies and invest in such ETFs?
Answer: Yes and no.
Even if you're right with your assumption, others probably have made the same conclusions, and so the 'bright future' is already 'priced in'. So you might buy for a too high price.
If can still be a good decision, especially if you are in for the long run.
Answer: If you believe either that sector X has growth potential, or you believe that your interest in Sector X allows you to pick winners within that sector, then it can make sense invest in that sector.
When people talk about diversification, that can mean that some of your investments are concentrated in a sector. You shouldn't have all your money in one sector, but it wouldn't be unusual to have 10-20% in a single sector.
One example is when people suggest that you should have some money in real estate.
It is not unusual to see people have some of their 401(k) money, or company shares owned through a employee only purchase plan. It would be dangerous to have all your retirement funds in you company, but 5-10% wouldn't be unusual.


Rest and Holiday for Gentiles

Question: I often read that Gentiles are not to keep the Sabbath or institute any holidays for themselves. How far does it go? Rest from our work activity without refraining from doing extra activities? If I decide that on Sunday I will do nothing since it is a day where virtually nothing can be done in the western world would I be instituting a holiday for myself for not having done anything creative or that requires activity like cleaning the house? Would having meals already break this possibility? If that's the case then it's impossible for Gentiles to establish a holiday for themselves since it's practically impossible to do nothing all day unless they copy the Jews am I right? Can the existence of Sunday as it is today be classified as an established holiday when it is basically a social convention that came into being on its own without the countries instituting it as a holiday? Are all gentile holidays disobedience? Or just those who demand a similar way that Jews practice on the Sabbath that does not exist? In this case, would Adventists be the ones who go head-on against this norm?
Comment: Who said gentiles can't establish holidays for themselves?  They only must not observe Shabbat *in all its details*.
Comment: Look, I see this a lot on Jewish forums. That by doing this they are instituting an obligation of rest upon themselves that God did not allow, that we must work without ceasing as in Genesis 8:22, that at most we can rest from paid work but without instituting upon themselves a holiday that obliges people to do that
Comment: Rambam in Melachim 10:9 certainly says they can't establish a holiday for themselves.    עכו''ם שעסק בתורה חייב מיתה. לא יעסוק אלא בשבע מצות שלהן בלבד. וכן עכו''ם ששבת אפילו ביום מימות החול. אם עשאהו לעצמו כמו שבת חייב מיתה. ואין צריך לומר אם עשה מועד לעצמו. כללו של דבר אין מניחין אותן לחדש דת ולעשות מצות לעצמן מדעתן. אלא או יהיה גר צדק ויקבל כל המצות. או יעמוד בתורתו ולא יוסיף ולא יגרע. ואם עסק בתורה. או שבת. או חדש דבר. מכין אותו ועונשין אותו. ומודיעין אותו שהוא חייב מיתה על זה אבל אינו נהרג:
Comment: Related: https://www.youtube.com/watch?v=FxBlC1ectjE
Answer: See Sanhedrin 58B where it discusses the fact that Non-Jews can't keep a sabbath (any day of the week).
Rashi d"h עובד כוכבי׳ ששבת there Rashi says one must not do מלאכה for one full day. Likely evening and morning which non-Jews don't do anyway. However Ravina points out according to Rashi any day made for resting (including non-creative work) is prohibited.
I would be curious if this point of Rashi to not allow any rest from Melacha, is similarly for a night and day (a Jewish day), which does not apply to a non-Jewish day which is from sunrise to sunset. If true there wouldn't be a violation of this specific prohibition for non-Jewish holidays. This would require much more research.
According to the Rambam Hilchos Melachim (10:9) it appears to be prohibited because it is like making a new religion.
According to the Meiri שם the Jewish holidays were given to the Jewish people and so someone who keeps them is liable to be punished, since he will look like a Jew and confuse others. I don't have a Meiri to check inside but this might imply clearly non-Jewish holidays are not at odds here.
Rav Moshe (YD 2 Siman 7) does point out that making a new religion is in itself an issue.
The Malbim states the issue seems to be that since Noach work must be done on the earth for it to provide food and only the Jews were given a break for the Sabbath, this would not be allowed for Non-Jews who are still under the conditions of work that Noah had to do. https://hebrewbooks.org/pdfpager.aspx?req=6686&pgnum=400
Comment: This thing of complying or not is more about conscience, isn't it? Like even if a person doesn't do anything in a day, not knowing anything about the reality of a Jewish Sabbath, he is not wrong since he didn't do it to identify himself as a Jew. Now the question is really about instituting holidays, do holidays as they are in the world hurt any principle of not keeping the Sabbath?
Comment: @Thales with my limited understanding I don't think someone can accidentally keep the sabbath as a non-Jew and be liable, no. Holidays instituted would need to be similar to the Sabbath to be in contradiction to penalty. I can't imagine non-Jewish holidays being a good idea if you believe in Judaism but they don't rest like we do...
Comment: I'm a gentile dear msj121 so I'm questioning about this because the explanations I've always heard led me to this doubt
Comment: @Thales I have changed my answer to reflect ur question about holidays more specifically.
Answer: I believe there are 3 relevant, interconnected principles involved here:

