Why does a radial engine need a master rod?

Question: Why does a radial engine need a master rod? Why can't slave rods be the only rods? Would this spider bearing (around 1:05 in the video) work for an IC engine, why or why not?
Comment: The video you link to does not have a master rod and nothing found in my research says that a radial engine will not function without the use of  a master rod. There may be some practical reasons for a master like, like assembly, lubrication, possibly balancing, or something along those lines.
Answer: Having a master rod means that the bottom bearings of the connecting rods follow a fixed path throughout the cycle. If they are all attached to the crankshaft via a spider bearing it  the spider bearing itself has an extra degree of freedom to rotate around the crank bearing, having a master rod constraints this rotation.
Because the con rod bottom bearings are centred at some radius from the centre of crank bearing they will exert a torque when the line of action of the cylinder is not on a direct line through the centre of both. The master rod resists this torque which is ultimately transmitted to the cylinder preventing the con rod bottom bearings from rotating around the centre of the crank bearing relative to the centreline of the master connecting rod.
Depending on the geometry this could potentially lead to collisions between the con rods and cylinder walls and is likely to waste power by making the cylinders fight against each other.
A master rod would not be required if the geometry of the engine is such that the torques on the con rod bottom bearings balance out naturally, this will depend on overall geometry, crank throw, stroke, number of cylinders etc.
Answer: I had the very same doubt, but the things got clear once I looked an animation https://upload.wikimedia.org/wikipedia/commons/f/f5/Radial_engine_timing-small.gif.
Since the 2 plates where all the rods are attached isn't blocked on the crankshaft, but instead it's mounted on bearings, if you had all the rods on these 2 plates running on bearings, at any fire of any cylinder these 2 plates would try to rotate freely over the crankshaft and mess up the entire engine. So you need 1 fixed con-rod in order to avoid this and actually discharge the force on the crankshaft.
Answer: The geometry of the radial engine prevents all the rods from being directly connected to the crankshaft.  All of the cylinders are in a single plane, thus the connecting rods are also in that same plane.
https://en.wikipedia.org/wiki/Radial_engine
Comment: This isn't clear as my why the master rod is used. Also, the example video in the question does not utilize a master rod. Also, wikipedia's animation shows a radial engine without a master rod. Please clarify.


Can I communicate 40 miles away with a base setup

Question: I'm wanting to get a ham radio license and a good base station set up in my home. The reasoning is to communicate to my family approximately 40 miles away from me in case of a emergency or SHTF scenario. What would we both have to have to accomplish this? I am really inexperienced in this field of ham but since this is the reason me and my family both want a setup for both our houses it's important I know what for us to purchase. Thanks so much! -Casey
Comment: What level license do you plan to get?  Any licensed hams at the other end?  What band do you expect to use?  BTW, Welcome to Amateur Radio Stack Exchange; please take the [tour] and read through the [FAQ] to learn more about how Stack Exchange sites work.
Comment: Other considerations are how tall of a tower you can erect both on your end and the other and what sort of antenna restrictions your respective jurisdictions might have.  And cost.
Comment: Ham radio is a great solution to many emergency situations but it is not likely to be the most practical for targeting a particular individual in an emergency.  Since emergencies are never planned, the other end of the comms must be actively listening on a given agreed upon frequency all the time.  I would consider ham radio way down the list for this sort of thing.  Alternatively, assuming that you can communicate with any other party (anywhere) that then can contact your family by other means (phone) then ham radio is an OK solution (but, not the best).
Comment: Another important factor is the geography.  Are there any hills, rises, walls of tall buildings, etc. directly in between the two sites?  Can you mount two 9 dB gain yagi's, 10M AGL or more, at both sites?
Comment: I live on a mountain and there is a lot of Tennessee river between both of our locations. They live in a valley at the foot of a mountain. Hope this helps and I do really greatly appreciate the welcome and all of the comments!
Comment: Me and the family on the other end will acquire any license necessary for the type of ham radio we will need. I live in north east Alabama in Marshall county(Boaz) and they live the next county over in Jackson County Alabama (Scottsboro). We don't have any restrictions in the rural areas we live in on antennas. I plan on having at least a 30'- 50' tower with whatever recommended antenna mounted to it to achieve my goals and them as well. We have foot hill mountains in Alabama unlike the really big and tall mountains like Tennessee.
Answer: With 2 meter FM and common 50 W base or mobile transmitter power and plain vertical quarter wave antenna, range over flat ground to a similar station is roughly twenty-five miles, or forty km (limited mainly by line of sight and horizon scatter).  Raising the antenna will increase this, but not dramatically.  Repeaters in my area that are roundly 1500 feet (~450 m) above average terrain have only about a forty to fifty mile (65-80 km) range to car-mobile rigs of similar power, and then only without intervening terrain.
What you need with the terrain and tower you describe (assuming the mountain your relatives live at the foot of isn't between the two stations) is a directional antenna.  A very modest Yagi at the higher end can give enough gain (both in transmit and receive) to give pretty reliable ground diffraction contact at forty miles (65 km) with fifty watts on 2 meter FM.  This makes you independent of repeaters.
Also very important is to ensure that both stations have emergency power -- at the least, a substantial battery backup, kept charged and tested regularly (a single car battery will run a 50 W transceiver, mostly receiving, for a couple days).
Comment: by the way, very nice 2M yagi directional antennas can be easily DIY-built using materials salvaged from ordinary (old school) VHF rooftop TV antennas. There are several sites on the web with instructions on how to do this. I built one from these plans and with 50 watts on 2 meters, I can hit a repeater almost 80 miles away. If you had two of these on tall poles, aimed properly at one another, you'd be set.
Comment: An excellent answer.  I'd add that one may want to consider adding some kind of digital communications to have the ability to leave some kind of text message in case the person is not at the radio at the time.  I'd also add a mention to consider non-Amateur options like CB, GMRS, or maybe even business band.  I will also emphasize emergency power should be a priority.
Comment: Thank y'all so much that is very helpful I may end up building a nice yagi vs buying one. I ended up this week going with a yaesu FT-2900 radio that is 75 watts. Came in today so have a lot more before I can get it set up. I do have a couple of 12v car batteries I keep fully charged at all times with two power inverters for use of power outages. Would like to get a couple of solar batteries and a few 100 watt panels.
Answer: For VHF or UHF, your range is mostly going to be limited by terrain, like Zeiss Ikon writes. On flat terrain the radio horizon can be estimated by a simple formula, but that's not of much use if the terrain isn't flat.
So, you can use a tool such as heywhatsthat to see what terrain is visible from where. If you have a clear line of sight over the path between the stations, just about any VHF or UHF radio should do. If you only just barely don't have line-of-sight, you may still be able to communicate with enough power and antenna gain.
A more sophisticated method to predicting propagation is the Longley-Rice model. There used to be some free online tools for this, but they've all gone away.
Alternatively, HF ground wave or NVIS could provide reliable communication at this range regardless of terrain. A 100W transmitter and a simple dipole in a tree would do nicely. You can play with VOACAP to run some specific scenarios.
Comment: Thank y'all so much for all the very helpful answers. I now know more of what I need now for us both than before. Now to just decide on what radio to go with. Also do y'all recommend a linear amplifier and if so what kind of wattage do you recommend?
Comment: @Casey for 40 miles, not necessary.
Answer: At 40 miles (65 km), assuming that terrain doesn't get in the way, you have a choice between HF and VHF/UHF.  For HF the radios are expensive, maybe \$600 for a good used one, and a simple wire antenna and coax would cost about \$150.  Several HF radio models also include VHF/UHF.  The antenna could be strung up between two trees. You could talk to half the hams in North America fairly easily, and hams in further places with persistence and skill.  Terrain isn't usually an issue, unless you're deep in a valley.
For VHF and UHF, the radios are less expensive; a good used one can be had for \$100–\$200.  At 40 miles (65 km) you could talk through a repeater with inexpensive omnidirectional antennas (say $80 for the antenna and coax), or directly through directional antennas mounted up high (20' or 6 m would probably do), which might cost \$120 for antenna and coax.  This assumes that the directional antennas are aimed at each other, and that terrain doesn't interfere.  If you get directional antennas, you might also want omnidirectional antennas so you can talk to locals in all directions.
The price estimates are for one radio and one antenna, so if you must also pay for the equipment at the other end then double your estimate.  Personally I'd budget at least another \$100–\$200 for miscellaneous items such as coaxial connectors, rope, shipping fees, nuts & bolts, etc.
I would echo @ZeissIkon's advice about emergency power: radios are useless without it when the power grid goes down.  I'd also suggest joining the local ham community, if for no other reasons than using the radios regularly and learning how to fix common problems.
Comment: Very good advice there on the different bands vhf, uhf and hf. I've went with the yaesu ft-2900 radio. I'm wanting to buy or build a tower to mount a yagi and possibly another antenna for local like you explained as well. I am a prepper and the one thing I have definitely waited on learning about is all the ham radio stuff. So much to learn seems very complicated to a beginner like myself. This post was a great place to start. Thank all of you guys. Awesome community!
Comment: You're welcome Casey!  Please upvote any answers you found helpful, and if you feel that your question has been answered satisfactorily, then you can "accept" one answer by clicking the check mark by the answer.
Comment: You might not need a full-on tower Casey, a pole or a tree might work.  If you have a pole that seems wobbly, you might be able to stabilize it with guy ropes or wires.


How and where are Annotations used in Java?

