Feyerabend's criticism against the fetishes of rationalism

Question: Why does Fayerabend see observation terms, scientific method and fixed standards as fetishes of rationalism?
Comment: Could you expand this question a little? Which papers/books by or about Feyerabend do you have in mind? Are you interested in Feyerabend's views in particular? Are you puzzled why 'rationalism' is the target, instead of, say, empiricism?
Answer: Feyerabend makes a detailed demolition of the so called "received view" of philosophy of science (i.e.Logical Empiricism and Popper) and its attempts to discover rules of scientific method.
In his book Against Method (1975) he uses historical case studies (i.e. the transition from older scientific theories, like Aristotle's theory of motion, to the scientific revolution of Galileo) to argue that there are no universal and exceptionless methodological rules governing the progress of science or the growth of knowledge.
According to F, the history of science is so complex that if we aim at a general methodology that is applicable in every historical context and to all objects of study, the only "rule" that is applicable will be the trivial one: "anything goes". The phenomenon of incommensurability between different "points of view" renders the standards which the "rationalists" (like Popper) use for comparing competing theories inapplicable.
The critics of F's book accused him of beeing an "irrationalist".
See: Paul Feyerabend, in Stanford Encyclopedia of Philosophy.
Comment: Fascinating, what Feyerabend says makes complete sense to me. I would identify the idea that there are timeless ways to do science with the adage, "If all you have is a hammer..."  I'd love to understand _why_ folks think there is a describable, forever-valid 'scientific method'. Why does this matter to them?
Comment: @labreuer From my readings it seems that the *demarcation* problem is a motivation for a specific method. However, I do think there is a *general process* that science uses, namely *evidential reasoning* and empirical testing, but I don't think these are solely the purview of science...I've used similar reasoning in a literature class when trying to justfiy a theory about a character's motivations (for example). Part of science is its subject matter, as much as its method. For example, history is not a "science" in the traditional sense, but it uses very similar methods.


installing ffi gem manually

Question: I am trying to install the ffi gem. it is a dependency for one of my apps. I have been trying for hours to get this to work. I am receiving this error:
#error "Use of <stdbool.h> is valid only in a c99 compilation environment."

I know the solution to this error is to add CFLAGS= -std=c99.
the problem is that when I run
gem install ffi -v '1.3.1' -- --with-cflags=-std=c99
I am still receiving the error the make and in the log I see that it is not recognizing the CFLAGS I have added.
I then decided to go into the makefile and manually add the CFLAGS then run make and make install
this seemed to work I received no errors but when I bundle install in my app it still does not recognize the ffi gem to be installed and recreates the makefile without the CFLAGS and fails again.
is there something I am missing when doing this manually??
or is there a way to force the CFLAGS from gem install??
Answer: Just guessing here but try this:
CFLAGS="-std=c99" gem install ffi -v '1.3.1'

Comment: no luck with this ended up with the same error :( thanks though...seems to be the only way it recognizes CFLAGS is when I edit the makefile

installing ffi gem manually


HTTP request minimum size in bytes

Question: What is the minimum size in bytes of an HTTP request? I mean the size of the mandatory data that an HTTP request should consist of, such as header's related fields and considering that the body of the request is empty.
Answer: 26 bytes
for the exceptional case of a 1 byte resource and 1 byte hostname.
GET / HTTP/1.1<CR><LF>
Host:x<CR><LF>
<CR><LF>

You need an initial request line and, if you're using HTTP 1.1, a Host header. Each newline is two bytes (CRLF). Two parts of this minimal GET request are variable: the resource path and the hostname.
A minimum initial request line is GET / HTTP/1.1 which is 16 bytes (including the two invisible CRLF bytes you don't see).
A minimum Host line is Host:x, that is, a one byte hostname which results in 8 bytes (again two CRLF bytes).
To signify the end of headers, you need another CRLF, so that's another 2 bytes.
16+8+2=26 bytes for a minimum HTTP request size.
Of course, this increases if you have a longer hostname or longer path to the resource. To take those into account, the minimum HTTP request size is: 24 + length(resource_path) + length(host)
Here's a real world example using netcat from bash (note the resource path and hostname are both longer than the minimum):
nc -c www.example.com 80 <<EOF
GET /index.html HTTP/1.1
Host:www.example.com

EOF

Comment: @MrMesees that's an extra 40 bytes (for IPv4), but the full picture is more complex since HTTP can run over TCP/IPv4 or TCP/IPv6. Also, if TLS is used there is additional overhead. There's also the network layers beneath IP which have their own overheads as well.
Comment: What about TCP IP overhead of making HTTP request?
Answer: The shortest possible HTTP request is a simple GET method, made by connecting directly to a specific server.  The shortest request is:
GET / HTTP/0.9<CR><LF>

which is a total of 16 bytes, including the CR/LF pair at the end of the line.
For HTTP 1.x (1.0 and 1.1), the presence of headers is expected, so to signify the end of the headers you need an empty line.  The shortest request is then:
GET / HTTP/1.0<CR><LF>
<CR><LF>

which is a total of 18 bytes.
(Added after comments by Doug; thanks:) For HTTP 1.1, the Host: header is required.  See @DougRichardson's answer for the shortest possible HTTP 1.1 request.
Comment: Also, for HTTP 1.1, the Host header is a required field when using an absolute path for the request URI. See RFC 2616 section 5.1.2, so the example (for HTTP 1.1 at least) of 18 bytes is not valid HTTP 1.1.
Comment: The parameter after GET on the initial request line is the request URI, not the hostname.
Comment: @DougRichardson: Which is why the first example was specifically `HTTP/0.9` and the second specifically `HTTP/1.0`.  And thanks for the correction about the parameter, I'll correct it.

HTTP request minimum size in bytes


Is There a Shorter Way of Saying/Word for "Person who gave birth to you"?

Question: When you're born and given up for adoption, what do you call the person who gave birth to you? I do not like the phrase "Birthmom" or "Birthparent" or anything like that since the person who gave birth to me is not actually my mom. She didn't raise me, so I would like a shorter way of saying this or a certain word for this? Thank you in advance!
Comment: Well, the only other phrase that I know of is "birth mother". You can get a hair more clinical if donor eggs were involved, but that simply makes things more awkward.
Comment: *biological mother* (but that does not imply that she gave birth to you)
Answer: As opposed to your adoptive parents, the people who actually gave you life in legal speak are called your biological parents (or sometimes your natural parents). So, to refer to your real mom, you would say my biological mother and to refer to your real dad, you would say my biological father.
Comment: I like the answer except for the "real". Adoptive parents (or any other type) as much real ac biological ones. Real parent is whoever the child feels like they are.
Answer: If the OP wants to avoid using the most common and easily understood terms 1. biological mother and 2. birth mother, I suppose they could describe their parent, rather icily, as their

hominid host

hominid
adjective
2. of, relating to, or belonging to the Hominidae

Any of various primates of the family Hominidae, whose only living members are modern humans.

Source: Dictionary.com
Comment: I think terms like this may come across as not just cold but potentially offensive.
Comment: +1 because this term applies to either (1) the genetic mother (gm), whose egg was fertilized by the genetic father, and who carried the fetus and gave birth to the child or (2) a non-genetic mother who received the fertilized egg from the gm and then carried the fetus and gave birth to the child. (Sometimes called surrogate mother.)  It does not cover the practice in The Vor science fiction series by Lois McMaster Bujold where a fertilized egg is put in a uterine replicator; the genetic parents are usually present at the decanting of the child,  unless they are exceptionally squeamish.


Is buoyancy affected by container geometry?

Question: Is it possible for something that can't float in a rectangular container to float in a triangular container?
Comment: This problem was solved about 2200 years ago by a Syracusian called Archimedes. You might even have heard the cry "Eureka!"
Comment: You may need to assume that the containers have the same volume
Comment: Possible duplicates: https://physics.stackexchange.com/q/316715/2451 and links therein.
Answer: No--not if the containers when submerged both displace the same amount of fluid, and if the empty containers have the same weight.  If one sinks the other will sink.
Comment: I think the question uses the word "something" for the object that is about to float or sink, the word "container" for the object containing the fluid (and thus containing the "something" as well). Your "container" is the OP's "something". IMO you answered a different question. In the actual question the variable is the geometry of the "container", not the geometry of "something".
Answer: Let's an imaginary vertical cylinder, with a very small radius, crossing the bottom and top surface of an object. The net upward force, disregarding internal stresses inside the object is:
$$\frac{P_{bottom}\pi r^2 cos(\theta_1)}{cos(\theta_1)} - \frac{P_{top}\pi r^2 cos(\theta_2)}{cos(\theta_2)} - \rho_o gh \pi r^2  = \pi r^2 (\Delta P - \rho_o gh)$$
On the other hand, the pressure gradient of the liquid is: $\Delta P = \rho_l gh$.
As it is valid for any very thin cylinder with volume $\pi r^2 h$ we can say for the whole object, with any form:
$$F_{up} = (\rho_l - \rho_o)gV$$
Answer: In a word, "No." Buoyancy depends only on the relative densities of the object and the fluid in which it is immersed.

I confess, I don't know how to prove it. But I'm pretty sure that the proof does not involve any mention of a container. It only mentions the geometry of the object itself (ultimately, in order to prove that the geometry does not matter) and, on the fact that the pressure of the fluid at any given point is directly proportional to the depth at that point.
Comment: Consider the centre of gravity of the combination of the fluid and the floating object. The system will be in its least energy state when the CoG is lowest.
Comment: @MartinKealey, are you hinting at a proof in which there is no need to mention either the shape of the object, or the forces acting on it?
Comment: That kinda depends on what you take as your axioms. If we're taking "uniform density regardless of shape" as an axiom, then the shape is clearly irrelevant: the water displacement is equal to the volume of the submerged part of the object, and the mass and total volume of the object is fixed. You do kinda need to take the forces into account, but you can simplify those down to pressure in the vertical direction (as a function of depth), since forces in any horizontal direction must cancel out. There are several ways to perform an integration that gets you gravity per volume of displaced water.
Answer: The generally accepted answer is "no", simply by application of Archimedes buoyancy principle, but there are limits.
Firstly, if you make your container long enough and thin enough, and place it end-on in the water, the bottom could be at a depth where the pressure exceeds the structural integrity of the container, resulting in it being crushed, and sinking (a bit).
(This is a bit easier to analyse if you simply split your container into two spheres connected by a incompressible rigid rod of negligible volume.)
But if we assume that the bottom of your container is infinitely strong and incompressible...
Secondly, the rate of increase in water pressure is not quite uniform, as gravity decreases the further below the earth's surface you get. This results in slightly less buoyancy.
Thirdly, the composition of the fluid may not be uniform. The bottom is likely to be more dense, resulting in greater buoyancy. (Earth's oceans are generally colder and more saline in the depths than at the surface, except under the ice sheets.)
Fourthly, if you touch the bottom of the ocean then all bets are off.