Do not create a new religion1
Do not add to the commandments1
Non-Jews may not rest on Shabbat2

If a Noachide wishes to rest from occupational work/weekday activities, or keep a secular holiday or a holiday that is designated to honour the One True God (such as thanksgiving or a national prayer day; secular examples are mothers day/fathers day or independence day), it must be done in a way that does not violate any of the above. In The Divine Code by Rabbi Moshe Weiner (approved by Rabbi Shlomo Moshe Amar), he explains that one can set up a day of rest from work, as well as acknowledge and join in with some of the rituals of a Jewish holiday - especially the ones that are relevant to non-Jews like Rosh Hashana or Sukkot.
When it comes to Jewish rituals, each must be taken in its own analysis. Based on here, he may sit in a Sukkah on Sukkot if it is hot that day, and eat matza on Pesach if he enjoys matza... all so long as he is not intending to fulfil the Yom Tov as part of the Jewish Mitzva, or set up a new "mitzva"/yom tov i.e. purely for his own satisfaction. He can wear nicer clothes on Shabbat, prepare a special meal and even light candles (to beautify the meal), even he does so in honour of Shabbat because he wishes to glorify and publicise Hashem.
As this matter is serious, complicated and subtle, I implore any Noahide reading this to follow the rules of the site and CLYOR for how to personally conduct themselves regarding this topic. This answer is grossly insufficient to form the basis for personal practice!

1 - both of these are mentioned in הלכות מלכים ומלחמות פרק י׃ט, see there for sources and discussion.
2 - See Sanhedrin 58B
Comment: Thanks, I viewed the link you left me and it answered everything I wanted to know.
Comment: See here: https://asknoah.org/essay/noahide-holidays
Comment: What a complex and difficult subject to express in words. I'll ask better. Are Gentiles forbidden to rest on the Sabbath but may they do so on any other day of the week? What is rest? Not going to work or copying the Jews? If I don't go to work on Saturday would I be disobeying this precept? I think that's what I really wanted to know.
Comment: If a non-Jew ritualistically abstains from any weekday activities and makes a sabbath for himself, even on a weekday, he is liable. Religiously prohibiting oneself from work (any work!) would count. However, simply establishing a day off from occupational work (resting), even Saturday, without any religious reasoning, is fine @Thales. Still CYLOR please
Comment: Only one thing was left unanswered. The question of Seventh-day Adventists, they say they follow the rule of keeping the Sabbath, not if they keep it like the Jews but in any case they do it purposefully and religiously. Are they wrong and if so in what way could it help them to understand that it is a precept purely for Jews and they don't count?
Comment: @Thales based on the above and what you've said (I am not familiar with their religion), it sounds like they are violating (3) above. It would be hard to convince them though - unless you think they are only breaking this out of ignorance of the law, or if you feel they would be interested in hearing what the Torah has to say - because they probably do not accept the Talmud, and the Oral Torah on the pasuk is required to understand it this way. Advise on this is outside the scope of this site. Note: all Christians keep a "ritual sabbath" on sunday. If that is forbidden is a separate question
Comment: I understand. They, at least those here in Brazil, are very attached to Sola Scriptura, that is, if there is no convincing and clear biblical basis regarding the exclusivity of the Sabbath to Jews, it is almost impossible to convince them. They even argue that the Bible encourages Sabbath keeping by Gentiles based on Isaiah 56:6

Rest and Holiday for Gentiles


What is the name of this functor's property?

