Wed, 02 Jan 2013
PF 2013
I wish happy year 2013 to everyone who reads this blog.
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Tue, 20 Nov 2012
SMD Soldering
For the first time in my life, i have tried to solder SMD components (as I have written before, I am working on DYI LED lights for my bike). The component side looks OK, and soldering through-hole components went without problems. The SMD parts were a bit tricky, though.
I have used an ordinary soldering station with temperature regulation, but the results are not pretty. I wonder what is required to achieve this level of quality (watch from 14:10). One possible problem might be that some components on my board (especially the smallest sensing resistors) are connected to the highest-current and thus thickest paths, which suck great amounts of thermal energy when soldering.
Anyway, from the preliminary testing, it seems that my board works. So far I have found the following problems:
- The programming connector is bigger than I expected. I have solved this by using the angled variant instead, and adjusting it using knife :-)
- The silk layer labels marking the polarity of components (electrolytic capacitors, diodes, etc.) can be placed under the components, except for the labels of connectors, which are needed even after the components are soldered!
- I should have added low-pass filters to the A/D converter inputs, at least for the feedback of the PWM-regulated converters. I think I would be able to overcome this in the firmware, though.
- Next time, I would probably design the board with round corners :-)
Now it's time to finish the firmware and to start adjusting the mechanical parts. I have already made the front spotlight and rear spotlight, and I want to make a LED string. Any tips about making a waterproof LED string out of 3mm through-hole LEDs will be appreciated. Should I use silicon, shrink-wrap tube, or what?
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Thu, 15 Nov 2012
Printed Circuit Boards
For my bike lights I needed a PCB. Out of several services for manufacturing PCBs, I have chosen Itead Studio PCB prototyping service (the other candidate was Seeed studio). Here are the preliminary results:
I have placed my order on October 29th evening (Central European Time), according to Hong Kong post, the package was received by them on November 7th, it left Hong Kong on November 11th, and I have received it today, on November 15th.
They also have an interesting "Open source" program - the customer declares that his design is open source (mine is anyway), they make few more boards in addition to those the customer has ordered, and they send them to their other customers. The original customers gets his orderd boards, and in addition to that, two more boards from other open source projects. I have in fact got their demo board (on the right side), and one open source board (the white one). Apparently, it is Arduino 512KB SRAM expansion board. I currently don't use Arduino, so if any Arduino user is interested in this PCB, just let me know.
Okay, now it's time to take a soldering iron and play more with the hardware :-)
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Tue, 06 Nov 2012
DNS Lookup :-)
It seems my registrar will
discontinue their "free" hosting (as in "bundled with the domain
registration") soon,
so I will have to move my domain yenya.net mail and WWW servers
elsewhere. There is no problem with that - I have a 24/7 running computer at
home with good connectivity. There is one challenge, though:
The new DirectNIC service allows only one A record in the registered domain, when the domain is hosted on their DNS servers (no AAAA and no DNSSEC). So I am considering running my own DNS server in addition to mail and WWW servers. This would allow me to have A and AAAA records, SSHFP, and possibly the new DANE records. So I need someone to host a secondary DNS server. The requirements are:
- Static IP address, running 24/7
- IPv6 connectivity, if possible
- DNSSEC enabled
- Hourly update interval if possible
- Preferably outside the SmartComp/Nebox network
Of course, I am willing to provide the same service to the other party. Is anybody interested? Thanks in advance.
1 replies for this story:
Adelton wrote:
I use freedns.afraid.org as my secondary DNS, for two(?) years now. IIRC it's IPv4 only. They should be DNSSEC compliant thou I don't use DNSSEC. I don't think there is hourly update option but you can just send notify and have the transfer initiated when something on your primary DNS server changes.
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Tue, 30 Oct 2012
Bike Lights
I have a new personal project: I am trying to build a set of lights for my bike. So far my setup is quite simple: I use a 700 mA Buck Puck current regulator to feed a front Cree XM-L white LED and three rear 350 mA red LEDs. It can only be switched on or off, and cannot blink at all. So I wanted to make something more sophisticated.