What is this type of jack with contacts and light emitting diode called (from schematic symbol)?

Question: I'm very very very new for electronics design. I have a basic electronics knowledge but I know there 's many things I don't know in electronics symbol universe. I searched for reference circuit of CM103AH and I found it but I don't know what this jack is, Is it jack with LED ? I only know that 1 - 5 is a jack.
Anyone can bring light to me what are 6, 7 and 8 ? or what is this type of jack called ?
Comment: I think it's a standard 3.5mm/fiber optic audio jack combination
Comment: Somewhere near this symbol should give you the part number of this component, then you can google for it.
Comment: Please link the full reference design and data sheet, and explain what the CM103AH is - it doesn't seem to be readily google-able.  Usually a reference design will include a bill of materials that specifies the part number for each component.  In the absence of other information I would guess this might be a TOSLINK jack.
Comment: It's an illuminated barrel connector of some type. Or perhaps a jack/fibre-optic combination.
Comment: BTW.. that may not actually be a part, but rather a phantom part what is really a connector where you connect a cable that  goes to the actual part(s). Or even a sub-assembly.
Answer: It's probably a Mini-TOSLINK port which combines 3.5 mmm electrical stereo and optical S/PDIF / TOSLINK in one connector.
Pins 6, 7 and 8 are related to the laser diode of the TOSLINK output.
Wikipedia says:

Combined 3.5 mm jack and mini-TOSLINK sockets exist which can accept a 3.5 mm jack or a mini-TOSLINK plug; mini-TOSLINK plugs are made 0.5 mm longer than electrical jack plugs so that the latter are too short to touch and damage the LED of combined connectors. Many laptop computer and portable digital audio equipment models, such as the Google Chromecast Audio device[6][7] and Apple AirPort Express and iPod Hi-Fi, use these connectors that allow for the insertion of 3.5 mm electrical headphone output or microphone input or mini-TOSLINK digital output.

This is an adapter used to convert standard TOSLINK to Mini-TOSLINK. Note the typical 3.5mm jack form:

(Source: radioshack.com)
Answer:
The first part of the image is an AUX female connector (from 1 to 5).
The second part is the bi color led (from 6 to 8).

My judgement would be

1 and 4 are the ground for AUX
2 and 3 are left and right channel for AUX
5 is unused
6 is ground for bi color led
7  is input for first color
8 is input for second color

The dotted line is the symbol for these parts to be coupled together, maybe encased alongside one another.
The similar circuit can be used to check if the connector is plugged in or not. If plugged in show green else show red color etc.
Comment: Why use a bi-colour LED to show whether a connector is plugged in when the connector is right next to it and it's obvious? What makes you even think it's a bi-colour LED? This isn't an answer, it's complete guesswork.
Comment: Why would they use that symbol for a bi-color LED?
Comment: I've seen many non standard drawings actually using the components as symbols. But now even I'm leaning towards the TOSLINK adapter.


What do you call a person who craves danger?

Question: What do you call a person who craves danger? Like how a person who believes that the pursuit of pleasure is the most important thing in life is known as a hedonist.
Comment: Thrillseeker?  Daredevil?
Comment: Sometimes "adrenaline junkie" if that narrowing applies.
Answer: As Steven mentioned,
Daredevil — ODO

noun A reckless person who enjoys doing dangerous things
"spectators watched in horror as the nineteen-year-old daredevil smashed into the ground"

Thrill seeker — ODO

noun A person who is keen to take part in exciting activities that involve physical risk
"thrill seekers are paying big bucks to swim with great white sharks"
Answer: Adrenaline junkie

A person with a compulsive desire for excitement and adventure:

(ODO)
This certainly gets to the "crave" part of your request. Whether it also fits the rest will depend a little on the kinds of dangers you have in mind.
Answer: As NVZ says, daredevil sure is the word for that. But here are other choices for you:
Swashbuckler

Someone who engages in daring adventures.

Also, I think risk-taker would probably replace that, because it means someone who loves taking risks.
The adjective would be dauntless

To show fearlessness and determination.


Window Air Conditioners Keep Tripping Breakers in Shared Home

Question: We are living in a sober house and have come across a weird complication and a few of us that have no clue on the electrical field but do have wits to fix simple things. The 3rd floor recently had a power outage which a week prior to that we kept on having to run down stairs to flip a tripped breaker. I thought I had fixed the problem when I moved to an empty room that was on a different circuit(2 of us had window AC unit which kept tripping the breaker. Everything was good for about a week and I woke up one morning to find out one of my outlets wasn't working and that the entire rest of the 3rd floor had no power. Breaker box is fine. The owner tested it with a voltage tester and everything has power. Today I went down to the basement to investigate the issue further (we now have extension cords running this way and that way...lol) I came across the g.f.c.i. box which was labeled 3rd floor/bathroom. I will not touch anything unless I know what I'm doing but I'm curious on what anybody's thoughts might be to what is causing this power outage. Trying to live a sober life through addiction is NOT an easy road. We all would like to get the issue fixed to get back on track of fighting this fight we are in. Any one have an idea as to what would be the problem. Thanks to everyone who read. Have a great day.
Comment: ...which for our purposes means, the homeowner *can't* do the electrical work, and any screwdriver-twisting work must be done by a pro electrician, *unless both owner and city hall authorize "trivial" repairs such as replacing receptacles*.
Comment: Did you try resetting the GFCI ?
Comment: What is the actual relevance of all the 'sober' stuff?
Comment: I modified the title of the question to better reflect the topic
Comment: @MichaelHarvey -- it's a group home environment
Answer: It sounds like your A/Cs are too big for the available circuits and/or they are tripping the GFCIs.    Either way, you should stop using these A/Cs and do not rely on repeatedly resetting tripped breakers.
It's better not to use A/Cs with GFCI outlets or with extension cords.
Some possible solutions:

Ask the owner to hire an electrician to install new circuits and outlets for the air conditioners.
Turn off all lights and other electrical devices on the third floor and only use one air conditioner.  This may or may not help but it costs nothing to try.
Buy smaller air conditioners.  This may or may not help, and it's a big gamble.
Use fans instead of air conditioners.  Fans that work will cool you better than A/Cs that shut down the whole floor.
Comment: If you are renting the A/Cs weekly ask the supplier if they have smaller ones.   And if you are renting them from the owner of the house he should be responsible for making them safe and functional.
Comment: I appreciate the input. This is a sober house for each of the 4 rooms on the 3rd floor are rented (170 a weekper room). Each individual is responsible for their own room and this house has no a.c.. We have to purchase our own air conditioners ($15.00 xtra a week). So each room is like individuals apartments. The owner is not to keen on fixing things quick as it's been two weeks and we are still to see an electrician. It was my curiosity that made me ask the question above. Thank you for responding.
Comment: @AdamRoyer if the property owner is not responding to electrical issues, it might be time to get the authorities involved. I'm not 100% certain who you'd contact in this case, but landlords are required to maintain livable standards, and I'd think that power outages for reasonable uses wouldn't be considered livable. Also, congrats on _getting_ sober and _staying_ sober! It won't be an easy road, but it'll be worth it!
Answer: You probably shouldn't do the "sparky parts" of the job.  However, there is a lot of legwork that you absolutely can do, that will make the job go much faster for the person who actually does it.
First, identify your circuits
You know there are some circuit breakers.  Identify each circuit breaker with a name or something (Thor, Odin, Freya, that kind of thing) and then label each of the outlets that is powered from that breaker.  I like labeling the breaker itself, so if it is moved around, the name sticks.
You know which one you have been resetting.  And you know what else was on that circuit.  So you should have some luck identifying the now-dead ones.
So label each outlet and light by which breaker it is on.
Now, figure out all the outlets on the dead circuit
My guess is some of the outlets are dead, yet others are still working.
What usually happens in cases like this is a burn-out of a wire connection at an outlet - usually circuits are in strings (hidden behind the walls), and it'll be at the last working outlet or the first "out" one.
The repair is usually as simple as re-seating or repairing connections on the faulty one.  Of course, finding the bad one is the trick.
"Back Stab" connections, where the wire is simply jabbed into a hole in the back of the outlet, is the most common culprit. Those connections are legal, but are not very good.  Fortunately, they usually fail like this, not in fiery flame.

Cars have computers in them now. I have a saying: "Replacing a car computer is a very expensive way to reset a car computer".  This saying has a corollary: Replacing a receptacle is a very cheap way to re-do all the connections at a receptacle.
That's because receptacles and switches cost $3 for the good ones.
And people replace them all the time for aesthetic reasons. There can be many tricks to it, but by and large, receptacle swaps are "handyman work".
Because of this, city permit offices and landlords will often allow simple replacement of receptacles by non-electricians.
Now let's talk about those air conditioners.
I am shopping for a window A/C right now.  It's unbelievable how much more efficient the new units are.
I have seen 6000 BTU units that draw 4 amps of power when running normally. 4 amps!
You know perfectly well how many amps the circuit allows; it's written on the handle you keep resetting.  (15 or 20 typically).
Obviously the circuit has to be able to power everything on it, including computers, laser printers, de/humidifiers and a host of other things. But you recently mapped the circuit, so you know what all that stuff is.
Now you need to look at the nameplates of anything that makes heat, and figure out how many "amps" each one draws.
Make sure all the loads will fit on the circuit (in terms of amps).
And use those new, efficient air conditioners to help hit the number!
Comment: Note that "anything that makes heat" doesn't mean "heaters", it means anything that's plugged in and uses electricity. (No electrical device is 100% efficient - the byproduct of that inefficiency is heat.)


