Imported model has odd wireframe color

Question: I have a model whose file type is 3D Object that i imported into blender as an OBJ. In object mode it looks fine but in edit mode the wireframe has an odd blue and black checker pattern. Can i make it look like the default black?
Answer: In Edit Mode, Select all - A, press CTRL+E > Clear Sharp.
They are Marked Sharp and this is why it looks like this. It happens sometimes when importing .OBJ files or other formats.

You can also check Data tab > Geometry Data for Custom Normals, they can cause troubles but they can also be good. So if want to get rid of them choose Clear Custom Split Normals Data.
Comment: @evanf if my answer helped you consider accepting it and upvoting.

Imported model has odd wireframe color


Can I use a NEMA 6-20r on a 15amp circuit?

Question: I just bought a new window unit and it has a NEMA 6-15p. My previous unit had heat also and therefore was on a 30 amp circuit on 8/2. I've always been told that using a bigger wire is never a problem since the max load is whatever the breaker is so I figured it's ok to just switch the breaker and receptacle, right? I got a 15a breaker, but they were all out of 6-15r so I got a 6-20r instead. Does the same rule of the wire apply for the receptacle as well?
Answer: TL;DR No
Wire is behind-the-scenes and totally generic. So bigger wire is OK - it will still do the job, and in fact will do the job better in a way that matters on really long runs (voltage drop). And nobody sees it so it will not affect what devices are connected.
A receptacle is a different story. In this particular case, it is not by itself a point of failure - it can handle anything plugged into it (15A or 20A). However, it can lead to two some real problems:

Nuisance Trips

If a future owner wants a more powerful unit and sees the 20A receptacle, they may (legitimately) buy a 20A unit, which could pull 16A continuous. That won't affect the wire (because it is oversized) but on a hot day running for long periods of time it will cause periodic nuisance trips of the 15A breaker. That will (a) annoy the owner and (b) eventually wear out the breaker, possibly in a dangerous way.

Extensions

A future owner could, incorrectly, assume that the 15A breaker means "14 AWG wire OK". After all, they will see the 8 AWG wire and know that is oversized. So when they decide to move the receptacle (e.g., to a different window) and extend from the existing location, they could splice in 14 AWG wire (fine for 15A) into the existing receptacle box and move the receptacle to a new box a significant distance away. Then another future owner uses the 20A receptacle to its fullest and instead of nuisance trips of the 15A breaker, ends up with overheated 14 AWG wires, possibly causing a fire.
Note that there is an exception in the other direction. You can have a 15A receptacle on a 20A circuit, provided there are at least two receptacles on the circuit. That is allowed so you can have, for example, two kitchen or bathroom appliances (one using a lot of power like a toaster or a hair dryer, one much smaller) running at the same time on a 20A circuit. All 15A duplex receptacles are designed to handle this. But you can't do the reverse - 20A receptacle on a 15A circuit.
So go back to the store and get a 20A breaker, or go to a different store and get a 15A receptacle.
Comment: Actually there is a code requirement to have a minimum of 2ea 15 amp receptacles on a 20 amp circuit. a single duplex fulfills this requirement as all 15 amp listed receptacles, switches, light fixtures, and devices are rated for use on a 20 amp circuit but in the case of a switch you cannot exceed the 15 amp load rating but they can be used in a 20 amp circuit.
Comment: No, that's fine. 6-20 (and for 120V, 5-20) *receptacles* are designed to safety accept both 6-15 and 6-20 *plugs*. On the 120V side, that is what lets you plug your phone charger or ordinary computer (some big servers have 20A plugs) or lamp or radio or TV or whatever into a 5-20 receptacle (not that common in homes but extremely common in commercial buildings). Perfectly fine and safe.
Comment: Thanks for the response! So it's ok to use a 20 amp breaker AND receptacle even though the unit calls for 15 amp and has a 6-15p? I figured that might be a hazard in some way, making it not trip when it should and frying the unit or something.


Is it appropriate to reschedule a phone interview?

Question: This past Sunday I was contacted by a recruiter to schedule a phone interview for later this week at 1:00 PM. However, she just notified me that the time will actually be 4:00 PM, because she didn't take into account that the interviewer will be in a different time zone (1:00 PM their time, 4:00 PM my time). Unfortunately, I have another appointment during that time, and cannot take the call without canceling the meeting. Is it appropriate to ask to reschedule for earlier in the day or a different day?
Comment: "(1:00 PM my time, 4:00 PM their time)" Wait, does this mean the time hasn't actually changed for you at all? Or did you have these backwards?
Comment: @TheSoundDefense, yes I had them backwards
Comment: I would be put off by a recruiter that phones me on a Sunday, and the fact that the recruiter missed details is another warning sign. A recruiter is your ambassador to an employer. They give the employer the first impressions of you before they even see your resume. If you want to be professional then find professional representation.
Comment: @MathewFoscarini - I am sure you never make a mistake... as for calling sunday, not everyone works an american standard workweek.
Comment: I didn't intend to offend. Sorry. I just wanted to indicate that a recruiter represents you and impressions matter.
Answer: Yes, it is appropriate. Your recruiter does not expect you to drop all of your commitments at a moment's notice for a phone interview. Tell them you have a conflict that you can't get out of, and suggest some more appropriate times or dates as a jumping-off point for rescheduling. Any company worth working for will be understanding of this.


Terminal name changed to 'Name@dhcp-xx-x'

Question: I have no idea what dhcp means, so I don't know why instead of just showing 'Name ~' as the beginning of each terminal line, it started showing 'Name@dhcp-xx-x' as the format of my username. Is this a virus or did I just accidentally change this? How do I undo it?
Answer: It is not a virus, nor did you actually change it yourself.
The prompt by default begins with the hostname of your computer. The host name is found by doing a so called "reverse lookup" in DNS of the IP address of your computer.
Every time you connect to a network, you'll get an IP address. The provider of that IP usually determines what the reverse lookup will say. Usually it is your internet provider.
Your ISP has thus chosen "dhcp-xx-x" as the hostname. It probably has some internal meaning to them.
DHCP is the name of a protocol used on networks to automatically deliver IP-addresses (and other configurations) to computers. Seeing this in your hostname typically means that your ISP used DHCP to deliver the IP and accompanying configuration to your computer.


Reason why the name Ben Tziyon is a Segula for a long life

Question: I saw in Igros Kodesh 11, page 73 mentioned in the Chida in the name of the Yerushalmi that the name Ben Tziyon is a Segula for a long life and good years. What is the reason that this name has such a strength?
Comment: It looks like the Chida's statement is in Shem Hagedolim volume one, in the Kuntres Acharon on Ma'arechet Bet. It appears that Hebrew Books does not have a version with the Kuntres Acharon, although I could just be looking in the wrong places. Here's a link to one of the Sefarim on Hebrewbooks.org (there are several): http://hebrewbooks.org/30594
Comment: Thanks to the wikipedia article http://he.wikipedia.org/wiki/%D7%A9%D7%9D_%D7%94%D7%92%D7%93%D7%95%D7%9C%D7%99%D7%9D, I found a much better version here: http://daat.ac.il/daat/vl/tohen.asp?id=306 . It does have the Kuntres Acharon, but it doesn't give much more information (page 6 of this pdf: http://daat.ac.il/daat/vl/shemhagdolim/shemhagdolim05.pdf )
Answer: The segula that the name "Ben Tzion" is associated with long life is also brought by R' Rachamim Nissim Yitzchok Palagi in Yafeh La-Lev (Chelek Gimmel Y.D. Siman 265 Ois 7). He connects it with two Pesukim in Tehillim:

שיר המעלות הבטחים בה' כהר ציון לא ימוט לעולם ישב - A song of ascents. Those who trust in the Lord are like Mount Zion, which will not falter but will abide forever. (125:1)
כטל חרמון שירד על הררי ציון כי שם צוה ה' את הברכה חיים עד העולם - As the dew of Hermon which runs down on the mountains of Zion, for there the Lord commanded the blessing, life forever. (133:3)


How do I set up a one layer custom tile in Leaflet

Question: I am new to Leaflet and I have a large image which I have been attempting to break up into tiles and save them using the correct filenames so that they can be displayed using Leaflet's tileLayer.  I am trying to keep it simple first by breaking up the large image into just one layer of tiles.  But I have not been able to get Leaflet to load the tiles correctly.  Can anyone show me how a one layer custom tile should be set up in Leaflet?
Answer: When your map is not georeferenced, you can follow this tutorial first for georeferencing it.
Now you can use gdal2tiles.py to create the tiles for your image. As a result you get a folder with all tiles from your image. gdal2tiles can be installed e.g. through the OSGeo4W Installer.
Now you can add this folder to your map with only some code lines:
<code>L.tileLayer('./folder/path/{z}/{x}/{y}.png',
{
  tms:true
}).addTo(map);
</code>
If there is no need to use "real coordinates" you can also try this plugin to gdal which makes it a bit easier to work with plain non-georeferenced maps in leaflet.
Comment: Although the image is a map of the U.S. (in Lambert Conformal projection), I don't think it is georeferenced.  How do I make it geo-referenced?  Alternatively, can I use tileLayer for non-georeferenced tiles?  Thanks again.
Comment: @kykong Do you want to visualize only your map or do you want to show additional "real" geodata like a map in the background and streets or railways as overlays on your map?
Comment: Yes, I basically just want to visualize my map in Leaflet.  It would be great if some geo-referencing capability (such as the latitude/longitude) is available but I can go without it.
Comment: Alright, I added a solution for both ways to my answer.