I have been playing with electronics many years ago in my teen-age years, but I have been doing only software since then. So I have taken this as an opportunity to find out what progress the world of DYI electronics has made, and to learn programming of microcontrollers. I want the resulting electronics to have the following features:
- LED drivers for high-power LEDs:
- Atmel AVR Tiny CPU, programmable in-system (various blinking modes, etc.).
- Power: 7 to 12 V battery pack (either lithium or NiMH).
- Ambient light sensor (for automatically setting the mode depending on the conditions).
- Battery voltage monitoring.
- Cycle computer illumination LED.
- Two status LEDs.
- Two buttons for adjusting modes, switching on/off, etc.
- Software on/off.
- High-power software switched output driven by a MOSFET transistor (I don't know the purpose yet, I just had a spare pin and MOSFET :-).
I have managed to learn how to use the gEDA suite of tools, and created my first PCB with it. Yesterday I have sent the result to the fab. Anyway, I have made the Project Bike Lights page for my project, where it is possible to watch the progress or look at the firmware code, schematics, and PCB design.
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Sat, 13 Oct 2012
Those Annoying Endorsements
Recently LinkedIn has added a new feature, endorsements. The most annoying thing is that the requests for endorsements are now near the top of the page, and people are clicking on it. So I have several mails each day saying "$somebody has endorsed you!" (with an "and you are expected to return the favor" subliminal message). So, my dear LinkedIn contacts: feel free to not endorse me and don't bother to write recommendations, as I don't plan to do the same either.
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Tue, 09 Oct 2012
Zacyklení 2012
I like outdoor puzzle-solving games, and last weekend I managed to take part in a really special kind of puzzle-solving competition:
Zacyklení is a puzzle-solving outdoor game for cyclists. And what is even more interesting, we have managed to create a purely recumbent team for this game. Those who can read Czech, here is the report from the game. Those who can't, follow the link anyway for more photos :-). We have not made it in time, but among all the teams we have finished somewhere around 5th place. Congratulations to the winners, and thanks to the organising team!
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Thu, 20 Sep 2012
Hanwag Boots
Afters about 10 years, my Hanwag Alaska boots have disintegrated while I've been walking in the forest during this year's Svíčky. I will need a new boots. Which boots do you recommend, my dear lazyweb?
I have been satisfied with Alaska, and I have chosen them because the big part of the boot is made from one piece with only one seam i the back. However, the middle part of the sole has completely disintegrated. The consipration theory follows: I wonder whether it could be intentional from the manufacturer, in order to not allow their customers to use the product for more than 10 years. In my opinion it should be possible to find a material which lasts almost indefinitely. That said, from my previous experience the sole was the weakest part of all my previous boots in terms of endurance. So maybe it is perfectly OK to expect the boots to last only 10 years. What do you think?
4 replies for this story:
Andrej Šmigala wrote:
I have very similar (maybe even exactly the same) boots, i've had them for five years (of what I'd call moderate to heavy use) and I'm going to have to buy a new pair for the next year. There are two problems with them: 1) the soles are almost flat 2) there's a hole where the leather meets the rubber lining near my right foot's toe (this probably has something to do with the way I walk, since most of my right shoes die much sooner than their left companions :-). So I too believe the sole is the Achilles' heel of the shoe, but I'd still say getting 10 years out of walking boots is quite enough.
b42 wrote:
I'd try to ask at Hudy (or wherever you bought them) if it's possible to replace the soles. From what I was told, some boots are made so that their soles can be replaced when they wear down. The cost will probably be significantlylower than that of new boots.
Bobby wrote:
I had precisely the same ones and I think they are the best. Makub bought them, too, few years ago. I had used my pair quite heavily for I think nine years, one (left one?) torn apart in Slovenia two years ago. I tested and compared many models and decided for Hanwag Alaska again.
Yenya wrote:
Thanks, everybody. As for repairing the boots - I have destroyed them by walking without the sole for several hours. But in case somebody needs it, I have heard good references to http://www.restday.cz/cs/oprava-treku - they do repairs and replacements of soles of trekking boots.
