Category: Documentation

WordPress errors

Askimet is a very excellent tool and it protected me from a whopping 80.000 spam comments  on  my WordPress based web site. That is for October alone. Those spam comments completely filled up my SQL database beyond the point where I could repair it following these instructions.

It was a classical Catch 22. To empty the database I had to “optimize” it, which does take some additional space. Which I did not have because the database was full. Askimet has just released their 3.0.3 update which might have solved the issue. Or it could have been my webhoster’s support worker I called that finally had mercy with me and hit the optimize button on his side.

In any case, getting from a “Warning: Creating default object from empty value in wp-admin/includes/post.php on line 567” error to the conclusion that my SQL database is full due to comment spam that Askimet caught was a rather interesting journey. And it only took me two days to figure it out.

 

 

Sensor readings Mindsensors Glide AS with EV3 problem

I was working on a new version of my Spirograph Automaton and once I fired up the EV3 software on my computer it informed that a new version was available, including a new 1.06H firmware. I installed both and expected my software to work as it did before. I got some very strange sensor readings. One sensor seemed to overwrite the value of the other sensors. Moreover, once I unplugged and reconnected the sensors it sometimes seem to work again. After rebooting the EV3 it sometimes worked and sometimes it did not. These types of intermittent problems are really annoying and it took me more than an afternoon to figure out that it was not my poor programming skills that caused the problem. Eventually I made a video of the problem and contacted the Mindsensors support.

They replied promptly and informed me that:

“The 1.06H EV3 firmware has a bug in its sensor handler. Even when the i2c addresses are changed the error still occurs. It seems the error stops once the program in executed and then the devices are disconnected and reconnected. This will fix the error until you restart your EV3. If this is too much of an inconvenience, you can use the 1.03H EV3 firmware. 1.03H has been tested and works with the rotation test-ms code. We have notified LEGO about the issue. Hopefully a new firmware fix will come in the near future.”

This information was not available on their website and I hope that my post will safe you some time. In case you want to downgrade to the 1.03H EV3 firmware, have a look at this file. To downgrade place the firmware in the folder (on Mac OS X):

/Applications/LEGO MINDSTORMS EV3 Home Edition.app/Contents/MonoBundle/Resources/Firmware

You need to right click on the EV3 software and select “Show Package Contents” to get into the desired directory. The firmware will then show up in the list of the available firmwares in your “Firmware Update” under the Tools menu in the EV3 desktop software.

installFirmwareEV3

Accessing scientific literature from home

I work for the University of Canterbury and once I am connected to the university network, I can easily access scientific literature since most publishers authenticate users through their IP address. When I work from home or from off-campus I do not have a university IP address and hence it is harder to get access. Many authors do post their PDF files online these days, but just not enough of them.

There are several ways on how to access all the literature from home. First, you can use the Firepass system, but it does remain rather difficult, in particular if you do not work on Windows or if you do not have the device with you. A much better way is to use the proxy server of the library in combination with Google Scholar.

First, you need to visit Google Scholar and log in with your Google account. The you need to click on “Settings”

settings

Next, you need to select “Library links” and enter the name of your university. In my case this is University of Canterbury. Hit the search button.

search

Google Scholar will present you with a list of search result and you need to select the right one before you click on “Save”.

select

When you now perform a search on Google Scholar you will see on your right a link to the full text via your library. Click on it.

ucLibraryLink

You will now be presented with a login screen from you university proxy server. Once you entered you login and password you have direct access to the PDF files.

login

If you are not a big fan of Google Scholar then you can still use the library proxy server. Simply type in the address bar of your browser: “https://login.ezproxy.canterbury.ac.nz/login?qurl=linkToTheArticle” where linkToTheArticle is the URL of the paper you are after.