Android: How to determine Network speed in android programmatically

Question: How to show a slow internet connection to the user when the network is connected
Note: Not a network type (2G,3G,4G, WIFI)
Comment: https://developer.android.com/training/basics/network-ops/managing.html
Answer: Determining your Network Speed - (Slow Internet Speed)
Using NetworkInfo class, ConnectivityManager and TelephonyManager to determine your Network Type.
Download any file from the internet & calculate how long it took vs number of bytes in the file. ( Only possible way to determine Speed Check )
I have tried the below Logic for my projects, You have also look into this, Hope it helps you.
ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    //should check null because in airplane mode it will be null
    NetworkCapabilities nc = cm.getNetworkCapabilities(cm.getActiveNetwork());
    int downSpeed = nc.getLinkDownstreamBandwidthKbps();
    int upSpeed = nc.getLinkUpstreamBandwidthKbps();

Comment: this requires API level 23
Comment: I too got the same values.
I think this will not work, as it may only return the maximum bandwidth supported by the network. In my case, it returns 1048576, i.e. 1Gbps, that is not possible in the network to which I connected. Second thing, the class name "NetworkCapabilities" itself says that capabilities of the network, so it's telling the maximum capabilities of that network.
Comment: This does not work as they have said it returns the maximum upload and download speed of the network
Comment: This requires API level 21
Comment: getLinkUpstreamBandwidthKbps and getLinkDownstreamBandwidthKbps in differente network always return same value. Why?
Comment: This does not give the actual speed. "Retrieves the up/downstream bandwidth for this network in Kbps. This always only refers to the estimated first hop transport bandwidth." If you have 1 GB router, this is always going to return that max of over 1m kbps. Not actually helpful for detecting speed - only potential. https://developer.android.com/reference/android/net/NetworkCapabilities
Answer: Check internet speed for mobile network to use this code
ConnectivityManager connectivityManager = (ConnectivityManager)this.getSystemService(CONNECTIVITY_SERVICE);
NetworkCapabilities nc = connectivityManager.getNetworkCapabilities(connectivityManager.getActiveNetwork());
var downSpeed = nc.getLinkDownstreamBandwidthKbps();
var upSpeed = nc.getLinkUpstreamBandwidthKbps();

If check internet speed for wifi network to use this code
public int getWifiLevel()
{
    WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
    int linkSpeed = wifiManager.getConnectionInfo().getRssi();
    int level = WifiManager.calculateSignalLevel(linkSpeed, 5);
    return level;
}

And more details refer this link
https://android.jlelse.eu/designing-android-apps-to-handle-slow-network-speed-dedc04119aac
I hope this can help you!
Thank You.
Answer: Requires minimum api:21. I use ConnectivityManager combined with NetworkCapabilities to get both the downstream and upstream bandwidth. Works just fine. You can decide whether speed is 2G,3G or 4G level based on the speed in kbps.
ConnectivityManager cm = (ConnectivityManager)this.getSystemService(CONNECTIVITY_SERVICE);
NetworkCapabilities nc = cm.getNetworkCapabilities(cm.getActiveNetwork());
var downSpeed = nc.getLinkDownstreamBandwidthKbps();
var upSpeed = nc.getLinkUpstreamBandwidthKbps();

2G GSM    ~14.4 Kbps
G  GPRS   ~26.8 Kbps
E  EDGE   ~108.8 Kbps
3G UMTS   ~128 Kbps
H  HSPA   ~3.6 Mbps
H+ HSPA+  ~14.4 Mbps-23.0 Mbps
4G LTE    ~50 Mbps
4G LTE-A  ~500 Mbps

Downloading a file is over-engineering the solution because after all, you aren't responsible for the users internet connection - they are (or rather their service provider is)! Giving them info based on their current status is more than enough for most use cases. This gives you a speedy way of checking current link speed before performing operations.
Comment: *** Requires minimum api:23 ***
Comment: i was pretty sure of the answer att, feel free to edit it with a source if it's incorrect now
Answer: UPDATE - DEPRECATED LIBRARY - no longer maintained
original post:
You can use Network Connection Class by Facebook.
Its ConnectionClassStateChangeListener has a method called onBandwidthStateChange that returns an instance of ConnectionQuality class:
public interface ConnectionClassStateChangeListener {
  public void onBandwidthStateChange(ConnectionQuality bandwidthState);
}

ConnectionQuality class is an enum class defined as below:
public enum ConnectionQuality {
  /**
   * Bandwidth under 150 kbps.
   */
  POOR,
  /**
   * Bandwidth between 150 and 550 kbps.
   */
  MODERATE,
  /**
   * Bandwidth between 550 and 2000 kbps.
   */
  GOOD,
  /**
   * EXCELLENT - Bandwidth over 2000 kbps.
   */
  EXCELLENT,
  /**
   * Placeholder for unknown bandwidth. This is the initial value and will stay at this value
   * if a bandwidth cannot be accurately found.
   */
  UNKNOWN
}

Comment: Sorry for the downvote :(. The library you pointed to hasn't been updated since 2015 and has reported issues with Android 9+.  I would advise AGAINST using this library unless it's updated in the future (if it ever is, I'll remove my downvote.  Promise :) )
Comment: @tbfp sorry :( I don't know how and when it's deleted.
Comment: i did converted this repo into kotlin and it's work in android 10. check it out [here](https://github.com/bhavin1994/network-connection-class.git)
Comment: @BhavinPatel is the repo still there?
Answer: You can't directly check it.
However, you could either ping a server and see if the response takes very long or doesn't come back at all.
You could also do a speedtest. In most applications this would not make much sense though, because it's a hog on the user's data.
Comment: Do you have a code snippet on how it can be done?
Comment: A code snippet for pinging? Or do you mean one for a speedtest to then calculate the download kbps?
Answer: The most basic thing you can do is to probe an URL whose uptime is almost 100% like, let's say, www.google.com. From the time you start the request, to the time it has completed, you can just measure the amount of data you have downloaded for the request. So you have the data (space) and time spent. Just divide space by time to get network speed. This is somewhat imprecise, because it also depend on the URL you probe.
Answer: It seem that android doesn't allow this directly. You can try to download some file to determine the speed of your internet.
Below are the list of the connection qualities:

POOR // Bandwidth under 150 kbps.
MODERATE // Bandwidth between 150 and 550 kbps.
GOOD // Bandwidth over 2000 kbps.
EXCELLENT // Bandwidth over 2000 kbps.
UNKNOWN // connection quality cannot be found.

You can check detail in this article
https://android.jlelse.eu/designing-android-apps-to-handle-slow-network-speed-dedc04119aac
Answer: Get network speed and network type
class NetworkUtils {

  companion object {

    // returns 102 Mbps
    fun getNetworkSpeed(context: Context): String {
        val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            val nc = cm.getNetworkCapabilities(cm.activeNetwork)
            val downSpeed = (nc?.linkDownstreamBandwidthKbps)?.div(1000)
            "${downSpeed ?: 0} Mbps"
        } else {
            "-"
        }
    }

    // returns 2G,3G,4G,WIFI
    fun getNetworkClass(context: Context): String {
        val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        val info = cm.activeNetworkInfo
        if (info == null || !info.isConnected) return "-" // not connected
        if (info.type == ConnectivityManager.TYPE_WIFI) return "WIFI"
        if (info.type == ConnectivityManager.TYPE_MOBILE) {
            return when (info.subtype) {
                TelephonyManager.NETWORK_TYPE_GPRS, TelephonyManager.NETWORK_TYPE_EDGE, TelephonyManager.NETWORK_TYPE_CDMA, TelephonyManager.NETWORK_TYPE_1xRTT, TelephonyManager.NETWORK_TYPE_IDEN, TelephonyManager.NETWORK_TYPE_GSM -> "2G"
                TelephonyManager.NETWORK_TYPE_UMTS, TelephonyManager.NETWORK_TYPE_EVDO_0, TelephonyManager.NETWORK_TYPE_EVDO_A, TelephonyManager.NETWORK_TYPE_HSDPA, TelephonyManager.NETWORK_TYPE_HSUPA, TelephonyManager.NETWORK_TYPE_HSPA, TelephonyManager.NETWORK_TYPE_EVDO_B, TelephonyManager.NETWORK_TYPE_EHRPD, TelephonyManager.NETWORK_TYPE_HSPAP, TelephonyManager.NETWORK_TYPE_TD_SCDMA -> "3G"
                TelephonyManager.NETWORK_TYPE_LTE, TelephonyManager.NETWORK_TYPE_IWLAN, 19 -> "4G"
                else -> "?"
            }
        }
        return "?"
    }

  }
}

Answer: There are two ways to solve this problem.

Write a code to programmatically check how long it takes download a small file and determine your bandwidth - I have used this and it is fairly accurate considering server location. I used google image on google server of course. However, the larger the file, the more accurate the result.

Use JSpeedTest - I have not tried this but it should work ok. Note, it uses 1mb file.

For solution 1:
 public static float bandwidth( Context context) {
    int len;
    int size = 1024;
    byte[] buf;

    String imageurl = "https://www.google.com/images/branding/googlelogo/1x/googlelogo_color_272x92dp.png";
    InputStream is = null;
    long start = System.currentTimeMillis();
    long end = 0L;
    float bandwidth=0.0f;
    try{
        Log.d("Network", imageurl);
        URL url = new URL(imageurl);
        URLConnection urlConn = url.openConnection();
        HttpURLConnection httpConn = (HttpURLConnection) urlConn;
        httpConn.connect();

        is = httpConn.getInputStream();
        if (is instanceof ByteArrayInputStream) {
            size = is.available();
            buf = new byte[size];
            len = is.read(buf, 0, size);
        } else {
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            buf = new byte[size];
            while ((len = is.read(buf, 0, size)) != -1)
                bos.write(buf, 0, len);
            buf = bos.toByteArray();
        }

        Log.d("Network", "ImageSize:"+buf.length);
        end = System.currentTimeMillis();
        Log.d("Network", "time:"+end);

        // Bandwidth : size(B/1000)=KB
        //That is KiloBytes per secs
        float kilobytesDownloaded = buf.length/1000;

        //Get the duration, convert milliseconds to seconds
        float diff = end-start;
        float duration = (float)(diff/1000);
        Log.d("Network", "duration in secs:"+duration);

        bandwidth = (float)kilobytesDownloaded / duration;

        Log.d("Network", "difference:"+(end-start));
        Log.d("Network", "bandwidth:"+bandwidth+"kb/s");
    }catch (MalformedURLException e){
        e.printStackTrace();
    }catch (IOException e){
        e.printStackTrace();
    }

    return bandwidth;
}

Your sample result should look something like this:

ImageSize:5969 bytes
time difference:129ms
duration in secs:0.129s
bandwidth:38.759693kb/s

For solution 2: click on the link, the implementation is on the page. You can get both download and upload speed with it.