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Wed, 19 Sep 2012
Playing with Prezi
A while ago, I've came across Prezi presentation tool. It is completely different approach to presentation than slides with bullet-points. I didn't like the dependence on either the on-line access with Flash, or on the Windows executable (with embedded Flash, of course). Today, I did my first presentation using Prezi (together with Šimon).
We have been given 10 minutes to present our approach to two sub-tasks of the Plagiarism Detection task of PAN 2012. We used Prezi in order to be able to focus on explaining our approach without devoting too much time to explaining the structure of the talk to the audience. I think this is a great strength of Prezi, if used correctly.
So, my dear readers, do you think Prezi can be a useful tool, or do you instead agree with Peter (in Slovak), that it is just an over-glorified eye-candy? You can see our presentation here. Thanks to Yuri for the photo!
5 replies for this story:
Milan Zamazal wrote:
How can I view your presentation? The link displays a web page with some Flash and Gnash can't play the Flash thing in my browser.
Yenya wrote: Re: Milan Zamazal
Yes,this is Flash. If Gnash can't play this, I am sorry.
dan wrote:
Do you know reveal.js (https://github.com/hakimel/reveal.js)? I've seen a couple of presentations in it and it was quite nice - it has a nice design and even animated transitions, although not as fancy as Prezi. And all you need is a browser.
Yenya wrote: Re: reveal.js
Thanks for the link - I have looked at reveal.js, and while it is interesting to make presentations in HTML, I think reveal.js transitions are exactly the kind of unnecessary eye-candy. I would guess exact positioning of elements is impossible, as well as automatic size scaling to fit different aspect ratios (which is what Prezi does, as I have discovered).
Peter Kruty wrote: impress.js
I compeltely forgot to mention impress.js, which might help you to have Prezi-like presentation, but remove dependency on flesh. Still have the same problem as Prezi :). I can't find the visual effects helping, but rather disturbing the presentation. It might help the speaker as it reflects his mental image of the presented concept, but I believe it doesn't help to build the same image with the audience.
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Sat, 14 Apr 2012
My New Bike
Several months ago, I have written about choosing a new bicycle. Here is the outcome:
Introducing my new AZUB Apus. I have rented and extensively tested several recumbents from AZUB (20" Eco with above-seat steering, 24" Max with under-seat steering, and 26/20" Apus with above-seat steering), and I have decided to go for Apus with under-seat steering.
The next thing to decide was gearing. After testing 24" Max with 48-38-26 chainrings and 11-34 sprocket (about 570% ratio) I've got the feeling that I could occasionally use even slower gear (and with 26" rear wheel of Apus the 26/34 gear would be a bit faster than on a 24" wheel), and I can definitely use more faster gears. Recumbents are fast, especially going downhill, because of lower aerodynamic drag. So I wanted gearing with ratio larger than 570% and with the slowest gear slower than 26/34. This is hard to achieve with current components, so I went for triple gearing: I have got SRAM DualDrive in-hub planetary gearbox (three speed gearbox and 8-speed derailleur), combined with tree chainrings, giving me 3x3x8=72 gear combinations and over 920% ratio. One of the biggest advantages is that the gearbox gears can be changed even without pedaling, for example after having to stop unexpectedly.
After five months with Apus, I am still excited with it. I really enjoy being faster on flat surface and on downhills, being able to pedal even while turning, having excellent view with zero neck, wrists and backbone pain, being able to brake without the danger of falling ahead, sitting lower in case of fall, and so on.
The drawbacks are worse view when entering street crossings, being slower uphill, and not being able to jump over obstacles higher than about 10 cm). And the front suspension of the SASO carbon fork is not as good as I expected. I plan to try softer coil spring.
If I had to choose again, I would buy the same bike, possibly with not-so-steep sprocket (11-28 instead of 11-32). Also, having used really narrow tyres on my previous (road) bike, I did not pay much attention to the brakes - I have got V-brakes on my Apus, and I am not able to make the front wheel slip even when braking really hard (on asphalt roads). So probably next time I would get disc brakes instead (at least on the front wheel). Anyway, watch this guy's commute riding Apus on forest paths:
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Mon, 18 Jul 2011
Which Bike?