Question: What are the major areas that we can use Annotations? Is the feature a replacement for XML based configuration?
Comment: Okay, I know this is super-old, but @delfuego: if you're going to tell the OP he's using bounties incorrectly, it might help to follow up by also explaining [how to use them correctly](http://meta.stackexchange.com/questions/16065/how-does-the-bounty-system-work).
Comment: cdb, I'm not sure you totally get the idea of bounties -- you have a bunch of pretty good answers here, and without any clarification of what's missing from them or what you're specifically looking for, you added a bounty.  (You also did this here: http://stackoverflow.com/questions/1746550/purpose-of-serialization-in-webapplication)
Answer: Annotations are meta-meta-objects which can be used to describe other meta-objects. Meta-objects are classes, fields and methods. Asking an object for its meta-object (e.g. anObj.getClass() ) is called introspection. The introspection can go further and we can ask a meta-object what are its annotations (e.g. aClass.getAnnotations). Introspection and annotations belong to what is called reflection and meta-programming.
An annotation needs to be interpreted in one way or another to be useful. Annotations can be interpreted at development-time by the IDE or the compiler, or at run-time by a framework.
Annotation processing is a very powerful mechanism and can be used in a lot of different ways:

to describe constraints or usage of an element: e.g. @Deprecated, @Override, or @NotNull
to describe the "nature" of an element, e.g. @Entity, @TestCase, @WebService
to describe the behavior of an element: @Statefull, @Transaction
to describe how to process the element:  @Column, @XmlElement

In all cases, an annotation is used to describe the element and clarify its meaning.
Prior to JDK5, information that is now expressed with annotations needed to be stored somewhere else, and XML files were frequently used. But it is more convenient to use annotations because they will belong to the Java code itself, and are hence much easier to manipulate than XML.
Usage of annotations:

Documentation, e.g. XDoclet
Compilation
IDE
Testing framework, e.g. JUnit
IoC container e.g. as Spring
Serialization, e.g. XML
Aspect-oriented programming (AOP), e.g. Spring AOP
Application servers, e.g. EJB container, Web Service
Object-relational mapping (ORM), e.g. Hibernate, JPA
and many more...

...have a look for instance at the project Lombok, which uses annotations to define how to generate equals or hashCode methods.
Answer: There are mutiple applications for Java's annotations. First of all, they may used by the compiler (or compiler extensions). Consider for example the Override annotation:
class Foo {

    @Override public boolean equals(Object other) {
        return ...;
    }
}

This one is actually built into the Java JDK. The compiler will signal an error, if some method is tagged with it, which does not override a method inherited from a base class. This annotation may be helpful in order to avoid the common mistake, where you actually intend to override a method, but fail to do so, because the signature given in your method does not match the signature of the method being overridden:
class Foo {

    @Override public boolean equals(Foo other) {  // Compiler signals an error for this one
        return ...;
    }
}

As of JDK7, annotations are allowed on any type. This feature can now be used for compiler annotations such as NotNull, like in:
public void processSomething(@NotNull String text) {
    ...
}

which allows the compiler to warn you about improper/unchecked uses of variables and null values.
Another more advanced application for annotations involves reflection and annotation processing at run-time. This is (I think) what you had in mind when you speak of annotations as "replacement for XML based configuration". This is the kind of annotation processing used, for example, by various frameworks and JCP standards (persistence, dependency injection, you name it) in order to provide the necessary meta-data and configuration information.
Answer: Annotations are a form of metadata (data about data) added to a Java source file. They are largely used by frameworks to simplify the integration of client code. A couple of real world examples off the top of my head:

JUnit 4 - you add the @Test annotation to each test method you want the JUnit runner to run. There are also additional annotations to do with setting up testing (like @Before and @BeforeClass). All these are processed by the JUnit runner, which runs the tests accordingly. You could say it's an replacement for XML configuration, but annotations are sometimes more powerful (they can use reflection, for example) and also they are closer to the code they are referencing to (the @Test annotation is right before the test method, so the purpose of that method is clear - serves as documentation as well). XML configuration on the other hand can be more complex and can include much more data than annotations can.
Terracotta - uses both annotations and XML configuration files. For example, the @Root annotation tells the Terracotta runtime that the annotated field is a root and its memory should be shared between VM instances. The XML configuration file is used to configure the server and tell it which classes to instrument.
Google Guice - an example would be the @Inject annotation, which when applied to a constructor makes the Guice runtime look for values for each parameter, based on the defined injectors. The @Inject annotation would be quite hard to replicate using XML configuration files, and its proximity to the constructor it references to is quite useful (imagine having to search to a huge XML file to find all the dependency injections you have set up).

Hopefully I've given you a flavour of how annotations are used in different frameworks.
Answer: Annotations in Java, provide a mean to describe classes, fields and methods. Essentially, they are a form of metadata added to a Java source file, they can't affect the semantics of a program directly. However, annotations can be read at run-time using Reflection & this process is known as Introspection. Then it could be used to modify classes, fields or methods.
This feature, is often exploited by Libraries & SDKs (hibernate, JUnit, Spring Framework) to simplify or reduce the amount of code that a programmer would unless do in orer to work with these Libraries or SDKs.Therefore, it's fair to say Annotations and Reflection work hand-in hand in Java.
We also get to limit the availability of an annotation to either compile-time or runtime.Below is a simple example on creating a custom annotation
Driver.java
package io.hamzeen;

import java.lang.annotation.Annotation;

public class Driver {

    public static void main(String[] args) {
        Class<TestAlpha> obj = TestAlpha.class;
        if (obj.isAnnotationPresent(IssueInfo.class)) {

            Annotation annotation = obj.getAnnotation(IssueInfo.class);
            IssueInfo testerInfo = (IssueInfo) annotation;

            System.out.printf("%nType: %s", testerInfo.type());
            System.out.printf("%nReporter: %s", testerInfo.reporter());
            System.out.printf("%nCreated On: %s%n%n",
                    testerInfo.created());
        }
    }
}

TestAlpha.java
package io.hamzeen;

import io.hamzeen.IssueInfo;
import io.hamzeen.IssueInfo.Type;

@IssueInfo(type = Type.IMPROVEMENT, reporter = "Hamzeen. H.")
public class TestAlpha {

}

IssueInfo.java
package io.hamzeen;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * @author Hamzeen. H.
 * @created 10/01/2015
 *
 * IssueInfo annotation definition
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface IssueInfo {

    public enum Type {
        BUG, IMPROVEMENT, FEATURE
    }

    Type type() default Type.BUG;

    String reporter() default "Vimesh";

    String created() default "10/01/2015";
}

Answer:
Is it a replacement for XML based
  configuration?

Not completely, but confguration that corresponds closely to code structures (such as JPA mappings or dependency injection in Spring) can often be replaced with annotations, and is then usually much less verbose, annoying and painful. Pretty much all notable frameworks have made this switch, though the old XML configuration usually remains as an option.
Comment: Supposedly annotations can completely eliminate the faces-config XML file for JSF.  Ran across this post while trying to find out how to do that...
Answer: There are 2 views of annotations

user view, most of the time, annotations work like a shortcut, save you some key strokes, or make your program more readable
vendor view, the processor's view of annotation is more of light weighted 'interface', your program DOES confront to SOMETHING but without explicitly "implements" the particular interface(here aka the annotation)

e.g. in jpa you define something like
@Entity class Foo {...}

instead of
class Foo implements Entity {...}

both speak the same thing "Foo is an Entity class"
Answer: Where Annotations Can Be Used

Annotations can be applied to declarations: declarations of classes, fields, methods, and other program elements. When used on a declaration, each annotation often appears, by convention, on its own line.

Java SE 8 Update: annotations can also be applied to the use of types. Here are some examples:

Class instance creation expression:
new @Interned MyObject();
Type cast:
myString = (@NonNull String) str;
implements clause:
class UnmodifiableList implements
        @Readonly List<@Readonly T> { ... }
Thrown exception declaration:
void monitorTemperature() throws
        @Critical TemperatureException { ... }
Answer: Frameworks like Hibernate were lots of configuration/mapping is required uses Annotations heavily.
Take a look at Hibernate Annotations
Comment: Whilst this may theoretically answer the question, [it would be preferable](//meta.stackoverflow.com/q/8259) to include the essential parts of the answer here, and provide the link for reference.
Answer: JPA (from Java EE 5) is an excellent example of the (over)use of annotations. Java EE 6 will also introduce annotations in lot of new areas, such as RESTful webservices and new annotations for under each the good old Servlet API.
Here are several resources:

Sun - The Java Persistence API
Java EE 5 tutorial - JPA
Introducing the Java EE 6 platform (check all three pages).

It is not only the configuration specifics which are to / can be taken over by annotations, but they can also be used to control the behaviour. You see this good back in the Java EE 6's JAX-RS examples.
Answer: It is useful for annotating your classes, either at the method, class, or field level, something about that class that is not quite related to the class.
You could have your own annotations, used to mark certain classes as test-use only. It could simply be for documentation purposes, or you could enforce it by filtering it out during your compile of a production release candidate.
You could use annotations to store some meta data, like in a plugin framework, e.g., name of the plugin.
Its just another tool, its has many purposes.
Answer: Annotations may be used as an alternative to external configuration files, but cannot be considered a complete replacement. You can find many examples where annotationi have been used to replace configuration files, like Hibernate, JPA, EJB 3 and almost all the technologies included in Java EE.
Anyway this is not always good choice. The purpose of using configuration files is usually to separate the code from the details of the environment where the application is running. In such situations, and mostly when the configuration is used to map the application to the structure of an external system, annotation are not a good replacement for configuration file, as they bring you to include the details of the external system inside the source code of your application. Here external files are to be considered the best choice, otherwise you'll need to modify the source code and to recompile every time you change a relevant detail in the execution environment.
Annotations are much more suited to decorate the source code with extra information that instruct processing tools, both at compile time and at runtime, to handle classes and class structures in special way. @Override and JUnit's @Test are good examples of such a usage, already explained in detail in other answers.
In the end the rule is always the same: keep inside the source the things that change with the source, and keep outside the source the things that change independently from the source.
Answer: It attaches additional information about code by (a) compiler check or (b) code analysis
**

Following are the Built-in annotations:: 2 types

**
Type 1) Annotations applied to java code:
@Override // gives error if signature is wrong while overriding.
Public boolean equals (Object Obj)

@Deprecated // indicates the deprecated method
Public doSomething()....