Can I take a 330g tin of Fois Gras Poitiers in my 10 kg cabin bag with Ryanair?

Question: Can I take a 330g tin of Fois Gras Poitiers in my 10 kg cabin bag from France to London Stansted with Ryanair?
Answer: As mentioned in the answers of the question "Food in hand luggage" tinned food is usually not allowed as there is liquid in the tin. Even tinned tuna in oil has been denied.
If you want you could try to take it with you, but be prepared to fly without it.
I'd put it in the same tray as the phone and liquids, clearly visible.
Comment: If fois gras is spreadable, which I think it is, it is not allowed in hand luggage over 100 ml, which this will be.


Index was outside the bounds of the array

Question: I am not sure why I am getting this error.
How can I dynamically set the error provider for a control?
if (errorList.Count == 0)
        {
            return true;
        }
        else
        {
            foreach (ErrorEntity ee in errorList)
            {
                if (ee.InError)
                {
                    Control[] ctl = this.Controls.Find(ee.FieldName, true);
                    if (ctl != null)
                    {
                        errorProvider.SetError(ctl[0], ee.ErrorMessage);
                    }
                }
            }
        }

Answer: My guess is that
this.Controls.Find(ee.FieldName, true);

is returning an empty collection, and not a null.
So when you check for null, you should also check for empty (ie: Count==0)


Major glitch with EE3 and multiple file fields

Question: I've got a channel that uses a file field for a logo and another file field for a building beauty shot. In EE3, if I change the image on one field, then change the file on the other, it change BOTH to the same image. The only workaround I can find is to change one, save, then change the other and save.
Even worse is to use this with the Grid setup, which I use for photo albums. Say I finally get 20 images added to an album (add 1, save, add 2, save, etc). If I try to edit multiple images between saves, it changes all the images I edited to the same image. So if I change image2, then image15, then image12, all three change.
This is absurd! Is anyone else seeing this (hopefully fixed it), or is it just my install?
EE3.4.1
Answer: Nevermind. This is a known bug in 3.4.1 and is supposed to have been fixed in 3.4.2. I will update and confirm.
Comment: confirmed. Updating to 3.4.2 fixed this bug.


A word looks similar to "frail" but means something like "whip"

Question: I remember there is a word that looks similar to "frail" but means something like "whip". Do you happen to know the word? Thanks!
Comment: I used to play a lot of DD
Comment: I think what you have in mind is 'flail', used for threshing grain and adapted as a weapon.
Comment: Thanks! How do you remember these words? I always mess up.
Comment: Dungeons and Dragons
Comment: incorrect but interesting: oldschool veterinarians and medieval doctors would hit a **fleam** with a mallet to open a vein, letting the blood and corresponding bad humours out. https://duckduckgo.com/?q=fleam&t=ffab&iax=1&ia=images
Answer: The word you are looking for is flail. It was originally an agricultural implement, used for threshing, separating edible grain from the straw and husk:

The long handle allowed the user to impart great speed to the end, while the hinged joint transferred this energy to the beater and changed its direction so the beater would hit the bundle of straw flat. Flails were occasionally used as improvised weapons, sometimes fortified with iron studs and spikes, valued for their ability to strike around a shield or interposed weapon. Eventually one-handed military-grade versions) were developed, which extended the hinge into a chain and reduced the striking surface to a pointy thing for hitting people with.

Pictures courtesy of Schweitzer and Tim "Avatar" Bartel, via Wikipedia, CC license.  This answer brought to you by snailboat and the StoneyB D&D Foundation; all reputation proceeds will be donated directly to the Community Wiki fund, where they will be used to purchase flails for orphans in need.


Add data from ArcGIS Online

Question: I want to add data in my map from ArcGIS Online, but ArcGIS does not allow me to complete that operation. I tried on the Add In Manager, by using the option Load All Ads-In without restriction, but it still does not allow me to add data from ArcGIS Online, nor from Add Basemap. I also tried to connect ArcGIS  to a ArcGIS Server, but I can´t find any server address in order to complete that operation. Any suggestions on how I can address this problem, in order to be able to Add Basemaps and Maps from ArcGIS Online?
Comment: Is the map you want to add data to from ArcGIS Online in ArcMap?  If so, what version of ArcMap are you using?
Answer: To add maps from ArcGIS online to ArcMap or ArcGIS Pro you need just simple click on Open in ArcGIS desktop button from ArcGIS online map page:

item.pkinfo file will be downloaded if you prefer to use ArcMap. Open this file in ArcMap. The ArcGIS online map content will be loaded. From ArcMap you can export the data to different formats like ESRI Shape:

If the map is not public, you will be asked to log in to your ArcGIS online account from ArcMap or ArcGIS Pro.

Add data from ArcGIS Online


The results of my magnetic flux data from voltage recorded

Question: For my electrical engineering senior design I created an experiment to test magnetic flux (more voltage) through a receiving coil. There is a large sending coil with A.C. voltage and a small receiving coil with an oscilloscope measuring voltage_pp. Its wireless power. I ran three tests. One with the two coils, and two experiments with different metallic materials in the center of the receiving lens. Sort of a wireless transformer. I have results. I found online that flux has a 1/r^2 relationship. My results show a 1/x at almost the entire range of distances. When the two lenses are close I think mutual inductance comes in and stops the constant increase of voltage measured. If I plot voltage against 1/distance I definitely get a straight line. This would mean a 1/x relationship right? But online everywhere its 1/x^2. Also my large sending coil has a big radius which I'm wondering if that matters. If i take my slope from the straight line its voltage/(1/x) = voltage*x which is a weber? Or flux? I was really happy to see the slope is units of magnetic flux but I'm unsure. (its cm so not exactly weber but i can change to meters later) Big takeaway is why my results are 1/x and am interpreting the results of my slope correctly? I'm all on my own on this experiment, my group mates have done nothing lol and my prof has admitted to not knowing what wireless power transfer is about. Any help would be appreciated. (I have a capacitor on my receiving coil so the voltage induced can have zero impedance by sending the ac voltage at its LC resonant frequency. The tested material would change resonance but everything was in the range of 190kHz - 210kHz.)
Comment: I think you have a significant detuning effect. These are definitely near field measurements and detuning of the transmit coil by a tuned receive coil can make a nonsense of measurements. At the frequencies you are using far-field will be 100s of metres away. Try the experiment without using tuning capacitors and please also explain what you mean by lenses.
Comment: "lens" A and B were how I labeled the two metallic materials i put inside my receiving coil. What do you mean by detuning? All three tests had some resonance because its an LC circuit. The metallic "lens" would lower the resonance frequency but not by much. Makes sense because f is proportional to 1/sqrt(L) and the metal inside increases L. Every time I ran the tests at each lenses exact resonant frequency.
Comment: As you bring the small tuned coil close to the big tuned coil you will get some detuning.
Comment: yes actually I left off data on that graph. I stop plotting at 7.5 centimeters because after that it wasn't a steady increase of voltage.
Answer: There may be some detuning effects, but another effect is that you have a large driving loop. The magnetic field along the axis of a circular loop of wire is actually proportional to
$$B_z \sim \frac{1}{(z^2 + R^2)^{3/2}}$$
where z is the distance along the axis and R is the radius of the loop(reference).
This alone won't account for your entire observation, as it is still steeper than the \$1/z\$ dependence you are seeing, but it is probably part of the story of what is going on.
Answer: I actually figured it out, I wasn't giving the whole story. (also re-did experiment for cleaner measurements). I knew the equation for B(z) ,like you suggested, from the center of the loop. Here are my original plots. (So many plots because the point is to test voltage as a function of material inside the receiving coil)

I thought this decline in the increase of voltage (guess d^2/dx^2 < 0) was from mutual inductance. Like the field from the receiver effecting the original resonance. (Even labeled it on the original graph)
I plotted a y(x) = 1/((x^2 + const^2)^3/2) online and it looks like that graph. I took one of the data points and plotted its x axis as 1/((x^2 + 11^2)^3/2). The entire range was almost linear
Please ignore the title or units, and I took off x-axis uncertainties. The radius of my large coil was about 11cm and I'm not even sure how "centered" my receiving coil was. Not bad.   If you try the fit with r = 15cm

See how wrong it gets. I'm happy about this and thought I would share. I believe this shows this classic B as a function of a loop of wire holds.
Comment: Thank you for following up and taking time to share your findings. It is nice to see the resolution.


Poisson fixed and random effect

Question: I have claim frequency panel data for five years consisting of age, CC, make of car, age and gender of insured person and geographical area. I have run a Poisson regression to model the claim frequency in R. Now I want to test for a Poisson fixed and random effect. How can I proceed?
Answer: There's a nice presentation on fixed and random effect analysis in R. It's not for Poisson data, but you may still find it helpful: http://www.princeton.edu/~otorres/Panel101R.pdf
Answer: Maybe it is too late now, but you can consider pglm package from Yves Croisant.
https://cran.r-project.org/web/packages/pglm/pglm.pdf
This package does poisson and negbin with fixed and random effects.