The 30 years old frame of my bike broke several weeks ago, so I will need a new bike. We have already decided to buy a new bike for my wife, so I have took the frame of her present bike, and remounted some components of my former bike to it. So I don't need a new bike right now, and I have more time to decide what I want.
My previous bicycle was road bike with drop handlebars. I ride on paved roads mostly (altough many roads in Brno resemble off-road riding :-), and we occasionally do touring as well. I am considering the following options:
- Using the frame of my wife's bike until it breaks :-)
- Buying a cyclo-cross bicycle, which is essentially a road bicycle with hardened frame and different tires.
- Buying a touring bicycle, something like Author Avion, which even has a carbon frame.
- Something really different. Last week I rented a recumbent bicycle, AZUB ECO. It was really interesting, very comfortable, yet a bit difficult to drive. I would like to try a bigger one with under-seat steering, like AZUB 5 as well. The only problem with recumbents is that it is not possible to use them with trail gator tow bar.
So, my dear lazyweb, do you have anything to recommend?
7 replies for this story:
Vašek Stodůlka wrote:
I have a scooter (koloběžka in Czech :-) model "Street" from Kostka, it is extremely handy in manipulation, it fits into sedan car boot without any diassembly. It is fun to drive with kids, when they have their own bycicles / trikes, it is possible to use it when others are roller-skating - you have similar speed about 16km/h. It is difficult to use it for longer trips and maintaining higher speeds, because it does not have any transmission. It is not a substitute for traditional bike, but it is very entertaining. A friend of mine has recumbent trike - azub also make theese. For me it looks like more fun, than bike, but on the other hand it is also less useful offroad. And when it comes to traditional bikes, anoher friend of mine (Aleš Habáň) has a shop in Brno - http://www.habbybikes.cz/. I think he is very experienced and can give you advices and if you tell my name, he may give you some discount. ;-)
Honza Obdržálek wrote:
Thinking about a CX bike, you may know that the differences include a slightly different frame geometry and brakes, which are weaker than the standard road bike brakes (if you do not go for the recently allowed disc brakes). The wheels are basically the same as for road bike, the only difference being the tyres. For the uses you specify (city + some touring) I do not see a point of buying a bike with drop handlebars. The "touring bike" you link is not really a touring bike (i.e. trekking bike) but a cross bike (the difference being the former usually comes with mudguards, pannier rack etc.) Cross bike can actually even lack attachment points for a pannier rack and mudguards. Note that in this price category you do not get much extra by having a carbon frame. For the uses you specify I would, however, buy a bike with a rigid fork (you save lots of weight, cheap suspension forks are useless, and you do not really need the suspension). Here I would recommend a carbon fork. As for recumbents, I'm having my reservations for use in traffic - you are too low to have a good situation awareness.
Yenya wrote: Re; Honza Obdržálek
Thanks, Honza (and sorry for my incorrect terminology). As for situation awareness with recumbent, after having ridden a recumbent for four days, I think it is actually better than on a regular bike, with one exception, and this exception has nothing to do with sitting too low, but with sitting "in the back" - when I enter the intersection, on a regular bike I am head-first, and I can see much better than on a recumbent, where I have to move much farther to the crossroads before I can see the situation.
Yenya wrote: Re: Vašek Stodůlka
The Kostka Street looks definitely interesting, but I am afraid it is not suitable for me - one of the purposes of my bike is commuting to work, which is about 8 kilometers with relatively steep hills (from Hády to the level of Svitava river, then uphill to the level of Mendel university, and back to the level of Ponávka). I don't think I would be able to enjoy it on Kostka.