Question: Assume there is a functor $L$ from a category $C$ to a category $D$ which satisfies the following property: for any objects $X,Y,Z$ from $C$ and morphisms $f\colon X\to Y, g\colon X\to Z$ such that $L(g)=\varphi\circ L(f)$ for some morphism $\varphi\colon L(Y)\to L(Z)$ there is a morphism $h\colon Y\to Z$ such that $\varphi=L(h)$ and $g=h\circ f$. What is the name of this property?
Comment: In model theory the dual of this property ($L(g) = L(f) \circ \varphi$ implies there is $h$ s.t. $L(h) = \varphi$ and $g = f \circ h$) is sometimes called "coherence". So ...... "herence"?
Comment: Do you require uniqueness of $h$?
Comment: Both cases are ok for me
Comment: @Mark Kamsma Thanks. Thus "coherence" of $L$ is equivalent to the fact that all the morphisms in $C$ are $L$-cartesian?
Comment: @8k14 It seems so, though I have not seen the uniqueness requirement before (and I must admit that I had never heard of the term "$L$-cartesian"), but it would be automatic in most model-theoretic contexts. Usually the model-theoretic context is where $L$ is an inclusion of categories (not necessarily full, of course). Even more specifically: $D$ could be thought of as the category of structures with embeddings and $C$ the category of models of some theory with elementary embeddings, and $L$ is then the obvious inclusion.
Answer: In case we require this $h$ to be unique, then the property that you wrote down is saying that $f$ is an $L$-cocartesian morphism (see Definition 2.1 here), so $L$ is a functor for which every morphism in $C$ is $L$-cocartesian. On its own, this does not bring us much (except that all fibers of $L$ are groupoids), but we could additionally ask for the following: for every morphism $a:A\to B$ in $D$ and every object $A'$ in $C$ such that $LA'=A$, there exists a morphism $a'\colon A'\to B'$ in $C$ such that $La'=a$. If this is also satisfied, then your functor $L$ is a Grothendieck opfibration fibered in groupoids, also called a left fibration in more modern higher category theory. (By the Grothendieck construction, this would mean that $L$ classifies a $(2,1)$-functor $D\to\mathsf{Grpd}$, where $\mathsf{Grpd}$ is the $(2,1)$-category of groupoids. Informally, this functor is of the form $d\mapsto L^{-1}(d)$.)
If we do not require $h$ to be unique, then I am not aware of any definition that talks about this.
Comment: Not on its own, as far as I know. Which functor are you exactly considering? It does hold that a Grothendieck opfibration that is also a Grothendieck fibration with the one-arrow category $0\to 1$ as target encodes an adjunction, so maybe you can restrict $D$ to a subcategory on which $L$ is such a functor, and then we would get a whole bunch of adjunctions encoded by $L$.
Comment: Thanks so much. My functor does not satisfy the extra property you describe but every morphism in $C$ is also $L$-cartesian. Does it give anything?


Can I remove the water supply hose from this valve?

Question: I'm trying to install a T-connector to this valve but it looks like the hose isn't removable, although I'm not sure. Can someone take a look and verify?
Comment: I am not aware of any supply lines which are not removable from a shut-off valve, but I would need a picture of the valve from the side and slightly above.
Comment: Does the end fitting of the supply line at the valve have "wrenching flats" or is it circular cross section?
Answer: NO, the tubing is part of the valve and not a seperate removeable piece. These valves were common (because they were cheap) a few decades ago. I have seen many where the tubing broke where it is connected to the valve, causing a suprise flood; be careful messing with it.
If you need to tee the line you will need to do it a different way. I recommend soldering a male pipe thread adapter directly to the copper, then using a threaded tee.
Answer: If there is no wrench flats it's not removable. Remove valve and replace they are only 10 bucks. Remove valve, solder tee to existing then replace valve with new or chance using existing.


Why can't a dislocation terminate in the bulk?

Question: We are told that they can only terminate on surfaces, grain boundaries or other dislocations but we are not told why they can't terminate inside the crystal.
Comment: Citation? It's a lot easier to answer when we know the exact phrasing of the statement in question.  But I suspect you'll see the reason (if I understand what you're getting at) if you arrange a bunch of marbles, simulating a 2-D crystalline structure with a dislocation.
Answer: The answer is topology. Dislocation is a topological defect - there is a conserved quantity that measures how many lattice points you "skip" when you go around (burgers vector). That misalignment cannot just disappear. Imagine going twice north, twice east, twice south, three times west and arriving at the same point. That defines a crooked lattice "square" that encircles the dislocation. Now move along the dislocation (the third dimension, perpendicular to this "map") - every time you move by a single lattice point in that direction, neighbors are still neighbors and there will always be one extra step in one direction (even if the crystal twists and the east-west direction is now at an angle). This can only end on a surface or a different kind of defect. There are conservation laws different for each lattice and material type, that basically just count the conserved quantities and tell you how they add together when two defects meet.
Energy has nothing to do with this whatsoever. The only thing that matters is local order: each type of local organization has its own topological rules for defects (which disappear when order disappears, e.g. at a phase transition).
Compare this to knots on a string - you can only remove it if you get it to the end of the string. Or how you can't get a kink out of your headphones while you're holding both ends.