Poisson fixed and random effect


Books about four people with telekinetic powers set in the future

Question: This book is set in the future (unsure how far) in the U.S., and it was in an outskirts city. The main character is a girl, and she learns that she has telekinetic powers, and these powers also keep her from being harmed from any sort of danger, except anything made from a certain material (titanium, I believe), and there are three others like her, all with a different weakness. The girl goes to a small school with two of the bad guys, and after learning of her abilities they try to kill her. The plot is really involved, so I can't get to it deeply on here.
Comment: Hi and welcome to the site. With our `story-identification` we normally recommend [not holding back on spoilers](https://scifi.meta.stackexchange.com/questions/10797/im-asking-a-story-id-question-should-i-include-spoilers), as the people reading and answering your question will either have read the story or be ready to accept spoilers, I suggest you give us all the details you can to help us better identify your story. Take a look at [this guide](https://scifi.meta.stackexchange.com/a/9337/68872) to see if you can [edit] in any more details
Comment: What is an "outskirts city"? Outskirts of what? Do you mean it's a suburb of a bigger city?
Comment: Unrelated, but it's funny how the bad guys always attend the same school as the protagonist!
Comment: Do you remember anything about how she gained her telekinesis or was she born with it?
Comment: @user14111 It is an outskirts city to a protected city. It is protected by a big bubble basically to keep it sheltered from the changing climate of the earth.
Answer: This sounds like Pulse by Patrick Carman. It is the first book of the Pulse trilogy.

With the help of her mysterious classmate Dylan Gilmore, Faith Daniels discovers that she can move objects with her mind. This telekinetic ability is called a "pulse," and Dylan has the talent, too.
In riveting action scenes, Faith demonstrates her ability to use her pulse against a group of telekinesis masters who are so powerful they can flatten their enemies by uprooting streetlights, throwing boulders, and changing the course of a hurtling hammer so that it becomes a deadly weapon. But even with her unusual talent, the mind--and the heart--can be difficult to control. If Faith wants to join forces with Dylan and save the world, she'll have to harness the power of both.
Patrick Carman's Pulse trilogy is a stunning and epic triumph about the power of the mind--and of love.
Comment: I've edited in some basic information, could you [edit] to explain how this matches the OPs description?


What's the difference between 派遣 and 出向?

Question: Both seem to mean borrowing an employee from another company but not exactly the same for both cases.
Comment: Related:  [Employed by one institution but work for another](https://japanese.stackexchange.com/q/6157/78)
Answer: 派遣 refers to sending a worker to another company while he/she is still employed by the original company. If someone works under the command of Company X but is paid salary by Company Y, he/she is called a 派遣社員. This can happen in various forms, but typical, "so-called" 派遣社員's are employees of large 派遣会社 (temporary staff agencies) dedicated for offering 派遣. They engage in various types of (sometimes unimportant, sometimes special) labor, but they usually don't have enough chances to get promoted. Despite its own advantages, generally speaking, 派遣 is not seen as an ideal style of working.
出向 is not a legal term, but it basically refers to temporarily sending someone to an associated company/office for various reasons. A 出向社員 is employed by the new company, but expected to go back to their original workplace usually after a few months or years. One important difference is that 出向 is often seen as a good chance to develop the career of an elite worker. In the case of 出向, one may be sent as a manager or even a board member of the new company. Kachō Kōsaku Shima is a manga which depicts a salaryman who experiences a number of 出向's within an imaginary conglomerate, until he finally becomes a president. (There are negative 出向, too.)
Comment: I often hear 派遣 used here in America by people who are working for the American 法人 of their Japanese company. It doesn't seem particularly negative in that case. I feel people don't say 出向で来てる etc as much for this for some reason...
Comment: @DariusJahandarie You're right, it should not be negative in your case. By "so-called 派遣社員", I mean unstable workers who belong to agencies and tend to be victims of [派遣切り](https://president.jp/articles/-/24393).
Answer: A 派遣会社 is basically a temp agency. 派遣, in this case, is being sent out (assigned/dispatched) temporarily to a company which has a contract with the agency for temporary workers.
出向 is simply one department of a company or the company itself 'loaning' their employee to another department or another company (An arrangement among peers). This term can be several months or even a couple of years. The employee who is 'on loan' essentially becomes an employee of the company or department they are being loaned to for this term.

A is a permanent employee at Alright Temp Agency in Tokyo.
B registers with Alright Temp Agency as a 'dispatch worker'.
A gets sent to help start a new Alright Temp Agency in Osaka, to help train workers and provide support for a period until their expertise is no longer required (出向).
B gets a temporary assignment at a nearby restaurant chain on Tuesday and another assignment to make bento boxes at another company on Thursday (派遣).

So, the main difference is whether you are specifically a 'worker specifically assigned to short-term contracts through a temp agency' or 'a permanent employee who is, for whatever reason, temporarily assigned to another location'.
Comment: Just a small thing, but my understanding of the "transitivity" of the actions depicted by the two words, if that makes sense, is the opposite of what you have. That is, 派遣 means "dispatching," sending people out, rather than being sent out. And 出向 means "transferring temporarily," as opposed to loaning an employee. I realize it's secondary to the meanings you were discussing, and maybe my understanding is wrong, but I thought it might be worth bringing up.
Comment: No, you're right about that. I was just not very specific about how they would be used in a sentence re: transivity/intransivity(派遣する vs 派遣される). I'll edit if you think it's a problem.


Who is the lowest ranked european team to qualify for world cup?

Question: If Iceland wins tonight against Croatia, would they be the lowest ranked team to ever qualify from Europe?
Also who is the lowest ranking to ever qualify for a world cup from any continent?
Answer: As of Oct 2013, Iceland is ranked 46th. Croatia is 18th.
Since, Iceland lost -- and with two games still remaining -- the lowest could either be Jordan (70th) or New Zealand (79th).
However, New Zealand would have to beat Mexico (24th) and Jordan would have to beat Uruguay (6th).
So if Jordan and New Zealand lose their qualifiers, then the lowest ranking European team qualifying in the 2014 world cup will be France (21st) and -- from any continent (bonus) -- Cameroon (59th).
Sources: http://www.fifa.com/worldranking/rankingtable/ and http://en.wikipedia.org/wiki/2014_FIFA_World_Cup_qualification
As for lowest ranking of all time from any continent, El Salvador (80th as of Mar. 2013, 89th as of Nov. 2013) seems to be the answer.
Source: http://www.funtrivia.com/askft/Question130166.html
Comment: If you go by the rankings as of the tournament itself, North Korea are the lowest-ranked side ever to qualify for a World Cup: they were ranked 105th when they qualified for the 2010 World Cup.


GE Air Conditioner cycles are too short

Question: We just bought a GE window air conditioner.  After installation, we turned it on and found that the compressor runs for 8-10 seconds, then shuts off for 1 minute (fan continues to run).  The instruction manual says this on/off cycle is normal.  But after several hours, the room has not cooled at all from the initial 82 degrees.  It seems that a machine that blows warm air 88-90% of the time will never get our room cooled down.  Is there a way to change this programing, so that our room can get initially cooled off?
Comment: 11.6 BTU would explain the short cycling, though ;)
Comment: The instructions say that 8-10 second cycles are normal?  That doesn't sound right,  sounds more like a defective unit.
Comment: 11.6 BTU is clearly not right. Perhaps it's 11.6 kBTU/hour (which would be 4kW)?
Comment: Model # so the rest of us can look up more details?
Comment: Sorry, I don't have the model number with me tonight.  It is an 11.6 BTU unit.  Instructions only said it is normal to cycle on/off.  It doesn't specify how long the cycles should last.
Comment: Take it back, yours is defective.
Comment: The model number of the air conditioner is AHS12AX.
Comment: I'm sorry.  Yes, it is 11,600 BTU, not 11.6.
Answer: A typical air conditioner will cycle the compressor on/off based on the thermostat setting. Typically that means:

Run for a long time initially to get the room down to the set temperature - that can sometimes take hours
Cycle on/off with on times anywhere from (rough guess) 15 minutes to 1 hour. Longer on times, after initially reaching the set temperature, would indicate either a real hot spell or an undersized unit.

Short times - e.g., < 1 minute - are an indication of something very wrong. Every on/off cycle is wear & tear on motors and other components. Ever see the lights dim for a few seconds when your A/C starts? That's because the power draw to start the compressor can be significant. If you have a "start" every minute or so, that will lead to premature failure. If you have a "stop" every minute or so with the system restarting again - as you have described - then it sounds like something is overheating which shuts down the compressor, then it cools and restarts again very quickly. Not normal - and not good for the unit or for keeping you cool.
Since you just bought it, I suggest a call to GE to find out what might be the cause and to ask for a warranty repair if needed. If this were an old unit then I'd recommend checking filters and other types of problems.
Comment: If you just bought it, you should return it for a warranty replacement

GE Air Conditioner cycles are too short


How to resize LVM partition on a RAID 1

Question: I am running Ubuntu 14.04 in a RAID 1 configuration. How do I expand one of my LVM partitions as my /var partition is 100% filled up? I have tried to boot in rescue mode but gparted is not available in this mode.
Answer: If your Ubuntu installation is using Logical Volume Manager (LVM) then most likely your /var is actually a Logical Volume (LV) as compared with a traditional partition.  The command to grow or shrink an LV is lvresize.  You will also require empty space in the Physical Volume (PV) if you wish to grow the /var LV.
Before attempting to resize /var, I recommend that you read and understand how LVM works.  Two places to start are Logical Volume Manager (Linux) and LVM - Arch Linux.
Answer: KDE Partition Manager might be able to resize it. It doesn't detect RAID yet, but latest unreleased version (will be released as 3.0 later) should be able to resize LVM logical volumes. Hopefully, no RAID support wouldn't interfere, but you don't need to resize LVM physical volumes.
Download Neon Developer Edition (Developer Git-Stable should be fine) from https://neon.kde.org/download
Then run "apt install partitionmanager"
start KDE Partition Manager and it should detect your LVM devices.

