Previous Up Next

Diary, September 2018

Sun Mon Tue Wed Thu Fri Sat
  2   3   4   5   6   7   8
  9  10  11  12  13  14  15
 16  17  18  19  20  21  22
 23  24  25  26  27  28  29

Sunday, September 2, 2018

Fractal Jigsaw

Yesterday and today, I made a new version of the program for generating Fractal Jigsaw puzzles. I added the option -space, which allows you to specify the space between the pieces. Most DIY-laser cutters make a very narrow cut, which means that if you make a puzzle, the pieces will fit very tightly together. To avoid this, the idea is to make two cuts and throw away the material in between. For this, I had to write a new algorithm. The old algorithm (still used when no value or a non-positive value for -space is used) would generate lines from top to down. The new algorithm generate a cut for each piece. For this reason the algorithm needs to track the sides of the pieces. This method can also be used to cut the border by following the (in)side of the border. Because now these are cut one-by-one, all the corners will be round, and the shape of the pieces and border is a little different from the single line cut. I am thinking about adding the option -round to implement this same shape in the single cut algorithm.

Monday, September 3, 2018


At 10:39, I bought the book FastFurniture, Multiples and Other Productions written by P.J.H. Kockelkoren in English and Dutch, and published by Uitgeverij AKI/ArtEZ in January 2007, ISBN:9789073025103, from charity shop Het Goed for € 1.50.

© Dave Borghuis

Tuesday, September 4, 2018

HyperBrain Machine

This evening at TkkrLab, I worked on putting together my new HyperBrain Machine, consisting of an old pair of safety glasses, a NeoPixel LED strip and a NodeMCU. Martijn, another member made a wooden box for the NodeMCU module and he also helped me with repairing the NodeMCU. I wanted to feed the LED strip from the USB voltage, but the VIN pin has a diode, after we removed it and short circuit it, it turned out that the connection from the USB to the VIN pin was broken (probably burned out under the load of the LED strip). I soldered a thin wire to repair the connection. And then it did work with some example program that came with the AdaFruit NeoPixel Arduino library. Now I still have to write my own program before Thursday evening when GOGBOT starts (or while I am there, because we have decided to just do our own things).

Thursday, September 6, 2018

First chestnut

Around 10:14, I saw pieces of the shell of a chestnut on the bicycle path. I stopped and found the chestnut that was inside it. I took it home and placed it in a pot in the garden and see what will happen.

GOGBOT: Hyperbrain machine

This afternoon and evening, I was with TkkrLab at GOGBOT. I wrote a program for the Hyperbrain Machine and walked around with it for some time, looking at the other projects. I used the questionair machine by Wiebe Audenaers about the Trolley problem with respect to AI. It printed a ticket with the result of my answers and a QR-code of a link to a website explaining it. in the evening, I also saw part of the robot pop-band Compressorhead that performed on the main stage.

Friday, September 7, 2018


Again, I spend the afternoon and evening at GOGBOT, most of the time in the TkkrLab area. We used the laser-cutter, to cut a piano fractal puzzle. It turned out, that the 'piece' consisting of the space in between the pieces and the border, was most interesting. The found the space between the pieces a little too much. I also walked around for some time to look at all the other things. The things I found noteworthy are (in the order I saw them):

In the evening, there were some interesting experiments with throwing dry ice in a pan with molted sugar (with a temperature higher than 100°C).

Wednesday, September 12, 2018

Bits, bots and brains

This afternoon, I visited the exhibition Bits, bots and brains at Tetem art space with a visiting friend. I did like the music being played.

Thursday, September 13, 2018

Rijksmuseum Twenthe

With a visiting friend, I went to Rijksmuseum Twenthe. We first went to see the exhibition Lief en Leed (Joy and Sorrow), which is about family portraits from wealthy families from the 17th and 18th century that are not totally factual and often hide some sad truth. Next we went to see Bernard Heesen and the folly of the 19th century. We watched a short documentary about Heesen make one of his glass art works. This made me appreciate the exhibition much more than the last time I saw it. Next we also watched the other exhibitions. Of course, I saw Falaises près de Pourville from 1882 by Claude Monet.