@SuppressWarnings() // stops the warnings from printing while compiling.
SuppressWarnings({"unchecked","fallthrough"})

Type 2) Annotations applied to other annotations:
@Retention - Specifies how the marked annotation is stored—Whether in code only, compiled into the class, or available at run-time through reflection.

@Documented - Marks another annotation for inclusion in the documentation.

@Target - Marks another annotation to restrict what kind of java elements the annotation may be applied to

@Inherited - Marks another annotation to be inherited to subclasses of annotated class (by default annotations are not inherited to subclasses).

**

Custom Annotations::

**
  http://en.wikipedia.org/wiki/Java_annotation#Custom_annotations

FOR BETTER UNDERSTANDING TRY BELOW LINK:ELABORATE WITH EXAMPLES

http://www.javabeat.net/2007/08/annotations-in-java-5-0/
Answer: Following are some of the places where you can use annotations.
a. Annotations can be used by compiler to detect errors and suppress warnings
b. Software tools can use annotations to generate code, xml files, documentation etc., For example, Javadoc use annotations while generating java documentation for your class.
c. Runtime processing of the application can be possible via annotations.
d. You can use annotations to describe the constraints (Ex: @Null, @NotNull, @Max, @Min, @Email).
e. Annotations can be used to describe type of an element. Ex: @Entity, @Repository, @Service, @Controller, @RestController, @Resource etc.,
f. Annotation can be used to specify the behaviour. Ex: @Transactional, @Stateful
g. Annotation are used to specify how to process an element. Ex: @Column, @Embeddable, @EmbeddedId
h. Test frameworks like junit and testing use annotations to define test cases (@Test), define test suites (@Suite) etc.,
i. AOP (Aspect Oriented programming) use annotations (@Before, @After, @Around etc.,)
j. ORM tools like Hibernate, Eclipselink use annotations

You can refer this link for more details on annotations.
You can refer this link to see how annotations are used to build simple test suite.
Answer: Java EE 5 favors the use of annotations over XML configuration. For example, in EJB3 the transaction attributes on an EJB method are specified using annotations. They even use annotations to mark POJOs as EJBs and to specify particular methods as lifecycle methods instead of requiring that implementation of an interface.


For what broad types of statistics are integral calculus useful?

Question: I understand how differential calculus is useful for basic Maximum Likelihood estimation techniques. However, my question is: what broad types of statistics require an understanding of integral calculus?
Comment: statistical intuition!
Comment: @user603 , Can you explain what you mean?
Comment: Could you please clarify what you mean by "statistics"? This word has a technical meaning (a number computed from data) but also has many common meanings covering a wide range. I'm having a hard time appreciating that this question is even appropriate here according to [the site criterai](http://stats.stackexchange.com/help/dont-ask) which (among other things) require that "You should only ask practical, answerable questions based on actual problems that you face."
Answer: Continuous distributions have cumulative distribution functions that involve integrals.  In general
$F_X(x) = \int_{-\infty}^x f_X(x)\,dx$
where $f_X(x)$ is the PDF
Comment: and, by extension, any statistic or parameter that involves moments, correlations, etc.
Comment: This answer would be more helpful with a bit more explanation. A person (like me) who asks about the usefulness of calculus for various unknown statistical techniques is unlikely to fully understand your answer.
Comment: @histelheim Well, you could tell us what you know in your question. Then we could give better answers. We can't read your mind or divine what your background is.
Comment: +1 I doubt we'll see an answer more fundamental than that!
Comment: last line should be $f_X(x)$ instead of $f_X(t)$ (system does not allow to make changes less than 6 characters, and I did not want to spoil this beautifully succint answer!).
Answer: Marginalisation is a fundamental part of Bayesian statistics.  Optimisation can easily lead to over-fitting and integrating over parameters, rather than optimising them, is a good way of avoiding this problem.  This is an excellent motivation for acquiring as good an understanding of integral calculus as you can manage (I wish mine were much better than it is!).
Answer: In addition, for discontinuous density functions, as encountered in continuous - cum - Dirac type delta mixed distributions, another type of integration (Stieltjes integrals) is still needed and useful. On the other hand, if you are looking to solve stochastic differential equations, your knowledge of standard integral calculus will be a hindrance, because you will need to learn either a new calculus (Ito calculus) or know how to deal with spurious terms in your solution (Stratonovitch calculus).
Comment: Are stochastic differential equations related to any type of Markov models?
Answer: If finding the cumulative distribution function does not impress you in your quest for useful statistics, remember that very fundamental quantities like the mean $X$ are obtained as $\int^{+\infty}_{-\infty} x f_X(x) dx$ and the standard deviation as $\sqrt{\int^{+\infty}_{-\infty} x^2 f_X(x) dx - \left ( \int^{+\infty}_{-\infty} x f_X(x) dx\right )^2}$. Skewness and kurtosis also require similar integrations. All these tell you what their universal, i.e., population values are, for an infinite sample set. If you are not equipped with skills for integrals, you will need to stick calculating these quantities from experimental data (finite sized samples), for which you only need to do summations instead of integrations. However, these have inevitable and inherent uncertainty on their calculated values (random sampling error). So, being able to calculate such benchmark values is very useful indeed.


Handlebars wobble when gripping center of bar

Question: My handlebars wobble when I am gripping the center of my handlebars at moderate-high speed.  When holding the grips on the end of the bar it's fine but I like to sometimes give my hands a rest with a center grip.  How can you prevent this condition?
Comment: By not doing it!
Comment: I had something similar happen when my front QR skewer wasn't tightened properly - probably worth checking.
Answer: Check the front wheel rim and tire are running true. Lift the front wheel off the ground and spin it. Looking at the rim and tire where they pass through the fork or rim brake makes it easier to see how much deviation from true there is.
If rim has more than a few mm of deviation, you can get a local bike shop to true it. If the tire is not on straight, deflate it, get it seated on the rim properly and re-inflate. Also check the tire for bulges or damage.
Check you have the wheel fixed in the fork correctly and the QR or thru-axle is done up sufficiently tightly.
Check the headset bearings. Hold the handlebars, apply front brake to rock the wheel and rock the bike forwards and backwards. If you feel any play between the fork and frame the headset bearing pre-load need to be adjusted. There are plenty of guides online that will show you how to do that.
BTW, you probably should not be gripping the bar in the center (right up against the stem) at high speed. You will have poor steering control and will not be able to get on the brakes in an emergency.
Comment: Not exactly gripping the bar at the centre, but aero bars are designed to put your hands near the centre line away from the brakes at speed. Steering control is better than a narrow grip on the bars themselves because of the forward leverage, but nowhere near as good as in the drops.
Comment: That's the reason (lack of control) why the UCI prohibits the use of aerobars in races.
Comment: @Carel being a long way from the brakes is a form of lack of control, and another stated reason for the ban is that they're capable of causing injury in a crash (see also disc brakes, at least for quite a few years)
Answer: Another possible cause is speed wobble, a phenomenon where steering, the frame and your body mass together create a sudden strong oscillation. There isn't a way to prevent it except switching to a stiffer frame, but fortunately it is easy to recover by changing the grip on handlebars or just touching top tube with your leg.
Comment: Speed wobble be exacerbated by a narrow grip on the bars also.


What is the easiest method to study a system as a UX person?

Question: I am assigned to a huge project as a ux design intern, currently this project doesn't have any documentation. And apparently anyone in the project doesn't know  100% of logic and domain of the system except for senior people. my senior wants me to learn all the things within 1 week of time. is there any quick method to do this?
Comment: You cannot do much for 1 week. UX is a whole discipline with a lot of principles and dependencies. If they want you to do this for 1 week, they should not expect great outcome. Ask for more time because you will not be able to produce quality work.
Comment: What's your role in the team ? what methodology is your team following ? how big is the project ? what's deliverable your team expected from you after one 1 week ?. For now, you may check design sprint, understand how you can plan a user-research , understanding of the problem, the context, the environment , target audience.Please share more information.
Comment: thanks for your response.
our client has three major products. even though I had a senior ux person and I am an intern one project is handled by me. previously i used to do only the HTML/CSS part, but now ux related decision making is also a part of my job.
we are following agile methodology.
actually this project is in a working state and I will be working on adding new features, changes and stuff. it is basically a document management system provided by a government with millions of users. currently they don't have any design related document, not even a persona.
Comment: I am assuming you want to start identifying the usability issue on the current system ? so that you and your team will redesign and adding more functionality and feature based on the result of user research and usability testing, is that what the objectives are ?
Comment: yeah, exactly. And also they are expecting to add an e commerce system to the existing site.
Answer: First you must stay as naïve as you can possibly be while you sit down with the system as it is and exercise it without recourse to documentation.
Exercise all of its functions, to the extent that you can figure out what they are.  Do the exercising systematically, and take copious notes about the difficulties you encounter, no matter what they are or how easy they are to get past.  What were you looking for, what did you find, how did you expect it to work and why, how did it actually work, and how hard was it to rewind your mistakes and escape back to where you were before you inadvertently pulled away the support holding up the roof.
You're basically trying to write the story of a fully-naïve but intelligent customer who believes that how to use some piece of software should be discoverable without documentation and without breaking anything, and what happened when s/he met the software.
When you've done that, get the documentation and do it all again, but this time using the documentation.  What role does the documentation play?  Is it trying to make up for things that the software itself should make obvious but doesn't?  Is it basically a reference manual, a tutorial, a marketing document, or something else?  Is it patchy and uneven, showing that too little time was given the writer(s)?  Is it confusing?  Is it accurate?  Is it complete?
When you've done that, you'll have made yourself a virtual customer, and be able to work from that standpoint.  But continue to stay naïve if you possibly can, because gaining expertise is a one-way street.  Once you're an expert, you'll forget how it was to be a novice and you'll no longer be able to find problems that novices find.
Answer: Your overall strategy should be to be curious, ask a lot of questions from different stakeholders in the company and how they work with the product. find out how these people contribute to the product. and their day to day work with the product.
In terms of the product itself, put yourself in the shoes of a user and use the product(s) thoroughly. Do it as a completely new user who as well as an experienced power user. This will help you to come up with flows for each product. when using it, make as much mistakes as possible to identify how the product handles errors and edge cases. also use all the features in various combinations. document all these features.
As you do these a lot of questions and improvements will come to your mind. voice them out and document them.
Answer: I tend to agree with Ameen, stakeholders have the info, even if no one stakeholder has it all. The 2 most important stakeholders for you are the Product Owner and the Business Analyst. If this is an existing solution then you could cheat and ask the UX who architected it. If it's a solution that's only just being designed then a good UX speaks to every department and stakeholder and aggregates and consolidates insight. I assure you, most stakeholders will have different ideas on what the solution is designed to do and how it works - actually, that's one of the reasons you need a good UX, to find and join up all the dots. Once you're happy with what you've been told, the and only then, look at the solution design and see if it fulfills your newly acquired expectations
Answer: It sounds like the system is large enough that you can't learn about the entire thing. I'd suggest you prioritize. Start with the primary user tasks. What's the main reason for people to use your system? What's secondary? Focus on the features that support those tasks.
Hopefully your seniors can give you that info. Another good way to discover how people are using the system is to talk with your Analytics folks.
Good luck.
Answer: In your situation, I would do the following :