How to resize LVM partition on a RAID 1


How to normalize input for machine learning (neural networking) on video games

Question: Recently, I have been creating neural networks with the plan to train them to play games that I have made (where the neural networks have access to all of the game data).  I have a strong understanding of neural networks, genetic algorithms, and the NEAT implementation.  The issue that I have run into, however, is normalizing the input for what the player sees.  If we have an enemy object, a medkit object, and a weapon object, they need to be input and treated differently.  I saw a video from SethBling here, where he gives a brief explaination to how he set that neural network up.  He used only the values 1, 0, and -1.  However, for more complex games, that wouldn't work.  I've tried getting a small simulation to return true when the input is .25 < x < .75 and false otherwise, however it couldn't find a solution.  Therefore, it seems that I cannot just toss the IDs of the objects into the neural network.  Any help is much appreciated!
Answer: I was going to leave a comment, but unfortunately I don't have enough reputation points. So, I have a couple of suggestions that will hopefully give you some ideas. I am going to assume that you are using the NEAT algorithm as your game playing algorithm. Now, from what I gather your issue is that because you have a varying number of actual objects to interact with in your game it is practically impossible to give everything a label for every frame. Therefore, as you seem to have figured out you would need to provide a non-integer domain for the objects, whether that be normalizing the detected class id by the total number of classes, or some other method. I have 3 propositions for you in order to try to accomplish this (or avoid the problem):
1: Use some type of image manipulation (whether it be segmentation or thresholding), object detection along with image moments in order to create a database of objects that you are interested in, and then while the game is playing, you can re-create a simpler version of the actual game environment
2: Train a semantic segmentation neural network in order to perform something similar to 1
3: Train (or use a pre-trained) deep convolutional neural network to extract high-level features. Then use these features (and potentially some kind of location encoding method) as the input to your NEAT algorithm. Your NEAT algorithm would then select which combination of filters it would like to look at in order to make the decision.
I think I would personally try option number 3 as it requires the least amount of manual work in order to set up initially.
I hope this gives you a couple of ideas.
Comment: I already have the entire environment boiled down to a simpler version (as you mentioned in option 1), however, the main issue is taking the object IDs and turning them into meaningful input.  For example, the Enemy object has the ID of 1, the Coin object has an ID of 2, et cetera and it needs to be normalized into data for the neural network to read.  Mind you, ALL Coins have an ID of 2, even if there are twenty of them in the environment.
Comment: As I mentioned, you can just normalize your data to the range of your activation function. For example, if you have 10 different objects (ie. 10 different IDs), then you just take the ID for the object and divide it by 10. In your example, the enemy would have a normalized id of 0.1 and the coin would have a normalized id of 0.2. This allows you to encode the IDs into the range of the activation function which prevents the saturation of the network.
Answer: When working with neural networks a good aproach is to think of them as humans. What would a human need to know?
What I always do is I give a network different sensors for different types of things. My sensors are almost always just rays of a certain length.
In your situation I believe you have no better choice than using for example 3 sensors for coins, 3 sensors for medic cits etc.
You also have to decide if you want to use boolean sensors (which would only tell the network if something triggered the sensor or not, no matter how close) or double sensors (which would return a value telling the network how close the event happened) or if you want to have both combined.


Chronological order of the Drizzt series

Question: A long time ago, when I was a wee child I read some of the Drizzt Do'Urden books, they really captured my imagination. I'd like to continue reading, but I've lost track of which books contain him, and indeed what order they should be read in.
I'm specifically interested in the chronological order (not publication order).
Comment: R.A. Salvatore posted a [suggested reading order](https://www.facebook.com/permalink.php?story_fbid=10152944925124811&id=54142479810) for *his* Forgotten Realms stories in April 2015.
Comment: personally I advice against reading the book in chronological orders since often there are references to later events or short cameos that you wouldn't get. The same was for me: you will miss the excited of seeing for the first appearance of a certain "black figurine" or after the cameo of certain characters you will simply wonder "why did he spend an entire chapter on this guy? What was his part in the plot?".
Comment: I read the Neverwinter Series and enjoyed it. If you follow some of the advice here, I would add that you should read Neverwinter series LAST. I read it and realized (despite knowing much of the back story) that I wanted to re-read the stories to better understand the Neverwinter series.
Comment: Please Please Please, If you enjoy Drizzt novels, Read through the transition series.... Amazing finish to your adventures with our beloved drow, if you feel you can stop there...
Answer: In chronological order, they are:

The Dark Elf Trilogy (Homeland, Exile, Sojourn)
The Icewind Dale Trilogy (The Crystal Shard, Streams of Silver, The Halfling's Gem)
Dark Mirror, a short story in the Realms of Valor anthology.
The Legacy of the Drow series (The Legacy, Starless Night, Siege of Darkness, Passage to Dawn)
The Paths of Darkness series (The Silent Blade, The Spine of the World, Servant of the Shard*, Sea of Swords)
The Hunter's Blade trilogy (The Thousand Orcs, The Lone Drow, The Two Swords)
The Transitions trilogy (The Orc King, The Pirate King, The Ghost King)
The Neverwinter series (Gauntlgrym, Neverwinter, Charon's Claw, The Last Threshold)
The Sundering (The Companions, Book 1)
The Companions Codex series (Night of the Hunter, Rise of the King, Vengeance of the Iron Dwarf).
Homecoming (Archmage, Maestro, Hero).
Generations (Timeless, Boundless, Relentless).
The Way of the Drow (Starlight Enclave, Glacier's Edge).

My actual recommendation is to read them in publication order (swap the first two series) as Drizzt changes significantly between the first series and later ones.  To my mind he is more an atypical drow rather than the pure force for good he ends up being in later series.
And if you want my really harsh recommendation, speaking as someone who read up to the Hunter's Blade trilogy, read the Icewind Dale Trilogy and stop there.

*Servant of the Shard is also the first book of The Sellswords series
Comment: +1 for harsh truths.  Even if you find you like and want to read more, *definitely* stop before the Hunter's Blade trilogy.  The editorial-forced-plot will scar your soul.
Comment: +1 I wholeheartedly agree with the above. Just read the Dark Elf Trilogy and the Icewind Dale trilogy and stop. I recently read the Legacy of the Drow series and, while there is a little bit that's interesting, it's mostly the same plot and the same character issues rehashed four times.
Comment: Any chance you could work in the stories from "The Legend of Drizzt: The Collected Stories" into this timeline?  Dark Mirror is already there.  http://amzn.com/B00L5F1IXM
Comment: Bonus for harsh truths +1
Answer: The books that feature Drizzt as a primary character, listed in the in-universe chronology, should be:
The Dark Elf Trilogy

Homeland
Exile
Sojourn

The Icewind Dale Trilogy

The Crystal Shard
Streams of Silver
The Halfling's Gem

Legacy of the Drow Tetralogy

Legacy
Starless Night
Siege of Darkness
Passage to Dawn

Paths of Darkness

The Silent Blade
The Spine of the World
Sea of Swords

The Hunter's Blades Trilogy

The Thousand Orcs
The Lone Drow
The Two Swords

Transitions

The Orc King
The Pirate King
The Ghost King

The Neverwinter Saga

Gauntlgrym
Neverwinter
Charon's Claw
The Last Threshold

The Sundering:

The Companions

The Companions Codex:

Night of the Hunter
Rise of the King
Vengeance of the Iron Dwarf

Homecoming:

Archmage
Maestro
Hero

Generations:

Timeless
Boundless
Comment: There's also a short story, Dark Mirror (in the anthology *Realms of Valor*) - I removed it from my list above because the question specifies "books about", but you might still find it interesting.


How to build Cura on Windows?

Question: I am interested in doing development on Cura.  Initially I want to start with the UI rather than the Engine.  I have found the repository and have cloned it to my PC.  I have also looked over the Wiki and searched the web.  For such a popular open-source product, I was surprised I couldn't find a build guide.
Can someone direct me on how to get started.  I have a LOT of experience in Software Development (more years and languages than I want to admit to); but, I have never used Python.  Consider that in your instructions.
Comment: This is related, but for Ubuntu [How to build CuraEngine?](https://3dprinting.stackexchange.com/questions/1309/how-to-build-curaengine)
Comment: I would LOVE to hear from someone that has actually gotten this to work!  In nearly 50 years of programming, I have never seen such a tangled mess (though I have seen some close).
Comment: I found the source code to Slic3r.  The build process appears to be MUCH better documented.  https://github.com/alexrj/Slic3r
Comment: For a similar saga see https://www.bountysource.com/issues/28750036-can-t-build-32-bit-cura-windows-10-32-bit.
Answer: The repository's README.md includes a section titled "Build Scripts", with a link to another repository: https://github.com/Ultimaker/cura-build
This includes dependencies and instructions for building Cura on Windows.
Comment: WOW, that is a LOT of stuff to install !!!
Comment: OK, instructions get a bit dicy when you get to numpi and scipy plugins.  I installed 64-bit Python 3.5 and I have an Intel processor,  I cannot find a match for that for numpy.  Best I could find in cp35m-win32.  When I try that I get unsupported wheel.  Only 64bit they have is amd.  What do I do?  Anyone done this?
Comment: Note: The cp35-win_amd64 versions install ... whether they will actually work or not is still a mystery.  Well, the 64-bit version of Cura up on the Ultimaker website had to have been built somehow....
Comment: Continuing down the path ...
Comment: OK, so it seems that the "cura-build" is intended to do everything in the README.md; but, there are no instructions on how to run it either.  Cura may be a nice application; but, their build instructions and environment is HIDEOUS.  Maybe that is why 8 contributors are responsible for 93% of the commits.  Seems more open source in concept than in reality.
Comment: To be honest, I have not even attempted building or contributing to Cura. (I have an interest in OSS, but don't have the time to keep up...) I skimmed the cura-build info, and thought it was complex and unclear as well.
Answer: As you are an experienced developer, these links should help:
This is a related question, but for Ubuntu How to build CuraEngine?
Wikipedia has an informative page on Cura, which lists the Github development pages:

Cura Github development page
Cura Github legacy (pre-Ultimaker) development page
Cura slicing engine Github development page

Reading the development pages is a good place to start. The Cura Github development page does contain resources for Windows.
The top level Ultimaker Github page contains links to all of the relevant repositories, amongst other useful resources, including:

CuraEngine - CuraEngine is a powerful, fast and robust engine for processing 3D models into 3D printing instruction for Ultimaker
  and other GCode based 3D printers. It is part of the larger open
  source project called "Cura".
Cura - 3D printer / slicing GUI built on top of the Uranium framework
cura-build - Build scripts for Cura

With respect to Python, I, myself, am slowly making my way through this Python tutorial, Python Code Academy. However, there are a many other good Python tutorials out there, the best resource is probably Python.org.
One thing to note is that Python 2.x and 3.x are markedly different (see Should I use Python 2 or Python 3 for my development activity?). What should I learn as a beginner: Python 2 OR Python 3? is also an interesting read.
Comment: Regarding the Python version, the Cura buid ReadMe says Python v3.5
Comment: I have been writing computer programs since 1971 and their build environment seems near impossible to figure out.
Comment: Interesting quote from one for the Cura developers discussing building Cura.  "I "jerry-rigged" a setup that lets me run Cura from source, on windows.".  Not very inspiring.  Another quote in the same discussion mentioned that all or the developers at Ultimaker have their own buid environment.  Reminds me of another product where the developer's version control approach was to keep a separate laptop with the last stable build on it.  My goal is to be in a position to be one of the developers (if I chose to be).
Comment: @markshancock - I feel your pain. With *certain* projects, I find that instead of trying to fix an issue yourself and submitting the change, in fact, it can be a lot more efficient to just report the bug that you wish to be fixed and just let the developers get around to it, rather than having to wade through the output of someone else's (badly commented) mind. Obviously, if you are looking to fix more that just a few bugs, and make a wholesale change/contribution then that approach is no longer valid... Good luck :-)
Comment: Hey,  I know!  Let's get  Linus to take over the project!  :-)

How to build Cura on Windows?