Saturday, September 15, 2018


With a visiting friend, I went to Utrecht. We first looked around at the travel bookshop Interglobe. Next we paid a short visit to Radio Centrum, an electronics shop that I visited for the first time around 1974. (The earliest record in my diary of a visit to the shop is of Saturday, March 27, 1976.) This is very probably the last visit, because they were having a closing down sale. I looked if I could find something interesting to build, but I could not decided on anything to buy. Next we went to Bookshop Broese. I did not buy any book, but my friend did. They were closing down their second hand books section. On our way to Dom Tower, we paid a short visit to the bookshop Steven Sterk. We went to visit the monastery garden, where there was (it seems) a reception for a wedding of two women. We also went inside the church were there we listened to the practice of Missa Assumpta est Maria by Marc-Antoine Charpentier. We also visited the The Oude Hortus. We saw the Sequoia Giganteum, the Ginkgo Biloba (one of the oldest outside of Japan), and the Victoria Amazonica.

Monday, September 17, 2018


We visited Amsterdam today. We parked at the Olympic Statium and took the tram to the center. We had to change near Het Martyrium and went in to have a short look. We went to Rijksmuseum. We only saw a small part of the museum. The works I found worth mentioning are:

We walked along the cannals to the Dam Square, and from there to Booshop Scheltema. At At 16:23, I bought the following tow books:

Tuesday, September 18, 2018

Group generation

This evening, I finished a first version of my program for generating the elments of a mathematical group from a generation expression. I have tested this on some of the generation expressions given on Small finite groups and Cayley tables. It seems that the algorithm works for most of them. With some of the generation expressions, the algorithm found shorter identity sequences than the ones given in the generation expression. Maybe these generation expressions are incorrect.

Wednesday, September 19, 2018

Kröller-Müller Museum

We went to the Kröller-Müller Museum. (At the entrance of the park, the visiting friend bought a map for me.) We first went into the Van Gogh wing and later walked through the sculpture garden. The works I found worth mentioning are:

The SAPA Project

My result of taking the free personality test from The SAPA Project

With respect to the big five personality traits, my percentile ranks according to the test are: 16 for Extraversion, 66 for Openness, 42 for Conscientiousness, 54 for Neuroticism, and 50 for Agreeableness. It seems I do not fit in any of the four personality types identified in the paper A robust data-driven approach identifies four personality types across four large data sets. I also scored 99 on cognition, but that was only based on only eight questions and consisted of some tests that I have done many times and that I am known to be good at. There were also no time constraints and I took time to figure out the answers.

Saturday, September 22, 2018

Dutch Kabuki Day

Andy and I went to the Dutch Kabuki day. In the morning there was a general meeting with some presentation. Connie Strumpel gave a short introduction with recent developments. Next, a presentation of the use of growth hormone. About 75% of children with Kabuki Syndrome have a short stature, which develops after they are born. High frequence in KMT2D (MLL2) mutation. The cause of the short stature is unknown. In the literature there is but one growth curve available. Based on questionairs in the Netherlands, growth curves have been made. There is also a clear tendancy of obesitas, especially with the girls starting from around six years, The average length of adult males is 161cm and females is 149cm. A growth spurt has not been observed. Also the development of the puberty is not clear (due to lack of information). Five of the 20 individuals in the study were eligable for growth hormone therapy. At the start of the study the average standard deviation of the length was -2.4. After two years, the average standard deviation had increased with 1.1. This is a good result. If the growth hormone thrapy is stopped after one year, the standard deviation drops again. This suggest that the therapy should be continues after the desired effect has been achieved. There are also clear indications that the metabolic rate of children with Kabuki Syndrome is lower than normal. Growth hormone therapy increases this to almost normal. The low metabolic rate could also explain the obesitas. The hormone therapy has not been found to have any averse effects. With respect to hypermobility. With Kabuki Syndrome there is a higher hypermobility with both boys and girls about the same. It seems that this is stronger with some joints. The growth hormone therapy also has a positive effect on hypermobility especially with those joints where it was worse. It seems that the therapy has a positive effect on the connective tissue.