Getting the error of OutofGas evm

Question: I've ensured EVM compatibility in my substrate-chain. The default contracts from Remix, such as storage, ballot, and owner are working correctly. However, when I deploy alternative contracts like ERC-721, they deploy successfully. Yet, when I attempt to call any function of these contracts, an Out-of-Gas error is displayed in the blockchain events.
Answer: Our team recently submitted two fixes about the OutofGas:

https://github.com/polkadot-evm/frontier/pull/1239
https://github.com/polkadot-evm/frontier/pull/1257

Check out the latest version of Frontier.

Getting the error of OutofGas evm


multiple conditional formatting

Question: New to the whole JSON code within SharePoint lists, hit a brick wall and having no luck with research.
I require 2 conditional formatting writing into the cod but am not having much look.
First - if the 'Re-Certification Date'(which is a calculated column) is
Over 1035+ days = Green
1035 days = Orange
0 Days = Red
To do so I have the below JSON Code wrote:
{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/column-formatting.schema.json",
  "elmType": "div",
  "txtContent": "@currentField",
  "style": {
    "background-color": "=if(@currentField <= addDays(@now,0), 'red', if(@currentField <= addDays(@now,60), 'orange', if(@currentField > addDays([$Certificationdate],1095), 'green','green',)",
    "color": "=if(@currentField <= addDays(@now,0), 'white', 'white')",
    "padding-left": "10px"
  }
}

Is this correct and the simplest way of writing it?
Question 2 - How do i add a second conditional formatting JSON code to the same column so that if the 'Status' column = 'Left the Company' the cell is filled black with black text?? i have tried a few ways and had no success.
Or is it possible to remove the date from the calculated column based on anothers status??
Any help is greatly appreciated!!!
Answer: Add a second condition to the background-color and color properties to check if the "Status" column equals "Left the Company". Here is the code snippet:
{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/column-formatting.schema.json",
  "elmType": "div",
  "txtContent": "@currentField",
  "style": {
    "background-color": "=if([$Status] == 'Left the Company', 'black', if(@currentField <= addDays(@now,0), 'red', if(@currentField <= addDays(@now,1035), 'orange', if(@currentField > addDays([$Certificationdate],1035), 'green','green')))",
    "color": "=if([$Status] == 'Left the Company', 'black', if(@currentField <= addDays(@now,0), 'white', 'white'))",
    "padding-left": "10px"
  }
}

Comment: Life saver, thank you very much!
Comment: @JB94 Im happy this worked for you, please mark it as the solution so that others may find it easier.

multiple conditional formatting


'Could not find the main class error' in a build file

Question: I have craated a Java application with an Ant build file containing the jar-task task that generate a jar file from the application.
<target name="jar-task" depends="compile">
    <mkdir dir="${jar.dir}"/>
    <jar destfile="jar/guix.jar" basedir="${bin.dir}">
        <fileset dir="${basedir}">
            <include name="${basedir}/images/**/" />
            </fileset>
            <manifest>
                <attribute name="Main-Class" value="IO.Deep.clk.GUI"/>
                <attribute name="Class-Path" value="${basedir}/SPLASH-2.0.0.jar ${basedir}/lib/dist/* ${basedir}/user.properties"/>
            </manifest>
        <filelist dir="${basedir}" files="user.properties"/>
    </jar>
</target>

When I execute on the command line however a NoClassDefFoundError stating
Could not find the main class IO.Deep.clk.GUI. Program will exit.

Now, the GUI file is exactly in the specific folder and in the same package, I really can't understand where the error may be...can anyone help?
Answer: The name images suggests, that the jar file will contain only images. But where is the actual code?

    <fileset dir="${basedir}">
        <include name="${basedir}/images/**/" />
    </fileset>

This piece

    <attribute name="Class-Path" value="${basedir}/SPLASH-2.0.0.jar ${basedir}/lib/dist/* ${basedir}/user.properties"/>

will write full qualified pathnames into the manifest. Are sure, that this is correct? Also note, that the code will not find user.properties by putting the file on the classpath. The classpath can contain only directories or jar-files in which classes or other stuff will be searched for. But simple files won't work.
I'm also not sure about the lib/* part. Is the class IO.Deep.clk.GUI in one of the jar files in that directory? That would be a hint, that all directories must be listed explicitly. If that's not a problem - good.
EDIT:
The classpath problems can be avoided by adding the task manifestclasspath (Ant docs) before the call of jar and by using the generated classpath value inside the manifest attribute. Outline:
    <manifestclasspath property="jar.class.path" jarfile="jar/guix.jar">
        <classpath>
            <fileset dir="." includes="*.jar" />
            <fileset dir="." includes="lib/*.jar" />
        </classpath>
    </manifestclasspath>
    <echo message="Class-Path will be: ${jar.class.path}" />
    <jar ....>
        ....
        <attribute name="Class-Path" value="${jar.class.path}" />

Answer: Are you sure your resulting filest inside the jar task contains all the files you need?
For debugging you can use a path convert to the fileset out of the jar task and echo it so that you can verfiy that you have the correct files. If this is OK then I don't see something else wrong in your file although I have limited experience with the jar task myself.


Using C# to iterate form fields with same name

Question: I have a section of a form that I need to handle differently from the rest of form results. In the section that needs special handling I need to iterate over 3 form fields that have the same name. They have to have the same name, I can't change it. The section of the form I am referring to looks something like this:
<input name="Color" size="20" value="" type="text">
<input name="Color" size="20" value="" type="text">
<input name="Color" size="20" value="" type="text">

Using C# I try something like this:
I try to handle it like this:
int i;

for (i = 1; i <= Request.Form["Color"][i]; i++)
{
    colorName.Text += Request.Form["Color"];
}

Which leads to the following exception:
System.NullReferenceException: Object reference not set to an instance of an object.
How should I be handling form fields with the same name?
Answer: You don't need to do any splits or other special magic; you can simply get a string array from ASP.NET:
string[] values = Request.Form.GetValues("Color");
Comment: And don't forget to do a null check prior to using "values" :)
Answer: I would suggest adding each form to a list and using the ForEach operator instead, although it's a bit more longwinded than what you're already trying to do.
e.g.
private List<Request.Form> newList = new List<Request.Form>();

newList.Add(FormName1);
newList.Add(FormName2);
newList.Add(FormName3);

foreach(Request.Form form in newList)
{
   //perform logic
}

Note: I'm assuming that Request.Form is the class name for the Form itself.
I've not tested this myself so there might be a few errors in it, hope it helps to a degree anyway.
Answer: It is important to remember that the form values posted is nothing more than a name/value collection, where the value is a simple string. So it does not make much sense to have multiple form fields with the same name. I don't even know whether it is actually allowed.
But as you say, you cannot change that. I performed a quick test in IE and Chrome, and at least in these browsers, it seems that they send multiple form fields with the same name as a comma-separated string. You might want to test some more to make sure this behaviour is consistent across browsers.
With that in mind, you could say:
string colorValues = Request.Form["Color"];
string [] colors = colorValues.Split(',');

Each element in the colors array now corresponds to the value of each input element that was posted.
Answer: Either Request.Form["Color"] is null, or colorName is not found on the aspx page.  I can't tell which based on your code.  Otherwise, it looks correct.  What type of html element is "Color?"  If it's just an html element, make sure that you have both id and name attributes on it.
Comment: Unless you're doing client-side scripting, ID's aren't necessary.
Comment: This is not why it fails. `i <= Request.Form["Color"][i]` is just wrong (int <= char, because Request.Form[...] is a string). The question has the HTML code (at least now it does, and three minutes before your answer got publisheds).


The most suitable ARMA software

Question: what is the most appropriate software for building an ARMA forecasting model? EViews, Minitab,...?
Best,
Milos
Comment: Define criteria for what is appropriate. In its current form the question is not answerable, since it does not have a definite answer. See the FAQ.
Comment: Do you know any statistical software already? Do you have any experience with ARIMA and variants? Do you have a budget to buy something, or would you be willing to use open source? Do you want a GUI, or are you comfortable typing commands? How large is your data source, and in what format? What kind of data is this? How are you preprocessing/checking the data (i.e. is the software ONLY to do ARMA, or does it need to handle the entire process)?
Answer: As mpiktas points out one has to specify the criteria. If one is concerned about adhering to fundamental mathematical/statistical principles you might look at the book ( page 671 and on) Principles of Forecasting. If you want to get a recent evaluation , incomplete in my opinion, you might see this software survey. Sometimes ease-of-use is important , sometimes detecting and incorporating Gaussian violations and augmenting the simple ARMA model is important. Sometimes the degree of "automatic model selection" is important and how they limit the "sample space" from wich to select the "best model". There have been a lot of developments in ARMA modelling and most pieces of software seriously lag academic developments. If I were you I would take one time series that you were interested in and evaluate the software vendors on that one series, not necessarily for how well their automatic procedure worked but HOW IT WORKED. In other words understand their model selection/validation procedure.