Read @MMacD answer, as he highlighted important tips and ideas that you should consider when you are analyzing the current system ( Formative evaluation ).
I advice you to bring all your stakeholders and plan a user research - You might find this tool useful " This tool was introduced by Tomer Sharon"    - The rainbow spreadsheet . This might take a long time depending on the participants to be involved in the research.  Meanwhile and since the product exist, I recommend to do a usability test ( from this test you will evaluate the usability issues,efficiency, effectiveness and satisfaction of the current system) additionally, you can include sus to test overall acceptance of the system. U will learn alot about why/where/how you can improve the experience of the current system.
Once you have all the data " Usability testing result, the users observation, frustrations  and the user research will unveil some important factors, user's goals, the demographics, cultural norms and other things to take in consideration when you and your team going to design/redesign the current system.

This is basically based on Test, build, measure, repeat. If you still want to learn more you can check the following link  also you might watch " Sprint-design by GV " it might help you to do a quick and fast lean user experience with your team.


How can I get the rights to my final year project?

Question: I live in the UK, study Computing and I'm about to start my final year. I have been told by friends that the University holds the right to my final year project. Is there a way of getting the rights and intellectual property of my final year project?
Comment: Did you actually check with the University? What your friends tell you and what the University owns is often delineated by the fine print. At many Universities for example, the University retains a license to use your intellectual property, but you are still free to develop it.
Answer: The first question is why you want the rights.  For example, if you are working on something with serious commercial applications and hope to start a company or sell the technology, then this is a very serious issue.  The first step is hiring a lawyer, who can advise you on precisely which rights you and the university currently hold, and who can help you negotiate with the university regarding commercialization.
On the other hand, most student projects are of no commercial value.  If you just want to display your work online (to help build a portfolio for job applications and in case this work is useful for someone else), then it's probably easier.  It may depend on the university, but presumably they don't want to limit the dissemination of student projects, so if you ask them I bet they'll grant permission.  You should think about exactly what you want to provide and under what sort of license (for example, if you put code on the web, nobody's allowed to use it unless you license that).  I imagine the university would be happy with some sort of Creative Commons license.
I'd recommend being very clear and straightforward when asking, to avoid raising suspicions that you are trying to trick them into giving up the rights to valuable technology.
Comment: Before hiring a lawyer, I'd recommend talking to the University's intellectual property office (or similar) to identify exactly what their rights are. They might be draconian (retain all rights, including ownership) but Universities are usually more interested in helping their alumni get rich through their projects than they are in trying to develop projects for themselves!
Answer: I expect that it differs from university to university, but in general you won't be able to do this unless you buy the rights from them. Somebody in your students' union/student support services might be able to give you a better answer.
Answer: I would double-check on that statement of your friends. If you are not employed by someone to produce some intellectual property, then you will own the copyright to all texts and other material that you create. You are then free to transfer that right to someone else (at least in the UK), or give out licenses.
So unless either

you have a work contract with your university for this project, or
you signed an agreement that the university will own the rights to your project,

I would expect that you retain all rights in the project.
There is one caveat: Any material that is provided to you by the advisor of your project is of course not your intellectual property, and you would have to deal with it as with any external source. This may include even the initial project description, if it is of substantial intellectual value!


Has the syntax of any programming language been usability tested?

Question: Before being release to the public, has the syntax of any programming language undergone usability testing? If so, what kinds of testing was performed, what were the results, and what impact did the testing results have on the design of the language?
Comment: [Studying the Usability of Generics in Visual C#](http://blogs.msdn.com/b/ricksp/archive/2004/02/10/70885.aspx)
Comment: http://www.artima.com/intv/csdes2.html
Answer: From Robert Harvey's comment I found this interesting quote from C# designer Anders Hejlsberg:

Anders Hejlsberg: Most of it was actually usability studies of IDE
  features. We might ask, "Can people understand that they right click
  to do this or that?" We did some usability studies for the pure
  language syntax itself—I think we did some with properties and events,
  for example—but it was not necessary really.
I don't think that you get as high a yield from usability studies for
  language features as for IDE features. IDEs are very interactive. You
  can watch users right click menu items and get good feedback. For
  programming languages, the question is more, "Is it conceptually
  understandable?" That's done very well by having a customer advisory
  councils, sounding boards. You want places where you can say, "Here's
  what we're thinking about doing for this particular new feature. What
  do you all think?" And you actually urge them to shoot as many holes
  in it as possible, because you'd much rather know before you put in
  the feature than after. So unless a language feature is a complete
  slam dunk, we tend to make use of those kinds of sounding boards.
Comment: Anyone who knows C++ syntax will tell you that there is no syntax like C++ syntax.
Comment: C# syntax is basically Java syntax which is C++ syntax which is C syntax...
Comment: "Anyone who knows C++ syntax will tell you that there is no syntax like C++ syntax.": thank God.
Answer: If by language usability you mean how the syntax and semantics of a programming language influences productivity, some studies have been conducted to evaluate the average productivity (time needed to implement a given program and quality of the solution) of programmers using several languages.
You can find some information (with citations of further articles) on this page.
The page has been written by a Lisp programmer so one might argue that it is biased (i.e. that it presents information that is favorable to Lisp). Still I find it interesting to look at how such experiments can be conducted and what one can try to measure. Also, the cited articles may provide more links to related studies.
Answer: One could argue that a "usability test" of Fortran II leaded to a complete new language:  BASIC, which was designed to be more usable (especially for beginners) than its predecessor. If you want to know more about the origins and design goals, there is a whole chapter in this book concerning that topic.
Comment: The book you refer to "Masterminds of Programming: Conversations with the Creators of Major Programming Languages" looks really interesting.  And the Kindle edition is only $13 compared to the paperback at $30.


Is it okay to increase stroke width of a logo for different background?

Question: Usually any line that looks okay on a dark background, looks much thinner on a lighter background. In that case, is it allowed in design principles to increase the stroke width of a logo on a lighter background, to match the visual intensity all around?
Answer: I, personally, don't think it needs increased based upon your sample images.
As for is it "okay".. Ideally no, it's not. Logos should never deviate from any brand guidelines due to a specific usage. But that's a generalization. If brand guidelines don't cover some aspects then there may be call for a new variation (such as reversing). Typically such variations involve color alteration, and not weight alterations.
Without seeing specifically the image you are referring to, In general, I'd suggest perhaps using a reverse version, black rule on light background.
Comment: Actually the main logo I'm referring to, consists of strokes and letters of the exact same width. You are right, increasing the stroke-width does mess up the whole structure, and it can be solved by reversing the colours but, the problem is that the alternate version is supposed to be a car sticker. Now, visual principle says black on yellow has the highest legibility from far. But that's a challenge for stroke based logo, because as soon as I put the logo on a light background, all strokes look thinner.
Answer: There are guidelines to design but they aren't rules that you must follow. Take Superdry for example, they have various logos which they use for specific circumstances. If your logo is black and you're putting it on black paper then obviously you're going to change it.
If it's your logo, do what you want. If it's for a client, suggest the change to them.
For this specific example, I don't there is anything wrong with it being on orange. If you are going to change it make the changes more obvious and intentional so it doesn't look like there is an error/inconsistency in your design.


can spacecraft heat be 'vented' with entangled particles?