Has the POODLE SSL vulnerability ever actually been used?

Question: Is there any evidence that the the POODLE SSL or TLS has actually been proven to be a risk for file transfer like SecureFTP etc...?   ...or is it just a theoretical exposure?
Comment: Considering that any random dude with a laptop can do it on a public WiFi network, I'd say yes - but since the vast majority of users don't pay attention to this stuff, no one would know.
Comment: Are you asking how exploitable the POODL vulnerability is?  That's normally how people talk about vulnerabilities.  Some vulnerabilities are real and provable, but difficult to exploit.  Sadly, that's perhaps better answered by someone who understands crypto, but this question was already thought it wasn't "on topic" (A real beef I have with the stackexchange mentality)
Answer: The POODLE attack is actually very hard to pull off in real world conditions. A SecurityMetric blog post lays it out well:

Here's an explanation of how an attack would have to take place in order for an attacker to exploit POODLE and assume the user's identity on the target site.
The victim must be logged into a site using HTTPS (and the session cookie must not be expired)
The victim must browse to another website over HTTP before the session cookie expires
The attacker must write a custom JavaScript code to exploit POODLE. To date [OCT 22, 2014], no prepackaged tool has been published to exploit POODLE
The attacker must inject ~5,000 requests in order to decrypt the session cookie
Basically, this attack is extremely difficult because both the merchant and the user have to be vulnerable.

So to answer your question, this risk leans heavily to the theoretical side. I haven't found any news stories, blog posts, or security advisories saying that this exploit has been confirmed in the wild. POODLE has a high barrier to execution, and it's paid off.


Whether someone able to see the profile users visited history?

Question: Profile view depends on the number of users visited the profile.Is it possible to see the list who is visited my profile?
Answer: No, that information is not available.
Whether Stack Exchange record it or not I'm not sure, but it's definitely not exposed to users.
Comment: On MSE one of the devs once mentioned that they only prevent short time revisits to be counted as separate views... Can't find reference now, but it would suggest that even if they store this information, it does not live long.


Crystal Report - Hide specific pages

Question: I have develped a crystal report. It must have 4 pages as default and additional 2 depending on the condition.
When the condition is success its showing all the text objects in 5th and 6th pages correctly, but in else condition, its displaying 4 pages with appropriate data and empty pages having page header in last 2 pages.
How to suppress/completely hide last 2 pages?
Pls advice
Thanks
Answer: Your best bet would be to create a report with multiple report footer sections. You can then either adjust each report footer section to be 1 page high and add the relevant conditions and objects or alternatively add a subreport to each report footer section containing the fields/logic.
I would probably create 8 report footer sections (2 being blank) then decide whether to show the 2 blank ones or the 2 with relevant objects.
Answer: In section expert, next to suppress use the below formula
if pagenumber in [99,100] then true
else false
Note; Assuming 99 and 100 are last 2 pages of the report.

Crystal Report - Hide specific pages


Do different data types allocate different amounts of memory?

Question: For example, if I add a short integer and a float data type, will each allocate the same amount of memory? They have different maximum values, but have different data structures as well, so I was not sure.
Also, do mathematical operations take different amounts of time with different data types?
Comment: What language/platform do you use? Adding appropriate tags will help you to have the best answers.
Answer: It's hard to answer this exactly without knowing which language/hardware you are using, but in most cases different data types do take up different amounts of memory and data type can affect the speed of mathematical operations. For example, in Java and C#, a short is 16 bits and a float is 32 bits. I would expect floating point math to be slower than integer math in general, although this can be complex as explained in this post.
For other languages (such as C), the size of the basic data types is hardware-dependent, so an int might be 32 bits on some machines and 64 bits on others.
Answer: the reason we have datatypes is efficiency. That includes both size and treatment of data(types).
A char datatype has 8 bits (you may also call it 8-bit integer since the numerical values are simply mapped to characters in the ASCII table) = 256 possible values
A 32-bit integer has ... you guessed it 32 bits = 2³² possible values
Mathematical Operations are performed by shifting or comparing those bits..
More bits = more operations = more time
Reference: http://en.wikipedia.org/wiki/Data_type