The most suitable ARMA software


The strangness of time

Question: What happened before time itself?Is a time period of an event necessary to say that this happened?In physics the passing of time is relativistic depending on your frame of reference.But we cant escape from time.Maybe from this point of view it is absolute for all of us.
Comment: Sorry, but "before time itself" does not make sense, and what is "this" in "this happened"? It is unclear what you are asking.
Comment: Before time was created and this is the event.
Comment: The event of creating time? Since events happen in time this is like asking about the shape of a round square, i.e. a meaningless play of words.
Comment: Time may be less absolute/more ethnocentric than we imagine. The goto reference is Whorf who claimed that the native American Hopi notion of time was fundamentally different from ours. This has been strongly de-fashionablized... But here is a [Hollywood version](https://youtu.be/6QAujmYORLA)
Comment: How much time does a thought take? Not communicating or indicating it, just the thought? In what time 'space' does logical formalism exist, immediate?, eternal? We do have access and use for atemporal concepts but trying to talk about these _in relation_ to temporal metaphysics, using temporal means of communication, just seems impossible. And what would 'atemporal communication' be anyway?
Comment: Conifold no  when I say before time itself I mean before time was created from the big bang.And I say that events outside of time are no longer events.We must be able to define when an event happened inside time.
Answer: Welcome to Philosophy SE. Your question makes some common assumptions which are not necessarily true.
Let me explain the problem with thermodynamics.
If we assume that gases are made of things (for example, molecules), we are able to describe their behavior using the laws of thermodynamics. That is science. Science is knowledge obtained using the scientific method; it is based on empirical facts (facts of our experience). Each one of us has the same experience with objects or things. So, we normally assume that objects are indisputable, non-debatable facts. Scientific knowledge help us surviving.
But there are issues with scientific knowledge. Paradoxes, errors, inconsistencies, etc. That is normal, scientific knowledge is not perfect. The main reason, for philosophers, is - precisely - that it is based only on our experience.
Because gases are NOT necessarily made of things! Things are just manifestations of our experience, more related with our mind that with the physical nature.
So, if you consider that a gas is not necessarily made of objects, thermodynamics is not anymore valid. For example, Boltzmann's formula is useless (because it is highly dependent on accountable objects, which might not be a real fact). After centuries of focusing on the object, science has started focusing on the subject: us, the observer. That is part of the great success of quantum mechanics.
The same happens with Einstein's relativity. It is based on our experience. For Immanuel Kant, time and space do not exist, they are just a framework that our mind creates in order for us to understand the context of our existence.
So, when you say "before time itself", you should consider first if time is not necessarily a fact of the nature outside of our perception, time might be just a fact of our experience, which raises from our five senses and our reason.
If you want to enter into the subject, I recommend you to get an introduction on the early empiricists, Locke, Berkeley, Hume and of course, Kant.
Comment: I voted this up... Though I must say that the statistical mechanics stuff I find a red herring. The worthwhile part is the last-but-one para which paraphrases Kant's great insight viz.  Space and time are forms of our mentation

The strangness of time


The shadow of a tree

Question: If we were limited to observing the shadow of a tree without the possibility of ever seeing the actual tree, what are some approaches that could be employed in order to determine its true nature. How could we ever know about its DNA, photosynthesis process, or its rough surface?
Comment: Even when we saw the tree itself, we saw it in our mind. This link does not address your question, but it does address the typical subject-object problem.  http://rugwig.blogspot.com/2013/10/john-deely-on-epistemologyontology.html?m=1
Comment: We couldn't seems to be the obvious answer.
Answer: I believe that when the observation is limited to the projection, part of the information about the original object is lost. Therefore, it will not be possible to determine with any certainty the nature of the tree.
The statistical methods used for the determination of the hidden parameters from the observed ones prevent the complete certainty about a single result.
Answer: As has been mentioned already: "When the observation is limited to the projection, part of the information about the original object is lost." That is inevitable. A two-dimensional picture cannot convey the complete information of a three-dimensional space. Nevertheless the problem can be overcome by projections under different angles as is usually applied in modern medical applications like X-ray and NMR. There it is possible to see the structure of human bodies, for instance the brain in three dimensions.
In order to investigate the tree we had to observe its shadow at different times and if possible cast by different sources.
DNA would be out of reach for shadow research.
Answer:
How could we ever know about [the tree's] DNA, photosynthesis process,
  or its rough surface?

If one shadow of the tree is the only information available to an observer, any further detail is lost.
However, if there are comparisons available, a lot of detail might be teased out about the tree. Is there available a shadow of a known object, such as a car, a building, a mammal or a bird? Can the tree itself be viewed in different colored light, or when lit from different angles?
It happens a lot that some unknown quality can be estimated only by looking at something else, comparing the two, and then making an uncertain decision. You just go with what you got.

The shadow of a tree


How to Install Multiple Add-ons with Python Script

Question: I am constantly using new workstations where I have to install a new version of blender. While the blender cloud add-on allows one to sync settings between devices, it does not sync user-installed add-ons themselves. If I have all the add-ons I want to install in a folder I download form a cloud location, how could I create a script that would automatically install and activate them?
Comment: you should try my addon. in one operation you can select all addons in a folder. confirm. it's done. this is checking if it's an update if you let the default option in the browser. you can also install an addon directly from the text editor https://github.com/1C0D/Addon_Installer-Script_Runner-BlenderAddon
Comment: I use it intensively when I'm doing addons
Answer: You can designate the folder with the scripts, create a list of files within this folder (i.e., directory), and use the preferences.addon_install() command on each file. You can create a list of the module names you want to install, and then loop through them with preferences.addon_enable()
import os
import bpy

# Define path to your downloaded script
path_to_script_dir = os.path('/Users/YourUserName/Downloads/scripts')

#Define a list of the files in this folder, i.e. directory. The method listdir() will return this list from our folder of downloaded scripts.
file_list = sorted(os.listdir(path_to_script_dir))

#Further specificy that of this list of files, you only want the ones with the .zip extension.
script_list = [item for item in file_list if item.endswith('.zip')]

#Specify the file path of the individual scripts (their names joined with the location of your downloaded scripts folder) then use wm.addon_install() to install them.
for file in file_list:
    path_to_file = os.path.join(path_to_script_dir, file)
    bpy.ops.preferences.addon_install(overwrite=True, target='DEFAULT', filepath=path_to_file, filter_folder=True, filter_python=False, filter_glob="*.py;*.zip")

#Specify which add-ons you want enabled. For example, Crowd Render, Pie Menu Editor, etc. Use the script's python module.
enableTheseAddons = ['crowdrender', 'pie_menu_editor', 'animation_nodes','blender_cloud']

#Use addon_enable() to enable them.
for string in enableTheseAddons:
    name = enableTheseAddons
    bpy.ops.preferences.addon_enable(module = string)


Do I need the plastic Rim liner installed on Bontrager Paradigm tubeless ready rims if I plan to install inner tubes and a clincher Tire

Question: I just bought a set of Bontrager paradigm tubeless ready rims that are set up as tubeless right now. If I'm planning on going with an inner tube and a clincher Tire can I remove the plastic seal strip provided by Bontrager that is on the wheel now? I've heard that strip makes Tire changes more difficult. Should I leave that strip in place when I go to a inner tube or remove it and use Rim tape instead? I'm fairly new to the tubeless ready setup and trying to learn all I can. I love all the advice that has given here
Comment: A photo would help. But you can leave the tubeless tape in place. That'll be helpful for if/when you got back to tubeless.
Comment: *If* the tubeless tape significantly increases the wheel diameter and an ordinary tape would not, removing it could indeed help. But I am dubious it is actually the case. Most likely the tape is thin and even if it covers a valley in the rim, it would have been likely covered by any other tape as well. Show us the details please.
Answer: Presumably the rim strip in question is a Bontrager TLR strip. Distinct both from regular tubeless rim tape and also from regular non-tubeless plastic rim strips, the Bontrager TLR strip design has a more sophisticated cross-section that is designed to match the rim and establish the bead lock properly. They come in different widths and colors, and each applicable rim only takes one variant.
If you take it off and replace it with tape or a conventional rim strip, the rim hook will hold the wheel securely for tubed use. What it won't do is provide anything like a proper tubeless bead lock, which the TLR strip is instrumental in creating in the rim designs that use it. So if you ever wanted to go back to tubeless, you're probably buying new ones. They don't tend to come off reliably without getting damaged. It's possible to use conventional tubeless tape instead, but it typically takes many layers to begin to create a proper lock, and even then doesn't work as well. It's not recommended. This is a controversial topic and the kind of thing where you can find many forum posts with people saying they've set up their Bontrager TLR rim with Stans tape etc. It can be made to work but absolutely does not work as well or as easily as just using the strips.
Without the bead lock acting as intended, yes the tire will be much easier to unseat. In many cases this issue is better solved with good technique, but there are also some tire/rim combinations that are just extremely difficult, so depending on the circumstances it could be reasonable to do this.
Comment: Is unseating really the issue? I normally struggle with getting the tyre over the rim wall. It often requires heavy use of tyre levers and heavy use of swearing. But just for changing an inner tube one does not have to do that, that is true.
Comment: @VladimirFГероямслава It usually isn't or doesn't need to be, but there are some situations where it is anyway. Also hand strength is one of those more variable things in humans it seems.
Comment: And thank you Nathan on the great information about tlr and Bontrager specifically with the factory supplied plastic Rim strip. I guess I'm leaning towards just going ahead with tubes and a clincher style Tire. I guess you are saying I can remove the factory supplied plastic Rim strip and install normal Rim tape to protect the tube and then go ahead and install a clincher Tire without the Bontrager plastic strip. That would imply that I have a hooked style rim which I'm not sure if the Paradigm is hooked or unhooked. Hooked rim I think I can go tube and clincher without factory plastic strip
Comment: Yes I was talking about the Bontrager Factory supplied strip. I guess I'm wondering if I can go tube and clincher and remove that factory seal strip. I know when you purchase the Wheels online it is not installed the buyer has to do that. So does that mean it's the buyer's option to not install it and then go with a tube and Clincher setup? My understanding is you can only go tube and Clincher if you have a hooked style rim. Does the plastic strip make that rim hooked and able to use a clincher or can you use a clincher without that Factory strip and then just apply normal Rim tape
Comment: @Michael The Paradigm is almost certainly hooked. There is no cost to changing an aluminum rim mold to add hooks, but they make carbon construction more complex. Generally, if hookless, the information page will say so explicitly. Also, hookless rims can run tubeless tires with tubes. They *must* be hookless-compatible tires.


What happens to a normal transformer when the frequency is increased and the sine wave is changed to rectangle?