Strong maximum principle for heat equation; If $u(x,t)$ is constant for times $t\leq t_0$, is $u$ also constant at times $t\geq t_0$?

Question: I am learning the strong maximum principle by following Evan's Partial differential equations. It is stated as follows: Let $U$ be an open subset of $\mathbb{R}^n$ and $T>0$. Let $u=u(x,t)$, where $x=(x_1,\ldots,x_n)\in\Omega$ and $0\leq t\leq T$. Denote $\partial_t$ the partial derivative wrt $t$ and $\Delta_x=\sum_{i=1}^n\partial_{x_i}^2$ the Laplacian on the variables $x_i$.
Theorem 4(b) (page 55) of Evan's book states, in equivalent terms

Theorem (strong maximum principle for heat equation): Suppose that

$U$ is connected;
$u$ is $C^2$ on the variables $x_i$, and $C^1$ on the variable $t$, on $U\times(0,T]$, and continuous on all of $\overline{U}\times [0,T]$;
(the heat equation) $$\partial_t u=\Delta_x u\quad\text{on}\quad U\times (0,T)$$
There exists $x_0\in U$ such that $u(x_0,T)=\sup u(U\times([0,T]))$

Then $u$ is contant of $\overline{U}\times[0,T]$.

My question is: Does the analogous result hold if we assume instead that $u$ attains its maximum at a point $(x_0,t_0)$, where $0<t_0<T$?
My guess is that this is not the case: If there is a nonzero solution $v$ of the heat equation on some square $U\times[0,T]$ which satisfies $v=0$ when $t=0$, then we can glue the constant function $0$ on $U\times[0,t_0]$ with $w(x,t)=v(x,t-t_0)$ when $t\geq t_0$, and hope that the resulting function is sufficiently regular. However we should not have any good boundedness assumptions on $v$ to avoid all those uniqueness theorems for solutions of the heat equation..
Answer: You are right. If $u$ attains its maximum at $(x_0,t_0)$, then you can only conclude that $u$ must be constant up to that time-point, i.e. in $\bar{U}_{t_0}$. Beyond $t_0$, the function may change value before reaching the final time $T$.


Installing Python modules on ChromeOS

Question: Is there any way you can download Python modules in ChromeOS without accessing developer mode? I am using a student Chromebook that blocks access to developer mode.
Answer: Without accessing developer mode there is not much you're going to be able to do. Your best bet would be to sign up for something like Heroku Free Dyno service (https://www.heroku.com/) and then SSH into the box and work that way.
If you would rather have something local to work on you can pick up a  Raspberry Pi 3 (http://amzn.to/2fkSjn1) and SSH into that and use it as a local development server.
None of this will bypass your schools restriction on allowing access to developer mode on your Chromebook but you will at least be able to do some development while using the machine, even if you are tunneling in to another machine

Installing Python modules on ChromeOS


How do the MAX endstops work?

Question: I'm building my new 3D printer and I have a doubt. I'm using limit switches on the 3 axes, but only the MIN switches. I also have another three switches which I want to use as MAX switches. How can I do that? I mean, if I insert a specific measure of the plate in Marlin and than the extruded stops before of the limit of the plate due to the MAX endstop what will happen? What should I do, upgrade to MIN and MAX endstops or only keep the MIN ones?
Comment: Most boards lack contacts for MAX.
Answer: You should see MAX endstops similarly as MIN endstops, or as an additional option to protect the printer:

Similarly seen as MIN endstops, you would define in the firmware that you are using them to set a reference point at maximum values, your offsets and bed dimensions would be calculated from the MAX positions;
You can configure the MIN endstops and have additional MAX endstops set beyond the bed size dimensions. If the printer would encounter a layer shift causing the nozzle to go beyond the printer (MAX) boundaries, the printer shuts down when the MAX endstop is triggered.
Comment: Ok, thanks. So i can't use both of them in one axis? I think i'm going to use only the MIN ones
Comment: @Valeri0S As explained in the answer under 2. You can use them both. But don't put them at exactly at the maximum axis positions according the bed size, put them a little further, then they will act as safety stops in case of layer shifting occurrences.

How do the MAX endstops work?


opensearch ie & firefox generator

Question: i have some sites that i search frequently and i want to make a quick search for them (open search ) on my firefox and ie browsers, i dont find somthing that can generate a code that works in both ff and ie .. is there app/site that generates quicksearch buttons easy instad of messing with xml?
Answer: I think this should do what you are looking for: http://customsearchprovider.appspot.com.
Answer: The following link works in Firefox.  Open http://mvinetwork.co.uk/opensearch and then you get a list of search providers on the search box drop-down menu. IE9 does not seem to support opensearch anymore.

opensearch ie & firefox generator


Digital Filters

Question: If I want to remove the baseline drift in my ECG signal, which digital filter should be used without distortion and shift in my filtered output?
What are the necessary things I have to look for the proper type of filters (like Chebyshev, Butterworth filter, etc)?
Answer: The easiest approach would be use a high pass FIR filter, mostly because it has a linear phase shift (constant group delay). Chebyshev, Butterworth are IIR type filters so their phase response is nonlinear (mostly) and may change the output.
Also one can considered using wavelet decomposition to eliminate low frequency component. There is a paper called "Baseline Drift Removal and De-Noisingof the ECG Signal using Wavelet Transform", it can easily be found on google. Using MATLAB or Python one can check this out with low effort.

Digital Filters


Why does Russia not declare war on Ukraine in order to incorporate their conscripts into the war?

Question: Russia has been saying that there is no war in Ukraine, just a "Special military operation". Their laws prohibit them from sending conscripts to military operations outside Russia. The war did not go the way they thought it would, and now they have a massive shortage of military personnel. They obviously need to deploy their conscripts, but they refuse to call it a war. Why do they not just declare war and send their conscripts to the war zone?
Comment: There are almost no circumstances in which a modern army wants it's conscripts involved in a difficult and controversial war. Conscripts are usually the least trained and the least loyal parts of an army. You send in soldiers who who don't want to be in the army and might have Ukrainian relatives and you're just asking for mass defections.
Comment: About 20-25% of the troops in the Ukraine War are conscripts.
Comment: @ohwilleke Maybe, I don't know, but if they are, they are all from the Far East. You are forgetting that Russia is actually Russian Federation, it has more than 190 peoples (or ethnic groups or whatever, I don't know how to translate Slavic word "narod" to English - I believe it actually doesn't have 1:1 translation). So a lot of people in Russia (from eastern Russia) actually don't have anything in common with Slavic part of country. And they were sent to Ukraine, precisely because of reasons DJClayworth mentioned.
Comment: I don't know enough specifics to answer, but a [Horns of dilemma podcast](https://www.listennotes.com/podcasts/horns-of-a-dilemma-texas-national-security-ohfy3-OCSvE/) I was listening to in early April had a short exchange about the word "war" having especially traumatic connotations to the Russian people, making the whole notion of a real "war" more problematic than we in the West might perceive.  This was about 1-2 minutes long, did not go into details, but the 3-4 participants, all Russia analysts, all seemed in rough agreement about this phenomenon.
Comment: @RobbieGoodwin The question is very clear and already got good answers (by other users). You can argue about "to" or "on", and it can be grammatically inaccurate, but the question is explained well and people seem to have gotten the idea perfectly, so it is not problem unless you want to turn it into a problem. I never claimed that "Russia or any other state needs to declare war before calling up its conscripts", this is something that you made up about my question. I just implied that it would be one way of doing so. And Russia has violated international law on enormous scale already.
Comment: Just today Putin has declared particular mobilization, so the question is not complete actual.
Comment: Do you not see different ideas there which by their diversity, make the OQ unanswerable?

Why Russia doesn't declare war on Ukraine is one thing - and please note that "declare war to" is a flawed translation; it could never reflect what you actually meant. Can you you re-phrase that to explain how your "… war to" matches English "… war on", or withdraw it?

What makes you think Russia or any other state needs to declare war before calling up its conscripts?