Question: Basically, the title. Trying to figure out how reasonable stealth in space would function, and while I have mitigated it, I am looking for methods to improve it. But mainly, is creating a sort of heat sink structure with a sufficient number of entangled particles viable to transfer enough heat to keep a crew-less ship near enough to or at background temperature?
Answer: Particle entanglement has no bearing in hiding heat emissions.
If you want to emit energy with a low probability of detection, use particles that interact very weakly with the normal matter/fields.
I don't know, eject that energy as neutrinos or "highly energetic beams of dark matter".Of course, the current level of science and the reality as we know it don't allow you to use such means, so you'll have to handwave them.
However, it is very unlikely that you could convert heat into high energy neutrino beams - if they interact so weakly with the matter/fields that there are good chances to stay undetected, it will also interact so weakly with the matter/fields that you won't be able to confine or accelerate them.So you'll have to handwave vigorously enough to use them (but not strong enough to generate more heat than you can exhaust).
Answer: Entangled particles share quantum states (stuff they do at the subatomic scale), but have different kinetic properties (how they move through space).  Heat is a form of kinetic energy; so, cooling one half of the quantum pair should have no effect on the other half's temperature.
Another theoretical phenomenon similar to quantum entanglement might work for you though.  Wormholes, like quantum entanglement, do freaky stuff at a distance.  But instead of shared quantum states, wormholes create shortcuts through timespace that make two faraway places simultaneously adjacent.  By connecting a wormhole to a far away cooling apparatus, you could pump cooling fluids between these distant points as though they were physically connected.
Just bare in mind that some theories regarding wormholes say it is impossible to move them or that they can not be created ad-hoc to where you want them to come out; so, you'd need to account for this as well. Best solution I can think of is that your ship has to stop, then it punches a wormhole to whatever random place in the galaxy it can find, then lowers its heat exchanger into the wormhole which may come out just some random place lightyears away.
Comment: Hmmm... unlikely that the spacetime will be so kind to quietly open a stealthy wormhole for you. The levels of energies required for opening a wormhole are likely above the energies emitted by a star, we haven't seen any evidence of this thing happening anywhere. I'm afraid `science-based` and `reality-check` don't let too much room to wiggle the worm able to create an undetectable wormhole.
Answer: hmm, lets see. No or at least not how you think. There is an easier way though: just turn everything off because of the law of conservation of momentum you could just use liquid nitrogen to cool it down and then vent the gas and even with your engines off you wont stop. if you don't want to alert anyone just use heat sinks to radiate off heat. only keeping basic functions on can help it stay cool. no fanciness required, but you would need to spin so it is heated evenly. the  cryogen fluid i suggested does seem like the coolest one tho. i'm no expert at entangled particles but i'm pretty sure they dont act how you think they do.


How did you know when to say "thing haveth or something"?

Question: I have been watching Hocus Pocus and wondered how people in the 1800s knew when to add eth on the end of words.
Comment: They just had a bad lisp.
Comment: You mean thou dost not know?
Answer: The Authorised (King James) Version of the Bible would be a good resource for the old usage, since it is easily obtainable.  The basic paradigm of the present tense in the old system is as follows.  You will note that -eth is merely the third person singular ending of a regular verb:
1st pers. sing. I am, I have, I eat, I speak
2nd pers. sing. thou art, thou hast, thou eatest, thou speakest
3rd pers. sing. he/she/it is, he/she/it hath, he/she/it eateth, he/she/it speaketh
1st pers. pl. we are, we have, we eat, we speak
2nd pers. pl. ye are, ye have, ye eat, ye speak
3rd pers. pl. they are, they have, they eat, they speak
You will commonly see such spellings as "saist" and "saith" for "sayest" and "sayeth."
Note that at this point in the development of English, "you" had not yet replaced "ye" as the nominative-case form, nor had it yet replaced "thou" as the singular.
Note also that you will generally see locutions along the lines of "thou didst establish" in favor of forms such as "thou establishedst."  The latter, while perfectly correct, was too awkward even for such dedicated archaists as the translators of the King James Version.
Answer: I'm pretty sure that '-(e)th' was largely obsolete by the 1800s.  It was an alternative to '-(e)s' in conjugating verbs.  The infinitive 'to run' becomes 'He runs.' in Contemporary English but could also become 'He runneth.' in Early Modern English depending on the dialect of the speaker or which they preferred in the situation.  Over time '-(e)s' became preferred over '-(e)th' in almost all dialects.
Early Modern English also variably used '-en', '-(e)th' and '-(e)s' the same way we use '-(e)s' to mark nouns as plural, which gradually shifted to just '-(e)s' as it did for conjugating verbs, with just a few irregular exceptions ('oxen', 'children')
Of course actual speakers of EME didn't think about rules any more than a contemporary speaker does.  How did they know when to use '-(e)st', '-(e)th', or '-(e)s'  The same way a contemporary speaker knows it's 'I run.' but 'He runs.' (with a few dialectal variations)  That's just what sounds right.
Comment: Actually, you seem to be correct, except maybe for Middle English and not Early Modern English. Consider [this link](http://www.ling.upenn.edu/~kroch/courses/lx310/handouts-09/MiddleEnglishVerb.html). For plural verbs, it was *-es* in the North, *-en* in the Midlands, and *-eth* in the South.
Comment: *They runneth*??? That isn't the usual Early Modern English conjugation (which would be *they run* or *they runne* or *they runnen*) ... do you have any references saying this was actually used?
Comment: @PeterShor I'm basically repeating Wikipedia although to be honest, I'd never heard of that usage either before. (Maybe I misunderstood what was meant by it being used as a plural form marker) https://en.wikipedia.org/wiki/Early_Modern_English#Marking_tense_and_number
Comment: I think I get where I misunderstood it now. The subsection of the article about "Tense and Number" is part of a section about "Verbs" so I assumed they were talking about *verbs*.  I'm pretty sure now that they were describing the plural marker for *nouns*, which makes a lot more sense now.
Comment: Interesting, maybe it's just a matter of someone behind that Wikipedia article having an earlier boundary between Middle and Early Modern.   I'll stick with my edited answer though as something that's at best *early* early modern English probably isn't relevant to a question related to the 19th century.
Answer:
I haven't seen the movie but the non-historical movies I have seen usually have zero idea about the grammar of past times. They tend to add the '-eth' ending randomly just to make the language seem dated.
I could ask you, "How do you know to say, 'I am', 'You are', He is' instead of 'I is', 'you am' and 'he are'?  The answer is that you know the grammar of your own language.
If you have learned French, German or Spanish for example you will know that verbs must be conjugated. The ending of the verb depends on the pronoun. In older versions of English this was true also. In modern English it only applies to the third person singular (he/she/it).

Compare the verb 'to go' in Spanish and in English of the older variety.
yo voy
tú vas
él/ella va
nosotros vamos
vosotros vais
ellos van
I go
thou goest
he/she goeth
we go
you/ye go
they go

The further you go back in the history of English the more complicated it gets.
What happened to English is that various waves of invasion of England by people of different  nationality and different languages gradually destroyed the grammatical structures. At one point, the ruling classes in English all spoke French. Later on educated English academics spoke in Latin when they were discussing academic subjects and in English for ordinary everyday purposes. Modern English is said by many to be a form of pidgin where the word order and context are more important than the strict endings of nouns and verbs.

We lost the ability to speak 'correctly'. If you want to know how to use the old verb endings correctly then I suggest you read about Old English and Middle English.
Also the Bible and Shakespeare are easily available sources of text that are entirely searchable online. They show by example how to use the correct endings.
Comment: Yeah, #5 is fairly disputable. There's been some discussion on this site: [Is English actually a pidgin or creole?](http://english.stackexchange.com/questions/142968/is-english-actually-a-pidgin-or-creole)
Comment: Downvoter. Please explain. Are you voting because of the facts or for some other reason? Constructive criticism is always welcome.
Comment: Hopefully I evened it out with a +1, just because I disagree with a silent downvote here.   My guess is that someone didn't like the discourse in #5.


Straightforward derivation of the sunrise equation

Question: I'm looking for a reasonably straightforward derivation of the sunrise equation$$\cos\omega=-\tan\phi\tan\delta$$as referenced in the Wikipedia article here. I've dipped into Astronomical Algorithms by Jean Meeus, where the formula is given on page 101. However, as far as I can see, the only explanation Meeus gives is by setting $h=0$ in his earlier equation 13.6, which he simply states as if obvious. I've also found an online paper called Derivation of Solar Position Formulae by Ross Ure Anderson, where there is a fuller derivation (starts on page 11), but which I'm having trouble following.
Comment: Would you mind specifying what $h$ is? My guess is it's the elevation, but it would be nice to know for sure. Also, at what point would you like the derivation to start? It's not tricky to figure out if you can start from the conversion formulae between equatorial coordinates and local coordinates (i.e. azimuth and elevation).
Comment: @HDE226868 - His equation 13.6 is $\sin h=\sin\phi\sin\delta+\cos\phi\cos\delta\cos H$, where $h$ is "altitude, positive above the horizon, negative below." $H$ is the local hour angle ($\omega$ in the Wikipedia equation).
Answer: We can start by converting between equatorial coordinates (right ascension $\alpha$ and declination $\delta$) to horizontal coordinates (azimuth $\text{Az}$ and elevation/altitude $a$). If you want to go past this, feel free to skip to the end. We draw a spherical triangle on the sky, with the three points being the object of interest at a given point $X$, the north celestial pole $P$, and the zenith angle of the observer $Z$. Just by the definitions of elevation and declination, you should be able to see that the distance between $X$ and $Z$ is $90^{\circ}-a$ and the distance between $X$ and $P$ is $90^{\circ}-\delta$. The distance between $P$ and $Z$ is then $90^{\circ}-\phi$, with $\phi$ the latitude of the observer. Here's a nice diagram showing the geometry:

Image credit: Fiona Vincent, University of St. Andrews.
The angle between $PZ$ and $PX$ is the hour angle, $H$. We can plug all of the above into the spherical law of cosines to get
$$\cos(90^{\circ}-a)=\cos(90^{\circ}-\delta)\cos(90^{\circ}-\phi)+\sin(90^{\circ}-\delta)\sin(90^{\circ}-\phi)\cos(H)$$
or
$$\sin a=\sin\delta\sin\phi+\cos\delta\cos\phi\cos H$$
which is the formula you say Meeus gave. Now, at sunrise or sunset, the Sun appears at the horizon, meaning it has an elevation of $a=0$; that's just the definition of the horizon and any object on it. This in turn means that $\sin a=0$, so our equation becomes
$$0=\sin\delta\sin\phi+\cos\delta\cos\phi\cos H\implies-\sin\delta\sin\phi=\cos\delta\cos\phi\cos H$$
Rearranging this gives
$$\cos H=-\tan\delta\tan\phi$$
as requested.
Comment: That's a first approximation. Sunrise comes earlier than that and sunset later because of refraction and the size of the solar disk. Calculating H is also trickier because of the equation of time. The wikipedia article, near the end, discusses some of the complexities.
Comment: I know zilch about astronomy, but came upon the sunrise equation the other day and found it intriguing. It never crossed my mind the thing would be derived from the conversion of two coordinate systems, which is rather neat. Thanks.