Project Idea for a AI related project

Question: I am a Computer Science final year undergraduate student.Until now,I used to shirk away from robotics as I believed that it is more related to electrical and mechanical aspects.But my interest in robotics grew by seeing some demos and I seriously want to make a robot which involves AI by teaming up with interbranch students of college.So what is the best project I can pick up as a beginner in robotics and AI and some experience in Computer Science so I can apply AI Machine learning concepts so that it learns something.How to start something?
Comment: How about we flesh the question out a bit, are you looking for something which will involve hardware design as well or an off the shelf robot?
Comment: @MatthewGordon,basically a robot that performs any task intelligently
Comment: I'm not sure it would be possible to come up with a wider spec... For some ideas take a look at existing university robotics competitions http://en.wikipedia.org/wiki/Competitions_and_prizes_in_artificial_intelligence.
Comment: Welcome to *robotics* XXX, but I'm afraid that *[life questions](http://robotics.stackexchange.com/help/on-topic)* really aren't a good fit for robotics.SE. We prefer *[practical, answerable questions based on actual problems that you face](http://robotics.stackexchange.com/help/dont-ask)*. Take a look at [ask] and [about] for more information on how stack exchange works.
Answer: This is quite a broad question.
Everything depend on if you want to involve hardware design as Matthew Gordon said already. Lets say you don't want to touch hardware design.
I, as well, will suppose you don't want to do control (like PID control) but more AI, in team work, K-means algorithm and so.
First of all, I honestly think that, you'll always have to know at least a bit how the hardware is working for it is just really useful to know that in the control process. You don't have to be an expert about it but know the limit and the possibility of the robot helps design the machine learning process. So you know what's possible and what isn't.
Apart from that if you have no robot at disposition already you should look at simulation software. Some like Stage or Gazebo are really good simulators. Gazebo implied a bit more of preparation to be run though.
Then you can just take an existing robot to do your simulation. An existing robot like PR2 or TurtleBot depending on your project would do the trick.
Now those robots run with ROS which is, as the name say, a Robot Operating System. The goal is to provide abstraction so if you design an AI in C++ or python you could just directly run it on those robots because all the controls are already done. Meaning if your program uses the standard type of message for moving the robot you just have to ask for things as simples as "go there" in your AI program.
Ros is definitely a good start if you want to team up with other people as well as it will give you conventions, rules and a lot of libraries already provided for your robot.
Comment: ,thanks for a well formed answer but the scenario is a little different.I am the programmer here with team of two electrical engineer to complete the robot.I think process illustrated above will hold good here too.
Comment: What kind of Intelligence are planning on creating ? Are your two electrical students going to program the motor drivers as well and  the sensor drivers and up to which level ?
In any case the simulation first is always a good start so you don't have to wait for your two friends to finish the robot to work on.
Answer: Basically almost any control system can be used with machine learning. You just learn the control logic instead of using some PID for example. Here is one simple example which doesn't have too much robotics involved but you'll get the point I hope: http://www.youtube.com/watch?v=XiigTGKZfks
Ball and Plate system could also be interesting to you. You could generally base your research on comparison of different algorithms, both machine learning (HMM, reinforcement, supervised...) and some more often used controllers like PID and Fuzzy logic.
Regards

Project Idea for a AI related project


Need a alternator for a 94 nissan pathfinder Le V6

Question: I have a 94 Nissan Pathfinder LE V6 and I wanna know if there is any other parts that would b compatible or a perfect fit for my suv beside an D21 hardbody, altima wit a v6 motor or an Infinity G35 I'm badly in need to know so I can get my suv running again so I can go to work.
Comment: Welcome to Motor Vehicle Maintenance & Repair!
Answer: The only thing I see as a fit for your Pathfinder is this:

91-94 Pathfinder
91-94 D21 Pickup

That is it.
Comment: Thank you very much coz I was out here looking for an altima as well n I was stressing out really bad. You helped me alot