Question: What happens if I grab a 220 sine wave 60 Hz transformer with an output of 12v if i feed it with a 220v square wave? And what happens if I increase the frequency? Like 100 Hz? And if I grab the secondary and set it to 220v I know that it will burn out the transformer, but if I put a resistor high enough to limit the current in the secondary it will burn out too? Or will I get high voltage in the primary?
Comment: 220V on the secondary will saturate the core, drawing excessive current and hopefully blowing fuses.You'll get excessive voltage on teh primary, determined by the saturation, so probably only a fraction of the 4kV you'd expect.
Comment: Do an FFT of the signal and keep in mind that the core losses increases about linearly with frequency.
Comment: Voltage time area is constant or you will saturate it if you go over. If you increase the frequency you can increase the voltage but the core losses will rise too. If you just need higher voltage, you can unwind the secondary and wind your own but you can easily get yourself killed in the process.
Comment: I would think that you would need to look at where to add capacitance, series inductance and skin effect resistance to the equivalent circuit.
Answer: Depending on how accurate you need results to be, you can model a transformer as equivalent to a series resistor, inductor, and an ideal lossless transformer.
See here for the equivalent circuit of transformer. You can measure your transformer to find the parameters for the model. If you have a model you can study performance versus arbitrary inputs.
A 220:12 transformer has a ~18:1 turn ratio. If you apply 220V to the secondary it will develop 4 kV on the primary side, which could exceed the breakdown voltage of the insulation coating on the primary side wires, causing a short-circuit in the primary side or possibly destroying the insulation.
Mains is not to be trifled with. Do not exceed the voltage rating on a transformer, and if this is an experiment you should have an isolating transformer or residual current device/ground fault circuit interruptor protecting you.
Answer: A normal transformer is operating pretty close to core saturation - please take note that core saturation has nothing to do with loading currents taken by the secondary. All of the saturation story occurs unloaded.
It is the primary H field that is saturating the core (too much flux density) and that H field is determined by ampere-turns divided by length around the core. The current is determined by the primary winding inductance and of course "turns" are turns in the winding.
So, swap the drive voltage to the secondary (one eighteenth of the turns), and you have an inductance that is the square of one-eighteenth i.e. secondary inductance is \$\frac{1}{336}\$ of the primary. Then you apply 12V RMS (secondary nominal rated voltage) and you would note that the current it takes x number of turns (\$\frac{1}{18}\$ of primary turns) divided by length around the core (same as before) gives you exactly the same H field that was borderline causing flux density saturation.
Try doubling the voltage to 24V RMS and you begin frying the core rapidly.
If you increase the frequency by 2:1 the current halves (due to doubling inductive reactance) and saturation no longer is a bad problem. You can now drive 24V RMS on the secondary and get 440 V RMS out of the primary.
However, you will hit another problem; the laminations will progressively short out the windings as frequency increases. If you made a core from solid silicon steel you have, in effect, one massive shorted turn aka the core. So laminations are used and each lamination is insulated from each other thus causing eddy currents to be minimized but, as frequency increases, you will need a lamination width that reduce proportionately.
Do you see the problem in what you are asking?


Step down transformer without coil?

Question: Isn't it possible today to make a down-transformer without coils, without the idea of induction? After all, the AC reaches every voltage in-between, so all we have to do is keep cutting the power flow and only letting current pass when the wave is at the desired voltage. Of course, this will be a series of pulses but it can be smoothed out with capacitors.
Comment: There are 2 kinds of reactive transformers. Inductive and Capacitive.  How many kilovolts did you have in mind? :)
Answer: Is it possible to make a step-down CIRCUIT without coils?
Sure, we typically call them "lamp dimmers" or "motor speed controls", etc. etc. There are millions of examples all over the globe. There may be one within a few meters of where you are right now.
Is it possible to make a (whatever) TRANSFORMER without coils?
No. By definition a transformer (in the ordinary sense) is made with one or more windings ("coils" if you will).
Answer:
There are 2 kinds of reactive transformers. Inductive and Capacitive.

But an R divider is Not a transformer.

simulate this circuit – Schematic created using CircuitLab
This is the most common high voltage transformer for low power.

simulate this circuit
Then we have R1/R2 dividers and PWM open close switches where the shunt R2 n series with PWM toggle between R2 and open cct thus R2'=R2/%d.c.
... or Triac Phase controlled switches which are similar to PWM but at line rate.
---- then there are motor / generators which can transform both voltage and frequency in ratios.
However the most popular practice today is to step up AC to higher DC with active PFC then DC-DC to step down with inductors in stead of use heavy bulky expensive cold-rolled grain oriented laminated steel core transformers for step down DC converters. This method has become mandatory in the EU for PSU"s >100W due to the THD overload of distribution transformers neutral wire harmonic currents from too many poor power factor rectified line caps.
Comment: Normally even switched-mode converters use a transformer to provide isolation and voltage conversion. It's just much smaller because of the higher operating frequency.
Comment: that's true my point to the newbie was that conventional transformers are passe except for >10kVA and up distribution and power transformers and even in DC-DC HiV these will become cascaded solid state modules.
Answer: Sure is possible.  What you want is a cycloconverter.  Overview of cycloconverters
Comment: THe old guys  just call them motor/generators
Comment: Motor generator is one way but not necessary.  Also both have coils the questioner is trying to avoid.  It can be done with Thyristors now
Comment: A cycloconverter is not a "transformer".  Unless stevie means "transformer" in the comic-book sense of the word and not the electrical/electronic traditional definition.
Comment: Well, Stevie used the word transformer but he described a cycloconverter.  He said "After all, the AC reaches every voltage in-between, so all we have to do is keep cutting the power flow and only letting current pass when the wave is at the desired voltage"  He is asking if this could be done.  The answer is yes, it is called a cycloconverter.
Comment: whereas a Capacitor Transformer is used everywhere in the Power Industry for measurement purposes.
Comment: Yes, it is unfortunate that a transformer does not mean an apparatus that simply outputs a lower voltage than its input but must necessarily involve coils. Engineering bureaucracy :-) So I just want to have lower output without coils whatever the name shall be. Transformer seemed a good enough word because it transforms, that is, changes.
Answer: Yes, it's possible to do that with an electronic switch that opens once the input AC voltage exceeds the desired output voltage, on each cycle or half-cycle depending on whether the input is half-wave or full-wave rectified. This Design Ideas article illustrates a method using only discrete components.
No coils needed, but the input does have to be something like a sinusoid (no square waves). With square wave input the pass device would have similar losses to a linear regulator, while causing a lot more EMI.
It does not have very widely useful applications because it puts a lot of harmonics into the input power, but it does work nicely and losses are not necessarily high (the peak current is higher than that of an equivalent rectifier-capacitor filter because the input voltage is higher so the dv/dt is higher) .
Comment: Speho, I love your EDN design how it works and love how EDN uses big dots in the layout with everything neatly placed.
Comment: I can't take credit for the layout- EDN has professional graphics arts folks that redraw everything to make it fit their standards.
Comment: yes EDN and HP's magazine had great graphics. I think I read every EDN before I graduated that was in the library, which allowed me the opportunities I had reading designs such as yours.  That's how I got a head start. Not that they were perfect, but they were quick to learn.
Answer: All of the methods involving motor/generators or cycloconverters are still going to have coils and induction, so do not fit the OPs desired solution.
But as alluded to, it can be done electronically with high speed solid state switches, as long as you only want to REDUCE the AC voltage. Do a search on "Phase Angle Voltage Control" for details that are too long to post here. But in a nutshell, that's exactly what it does, delays the firing of a thyristor (SCR) so that only a portion of each sine wave gets through and results in a lowering of the RMS voltage. The main difference however is this; in an electronic voltage controller, the CURRENT on the output will be the SAME as the current on the input, just at a lower voltage, so the POWER is LOWER. With a transformer, the current on one side it DIFFERENT from the current on the other side by the ratio of the windings (inverse of the voltage change), so the POWER is the SAME . There are losses involved in both methods, so for simplicity, call them the same.
The capacitor method, also called a "voltage doubler" circuit works too, but only if the desired output is DC, plus becomes incredibly cost prohibitive compared to transformers in higher power levels.
Comment: Cycloconverters have been being done with only thyristors since at least the 70s.  Check the link in my answer.
Answer: The only way to make a voltage changer that can (in therory) be lossless (100% efficient) is with inductance(s).
(You can make a current changer with (switched) capacitors.)

Step down transformer without coil?


Command line to disconnect or connect 802.1x authentication

Question: I have been searching for a terminal command line to disconnect or connect 802.1x authentication, but not the network interface. I was searching some help pages and it showed command lines to export and import 802.1x settings/certificates but not disconnecting and connecting.
Answer: This button is tied to the eapolclient. When it's connected, you can disconnect it by killing the eapolclient process:
<code>$ ps ax | grep eapol
83601   ??  Ss     0:00.05 /System/Library/SystemConfiguration/EAPOLController.bundle/Contents/Resources/eapolclient -i en0
$ sudo kill 83601
</code>
When I do this the GUI button switches to show it's disconnected. The bad news is, I don't know how you can start it again :(
Perhaps you can achieve the same by turning the interface off/on:
<code> sudo ifconfig <interface> down
 sudo ifconfig <interface> up
</code>
Answer: Disconnecting from WiFi Networks
<code>sudo ln -s /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport /usr/local/bin/airport
sudo airport --disassociate
</code>

Run these commands in Terminal. Your WiFi will disconnect, while the AirPort Network Interface remains enabled.


How to use flume to read data from mysql?

Question: How to use flume to read continously from mysql to load to hbase?
I am familiar with sqoop but I need to continuously do it from a mysql source.
Is it required to have custom source to do this?
Comment: Almost the same as http://stackoverflow.com/questions/10548538/flume-to-migrate-data-from-mysql-to-hadoop
Answer: Sqoop is good for bulk import from RDBMS to HDFS/Hive/HBase. If it's just one time import, it's very good, it does what it promises on paper. But the problem comes when you wanna have real-time incremental updates. Between two types of incremental updates Sqoop supports:
Append, this one allows you to re-run the sqoop job, and every new job starts where the last old job ends. eg. first sqoop job only imported row 0-100, then next job will start from 101 based on --last-value=100. But even if 0-100 got updated, Append mode won't cover them anymore.
last-modified, this one is even worse IMHO, it requires the source table has a timestamp field which indicates when the row gets last updated. Then based on the timestamp, it does the incremental updates import. If the source table doesn't have anything like that, this one is not useful.
I'd say, if you do have hands on your source db, you can go for the last-modified mode using Sqoop.
Answer: There are a number of ways to do this, but I would write a script that takes your data from MySQL and generates an Avro event for each.
You can then use the built-in Avro source to receive this data, sending it to the HDFS sink.


Equations of idealized greenhouse model with $n$-layers?