How d'you see that working in any one state's military procedures, let alone in international law?
Comment: @RobbieGoodwin "What makes you think Russia or any other state needs to declare war before calling up its conscripts?" There are some hurdles. [Current law precludes conscripts from deploying to combat with less than four months of training; however, martial law or general mobilization could supersede the current policy, allowing for the immediate employment of new conscripts or mobilized reservists.](https://www.understandingwar.org/backgrounder/explainer-russian-conscription-reserve-and-mobilization) However conscripts from 2021 are already been confirmed to take part in the war.
Comment: The term war seemd to be not really defined in Russia, this is changing now: https://tass.com/politics/1510625?ysclid=l8apmjg7ey940711776
Comment: Might be [episode The Army, the Government, and the People in the Russo-Ukrainian War](https://www.listennotes.com/podcasts/horns-of-a-dilemma/the-army-the-government-and-N-cp1u04DBP/), date and subject seem about right.
Comment: @ohwilleke interesting. Any sources to support this claim?
Comment: @ArchilZhvania There is a bit of a point, Russian conscripts can and already do take part in the war, but only to a small extent.  Maybe the question could ask why it's not done on a larger scale instead.
Comment: @Trilarioin Would you mind first addressing whether "current law" also precludes invading your neighbour? Duh!
Comment: "Their laws prohibit them from sending conscripts to military operations outside Russia" They found a loophole. For them Ukraine is actually inside of Russia. It's that simple if you make the laws yourselfs.
Answer: Communications
The Russian government has spent a lot of time explaining to their citizens (and to the rest of the world) that the war was no war. A sudden reversal needs to be explained, or credibility will be lost. Besides, Russia has already used conscripts. Obviously they find it easier to explain the death of conscripts on the frontline than to call a war a war.
Comment: @ArchilZhvania The current Russian regime's concern is about their credibility *within* Russia. Within Russia, tight control of media lets them control the narrative and (dis)information, but a declaration of war would be too much of an about-face to spin.
Comment: @ArchilZhvania, I actually think that it would make no difference to the ease of deploying conscripts. Changing the law is no harder for them than declaring war. The real problem is angry mothers. And as to the credibility, yes, in many parts of the world. But not all of them.
Comment: @o.m. The angriness of mothers whose children have "disappeared" can be important. Arguably, it was the Madres de Plaza de Mayo (Mothers of the Plaza de Mayo) who brought down an Argentinian dictatorship in the late 1970s / early 1980s. It's rather difficult to justify executing moms.
Comment: Well hasn't Russia lost its credibility anyways? What difference does it make? And yes they used conscripts, but first they make them sign the contracts. Are you suggesting that calling it a war would not make it easier for Kremlin to deploy more conscripts?
Comment: @ArchilZhvania If they are already using conscripts I don't think what they are calling it matters.
Comment: @DavidHammen, just my point. Loss of popular support might topple President Putin, the letter of the law won't do it.
Comment: @o.m. That was a "just sayin'" comment from me. You also got an upvote from me for this answer.
Comment: Hi there again! Well, if you will just delete an opposite voices than this resource will be really useless. Once more in another words: Rassia and russians fight for own real independence against US/GB "whole"(nope) world, for new world order with Jesus Christ (He directly strictly denied "LGBT", trading in churchs, lying and any untruth and so on), true justice (no double standards) and real "King Arthur" equality for all of Earth civilizations, declining any "exceptional" people like US still positioning itself or anyone other could try - no exceptions, everyone are in front of round table.
Answer: The government of the Russian Federation does not declare war and announce general mobilization for the following reasons:

Mobilization would increase domestic resistance. Even as is, there have been a number of "voenkomats" (military recruitment centers) set on fire (!) all over Russia.
Mobilization would harm the economy and the living standards would fall, leading to popular unrest.
Russian administrative system, unlike the Soviet system before it, may not be able to handle such a massive task.
Newly recruited soldiers would be less likely to be well-trained and motivated.

REFERENCES:

But despite failing to achieve any of Russia's strategic objectives in its all-out invasion of Ukraine in over four months, Putin has been reluctant to carry out mobilization.
Some experts suggest Putin may fear that mobilization would trigger domestic resistance, with large numbers of potential recruits evading the draft. He may also be wary of the devastating effect that it would have on Russia's economy: thousands would be removed from the civilian sector and living standards would fall drastically.
Another potential fear is that Russia's administrative system may not be able to handle such a tremendous task. Moreover, mobilization in Russia would likely entail a transition to an even more totalitarian system, and it may not prove so easy to transform Russia into North Korea.

Putin lacks troops in Ukraine but fears mobilization in Russia. By Oleg Sukhov. Kyiv Independent, July 5, 2022: https://kyivindependent.com/hot-topic/putin-lacks-troops-in-ukraine-but-fears-mobilization-in-russia

Russia is likely rapidly exhausting the manpower it can readily use to generate additional effective combat power even as its forces lose combat effectiveness in Ukraine amid high losses. Russian efforts to mobilize more manpower can bring more people into Russian combat units, but those people are unlikely to be well-enough trained or motivated to generate large amounts of new combat power.
Mobilization efforts are likely to start producing diminishing returns as Russia moves through the categories of fully-trained and recently-released reservists into categories of people further removed from their initial military experiences and/or those who will undergo hasty training before deployment to the front lines. Individual replacements for battlefield losses are unlikely to have the same training as their predecessors, and new units or those reinforced by these augmentees will not have undergone unit-level training prior to employment. More units and reservist replacements will likely appear in Ukraine, therefore, but the net effect on Russia's actual combat capability will likely be small and diminishing.
A declaration of martial law and general mobilization would not overcome the structural challenges of Russia's hybrid cadre-and-reserves and contract-soldier system. Creating cohesive fighting units cannot be accomplished overnight. Replacing individual combat casualties in Ukraine with recalled reservists who have gone years without military training is unlikely to dramatically increase Russian combat power.

Explainer on Russian Conscription, Reserve, and Mobilization. By Kateryna Stepanenko, Frederick W. Kagan, Brian Babcock-Lumish. Critical Threats, March 5, 2022: https://www.criticalthreats.org/analysis/explainer-on-russian-conscription-reserve-and-mobilization

The 2022 Russian mystery fires are a series of unusual fires and explosions that have occurred since the 2022 Russian invasion of Ukraine,[1][2] which have not been formally explained.[3] There have also been several notable arson attacks on military recruitment offices in Russia since the beginning of the war,[4] and there has been speculation that some of the fires or explosions have been the result of sabotage efforts by Ukraine.[5]

2022 Russian mystery fires. Wikipedia: https://en.wikipedia.org/wiki/2022_Russian_mystery_fires

A spate of recent fires in Russian cities has led some to speculate that the blazes may be linked to the war in Ukraine. Some of the fires have damaged military objectives while others have hit buildings unrelated to Russia's war infrastructure.

In Photos: Russia On Fire With Mystery Blazes. By RFE/RL, June 06, 2022: https://www.rferl.org/a/russia-fires-mystery-ukraine-conflict/31884503.html
Comment: @JoeW: From what I've picked up, a significant part of the problem would be that the professional, experienced soldiers who ought to be training the new recruits are currently in Ukraine! You'd have to withdraw experienced soldiers now, and in three months time you'd get conscripts with just basic training. That's not a good trade. But it's not historically unique. Nazi Germany had the same problem, with their air force aces dying in combat instead of teaching.
Comment: @MSalters This was even more of an issue for Japan in the Pacific. The Americans would rotate their high scorers back to the States to serve as trainers, ensuring that the supply of quality airmen remained high. The Japanese tended to let them stay in-theater and rack up the kills, which almost inevitably resulted in their deaths over time and ultimately causing a catastrophic decline in quality by the late stages of the war.
Comment: To add to your first two bullet points, currently Russia seems to be recruiting mostly in poorer regions away from Moscow. See "The high death toll among ..." in the NYT's [Desperate for Recruits, Russia Launches a 'Stealth Mobilization'](https://www.nytimes.com/2022/07/10/world/europe/russia-recruits-ukraine-war.html). If they start mobilizing then they'll also be recruiting closer to Moscow where domestic resistance and economic consequences may be more impactful.
Comment: @JoeW I think that it is simply a matter of numbers. Perhaps an army, to continue being functional, can tolerate no more that a certain percentage of poorly-trained soldiers. As you increase the number of poorly-trained, unmotivated soldiers, at some stage you hit the point of diminishing returns.
Comment: @SebastianLenartowicz I've heard this was one of the motivations for Kamikaze: they reached a point where they didn't have the resources to train people to be full-fledged pilots, so they just trained people to fly into ships.
Comment: If they are already taking conscripts into the fight why would newly recruited troops matter?
Comment: What "number"? Could you state a percentage? I can write "right now a number of Western citizens are eating shit" and you can be sure thanks to amount of people in the West that would be true.
Answer: When Russia started the war the predominant idea circulating on Russian propaganda channel and in fb/vk/twitter account of Russian politicians were:

Ukraine has no chances to compete with our military might
this will be a short operation and in 3 days everything will be conquered
ordinary citizens in Russia will not be affected

Now it is clear that:

a 'military might' is a joke. Before the war most of the people in the world would consider Russian army is second in the world, now the incompetency, corruption and outdatedness is visible even to people inside Russia
what was planned to achieve in 3 days operation is not even close to being achieved after 143 days (and with a very very high probability never)
ordinary person in Russia has hard problem leaving the country. The prices are increasing sharply even in Moscow, many of the brands disappear, the job market shortens

Declaring the war and conscripting people is not free. If Putin could have done it, he would already have done it long long time ago. But it has consequences, among them are:

you clearly tell: I severely miscalculated the situations and now it is out of control
ordinary person will bear consequences: it is one situation to sit and support fighting in front of a propaganda TV listening to how your amazing army conquers for the 10th time in a row the same village, and completely another to be sent to the front line

Apart from this mobilization is not similar to a computer game where when you need to get more army units, you click on barracks and buy 20k additional riflemen. There should be done a lot of preparation among which is:

have a list of all people whom you can conscript (this is one of the reasons why many mobilization departments in Russia were set on fire: if the lists were burnt, people do not know whom to conscript)
being able to send the conscription letters to all of them (knowing that those people do not want to get those letters)
accommodate all the people and prepare them for the war. You need enough food/clothes/ammunition for each of the soldier.
you need to transport them to a place where you will train them
you need to train them as you can't get ten car mechanics give him a rifles and consider them a squad (you can but it will not survive for a long)
to train you also need people who will train them and have various schedules who trains whom for how long and what is needed for training
you need to have infrastructure what to do with people who would try to run away
you need to move all the trained people to the war zone