The second presentation was about genes and behaviour. Neuro psychology covers more than just intelligence. It also has to do with memory and executive functions, for example. These can be even further divided. Social cognition is another important area: recognizing emotions. The research program included two different rare syndromes and the general group of people with a mental handicap. One of the research question was if there are specific problem areas with respect to Kabuki Syndrome. The study involved 13 female and 15 male individuals. Not everyone was able to do all the tests. The conclusion is that the development age is lower and stops earlier. With respect to intelligence there was a great variation. Individuals were worse with remembering visual information, while they are better with verbal information. This also has an effect on the executive functions. In the behaviour area there were problems with attention or with social interaction, but these seems not worse compared with similar syndromes and could be explained with lower development age. Auditive memory is good. There are behaviour problems but these are not very specific. (To me it seems that this findings are compatible with the delayed myelination hypothesis.)

In the afternoon, there was a short documentary about one of the young women with Kabuki Syndrome. There was also a presentation an organisation dealing about rare diseases and conditions. Rare means less in 1 in 2000. Often it takes a long time before a rare disease or condition is diagnosed. About one in seventeen people have a rare disease or condition. There are now 400 expert centres in the various academical hospitals in the Netherlands. A GP sees most rare disease or conditions at most once in their practice. They now want to combine all information with respect ot Kabiki Syndrome into one document, both for medical specialists as for the parents.

Tuesday, September 25, 2018

Computers old and new

I have decided to do some system adminstration work on my old and new computers. Yesterday, I bought a Seagate Expansion+ 2TB external harddrive to backup the contents of some harddrives.

I first started lixia. I discovered that the new external harddrive still needed to be formatted. When I removed it lixia rebooted. I started copying the D drive, but it looked like the PC locked-up, and I switched it off after some time. I tried it again with a batch file with XCOPY commands. That seemed to work better.

I tried to start up the OptiPlex 755, but it not seem to work. The attached monitor did not register a VGA signal. I opened it to see what was inside. (Later on the day, I removed the clock battery, and put it into johan to resolve the issue with the internal clock.) Next, I switched on the Lenovo Thinkcentre Edge72 to discover that it had a fresh install of Windows 7. But I guess, I do not have a valid licence key, meaning that I can only use it while not connecting to the internet. Anyway, I had promised that I would install Linux on it. I tried to install Debian 9 with a USB stick created with UNetBootin, but after the installation, the BIOS reported that no operating system was found. I tried some other tools for putting an ISO image on an USB stick, but in the end I used the Cygwin dd command to copy the debian-9.5.0-amd64-netinst.iso image. When I started the install, I did not get the question to choose for the UEFI install as I did the first time. However, the second time, I did get the option to install GRUB. And this time, the installed worked.

LED Matrix

At TkkrLab, I first helped someone with the first lesson of our Arduino course (in Dutch). Next, I worked a little on a program for the Irregular Chocolate Bar problem. When I was about to leave, someone showed the clock display he had developed for the 17 by 10 LED Matrix in the space. Someone else suggested that more people should start writing software for the LED Matrix. I decided to give it a try, and with some searching on the internet, hacked a small C++ program together. First thing I did, was setting the colour #FFAA5E on all the LED's. I plan on writing a small C++ library for controlling the LED Matrix.

Wednesday, September 26, 2018

LED Matrix

This afternoon, I went to the TkkrLab space to compile and test the first version of a program to use the LED Matrix in the space. The LED Matrix is controlled through (a slightly relaxed version of) the the Art-Net protocol. I am thinking about at least add another class between the classes UDPSocket and LEDMatrix to implement the Art-Net protocol, as there are some other devices in the space that can be controlled with the Art-Net protocol.