Question: I wanna work with this climate model, the idealized greenhouse model. The Wikipedia page explains it very well with an example using one layer of atmosphere. Then it mentions that you can add more layers to model more powerful greenhouse effects. And there are some examples online with two and three layers. But what are the generalized equations to find the surface temperature $T_s$ with $n$-layers of atmosphere with this model?
Comment: Owens, A.J., Hales, C.H., Filkin, D.L., Miller, C., Steed, J.M., and Jesson, J.P.,  A Coupled One-Dimensional Radiative-Convective, Chemistry-Transport Model of the Atmosphere, 1. Model Structure and Steady State Perturbation Calculations, J. Geophys. Res., 90, D1, 2283-2311, (1985)
Answer: Problem with the layers model
I cannot answer properly to your question, but let me tell you that this is a very interesting one.
There are no physical layers in atmosphere, optically speaking, because the optical index of gases varies continuously with altitude (air + other gas in troposphere, then less and less gases + ionized gas like ozone in the upper layers in very few quantity). For me, the layers model have not a clear physical sense.
Two layers problem
Take for example the 2-layers model: let's look a bit.

The lower layer is clearly the earth surface, with its associated emissivity $\epsilon_s$ which is according to Kirchhoff's law equal to its absorption at thermal equilibrium, so in other words $\epsilon_s = 1 - t_s - r_s$, with $t_s$, $r_s$ being transmission and reflection coefficients of earth surface / air interface.
The upper layer is undefined, but regarding to the temperature of the upper layer (around $-40$ °C), it seems that this is the upper troposphere altitude around $10$ km). Anyway, to this layer is associated an emissivity $\epsilon_a$, which does not make sense for a continuously varying optical index of gases ! There is no interface that means $\epsilon_a = 0$ (because the transmission between two very close layers of air is $1$), the emissivity is defined in everyday life by an interface between two media like a hot resistance and air, the earth surface and surrounding air, the wall of a oven and the surrounding air etc.

Absorption of a column of gases
As I discussed last time we can clearly compute the absorption $A$ by a column of length $h$ of gas (see this topic for example) with a Beer-Lambert like law to obtain something like (the exact expression exists also in terms of hypergeometric function):
$$ A = 1 - e^{- k h \sum_i N_i  \text{Im}(\alpha_i)} $$
with $k$ wave vector, $N_i$ number of particles per unit volume of species $i$ and $\alpha_i$ molecular polarizability of species $i$. We find $1$ roughly speaking just for the CO2, you see that $\epsilon_a$ and $A$ are completely different quantities since $A = 1$ just for CO2 and $\epsilon_a = 0.78$.
The "emissivity" of the upper layer $\epsilon_a$ is chosen to have $T_s = 288$ K
In this model, the emissivity $\epsilon_a$ is put equal to $0.78$ just to have the temperature surface $T_s = 288$ K. This constant has simply no physical sense, it is just to adjust the earth surface. The recent video of Sabine at 10:30 shows that we don't have to consider two or more surfaces, but a continuous set of surfaces that emit radiation (in computations of radiative transfer there are some contradictions and misunderstandings... but never mind).
Why doing multiple layers model when the two layers does not make sense ?
I don't know.
How to compute earth temperature? Heat equation and electromagnetic propagation
Let us focus on what is really solid: electromagnetism and heat equation. I am trying to do so at the moment, I will maybe publish the question to discuss with people from the forum... There are some issues to put in the solar flux inside the heat equation (as a boundary condition or inside the flux divergence?) and some others ... But clearly if you want to lose your time in days of nonsense computations, take a n-layers model and make a ton of assumptions... but this is not physics, this is called speculation.
Comment: The use of this model is to easily explain and calculate the greenhouse effect on a planet. I think Universe Sandbox, a space sandbox PC game, uses this aproximation to model climates without doing to much math. Of course it has its limits. And it doesn't predict atmospheric composition nor structure and temperature. But that isn't the goal.
Comment: Yeah but you cannot do anything with this model. How to add carbon dioxide or water concentration in this model ? You cannot still it does not have a physical sense.
Comment: Change in CO2 can be modeled manually by increasing the emissivity of the layers. It's just a very simple aproximation to introduce the concept of the greenhouse effect.
Comment: Ok then do it ? The absorption due to CO2 is $1$ for a couple of $10$ m, what is the link between absorption of a column of decreasing CO2 and  the emissivity of an imaginary layer which does not have an emissivity in principle ? You have no idea and no practice in the topic. Stellar engineer... a title that should be deserved maybe for other people ^^
Comment: After long time, this model is totaly crap. The only way to compute "easily" outgoing flux from the earth is to solve Schwarzschild equation. There is no $\sigma T^4$ for a gas, except if it is highly dense. Otherwise, it is a complicated integral involving spectral absorption band of the gas.


Add reStructuredText support for Juptyer notebooks

Question: I needed to view reStructuredText files in JupyterLab, and the best I found so far was @akaihola's answer to a related issue on github.
I added a work around that would allow rendering the file without viewing the source, provided below.
Answer: In case anyone else may need it, here's the solution I am working with for now:
import docutils.core
import docutils.writers.html5_polyglot
from IPython.core.magic import register_cell_magic, register_line_magic
from IPython.display import HTML

@register_cell_magic
def rst(line, cell):
    "Render ReStructuredText"
    writer = docutils.writers.html5_polyglot.Writer()
    return HTML(docutils.core.publish_string(cell, writer=writer).decode('UTF-8'))

@register_line_magic
def rstfile(filename):
    "Render ReStructuredText"
    writer = docutils.writers.html5_polyglot.Writer()
    with open(filename, 'r') as file:
        cell = file.read()
    return HTML(docutils.core.publish_string(cell, writer=writer).decode('UTF-8'))

To view the rst file, without the source:
%rstfile <your-rst-filename>

To use the original solution, as an rst cell, showing both the ReStructuredText source and the rendered output:
%%rst
============
 Main title
============

Some **heavy** markup.


How does a collator or validator choose their signing key?

Question: If I were to insert multiple (valid) author keys over RPC, how does a collator or validator choose which key to sign with when producing a block? As far as I know this cannot be set on start-up.
Comment: It's generally not recommended to do this, because certain parts of the validator code don't handle 'validator virtualization' well. But as Joe says, nodes will just search for keys that they control within the active validator public keys recognized by the chain at any point in time.
Answer: This is what session.set_keys achieves, it declares that an on-chain account (presumably with keys in some form of cold storage) will sign blocks/consensus messages with some other key. When a node starts, it checks the chain state to see if any private keys in its keystore match the public keys that are registered on-chain. If it has the keys, then it will sign the corresponding messages with them.


Representing biometric data with solidity variables -- bytes 32 perhaps?

Question: would like to know which variable type comes closest to representing biometric binary data? Assuming computing storage and power grows exponentially and network latency can be further reduced, would it be possible to store one,s private key as biometric thereby enabling a web of decentralized identities?
Answer: Your question cannot have a unique definite answer.
In biometric analysis you need to fix some minimum and maximum treshold for data complexity in order to fix the unicity of your identifications.
Think to the complexity of a fingerprint analisys versus some facial analisys, versus some like rapid-DNA Analisys and so on.
Different recognition targets (in terms of identification precision) give you very different complexity amount in data representation and suggest you to use different techniques for measuring that information.
In general the answer is "yes, surely it is possible to have those data on a blockchain", but "how much precise" and "when (2018 or 2028...)" is very relevant in order to choose the proper binary representation.


Example of bundle-mapping over $S^4$ with singularity $S^2$

Question: Could anyone give a non-trivial example of a bundle-mapping over $S^4$, i.e. find two complex rank 2 vector bundles $E_0,E_1$ over $S^4$ and a bundle mapping
$$0\to E_0\overset{v}{\to}E_1\to0$$
such that the singularity set of $v$(where $v$ is not an isomorphic mapping) is equal to the embedding sphere $S^2$ of $S^4$?
Comment: For the point singularity case, there is an example. Since outside the equator $S^3$, $S^4\setminus S^3$ can shrink to points,we can use the standard identification, but near S3S3 we use the coordinate of the point by $(\alpha,\beta)\to\rho(\sqrt{|\alpha|^2+|\beta|^2})\left(\begin{array}{cc}\alpha&-\bar\beta\\
\beta&\bar\alpha
\end{array}\right)$, where we use the complex coordinate $(\alpha,\beta)$ and $\rho$ is the cut off function near the point, by the partition of unity, we can have a global mapping. But I do not how to give the sphere singularity example.
Answer: The answer is YES. First of all, notice the following lemma :

Let $M$ be a smooth manifold and let $K$ be a closed subset in $M$. Then, there exist a smooth function $f$ on $M$ such that $f^{-1}(0)=K$.

We can deduce this lemma by using a partition of unity.
Then, for $M=S^4$ and $K=S^2$, you can construct such an example by setting $E_0=E_1=E$ (where $E$ is an arbitrary complex vector bundle) and $v=f\cdot\text{id}$.
Comment: Could you give the reference of that Lemma. Well, I want to find two different vector bundles $E_0,E_1$. But is is also usefull. Thank you for your sharing.@nsmath
Comment: @DLIN For example, see the Theorem 2.29 in a Lee's textbook _Introduction to Smooth Manifolds Second Edition_ (available free online). Be careful of the Edition number.


Is it possible to play GTA V on Xbox 360 with the first disc only?

Question: I recently bought GTA V for my Xbox 360. I received disc 1 and I still want to play but I don't want to pay for another disc. So my point is, is it possible to play without getting the second disc?
Answer: No, you need both disks to play the game. The first disk installs the game and the second disk allows you to launch it and play. You could try purchasing the missing disk off eBay, or get another copy of the game with both disks in it.


Is it possible to get search engines to index hundreds of thousands of personal profiles from my site?