RPI as forwarding server

Question: I've just got my RPI and im aiming to use it as a server (forwarding sent chars from android device over wifi to arduino) any ideas how can this work(or at least a part of it)?
Answer: You can setup a node.js server (TCP or HTTP) to capture input from your Android over wifi to a serial port where the Arduino is connected.
If your RPi and Arduino are not connected with a cable, you can use BT modules to connect them.
Comment: thanks for the quick answer but by using node.js server can i send back data such as video stream from a connected cam to RPI to the android device?
Comment: I'm sure there's a way to do it, but I'd suggest you go with another solution that fits your application better.

Try taking a look at `motion`, it allows you to stream video from a camera attached to the RPi: http://linux.die.net/man/1/motion

RPI as forwarding server


Sharing Tables between Azure Mobile Service and Azure Website

Question: I want to create a website and a windows 8 app that share the same database. I followed this tutorial to create the website https://www.windowsazure.com/en-us/develop/net/tutorials/web-site-with-sql-database/ and I used the Azure Management Portal to create my mobile service.
Though each of them work perfectly, I cannot get the tables I publish through the web application to show up in my mobile service. And when I connect in my JS app using
<code>var mobileService = new Microsoft.WindowsAzure.MobileServices.MobileServiceClient(
 "url",
 "secret"
 );
</code>
the tables don't exist.
How can I share these tables between the two services?
Answer: the Azure Mobile Services creates its tables under it's own schema (the service name). you have to move your existing tables to this schema and you have to add them in the Azure Mobile Services Portal.
see:  Using existing database with Azure Mobile Services
Comment: I tried changing the schema name before, but I wasn't naming the primary key field "id". Thanks a lot for the link!
Comment: Also, you might want to do something like this to make the website work with the new schema name: http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/e276fb02-ef9b-44eb-b481-699c1c25602d
Answer: Paul Batum, a PM on the Mobile Services team, outlines a quick solution here: http://social.msdn.microsoft.com/Forums/en-US/azuremobile/thread/60764eb6-17d0-4395-a887-2a793b44ce88
Chris Risner, a Developer Evangelist for Mobile Services, also provides a full walk through here: http://chrisrisner.com/Connecting-an-Existing-Database-to-Windows-Azure-Mobile-Services


Politically correct term for *Mutant*

Question: The more I think of it, I don't think mutants would want to be identified as mutants but not all of them will be super heroes or super villains. In a modern western culture, what would the politically correct term for Mutant be?
Comment: Genetically challenged?
Comment: [If you drink milk and don't get sick, you're a Mutant](http://gizmodo.com/if-you-drink-milk-and-dont-get-sick-youre-a-mutant-1583107189)
Comment: Might be a better question for the English StackExchange.
Comment: Well, in point of fact we are all mutants.  Estimates I've seen put per-birth mutations in humans at anywhere from two to 100+.  So it's not that useful a category to begin with.  But I assume you mean "visible" mutations, similar to "visible" disabilities, but sometimes granting greater ability (making "genetically challenged" a poor choice.)  My guess is the "burn them" crowd would dig in on "mutant" (precision matters not to the witch-burning mobs) and mutant-rights partisans would come up with 5 or 6 euphemisms and spend 90% of their time arguing which one will magically liberate them.
Comment: @AndersGustafson  I'm assuming that he wants to create a universe like that of the X-Men but wonders if mutant would be considered prejudicial.  Would another name be more realistic in universe?
Comment: "differently genomed"?
Comment: If this helps any- I considered for a project involving a sub-species of humans with very visible mutations referred to as 'hetero sapiens' (hetero referring to its original definition -different- rather than sexual connotations imposed on it by modern society) The specific changes varied on the individual but I intended they could have offspring with possibly different physical traits.
Comment: I voted to close this question because it doesn't seem to be about worldbuilding.
Comment: I prefer the politically correct term, individual who happens to be Mutant-American.
Comment: @TrEs-2b - are you referring to the "comic" style mutant, within the X-Men series?  If so I think I could try to answer this.  But if you mean a biological mutation, this is semantics and not for WB.
Comment: "differently abled"
Comment: @kingofpanes that's not how subspecies are denominated.  If a scientist name Bailey identified such mutant genes, their name would eventually be *homo sapiens bailei*.
Comment: @kingofpanes also, heterosexuals are called "hetero" *because* they are attracted to the *different* sex.  Ditto homosexuals, whether they be male or female, since the Ancient Greek *homos* means "the same".  (The *Latin* word homo means "human".  Andro- means "male".)
Answer: Scientifically, humans with natural genetic alterations would be Homo sapiens sapiens if they can breed with, and produce fertile offspring from, Homo sapiens sapiens. If they can't, then they would be Homo sapiens deinde. (Deinde is Latin for next, if you're curious.)
Most people don't go by scientific names, however. The average individual instead refers to other individual(s) as he/she/them/we/us/you. There's also countless ways to refer to the gender identity of individuals, not all of which are politically correct, of course.
Laws already account for the generic case: person.
There's no reason not to keep using the term person to refer to both Homo sapiens sapiens and Homo sapiens deinde. Assuming, of course, the latter is legally a person...
Comment: Typically, the production of fertile offspring is set at the species boundary, not the subspecies boundary. So I'd expect it would be possible for *Homo sapiens deinde* and *Homo sapiens sapiens* to interbreed, like *Homo sapiens neanderthalensis* and *Homo sapiens sapiens* are thought to have. If there was a fertility barrier, you would normally change the species name, e.g. *Homo inamabilis*. (*inamabilis* is Latin for unlovable).
Comment: @R.M. I'm not biologist, so you may be right. I'm going off previous discussions on the topic. Thanks for pointing it out.
Comment: @R.M., as you probably know, delineating species is a notoriously tricky problem (https://books.google.com/books?id=ct29BwAAQBAJ&pg=PA8&lpg=PA8&#v=onepage&q&f=false), and it must get even more fraught when you try to do it with individual people. (Is there a practical way to decide whether your spinster aunt or your infertile brother is *Homo sapiens*?) Given that ambiguity, I imagine some biologists would strongly resist terminology that literally dehumanizes coworkers, friends, family, or selves (although others, as your proposed species name suggests, might see things differently).
Comment: OFC you are right but I think the OP is curious how one should refer to someone who is the part of the... err... further evolved community.
Answer: Shadowrun's answer to this is Metahuman.  As the wiki page explains, the word "metahumanity" can be used to refer either to humans (homo sapiens sapiens) and their mutated cousins, or to only the mutated races excluding humans.  Assuming you want a linguistic distinction to be able to talk about mutants without using the word mutant, you'll want to go with the latter case.
You could come up with a variety of similar words that perform the same purpose ("novohuman" for example), but I think metahuman rolls off the tongue better, and meta is a commonly used word in its own right these days, so you'll probably have to do less constant explaining of what you're talking about.
Comment: It will be the challenge of the near future. Metahumans (genetically evolved people) might or might not appear, but transhumans (technologically evolved people) and posthumans (AIs which once has been people and the descendents of those) will surely appear in the next few decades.
Answer: Homo superior is a possibility, if the mutations provide advantages.
If you want something that isn't going to be threatening to non mutants (recommended) then Homo mutandis "The Changed Man" would be better.
Building off of that, Changed might be a good start.
If you look at the history of some of the current politically correct terms, it's kind of a moving target. For the "Intellectual and Developmental Disabled", past PC terms were Cretin, Idiot, Imbecile, Moron, Feeble-minded, Retarded, and others. All these entered the language, and then became insults, which forced a name change.
Answer: As you might expect, there are lots of slurs behind most of the links in this answer.
Given the frequency with which marginalized groups reappropriate slurs, I think it's likely that at least some mutants would call themselves mutants, around each other and maybe also around genotypical people. I think it's equally likely that many hypervariant and hyperabled people would be wary of reappropriation efforts. I expect clinical terms taking on lives of their own, names originating as slang within charm communities, names constructed to emphasize Varied people's friendliness and respectability, names reflecting the gallows humor of the freaks and the Cursed, insipid Latinate terms intended to convey neutrality toward parahumans but crawling with fear and revulsion, and hopefully also enthusiastic co-opting of classic monster movies.
Answer: The most politically correct one would be the one selected by that minority group. In all cases of vernacular syntax, there's a wave of names that will be attributed to a certain group or groups. It follows a fairly recurring progression:

Exterior label
Derogatory label
Corrected Exterior Label
Internally Accepted label

For example, Followers of Jesus were originally all considered
1) Jews in a cult, then were called
2) 'Christians', which translates to "Little Saviors" or "little Christs" by Greeks and Romans, then Romans separated
3) Jesus-Followers from Jews, calling them Followers of the Way, and finally
4) They incorporate the name "Christian" for themselves.
You can see that with other groups as well - 1) Deaf 2) Dumb 3)Hearing Impaired, then they agree on the label 4) "deaf". Something similar happened with people unable to walk (although it took effect over a LONG period of time) 1) Handicapped 2) Lame/Cripple 3) Disabled 4) Impaired.
In your story, there should be a similar progression. For example, if you're in a X-men, Inhuman, Chronicle or similar style of world, that can be a minor plot element. Something like a: 1) Biodynamic 2) Mutant 3) Genetically Different 4) Biodyn.

Politically correct term for *Mutant*


Why are we only electing three moderators?