Tom wrote:
I've recently bought Mongoose Croix Elite and I'm quite happy with it. (It was 2009 model which I ordered, but 2010 model actually arrived. Well, there's probably not much of a difference except for the price :) Anyway, what I intended to get was something close to a road bike which I wouldn't be afraid to use in light terrain. And after I switched to slick tires (35 mm wide, 6.5 bar max pressure) it pretty much fulfills my expectations, though I don't have that "light" feeling of a road bike completely, which I guess can't be achieved without those thin, heavily pressurized tires. There are V-breaks which I do not find to be insufficiently effective -- it's not a problem to block the wheels, and I personally prefer drop handlebars which you can hold in many ways. I also use the bike for commuting (Lesná Gorkého) and it's alway a pleasurable part of a working day :). So I would probably go for a CX bike rather than some normal cross bike.
J.C. wrote: Option 1
I suggest option 1, the easiest one ;-). You will have enough time to consider the other possibilities.
job wrote:
i use to room in my bicycle but i brought my first motorcycle. my bike is sleeping for years :(
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Fri, 03 Jun 2011
Citroën Xsara
It has been seven years since I have bought my Citroën Xsara. At that time, I have considered several models, looking for an estate car for my family. Having used several Škoda Felicia cars in my previous job, I have definitely wanted a car from some other manufacturer. My opinion was "the car can have its problems, but at least let it be different problems than Škoda have".
That said, I have never considered Citroën, and in fact I did not know much about Citroëns. When I have been offered a 4.5 years old imported Xsara, however, I have found it "good enough" for me to buy.
Subsequently, I have been pleased to find out how comfortable my Xsara was, and how well equipped compared to the cars of similar age and class it was. It provides enough leg room in back seats (especially when compared to Octavia), and the 82 kW engine provided enough power for most of my needs. During almost 100,000 km in seven years I had only few malfuncions, the most serious one was a broken exhaust pipe because of corrosion.
Even though I did not originally considered buying Citroën at all, the next car which I have bought and which I use these days is also Citroën. So, my dear lazyweb, is anybody in your social network interested in buying a cheap, well-equipped, used car? If so, look here.
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Mon, 31 Jan 2011
Is My Teaching Getting Bad?
The results of the final exam of the UNIX - Programming and System Administration I course make me wonder whether I am getting gradually dumb or bad at teaching.
I used to think that as I teach, I am getting to know more and more about the subject, as well as have less errors and more clean formulations in my presentations. My lectures are now available from the video archive, so the students can rewatch me presenting the topics they have not understood the first time again, if they wish. I have switched the presentation format from old and boring black-and-white DVI slides to new, colored, shiny and graphically rich LaTeX-beamer format (thanks to Jiří Boček from servistech). Also the exam format and even some of the questions are still the same as they have been since eight years ago.
So what am I doing wrong?
18 replies for this story:
Martiner wrote:
As a former (successful) attendee of this course I believe that you have to find better students :) You are talking about ratio, but the base is growing, isnt it? If the count of successful students is the same (or is decreasing slowly), I believe there is nothing wrong with you.
Yenya wrote: Re: Martiner
Well, quite the opposite is true - the total number of students attending the course is slowly decreasing.
Kurochenko Andriy wrote:
As for me, I liked your presentation and I appreciate lectures in the video archive. The new slides are colorful and contain more information, but are inappropriate for printing in contrast with the old ones (I also like them more because they look like man pages :-) ). As for decreasing percentage of successful students. Maybe C and kernel functionality are less popular among the students every year. Who knows?
sev wrote:
Please don't start Y-axis at 45% - this is confusing visualization. Ad topic: Do you feel like the requirements to successfully pass the course are higher?
Peter Kruty wrote: Some thougths
I find this really interesting. Maybe we are loosing the real geeks used to terminals and man pages and new generation is growing, which still is interested in Unix, but also are used to Web 2.0 simplification, to the point information and easy to find core information (a la wikipedia)? I have not seen new slides, but I guess that overall approach of the seminar is still same and I remember it as comprehensive, detailed and precise. Maybe new student have issues with digesting it? I'm wondering how they score in other courses in general? How are the scored of students changing in general. Interesting, I will definitely like to talk that through :).
Petr Bartel wrote:
As a former student, I used to be fully satisfied with a form of lectures, with your presentation skills and materials were great too. Perhaps for someone who didn't pass some C/C++ introduction it could be somewhat tough. I was very surprised with your being able to know all these structures, pointers and so on by heart. Maybe it could be great to get hands on. There is some new subject PB173 where it is possible. Or maybe insist on doing supplementary tasks in slides for some points.