Question: I have a database of several hundred thousand profiles that include names, careers info, and contact info. I was thinking of creating a teaser webpage for each profile that could be indexed by search engines. But I am not sure if this is the best way. Thoughts?
Comment: Sounds like low quality content to me
Comment: You have everyone's permission to post their info?
Comment: @DamithRuwan Depends on the information. If all of the info is publicly known (e.g. web sites, social media accounts) then no.  But you mentioned contact information which leads me to think of phone numbers and email addresses and posting that without permission will get you into trouble at some point.
Comment: @JCL1178 I agreed that what you said. But, is big companies like "crunchbase" get permission before publishing use information in their site?
Answer: Search engines will only index that many pages from your site if your site has very high reputation.   Facebook or LinkedIn could probably get that many pages indexed, but your site won't be able to.
Google doesn't like sites that publish tons of pages with very little content on each.   If you publish that many pages and then users don't find them useful, you will likely find your website punished under Google's Panda algorithm.
I would recommend testing the waters by testing out 1000 or 10,000 of the highest quality pages.   Find the ones where you have the most data and publish those first.   If you find those get search engine traffic and can satisfy the searchers that land on them, then expand from there.
Answer: If you are determined to post that, the method you describe is the way to go. Whether or not you get any traction for it is a different question.
Answer: I don't really understand what you mean by teaser webpage. Are you actually going to show the profile data on the teaser page?
IF you mean the profile info is used as a teaser to get you to enter into your site. I'd probably start that operation by collecting a bunch of profiles into some sort of useful classification and showing larger lists of the database results. Hundreds of thousands of think little profile pages that do not lead to a directly relevant site are gonna get bounced, with negative ramifications for your whole site.
Comment: It sounds like LinkedIn. They show a partial profile (like name & basic info) but you have to logged in / connected to view everything.


What happens if someone gets a patent granted and starts selling products but someone else had a patent for the same invention before that?

Question: Let's assume Person A gets a patent grant for their invention and starts producing and selling a product based on that invention. After the patent opposition period Person B sues Person A for infringing on their patent, which has been granted way before Person As' patent was granted. Both patents describe the same invention. Who is liable at that point, the patent office that falsely granted the patent or the person seeking a patent grant? Who keeps the monopoly right for the invention? Were there cases like the one described?
Answer: This scenario is rare as examiners are pretty thorough at reviewing their own country's patents. More likely is that the second patent is a refinement of the first.
The important thing to remember is that a patent doesn't guarantee you freedom to operate. If there is an existing patent on your device, it precludes you from using your device without a license.
Comment: Do you know of any scenarios when this happened? In that case, how is it even possible to be 100% sure that you are not infringing on any granted patent?
Comment: It's more likely if both patents are applied for close in time as the applications take time to publish. You can't be 100% sure of avoiding infringement, but a thorough freedom to operate analysis by a patent attorney is usually enough.


Scanning Items into SharePoint

Question: Is it possible to scan documents directly into sharepoint as an attachment to a list form? We are using SharePoint online.
Answer: I've had pretty good luck with KnowledgeLake but there are plenty of other options.
SharePoint Scan and OCR App - seems to be able to take documents already in SharePoint and convert them.
Aquaforest Searchlight
ABBYY
Most of these have OCR software too so you can make the PDFs searchable once they are in SharePoint.

Scanning Items into SharePoint


Django: How do I quote and unquote special characters in the same template?

Question: My app has a 'tags' functionality. I want to allow special characters (like '+' and '.') and, as a result, I need to escape these characters in the url:

But need them unescaped when printing inside of the "a" tag:
{{ tag|UNESCAPED }}

The problem is, I can't seem to find the proper filter to escape the special chars (I've tried "urlencode", but this doesn't seem to do anything, at least with '.'). I've thought about translating special chars inside of my view, but then I would still have to unquote/unescape them when printing them inside of the "a" tag. So how does one go about doing this?
Answer: Maybe try to write Your own custom filter


Is there a way to add external links to images uploaded in media browser?

Question: A customer of mine, when they upload an image through the media browser, want to add an external URL to it. I tried adding the URL to the image field in the image type of media browser but I am not sure how to achieve this functionality.
Comment: A lazy/dirty hack way to do this is to add the link field to the node, and then hide the link from the display and use a theme template to make the media item into a link for that node type. Not pretty, but easy to do using only core functionality.
Answer: 1. How can I add a new field to a media item's form in the media browser?
Media have a 'Media library' Form Display mode - add the new field to this form display and it'll appear when adding the media item through the media library.
2. How can I render the media item with this new field?
Media have View modes, (configurable via the 'Manage display' tab of the media type). The first step is to configure a view mode to display your new field. Then configure your system to use that view mode when it renders the referenced media item.
If the media is added via an entity reference field on a node (or some other entity), configure the node to render the media with that view mode via the node's Manage Display screen.
If the media is uploaded through a WYSIWYG, configure the appropriate text format(s) to render media with the view mode you configured. This configuration is provided by the 'Embed media' filter and is unique per text format. (Text format configuration is found in the Administration menu at Configuration > Content authoring > Text formats and editors.)
p.s. To render the image linked, without custom code or templates, use the Linked Field module.


Isomorphic subgroups, finite index, infinite index

Question: Is it possible to have a group $G,$ which has two different, but isomorphic subgroups $H$ and $H',$ such that one is of finite index, and the other one is of infinite index?
If not, why is that not possible. If there is a counterexample please give one.
Comment: Nonabelian free groups give finitely generated examples, as opposed to taking infinite products as suggested in the answers.
Answer: The other examples are infinitely presented (indeed, generated). That is, they are of the form $G=\langle X; R\rangle$ where $X$ or $R$ is infinite. In group theory, the challenge is often to find finitely presented groups with extreme properties because it is "easy" to find  infinitely presented groups (indeed, finitely-generated infinitely-presented groups!) with extreme properties$^{\ast}$. For example, there exist infinite finitely generated groups where every element has finite order, but all known examples are infinitely presented...or hopfian groups - it is easy to reel of a non-Hopfian group, but finding one which is finitely presented is harder (indeed, the other two answers both give you non-hopfian groups). See this question for the definition and examples of non-Hopfian groups.
So, I now need to give you a finitely presented example. A few things we need to know first, and they are all well-known and proofs should all be easily obtainable (they should all be in Magnus, Karrass and Solitar's book "Combinatorial Group Theory", or can be found on this here website, or you can try and prove them yourself - one of them is pretty easy...).

If a group is finitely presented then every subgroup of finite index is finitely presented,
Subgroups of free groups are free,
If $G$ is a free group of rank at least two then $G^{\prime}$ is the free group of countable rank, and is of infinite index.

Okay, let $G=F_n$ be the free group on $n$ generators, $n\geq 2$. Then $G$ has subgroups of finite index (why?) and these are all finitely presented and free. So, take one of them and call it $F_m$ (as it is free, on $m$-generators). On the other hand, take $m$-elements of the basis of $G^{\prime}$. These are both $m$-generated, and as subgroups of free groups are free and free groups are isomorphic if and only if they are free on the same cardinality of generators we are done!
$\ast$: I say "easy", but I really mean "easier". For example, Ol'shanskii proved that there exist infinite groups where every subgroup has order $p$ for some fixed, large enough prime $p$. His construction gives a two-generated, infinitely presented group. He has a book, which is pretty much 500 pages long, and is basically just the proof. It isn't light reading, either (it is called "Geometry of Defining Relations in Groups").
Comment: @DonAntonio: $F_m$ is of finite index, by assumption. The other subgroup is of infinite index as it is the subgroup of a subgroup of infinite index. If $G<H<K$ then $|G:K|\geq |H:K|$ (with equality if and only if $H$ is of infinite index, because we took the subgroups to be proper as I am too lazy to type $\leq$).
Comment: And how do you know that your $\,F_m\,$ and that group generated by $\,m\,$ elements in the commutator subgroup one is of finite index and the other one isn't?
Comment: For your first paragraph there's also a relevant MO thread *[Finitely presented infinite group with no element of infinite order?](http://mathoverflow.net/questions/78410/)*
Comment: @user1729 Thanx. I misread. Clear now +1
Answer: $\mathbb Z^{\mathbb N}$ has itself as subgroup of infinite index. That is:
Let $G$ be the (abelian) group of all maps $f:\mathbb N\to \mathbb Z$. Let $H=G$ and $H'=\{f\in G\mid f(1)=0\}$. Then $G/H\cong 1$, $G/H'\cong\mathbb Z$ and $\phi:H'\to H$ given by $\phi(f)(x)=f(x+1)$ is "obviously" an isomorphism.
Answer: Yes. For $n\in\Bbb N$ let $G_n$ be a copy of $\Bbb Z/2\Bbb Z$, and let $G=\prod_{n\in\Bbb N}G_n$ be the direct product. Then $H_0=\{0\}\times\prod_{n>0}G_n$ is isomorphic to $H_1=\prod_{n\in\Bbb N}A_n$, where $A_n=\{0\}$ if $n$ is odd and $A_n=G_n$ if $n$ is even. Clearly $[G:H_0]=2$ and $[G:H_1]$ is infinite.
Of course $H_0$ and $H_1$ are both isomorphic to $G$, so I could have used $G$ instead of $H_0$, but I thought that you might like the subgroups to be proper.


Can an object accelerate to infinite speed in a finite time-interval in non-relativistic Newtonian mechanics?