Thursday, September 27, 2018

Escape room: The Time Machine

As part of my farewell party, we had some dinner in the city and also played some escape rooms. Together with five others, I played The Time Machine escape room. For all of us, it was the first time we did it. We did not make use of any hints, but did get one hint, because we did not realize that the piece of paper behind which a key was hidden, actually was an envelop with instructions inside. We did not finish the escape room within the set time limit of an hour. We failed to complete the last three puzzles. But we still were proud of our achievement, because it was the first time and we finished some of the puzzles rather quick according to the game master. We also had a lot of fun and we worked as a team, I think. As a farewell gift, I was given a framed poster which contained a compination of a picture of myself and the work CONW54 TGCOL 1 by Peter Struycken. The poster was made by one of colleagues.

Sunday, September 30, 2018


Two years ago, I got a new pair of glasses to be used behind the computer. Just like everyone else, I suffer from presbyopia due to a reduced ability of my eyes to accomodate because I am getting older. I have been near-sighted all my life with a high myopia of about 8 dioptre. It is easier to work with dioptre when calculating the effect of combining lenses (at short distances), than to work with focal distances. For a long time, I had been able to correct my presbyopia by moving my glasses a little away from my eyes by placing them at a lower point at my nose. But at some point, it required to tilt my head backwards to look at a computer monitor, which was causing strain. The pair of glasses I got two years ago, had a correction of +0.75 dioptre with respect to my standard prescription. Although, these glasses were intended to be used behind the computer, I noticed that I could also use them for biking around and I began to use them all the time. While riding a car, I often used a pair of sunglasses with no correction. Only when going to the movies, I used my old glasses. I got the impression that my nearsightness had become less.

In the past half year, I noticed that I was moving my glasses down my nose again. So about a month ago, I went back to have my eyes examined. It turned out that my nearsightness had remain the same. The optometrist who checked my eyes, suggested that I should have a correction of +1 dioptre. Because of the small difference and the prices of the glasses, I decided to give it some second thoughts, also thinking that maybe I was confused about how often I lowered my glasses. On Friday, September 21, I went back to have a second look. I talked with another optimetrist who gave me a pair of test glasses and after some experimentation we agreed on correction of +1.25 dioptre. When I suggested that we also should test +1.5 dioptre, I got the remark that I should not make my eyes lazy. Although I tried to keep the test glasses as close as possible to my eyes, I still had some doubts about the measurement method, because I know that moving my glasses but a few mm, will have a dramatic effect on the focal distances and the correction lenses where the furthers away from my eyes. Yesterday, I went to collect the glasses. I already noticed that I was still able to see sharp at quite some distance. In the evening, with poorer lighting conditions, I suddenly noticed that I was wearing my glasses in the same way as before. It seems that the extra +0.5 dioptre did not have much effect at all. In the evening, your pupils open further and by doing so reduce the range at which you can see sharp. I started looking at some websites for more information and also started to some calculations. At my age, the average correction for reading glasses is +2.25 dioptre. The prescription is measured at about a distance of about 10m, which is equal to 0.1 dioptre. For reading at 30cm, which equals to about 3 dioptre, you need a correction of 3.1 if you would have no accomodation at all. And indeed, at a high age, the correction for reading glasses is +3 dioptre. When I work behind the computer, the distance is between 60 and 70 cm. With my new glasses at daylight, I need about 110 cm to see sharp. When at that distance, I put my pair of glasses the furthers away from my eyes, and then test at which distance, I can still see sharp, I can get as close as 55 cm. This is equivalent with about 0.9 dioptre accomodation, which is about the average value on my age. I have done some calculations, and it seems that with a correction at +2.25 dioptre, my range becomes 53 cm to 99 cm with an ideal looking distance of 68 cm.

This months interesting links

Home | August 2018 | October 2018