I probably missed many other things you need to do. Russia showed that their logistics is terrible and they struggle to get proper equipment (mosin rifles from ww2, t62 tanks are not there to show military advancement). With a tremendous corruption it is not clear whether there is equipment for a mass mobilization.
Right now Putin's plan is to use hidden mobilization. People are enlisted using:

threats. By telling that they will be treated as deserters, that they betrayed their country and their friends who are already fighting
proposing very lucrative contracts: 4-5k per month (for many places in Russia you would be happy to earn 300$-500$ per month) and forgiveness of loans. Of course you need to survive to get the money
proposing loan forgiveness and 7 mln rubles if you die in Ukraine. Of course military should confirm that you died in Ukraine and as right now Russia claims that they do not have losses and even sailors on Moscow cruiser just missed, it is a dubious proposition
enlisting people from prisons in exchange for money and forgiveness of crime
enlisting people from factories who lost their jobs
Comment: Not 3 days.  "A day or two."  Kadyrov.  https://twitter.com/samrireports/status/1500628970169065472?lang=en  Who is this rando?  Well, only one of Putin's more powerful backers, one who just is just reveling in his promotion to Colonel General or whatever.  So whatever he said probably fits general belief at the time.  Besides.... are you familiar with Hostomel operation?  Using paratroops that way means you **do** think you'll have the whole area - next to Kiev - secured within 48 hours, otherwise it is suicide militarily.
Comment: "this will be a short operation and in 3 days everything will be conquered". Quote? I'm seeing this in ever-lying Western media, but not in Russia.
Answer:
The war did not go the way they thought it would, and now they have a massive shortage of military personnel. They obviously need to deploy their conscripts,

This is not totally true. While the war may not go the way that Russia would like it to go and they have lost many soldiers and equipment it also hasn't been a complete failure on their side so far. In the last weeks they have gained territory in the Lugansk area and kept the South. They may think that they actually do not need conscription, which is always unpopular except maybe when defending yourself, and still be able to reach their objectives (whatever they are) within a reasonable time frame.
Indeed they currently try to recruit volunteers incentivized by promises of large cash bonuses or in case of prisoners acquittal of punishment. These recruits will only get minimal training and not be that valuable as professional soldiers but also casualties from them will probably result in lower backlash from the population.
Russia may simply think that conscription isn't needed yet because even with only volunteers they can still win the war and occupy more of Ukraine.
Should Russia not find sufficiently many "volunteers" they may use other methods to effectively conscript even without calling it conscription. Maybe calling in the reserves or something like that.

In September the situation must have changed, maybe because of previous gains of Ukraine around Charkiv, because then Russia did actually start drafting. However, they still did not need to declare war, because they declared an annexation of the occupied territories (including unoccupied territories of Donetzk or Kherson for example). This let's Russia use officially their conscripts in Ukraine but the draft is also deeply unpopular and the morale and level of training of the drafted units won't be very high.

And indeed now in February 23, the frontline has stabilized with even predictions of an upcoming Russian offensive. The partial mobilization of ~300000 Russians and additional half yearly conscription cycles generated enough manpower for at least continuing with the war from the Russian side. No formal declaration of war needed for that, but then again this is only a formality. For all practical purposes Ukraine and Russia are at war since the invasion of Crimea in 2014 (or at the latest since February 2022 but rather since earlier).
Comment: In particular, shortening the front line by abandoning the north (roughly from Kyiv to Kharkov) has significantly reduced the amount of personnel Russia needs.
Comment: Maybe this is Putin's way of giving the non-combatants (read conscripts) some real front-line combat experience.
Comment: We are nearing in to a time frame of their invasion taking more than teo orders of magnitude than they calculated, yet the territory they successfully consolidated control over (a.k.a. the invasion concluded) is 0. I was going to argue that in two orders of magnitude more time they gained one order of magnitude less territory for an order of magnitude more casualties than that of Ukraine, but even that is not true because they haven't gained any territory. F— zero. Not concluded, they aren't safe in any Ukraine territory, not even in Odessa now, & you can't divide by 0, success is incogitable.
Comment: @SilvassyPetrirov Do you want to answer the question? Anyway if you mean that Russia haven't gained any territory, I'm not so sure about that. I think they have and going back to pre Feb 24 would indeed mean a retreat for the Russian army currently.
Answer:
Why does Russia not declare war on Ukraine in order to incorporate their conscripts into the war?

Why do they not just declare war and send their conscripts to the war zone?

The premise of your questions is mistaken.
Even if war is declared, conscripts cannot be sent outside Russia.
Sergio Miller (2022):

Under the 23 June 1995 Federal Law No 93, conscripts are currently prohibited from serving outside the territory of the Russian Federation under any circumstances. Conscripts cannot even participate in peace-keeping missions. ...

The only service personnel legally permitted to deploy outside the territory of the Russian Federation are the professional officer and warrant officer classes, and the so-called kontraktniki ('contract soldiers') who sign three year contracts.


How did the NBA decide on 23.75 feet for the 3-point distance?

Question: In 1979, the NBA voted to have a 1-year trial of the 3-point line, which later became permanent. Although the ABA used a 25 foot 3-point line, the NBA used a 23.75 foot line. How was the 23.75 number settled on? Was it random?
Answer: While I can't find any sources that clearly specify why the line was set at that level, one can speculate on a few good reasons for the distance being what it is based on deduction.
Firstly, a standard NBA court is 50 feet wide.  In the original implementation of the 3-point line in the American Basketball League(1961-1962), the line was set at 25 feet, as you mentioned.  When the ABA introduced the 3-pointer in 1967, they actually used the same 3-point line currently used in the NBA, which is 23 feet, 9 inches. (Source) When the ABA folded into the NBA, initially, the 3-point line was not included in the deal. (Source)  It took the NBA 3 years to adopt the 3-point line and they simply used the same measurements that the ABA had used.
However, the line is drawn to allow 3 feet minimum along the sidelines to provide some space to shoot a 3-pointer from all legal angles. This means the distance is only 22 feet from the corners where the line is parallel to the sideline.  For these reasons, it is likely that a 25 foot line would create a major advantage to shooting a three from the sideline areas in that it is 3 feet closer to the basket.  As it is, there is still something to be said about the 1 foot 9 inch difference, but looking at an image of the current NBA court may help demonstrate another point of potential issue.  Pushing the line back further would create additional space inside the 3-point line which would cause the defense to spread even further to defend outside shooters.  The NBA attempted to increase scoring for 3 years starting in the 1994-1995 season by reducing the distance to a uniform 22 feet around the basket, with the change ultimately reverted in the 1997-1998 season.  One could then infer that any longer distance would reduce scoring -- something that the NBA clearly doesn't want.
An additional point to be made is the comparison between the college and pro levels in the US.  At the college level, the distance was initially set at 19 feet 9 inches during the 1987-1988 season -- a full 4 feet closer. It was later lengthened to 20 feet 9 inches in 2007.  As the collegiate level is an amateur league, it makes sense that the court is shaped with that in mind.  Using a shorter line enforces the relationship between amateur and professional.
Finally, using the measurements below -- it is likely that the measurement was set based on distance to the backboard, though it is usually referenced by distance to the middle of the hoop.  The image below shows a 15 inch measurement between the center of the hoop and the backboard.  Adding 15 inches to 23 feet 9 inches equals a full 25 feet, backboard to top of the 3-point line.


Where can I host my pictures for free without giving up rights?

Question: I want to host some pictures at low cost (less than flickr). I have come across Shareapic and Imgur. However, imagur strips the meta-data off of uploaded images, and I couldn't find much information on shareapic. Note: I want to retain ownership of my photos so Picasa web-upload won't work.
Comment: That isn't giving up ownership, though. Some of those rights are needed just to be ae to host and dismay the photos. The advertising-use clause isn't something I like, but it's still not giving up ownership. Also, all of those terminate if you remove the images.
Comment: ...especially as Flickr can be completely free...
Comment: You are mistaken about Picassa. _Google claims no ownership or control over any Content submitted, posted or displayed by you on or through Picasa Web Albums._ http://picasa.google.com/intl/en-GB/web/tos.html
Comment: By submitting, posting or displaying Content which is intended to be available to the general public, you grant Google a worldwide, non-exclusive, royalty-free license to reproduce, adapt, distribute and publish such Content for the purpose of displaying, distributing and promoting Google services.
Comment: That just grants Google use of the image for something, I would wager any albums set as private wouldn't be used. Nobody else would use them, but I imagine it would cover their ability to return them in search results and so on... Flickr is so cheap though, I can't see why you wouldn't just go with that.
Comment: See also: http://www.robertstech.com/blog/?p=327
Answer: I recommend Flickr. You can even choose Creative Commons licenses to assign to photos based on what licensing rights you want to permit.
Answer: www.deviantart.com
Answer: I use Fotki - less known than some but flexible enough and reasonable features and CHEAP.
You can set licence rights of your choice - they offer various variants of GPL and you can add your own in several says. I use non-commercial use only, no derivates, attribtution and suggest people email me. That does not stop copying but allows you to retain rights. You can password and/or hide albums etc.
In your account settings it says: Copyright holder:
 Set the default copyright message for your account.
 It can be overridden for a particular album or photo
From memory cost is about $US/10 per year if you buy a few years for unlimited storage, high resolution photos (may have a 10 MB limit?) . I think there is a 2 GB/day upload limit. Supports FTP an slideshows (and I seem to know more slideshow settings than any one else in public as I played and then asked them). All up its very good.
I have 90 GB and 119,000+ photos on Fotki at present. That's 'acceptable' [tm] for $10/year.
Here j.mp/NZPHOTOS
They offer album per photo view, thumbnails, slideshow and a very nice roll view like this - roll down - do not click until you see a photo you want to interact with in some manner.
Answer: I'm not exactly sure what your needs are, but if you are just looking for raw storage, try Amazon's/AWS Simple Storage Service.
It's primarily a paid service, but they have a FREE plan that will start you with 5GB of storage 15 GB transfer out / monthly.
http://aws.amazon.com/s3/
You'll need to read over the page thoroughly to get a sense of what they offer and how they work, but for what they offer, I think they are worth the effort.