Dock shows on only one screen on OS X Mavericks

Question: I understood that every display would behave independently on OS X Mavericks, and that it would get its own bar (top of the screen) and dock.
However, the dock shows only on the main screen, and not on the other screen, is it normal?
Comment: IF you check this in Windows, it does have one bar either.
Answer: If you're using a stacked display configuration, as in main monitor with the secondary above, then the dock does not appear on the second display. If it can or does, I'd like to know because this is how I run my setup.
If you have them oriented right to left, then the dock will appear. In my limited experience, only one image of the dock appears at a time on whichever monitor you activate it on. You have to play with it, as the cursor motion seems to need to be elongated or dramatic or whatever. Not a big thing, just different.
It's there by default, trust me. HTH.
Comment: I have them from right to left, and the dock only shows on the right (even if I'm working on the left monitor). I haven't restarted since the install yesterday, maybe it's just a bug that will go away, i'll try that tonight.
Comment: It seems there are some bugs :( After restarting, the dock started showing up on all monitors like it should, but after waking up from sleep, the dock only shows on the main monitor.
Comment: Update on the bugs: sometimes, the dock seems to be "locked" on one screen: on screen 2, I can't show it. I have to show it on screen 1, and then the dock will properly show on both screen. It is random, not related to restarting, and affect both monitors randomly. Maybe it's a sideeffect of an app like TotalSpaces…
Comment: This just happened to me, I found that opening display preferences, changing the alignment and then changing it back fixed the problem for me.
Comment: The dock will never leave the primary display if you have unchecked `Displays have separate Spaces` in `System Preferences` -> `Mission Control`.
Comment: To get the dock to switch displays, move the mouse pointer to the bottom of the display you want it to move to, then move the pointer further down below the bottom of that display.
Answer: None of this works if you use a left or right positioned dock in Mavericks.  The dock will ONLY migrate with a Bottom mounted dock and ONLY if the monitor positions are set side-by-side (corner or top/bottom mounted will not work, at least as of 10.9.1 and 10.9.2 versions of OS X). Apparently, people who prefer left/right positioned docks (to maximize vertical space without hiding since most monitors are now wider than tall) are now second class citizens.  The now semi-opaque color is also much brighter for such left/right docks as well, which many seem to hate).
Answer: The dock only shows on one display at a time. It is hidden on all other displays, but can be made visible just as you would any hidden dock. That is, moving your mouse cursor below the display you would like the dock to appear (or left/right depending on where your dock normally is). Then the dock will hide on it's current display and appear on that display.
Answer: Please see this link:
http://rwillgo.wordpress.com/2013/10/26/mac-os-x-mavericks-how-to-move-the-dock-from-one-display-to-another/
The gist of it is that you have to tap + hold + drag the mouse to the bottom of the screen for the dock to move.
Answer: The issue is nothing to do with which screen is active, and more to do with a "safety feature" that prevents the Dock from popping up too easily.
To get the dock to appear on another screen (active or inactive), you need to move the mouse pointer to the bottom of the screen and keep moving past the bottom edge until the dock appears.
Leaving the pointer at the bottom edge of the screen will not work.
With a Magic Trackpad,  it's a bit more fiddly - you can either take one giant fast swipe down past the bottom edge, or swipe down several times (about 4) in quick succession after the pointer has already hit the bottom of the screen.
And, once again, you do not need to click on the screen to make it active before the Dock will appear.
Answer: In order to make the dock switch from one screen to the other, you should "jump" with the mouse on the bottom of the screen you want it to be shown on.
Here it is shown more: http://support.apple.com/kb/HT5891?viewlocale=en_US&locale=en_US (look for "Working with the Dock")
Answer: To bring the dock over to a different display:
If you've clicked on a display to make it active, note how the Menu Bar brightens. But you don't need to.
Without clicking the mouse again, move the cursor all the way down to the bottom of the screen. This is the same technique as if you had invoked System Preferences > Dock > "Automatically hide and show the Dock."
When the cursor touches the bottom, the Dock will rise up from the bottom and stay there on the selected display. (If you had previously enabled "Automatically hide and show the Dock," it will disappear as you move the mouse upwards, but remain tied to that display.)
To move the Dock back to the main display (or any other display), repeat the process starting with Step #1.
Answer: exactly correct. move the cursor to the next screen, all the way to the bottom and then keep scrolling as if to move it beyond the bottom for a second and the dock will appear. It does not do this if you just tap the bottom of the screen with the cursor, bouncing it off of the bottom so to speak, apparently because this may be an unintentional mouse movement. with a little practice, this becomes second nature.
Answer: It worked fine here:

Moving the dock to a second display is not straightforward but it's easy to do. Assuming you are using an Apple Magic Mouse, you can tell OS X to move the dock to the active display by following these steps:
First, click the desktop or any window on the display where you want the dock to move to. This will make the menu bar go active.
Then, place your finger on the mouse while moving the cursor towards the bottom of the screen. The dock will them pop up.