Question: According to my question from a few hours ago we're potentially replacing our current moderators, which is fine, but it does make me wonder why we are only electing 3 moderators to replace the 4 that we currently have? (@chills42, @Guffa, @jrista, and @Rowland Shaw) Wouldn't it make more sense to at least try to maintain a consistent number of mods moving forward?
Comment: Has any thought been given to spreading them around the time zones?
Comment: @labnut Well, I'm in Europe, if that helps my case :)
Comment: @Rowland, Yes! In principle I think we need moderators in each of the three major zones, 1) American, 2) Europe, Middle East and Africa, 3) Asia. This would allow for timely actions and be more culturally inclusive. But I don't know what our user base is or their geographic distribution so this might be premature. I am sure though, that this will become necessary when our base becomes large and widespread.
Answer: Three is the standard number of moderators for a graduated site.
There will be more elections in the future, generally yearly.
Comment: That's somewhat of a "because I said so" answer, isn't it? ;-) I'm just curious because it seems weird to have 4 Moderators Pro Tem and then have the 'official' elections where 3 mods will now be elected to do the work done previously by 4. I'm not running this time around so I'm not asking because I will have a "dog in the fight," per se, I'm just asking because it doesn't make a lot of sense to me and surely there must be a better reason why its being done this way than "that's just the way it's done, so get used to it."
Comment: I actually think that having more moderators in the early stages makes sense, because there were less people with high enough reputation to manage the site properly.  As more people have earned the ability to vote to close (3000 rep) and acquired access to the mod tools (10000 rep) there is less need for intervention be the moderators for normal activities.
Comment: @Jay I'd suggest that pro tempore mods are unproven and not self nominated, so you might need more just in case one doesn't carry through with the commitment involved. It does mean of course that *at least* one of the mods will no longer be...
Comment: Why is it 'standard'?


Mark seam's shortcut code?

Question: Blender has a lovely system for creating new shortcuts. Can anyone advise me on the code for the "Mark seams" operation? Bonus points for the button-toggle (one button to mark/unmark).
Comment: You may also assign your own buttons to these operations in the same manner as here: http://blender.stackexchange.com/questions/36894/how-to-assign-a-keyboard-shortcut-for-a-mesh-selection-mode
Comment: Two buttons, but you have that on the toolshelf, 'shading/UV' tab. For the shortcut Ctrl+E then choose in the list
Comment: Paul Gonet deserves a plus because he actually showed hot to create the shortcut (even by just pointing to the solution). U wana post an answer?
Answer: Press Ctrl+E and choose "Mark Seam" or "Clear Seam" from the list.
Then, in order to add a shortcut, you can do as explained here: How to assign a keyboard shortcut for a mesh selection mode?
Comment: Please aprove my edit to your answer.
Comment: Btw, for anyone concerned, there indeed seems to be no way for a one-button solution. You would need separate buttons for mark and clear.
Comment: You can also (now?) press ctrl + e then press `m` on your keyboard
Answer: If you are ready to invest a bit more work (Like I did for my Spacemouse Pro), you can also create a Pie Menu with mark and unmark, so you just need to press a key and move the mouse.
https://vimeo.com/103321600
Code you will need is:
pie.operator("mesh.mark_seam", text="Mark Seam", icon='EDGESEL')

pie.operator("mesh.mark_sharp", text="Clear Seam", icon='MESH_CUBE').clear=True

Instead of the sample code with pie.operator_enum...
To register it as an add-on to keep it permanent just use the code below on top of your script
bl_info = {
    "name": "Mark Seam Pie Manu",
    "description": "Edit mode Edge Menu",
    "author": "...",
    "version": (0, 1, 1),
    "blender": (2, 79, 0),
    "location": "3D View",
    "warning": "",
    "wiki_url": "",
    "category": "Pie Menu"
    }

Answer: If i understood the question you want to add shortcut for mark seam
In Edit Mode -> Select the Edge and Press Ctrl+E

and how over the mouse and press right click and select Change shortcut

As soon as u click on change shortcut u get a pop-up press a key

I have selected the dot button from left of the keyboard
Now open user preferences and click the save user settings so that next time when you open blender mark seam setting will not disappear.
Comment: If you copy the entrance at the userpreferences in input/3DView/Mesh you can add even more than one shortcut for the same action (as i recently learned here). This solution is the most simple one you could get!
Answer: In addition to the other answers. what i do is use CTRL + E then mark seam on one edge then for the rest i use SHIFT + R which repeats the last actions. So if you do anything other than selecting the edges like say add another edge loop you need to mark one seam again and then use shift + R to repeat. hope this helps someone, i know this is an old question.

Mark seam's shortcut code?


What is the voltage potential of ground during a short

Question: During a short, is it possible for the voltage potential of the ground to change? Say for example, we short a 9V battery, how does the ground stay at 0V and not become 9V?
Comment: @Dampmaskin that started out a great comment then got lost in well... gibberish to the uninitiated.
Comment: @Trevor_G It well grounded gibberish!
Comment: 0V in relation to what? 9V in relation to what? In relation to ground, ground is always 0V because ground is identical to ground.
Comment: This is a very interesting question.I suspect it can have two answers: one for the ideal world of instantaneous fields and KCL-KVL ruled lumped circuit theory. And another one for the real world of light-speed propagation, distributed resistance and Maxwell's equations ruled EM theory. Food for thought.
Answer: Ground is a reference point so it is always regarded as 0 volts.
Of course in a lightning strike the localized area around the strike can create massive potentials per metre so if you value your life (and the lives of any future children you wish to bear), keep your feet close together if there's a risk of lightning.

Picture source
Comment: +1 for nice graphic.. I always had issue with that though. They tell you in a lightning storm to take shelter but also tell you to keep your feet together. Since you have no idea when it's going to strike in your vicinity that's a bit of a catch-22. Maybe they should tell us to hop on one foot to safety ;D
Comment: @Trevor_G prisoners on chain gangs manacled at the ankles had their prize possessions much more protected!
Answer: Circuit ground is just some point from which we measure or reference voltages. If you like, it's the point where you connect the black lead of your multimeter. All other voltages can then be measured with respect to that point.
It should be clear from above that if you connect the red lead of your multimeter to the circuit ground that it will always read 0 V no matter what is happening to the battery. (In real life it can be a little more complex if there is a current flowing in the ground circuit and there is some resistance between the two points.)

simulate this circuit – Schematic created using CircuitLab
Figure 1. Both VM1 and VM2 will read zero volts. Battery internal resistance limits the current flow.
Answer: The resistance of standard PCB foil is 0.0005 ohms (500 microOhms) per square of foil ---- for any size square of foil.

simulate this circuit – Schematic created using CircuitLab
Each square is 0.0005 ohms. To exit the entry point, there are 8 surrounding squares, thus R of that first ring of square is 0.0005/8 = 0.00006 ohms. Then the next (3x larger) ring adds another 0.00006 ohms. Etc. But in the larger rings, the current is mostly heading toward the DESTINATION output node, and not all squares get equal current density.
Comment: What are you basing this on?  I agree changing the width and length together maintaining a square makes no difference because the length without doubling the width you have doubled the resistance  but no-longer have a square to make it square again you half the resistance so are back where you started but depending on what I need I use between 1/4oz and 4oz (per square foot) copper and that makes a big difference. What in this context is standard?
Answer: Ground is just a reference point, it does not need to be an actual connection to the earth.
When you short a 9 V battery, things which you can normally ignore (like the battery's series resistance) come into play. This prevents the ground potential from changing depending on what you choose as your ground reference point.
In the left circuit, the 1 ohm series resistance of the battery can be ignored as the resistance of the load is 100 times higher. R1 doesn't do much really.
In the right circuit R3 does come into play, it limits the current which will flow. The full 9V will be across R1. The ground will still be 0 V, it cannot even change as ground means that it is 0 V by definition.
Theoretically if you had an ideal battery with zero series resistance, an infinite current would flow if you shorted that ideal battery. But also then ground remains 0 V.

simulate this circuit – Schematic created using CircuitLab
Answer: The term "Ground" has historically meant ground literally: an electrical connection to the earth itself, typically via a rod driven into the earth.  This was used in power and telecom systems to obtain a voltage reference, and sometimes as a current return path.  In electronic circuits, the term has persisted and is typically used to denote the negative side of the power supply, even in cases where the circuit is isolated from the actual earth ground.  In circuit analysis, "Ground" is often used to specify a reference point from which other circuit voltages are measured; therefore it is by definition at zero volts.
In the 9V battery example, suppose you specify the negative terminal as Ground.  If you short the positive terminal to Ground, a current flows through the short circuit, and the positive terminal will be (nearly) at zero volts, since a physical battery, unlike an ideal voltage source, has an internal resistance.
Answer: Ground and Earth are often confused. Personally I only refer to Earth as a connection to to the local electricity supply earth which is literally connected to the planets ground as pointed out by others.
Ground on the other hand means a circuit reference and may, but is not required to, be connected to earth.
Consider the circuit below we have two volt meters what do they measure?
VM1 if sensitive enough should measure a positive voltage because there is current flowing in the connection between its inputs.  Theoretically we have zero resistance so no matter how many amps are flowing out of the shorted battery it should be zero but we never, except possibly with super-conductors, really have zero resistance.
VM2 does not see the drop from the battery current so sees 0V as expected.
We talk about 'local grounds' for this reason each bit of circuit cares about the point it is referenced too which may not be the same everywhere if significant currents are involved or at 'high' frequencies due to inductive effects.

simulate this circuit – Schematic created using CircuitLab


How does having bent antenna impact reception?

Question: I have heard that when an antenna is bent, it can reduce the performance of the antenna and thus limit the range of a drone. This is mentioned in this video at 5:29. I am wondering why a bend in an antenna would cause this loss of RF signal? And how significantly would having slightly bent antennas on an XM+ receiver actually impact the range of a drone?
Answer: Antennas are weird and the answer isn't really clear cut.
As long as the wire within the antenna isn't damaged, it should work fine (1, 2).
Sometimes bends in antenna can improve it, like with NASA's Evolved antenna for the ST5 spacecraft.
Answer: Antenna design is typically done to tune the transmission to a combination of specific wavelength frequency and polarity. In the case of whip antennas like those usually used on radio receivers, these are monopole antennas tuned to the 2.4ghz band (at least, the FrSky ones are. Some radios transmit on other frequencies).
By bending the antenna, you change it's ability to radiate on the proper frequency. Generally you will still get some energy on the desired frequency, but the signal will be worse because it is less efficient. It's worth noting that this only applies to the active element; in the case of the whip antennas, the black cases portion is simply feeding the short clear cased bit at the end. The only part that matters for signal strength is that bit at the end, assuming you don't damage the wire in the black cased portion.