Milan Zamazal wrote:
Interesting. Perhaps the course is basically the same while world changes. People work with computers in very different ways than they used to 8 years ago. There are several aspects of it: a. When we started to learn Unix we read the single "wise" book several times and tried to understand everything. Some years later there still used to be extensive HOWTOs available. Today? Most often googling for answers to questions in newsgroups, i.e. quick retrieval of isolated information without deeper understanding. b. We all started with C. How many programers use C regularly today? c. It was easy to get exposed to powerful things when the choice was limited. There are so many choices today, that it's difficult to discover and start using the right tools. d. The same applies to system administration. Things used to be done using simple, basic, powerful and well documented tools. Today many things are hidden behind undocumented interfaces without understanding what really happens (I'd often like to know, but it's difficult to find out). e. You couldn't use a Unix computer without some essential knowledge of the operating system some years ago. This is no longer true (I've got several GNU/Linux users who don't know what a file is). So simply: Your course probably becomes a specialist topic; while students answered questions related to their everyday use of computers years ago (easy), they have to handle abstract subjects separated from their computer experience today (difficult).
avakar wrote:
I think the decrease in the quality of students is not limited to your lectures. The number of accepted first year students is increasing every year (it's about three times as high as it was when I got enrolled), but of course the number of talented students stays the same. Also, ever since IB000 was taken over by doctor Hlineny, the lecture no longer serves to separate chaff from the wheat, allowing some of the talent-impaired student to get to as far as the second year. So while I can't comment on the quality of lectures, as I never bothered to attend them, I don't believe that your lectures are becoming less comprehensible, rather the students are becoming more soft-brained. For the record, I attended PV090 and I loved it (most of the people from our group dropped out, so there were only two of us, yay!). P.S. Maybe I'm wrong, maybe good students stopped attending your classes when they found out what your stance on The One True Programming Language (C++) is ;)
avakar wrote:
By the way, how do I structure comments into paragraphs here?
gRis>> wrote:
I believe there is some negative correlation with programming language popularity - everyone does Java these days, C is too old and lacks the high level comfort and C++ is a pile of incoherent mess. Also, actually using Unix on day-to-day basis now neither requires nor develops substantial terminal skills.
Vlastik Krejčíř wrote:
Well, I think (and hope :-)) you teach as good as I remember. However, I can agree with Milan Zamazal's post - the world has changed. How many students started with 8-bit computers 20 years ago? The level of abstraction has increased. My experience is they aren't sure what is the difference between GET and POST...
Joey wrote:
I am interested in UNIX, I wanted to learn new things and I declare myself as geek. So I didn't hesitate to waste 3rd attempt to pass colloquium. Luckily I did, even though I hadn't study anything since 2nd attempt (and I've made +7 points progress). I accept your test as challenge, but I think it can't give you good reference about students knowledge. There are a lot of questions which are rather difficult with quite confusing answers, and with many of them I had the feeling, that I am on the right way, but I'd like to talk about it, since there were many aspects I had to keep in mind. But the test evaluation is from this point of view quite strict (+2/-1 means 3 points difference). I can realize myself, making another silly mistake in last test, resulting in not passing the course, but I think there won't be any relation with my real knowledge, skills, etc.
Me ... once again wrote: statistics
Is the stats about 47% success rate correct? Because when I look into 'Given Credists Stats' it says that 60% of people failed?
Yenya wrote: Re: 47 %
My graph does not include the "-" grade (i.e. people who did not try to pass the exam), while the credits statistics in IS MU counts them as failed.