Question: Obviously this is impossible in relativity; however, if we ignore relativity and use only Newtonian mechanics, is this possible?  How (or why not)?
Comment: The question as posed is trivial. If the force as a function of time F(t) integrates to infinity, then of course the answer is yes.
Comment: @Ben Crowell, what is infinite speed? It's nonsense...
Comment: Vector quantities like velocity etc. cannot be infinite. This is meaningless. You should reformulate your question (the title).
Comment: @ANKU: It's not meaningless - please see BebopButUnsteady's answer
Comment: @ANKU One comment about one topic is enough.
Answer: The answer is yes in some unintersting senses: Take two gravitational attracting point particles and set them at rest. They will attract each other and their velocity will go to $\infty$ in finite time. Note this doesn't contradict conservation of energy since the gravitational potential energy is proportional to $-1/r$. This isn't so interesting since it's just telling you that things under gravity collide. But its technically important in dealing with the problem of gravitationally attracting bodies.
Now a more intersting question: Is there a situation where the speed of a particle goes to infinity without it just being a collision of two bodies?
Suprisingly, the answer to this question is yes, even in a very natural setting. The great example is given  Xia in 1995 (Z. Xia, "The Existence of Noncollision Singularities in Newtonian Systems," Annals Math. 135, 411-468, 1992). His example is five bodies gravitational interacting. With the right initial conditions one of the bodies can be made to oscillate faster with the frequency and amplitude going to infinity in finite amount of time.
Added
Here is an image. The four masses $M$  are paired into two binary systems which rotate in opposite directions. The little mass $m$ oscillates up and down faster. It's behavior becomes singular in finite time.
Comment: @AlanRominger: I know this is a very old discussion, but since nobody's responded to it: the trick in the paper is that the orbital periods are tuned so that each time the small body encounters one of the binary systems of large bodies, it steals a little bit of energy from the binary, thus pulling the bodies in the binary closer together (and so reducing their mutual potential energy) while getting flung back with more velocity (and thus more kinetic energy) than it had before. Of course, since momentum is conserved, each encounter also pushes the two binaries further away from each other.
Comment: … Also, since pulling the binary closer together reduces its orbital period, it's possible to arrange the system so that a suitable encounter is always possible even though the smaller body keeps bouncing more and more frequently between the two binaries. In the limit, the semi-major axis of each binary tends to zero (which, for pointlike bodies under Newton's laws, makes their potential energy tend to minus infinity) while each binary is pushed away from the other at a velocity that tends to infinity as a result of ever more frequent encounters with the small body shuttling between them.
Comment: Amazing!  Just the answer I was looking for.  [Here](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.22.4458&rep=rep1&type=pdf) is a link to the paper mentioned, and [here](http://plus.maths.org/content/outer-space-twos-company-threes-crowd) is an article trying to explain it in laymen's terms.  Could you perhaps add some more information about the "five bodies interacting?"
Comment: We can tell the same for atracting point charges. As the distance r decreases the force between them increases. Taking limit $r\to 0$ you get $F\to \infty$, therefore $u\to \infty$. But this means that the speed aproaches the infinity, not that the velocity is infinite. Take a look at definition of the limit.
Comment: I'm having trouble understanding your diagram.  I'm fine with the fact that $m$ is a comparatively small mass, but where does it go when it oscillates to infinite speeds?  Does it get out of the gravity well eventually?  And how do the 2 binary systems maintain the distance from each other?  Is it supposed to be implied that they're rotating, or that they're oscillating as well?
Comment: @Zassounotsukushi Check page 8 of [the paper](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.22.4458&rep=rep1&type=pdf).
Comment: @Zassounotsukushi: Imagine the left-half of the position-vs-time graph `1/t`, with `t < 0`.  No matter what speed you give me, I can find a time `t < 0` where the object is moving at an even greater speed; thus at the limit, the object's speed is infinite.  Xia found a case where, under Newton's laws, this happens *(though the graph behaves a bit more like `(1/t) sin(1/t)`)*.  At `t=0`, there's what we call a singularity; I'm not really sure how to answer the question of where the object is, or what it looks like, at or after `t=0`, partly because singularities don't make physical sense.
Comment: @Blue I take the image here to show a mass moving through the CM of two binary pairs, this means that it does not have the possibility of coming infinitely close to one of the large $M$ masses.  The 1/t sin(1/t) still sees an even greater magnitude derivative and 2nd derivative than 1/t.  If it does not come infinitely close to any other mass, there is no plausible mechanism to have the acceleration increase infinitely.  I've only glanced at the paper a little bit, but on the surface these claims are still incoherent.
Answer: If by "ignoring relativity", you mean ignoring the fact that nothing can move faster than the speed of light, then the answer is still no.
Since kinetic energy is proportional to the square of the speed, infinite speed would mean infinite energy, which you cannot provide, whatever the amount of time you are considering.
Comment: Others have provided simple counterexamples to your statement.
Comment: I'm sure the quest to accelerate to infinity will be easier due to the numerous physically implausible inventions that are possible in this world without relativity :-P
Answer: Lab Reference Frame
Let's start assuming a force is exerted on the object from equipment "lab" reference frame, meaning that there is negligible recoil on the lab frame from accelerating the object.  Not only is it the case that $F=ma$, but the power delivered to the object grows as $P=v F$.  Take a device like the large hadron collider, and just completely wave off the technical difficulty of applying force to an object of progressively increasing velocity, and let's not the following.
$$v' = a = \frac{F}{m} = \frac{P}{v m}$$
The requirement is that $v \rightarrow \infty$ in a finite time.  You know, just for fun let's use an actual functional form.
$$v(t) = -\frac{1}{t}$$
For t from $-\infty$ to $t=0$.
$$P = m v' v = -\frac{m}{t^3}$$
So the power delivered must increase at the hilariously fast rate of $1/t^3$ as $t$ goes to zero, not that it matters because we all knew this would result in requiring infinite energy, but this just shows exactly how intangible it is.
Rocket
In the case of a rocket the propellant has to be hauled along with the payload, but the tradeoff is that you then don't have the $P=v F$ proportionality, since the propellant itself is still moving after being ejected.  The equation of motion for a rocket that starts with mass $M$ and ends with mass $m$, ejects propellant with speed $v_e$ is as follows.  I'll add in the approximation for $M \gg m$, because obviously that must be the case since we're talking about going to infinity.
$$v = v_e \ln{ \frac{M}{m} } $$
This is certainly interesting.  It is interesting to note that the speed the rocket can reach is proportional to the speed the propellant is ejected at, which is also not limited by the speed of light.  The energy required to expel that propellant also isn't a problem (haha) because it is not the case that $E=mc^2$ in this world.  But it would be skirting the problem to say that the propellant is ejected at infinite speed, so we still seek a way for the above expression to limit to infinity with $v_e \neq \infty$.  But we would also really like $\frac{M}{m} \neq \infty$, because that would require either an infinitely large starting mass or an infinitely small ending mass.  Neither of these options are appealing, unless atoms also don't exist in this world, allowing us to use fractal math to claim that an infinitely small chuck of something went to infinite speed.
To the extent that we don't make these absurd assumptions, your request is impossible, even given the already absurd assumption of allowable superluminal speed.
Comment: "Let's start assuming a large reference frame acts on the object." What does this mean? A frame of reference is not an object that exerts forces on other objects.
Comment: Downvoted because it's too limited in imagination --- as the top comment makes clear. There seems to be a great deal of "classical" work that people are in the dark about. You've done a great job of explaining a particular situation, but clearly failed to account for the full general case.
Comment: @Ben Edited the answer for clarity.
Comment: Will somebody PLEASE explain the downvotes, because as far as I can tell this is a useful and thoughtful answer.  If there is something that you know that I don't, of course I want to hear it.
Comment: @genneth That's fair.  I would just add that the case of two passing charges fully satisfies the requirement of delivering the rate of power specified, that being the $1/t^3$ form I gave.  It's interesting to put things in these terms, because it shows that no answer can really be "right".  Since it's a made-up world, quantum mechanics could prohibit the flyby that leads to infinite velocity... or it could not.
Answer: It sounds like the answer is yes for particles with mass but zero physical extent. I assume if the particles have finite extent (or we bring in quantum mechanics), then the answer is no, as it would be if we brought in relativity.


When to use 云う vs 言う?

Question: They're both pronounced the same, and seem to mean the same thing; is there a difference, and if so, what is it?
Answer: Broadly speaking, 云う seems to be somewhat more old-fashioned in use.  It appears with some frequency in Natsume Soseki's works, but not so much in recent publications, which use 言う instead.
The Weblio page giving the Daijirin entry show that the 言う spelling is jōyō, while the 云う spelling is not (the black downward-pointing triangle indicates non-jōyō characters).  Moreover, towards the bottom of the long entry, we get this:

(2) 漢字表記は現代では「言」が主に用いられる。古くは❸ ③ には「云」がよく用いられ,「謂」は「いわば」「いわゆる」の場合に用いられた。
(2) For the kanji spelling, 言 is the main modern usage.  In older times, 云 was often used for sense ❸ ③ [note: prefaced as (「…だと言う」「…と言う」の形で)], and 謂 was used for いわば{iwaba} and いわゆる{iwayuru}.
Comment: NOTE: Due to licensing changes for Daijirin, that dictionary has disappeared from various online dictionary aggregator sites, such as Weblio or Kotobank.  Daijisen is still included (as of 2021-04-19), and their notation for non-Jōyō kanji is a × mark instead.

When to use 云う vs 言う?


How can I display a list of WordPress custom posts?

Question: I am using WordPress 3, and I created a custom post type called article, which gives me the URL format of mywebsite/articles/article-title. How do I see all the article entries in the URL mywebsite/articles?
Answer: Assuming you set up everything correctly and you want to see the post type on a public template page, try this code into mycustomtemplate.php or the equivalent.
<?php $loop = new WP_Query( array( 'post_type' => 'article', 'posts_per_page' => 10 ) ); ?>

<?php while ( $loop->have_posts() ) : $loop->the_post(); ?>

    <?php the_title( '
', '
' ); ?>

        <?php the_content(); ?>

<?php endwhile; ?>

You can customize the loop just like you would blog posts and pages. If you want to get all on one page you'll want to remove the limit of 10 on post_per_page I wouldn't suggest it though. I would say set it to 50 or 100 and still use pages.
Source: Custom post types in WordPress
Comment: How do i make mywebsite/articles use the template mycustomtemplate.php?
Comment: You should be able to add `'rewrite' => array( 'slug' => 'articles', 'with_front' => false ),` to your array when you set up the `register_post_type` variable. See the link I posted as the source above.
Comment: You should also be able to add something like single-mycustomtemplate.php
Answer: I have the simplest solution. Just create file archive-{custom post type}.php and then, just do loop content as usual.
If you already set the permalink, just type yourdomain.com/{custom post type}.
Comment: This works great.  However, I've found that after creating a new custom post type, I have to go into Settings > Permalinks and click Save, which somehow refreshes the cache of permalinks.  Otherwise `yourdomain.com/{custom post type}` gives a 404 error.  Hope that helps someone.
Comment: I'm still getting the 404 even after following Simons instructions. I have the custom post type registered with `has_archive` set to true.
Comment: `If you already set the permalink` how does one do that? I'm seeing 404 too and don't know how to create a page for displaying **list** of posts from my custom post type
Comment: Ejay you can go into Settings > Permalinks and click Save, just like Simon say.
Answer: You can easily achieve this from the definition of your custom post type, starting with WP 3.1. Just set has_archive to true.
Source: http://codex.wordpress.org/Post_Types#URLs_with_Namespaced_Custom_Post_Types