Segwit Addressed from xpub key

Question: How can i get the public key of my segwit address with my extended public key. when i import the xpub into electrum it automatically creates a legacy wallet for me. i'm not with my nano and won't be with it for a while, please how do i go about it, thanks.
Answer: You have to convert the xpub into p2wpkh or p2wpkh-p2sh format. You can use this script to do it.
Comment: I have no idea how i am meant to run that script, can you please guide me?
Comment: see the readme file. you have to run it with the python3 interpreter in a terminal/shell.
Answer: You should change derive path to 49 instead of 44. if you are planning to use bech32 addresses then you should make your path 84 but it's not supported yet on electrum.
Comment: Thats the problem it doesn't let me choose the derivation path, it goes straight to creating the wallet when  i put in my xpub key
Comment: you should use the mnemonic phrase to import your wallet because I think they assume the path is 44 for that xPUP
Comment: As i said in my original post, i am not close to my ledger or my seed i just want to monitor my address, please do you know another way?
Comment: if you have your addresses you can add it to electrum as (watch-only) so you watch it.
Comment: I only have the xpub, i thought that was all i needed and when i import into electrum i get the legacy address and i use segwit.

Segwit Addressed from xpub key


12-hour layover in Paris, 10 pm to 10 am

Question: I will have a 12-hour layover in Paris Charles de Gaulle on August 21/22, between 10 pm and 10 am. What to do in the middle of night? Is it relatively safe to take a train or taxi into Paris and go for a late dinner and sightseeing? Are there sightseeing companies to take me around from the airport into Paris and back at that time of night?
Comment: Adding details of what terminals you arrive/depart from, the airlines involved, whether both flights are on the same ticket, if you have checked luggage, and you nationality would help giving you a better answer. Please edit your question with the relevant details.
Answer: I think the biggest problem you will have is getting out of CDG and into the centre of Paris quickly enough.  In all likelyhood, if you don't land until 10pm, it is going to be 11:30pm or midnight before you are in the centre of Paris.
It is not impossible to eat that late in Paris, just harder to find something decent.
As for sightseeing, a quick search online revealed there are nighttime tours, just not that late.  Some museums are open late, but again not that late.  The Metro & RER typically runs until ~1am.
Paris though is an attractive city at night and you can probably put together your own walking & taxi tour, or maybe you could rent a bike (though the Velib Metropole scheme has had some troubles recently).  I do wonder though if that is sufficient to fill the entire night.
Lastly, getting information or help that late could be difficult.  Do your research before you arrive and come up with a plan.
Getting back to CDG by 8am shouldn't be a problem.
Comment: Thank you very much, Nick. This gave me some ideas. I already had researched the nighttime tours too and ran into the same problem. I was also thinking of just having a meal in Roissy, the town where the airport is, but the restaurants seem to be closed by the time I get out of the airport. A walking and taxi tour may be my best bet. How safe is walking in Paris in the middle of night as a female, I wonder. I have travelled a lot and am quite brave, but I don't want to be stupid either...
Comment: How safe is Paris?  There didn't seem to be too many "crazy types" when I lived there, but that was more than 10 years ago.  I felt quite safe, but it is hard for me to give a fair assessment because I'm quite a big guy; and I appreciate it is certainly different for a female.  Of course there is all the standard advice for tourists in a new city and as you would expect those risks increase at night.  If you are careful with your personal space, aware of your surroundings, and avoid dark areas and rough parts of town, I would like to think you would be OK.
Answer: First all, you'll have to check you have the appropriate paperwork to actually enter France. For many citizenships you don't need anything, for others you may need to arrange a visa ahead of time.
Also, you need to check if your luggage is checked through (both flights on the same ticket, and the stop counted as a layover, not a stopover). If you need to collect your luggage, you probably won't be able to check it back right away (though the rules vary depending on the airline for the second flight), and you would then have to carry it with you.
The next step is to get to Paris. You can take a taxi, ride the RER, or take Le Bus. For the last two (especially the RER), check schedules ahead of time, and be attentive to any service changes due to track works which may affect those schedules.
If you have luggage and/or if you want to get a few hours sleep, you'll have to get to a hotel (you want to book that in advance and make sure they have a 24h reception, which is the case for larger hotels, but not necessarily for the smaller ones).
If you want to eat, there are few options to eat that late. I would recommend Le Pied de Cochon near Les Halles (close to the Louvre), which is open 24/7 and where you will find very typical french fare.
You may find a few (probably overpriced) places on the Champs-Elysées, but otherwise, other than fast food outlets, the choice will be pretty limited at that hour.
Depending on where you eat and sleep, you could have a nice walk through Paris. Many monuments stay brightly lit and you could see quite a few things. You could for instance start from Le Pied de Cochon, walk towards the Seine, and take a right along the Seine until you reach the Eiffel Tower, then walk up the Trocadero, take avenue Kleber to the Arc de Triomphe. It'll probably take 2 good hours.
Don't forget to fully charge your phone beforehand and take a power bank, between photos and maps you'll probably drain the batteries.
Then get a short night's sleep, and get back to CDG in the morning.
Comment: thank you very much, jcaron. That gives me some great ideas! No problem with entry into France. I live in the US but have a German passport. Luggage will be checked through. I will be flying in from Vienna and have the layover on my way back to California. Again, thank you very much for taking the time to answer.


Can knowledge of robot's dynamics help in motion planning?

Question: Some planners assume a kinematic model of the robot for example diff drive or omni directional etc. while generating motion plans for the robot. Can knowledge of the dynamics of the robot help generate better motion plans ? If yes, why is this not typically done apart from the difficulty in identifying or coming up with such models ?
Answer: Yes it helps but it definitely adds complexity to the planners. Depending on the wheel configuration, how many wheels, the mass of the robot, the moments of inertia, same as the mass of the wheels, moment of inertia of the wheels, and friction as well. All this parameters add more complexity that is hard to generalize. For this reason all these planners assume a robot that follow the specified velocities to a certain accuracy - the low level controllers take care of this part, while the planner acts as a high level controller.
As an extra you can take a look at this video of Disney that improves the trajectory tracking of its animatronics by knowing their dynamic model.
https://www.youtube.com/watch?v=Z1jgaEO9aRs


Text Classification on a very small data set with a lot of classes

Question: I have a data set consisting of 455 rows spread over 21 different classes. The data set is imbalanced as well as you can see below.
<code>job_alerts                    45
howto_apply                   40
application_status            31
salary                        30
job_close_date                30
multiple_role                 27
feedback                      26
assessment_campatilibility    24
interview_reschedule          23
disability                    22
reinstate_application         19
job_account_issue             19
assessment_link_problem       16
age_limit                     16
assessment_timebox            16
cv_past_experience            15
late_for_interview            13
interview_response_time       13
work_experience               11
assessment_validity           10
special_needs_at_work          9
</code>
I'm trying to perform classification on this. Firstly, when preprocessing the data I convert the text to lowercase, remove stopwords and punctuation and convert words to their lemmas using spaCy.
So far, I have tried the TextCategorizer in spaCy which uses a simple CNN for classification and I'm getting around 70% accuracy on an 80-20 split of the data. I have also tried various Sklearn algorithms such as SVC, LogisticRegression, RandomForestClassifier and MultinomialDB with the  TfIDVectorizer. I have used GridSearchCV to tune the parameters. The best results I get are with SVC at around 74-75% accuracy.
I want to know what else I can try to improve my accuracy. I am a beginner to NLP and I haven't worked on something like this before. Right now the ideas I have are to improve the TfIdVectorizer through some parameter tuning and to try a One vs all classifier for SVC. What else can you suggest to me?
Answer: Accuracy is not the best measure for imbalanced data. Prefer precision and recall.
Do undersampling/oversampling to get equal samples for each class and try XGBoost.
Or else you can use SVC with class weights, give lower class weight to classes with more samples and vice versa.


has Geomagnetism being used for generation of electricity?

Question: I have invented a device which uses earth's magnetic field to generate a good and usable amount of electricity more efficient than solar cells.Is this device patent-able or this has been already patented?
Comment: If the device work and more efficient than solar cells then it is worth every trouble .And usable energy from geomagnetic field ! You may get much more than Patent as quoted by Maca
Answer: I know nothing about the prior art in this field. That is something which really can only be assessed by a patent search. Nevertheless, I would be reasonably confident in assuming that there is no enabling prior art in this.
Assuming my assumption is correct, your invention would in principle be patentable. However, it would not have an easy ride.
A patent will only be granted in the US if an invention is useful (35 USC § 101). This is usually a low bar. However, it is particularly salient when it comes to machines which produce "free power".
There is a long discussion about the requirement for usefulness at MPEP § 2107. However, one passage which succinctly summarises the position would be:

Rejections under 35 U.S.C. 101 based on a lack of credible utility have been sustained by federal courts when, for example, the applicant failed to disclose any utility for the invention or asserted a utility that could only be true if it violated a scientific principle, such as the second law of thermodynamics, or a law of nature, or was wholly inconsistent with contemporary knowledge in the art.

I suspect that your invention would be regarded as wholly inconsistent with contemporary knowledge in the art. Therefore, if you applied for a US patent, I would expect you would receive an objection that your invention is not useful. You would then be required to provide sufficient evidence to prove that your invention works in the manner you suggest it does. This may involve testing by an independent agency.
If you can show that your invention works to achieve a useful result, I can't see any reason why you couldn't get a patent for it. But if you can generate a substantial amount of free power from the Earth's magnetic field, I suspect getting a patent would be the least of your achievements.