Vasek Stodulka wrote:
It is simple - in 2002 a) everyone was installing some Linux distro and b) everyone, who was installing linux in 2002 had to know man pages, text configurations, basic commands and more then half students was downloading and compiling kernels and other stuff - so much tools was in form of source only those days. When something did not work, we simply repaired it in kernel (or i. e. mplayer) source, recompile that and had fun - I remember patching kernel for my TV card and remote controller, patching mplayer not to change resolution when switching fullscreen in SDL and making some crazy SiS chipset to work. Nowadays nobody does this stuff I think, because software is much more complicated, everything is available as binary packages and last but not least Windows is much more usable then in old times, so a lot of present students (as I heared) do not use Linux at all. And one more thing - back around 2002 there was Us doing the exam. :-)
Pavel S. wrote:
Hello, I have read such an interesting article today [in czech] http://zdrojak.root.cz/clanky/konec-starych-programatorskych-casu/ and I guess the author is right. The world has changed a lot and it's still changing. I attended your first UNIX course last year (succesfully passed) and I guess it was one of the most interesting and best-taught courses I have seen at FI. On the other hand, as several people remarked, sometimes I have found the topics a bit theoretical and not really usable for maintaining my own Linux computer. However, during next year that information saved me a lot of time several times. To sum it up, your teaching is OK (still the same?) but both the students and practical usability of the course topics are different.
Petr Šigut wrote:
Já myslím že mám daleko jednodušší odpověď:) Dříve jste recykloval nějaké otázky z předchozích let, takže se někde na FIMUNY ty otázky pomalu skladovaly a studenti ty opakující se uměli. Jak jsem dělal zkoušku já tak jste přišel s tím že jste udělal úplně novou sadu a zvládli to snad jen 3 studenti... Jinak mi se přednášky líbily a byly zábavné, ta jednička mi nešla protože C moc neumím a nechtělo se mi učit co dělá která funkce...
Yenya wrote: Possible answer: Population
Yesterday's presentation of Radek Pelanek had an interesting fact: in 1996, the population of 18 years old Czechs has been about 200,000, and about 50-100 students enrolled to the first semester. Nowadays it is 120,000 possible candidates, and 400-500 students entering the first semester. And the situation will get even worse (to about 80,000 possible candidates).
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Tue, 04 Jan 2011
Outgoing Mail
I archive every e-mail message I have sent since April 1999. Today during making backups of this data I have decided to count how many messages I have sent each year:
| Year | Messages | Bytes | Bytes/message |
|---|---|---|---|
| 1999 | 2110 | 5082832 | 2408 |
| 2000 | 3211 | 9393052 | 2925 |
| 2001 | 4693 | 30317777 | 6460 |
| 2002 | 7122 | 22466804 | 3154 |
| 2003 | 7669 | 25649473 | 3344 |
| 2004 | 5664 | 19496614 | 3442 |
| 2005 | 5311 | 22807724 | 4294 |
| 2006 | 5375 | 22106651 | 4112 |
| 2007 | 4828 | 33458711 | 6930 |
| 2008 | 4575 | 28287830 | 6183 |
| 2009 | 4715 | 27140012 | 5756 |
| 2010 | 4727 | 35894517 | 7593 |
The variance is relatively high, but apparently e-mail messages are getting bigger with time (no surprise here), and I have sent less messages than I used to send five to eight years ago.
4 replies for this story:
Karel Zak wrote:
You're a bot :-) I sent 7314 e-mails in last 12 years.
Yenya wrote: Re: Karel Zak
No, I am not :-). It is just some people are used to communicating over e.g. IRC (such as in RHAT, as I have been told), and some use e-mail as a primary means of communication. I, for example, barely use Jabber, and do not use other messaging tools at all (ICQ, Facebook, IRC, etc.).
Bobby wrote:
Hi Yenya, do you count your private communication and the work one together? I am not able to sum up all my e-mails as I use many different addresses for different purposes -- I am rather curious about statistic of my communication. However (and without any data), I am pretty sure that the proportion of my personal e-mails is diminishing almost to zero in a couple of last years...
Yenya wrote: Re: Bobby
Both private and work (I use a single system for both types).
Reply to this story:
Mon, 03 Jan 2011
PF 2011
I wish happy year 2011 to everyone who reads this blog.
The image is from Pink Granite Coast in Brittany, France. I plan to post a follow-up series about the places I have visited last year, including this one.
