Mar 03

Learning a new language

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I admit it, I sucked at French in high school. I did not like reading it, I did not like speaking it and I certainly did not like learning it. But now I look back at those years in regret, wishing I had put more effort in it. Luckily the internet came up with a solution which my brain seems to enjoy.

One word: Gamification. Whatever is a chore to you, turn it into a game (like an RPG where you get points as rewards) and chances are you will do them without much hesitation. The newcomer on the scene who just had a Kickstarter is HabitRPG, its simplicity is astounding but it has an incredible effect on your habits.

There’s a ton of sites out there to learn languages but so far I’m the happiest with DuoLingo (for learning words in context and sentence translation) and Memrise (for pronunciation and vocabulary). I easily spend 30 minutes a day on both Spanish and French since I’ve started using those sites.

These sites managed to turn something that felt like a chore in something my brain wants and needs to do before it feels satisfied with my day. Pretty incredible if you ask me.

Mar 01

Copper Line Attenuation MAR1 Model

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One of the homeworks I had to do during my Communication Systems course at the PoliTO was calculating some attenuation values of a copper line in function of distance and frequence, based on the MAR1 model. Oddly enough, Googling MAR1 I couldn’t find a single thing about the model so I decided to post my work here so people can take a look at how it works. I’ve made this in Matlab.

The following function computes the attenuation:

function [att] = mar1(d, f)
% mar1(d, f)    Calculates the attenuation in dB
%               depending on length d (in km) and
%               frequency f (in Hz)
 
 mu0 = 4*pi*10^-4;
 R0 = 277.623806;
 Lalpha = 421.576013 * 10^-6;
 Linf = Lalpha;
 a = 1.470148;
 b = 2;
 c = 2.765;
 delta = 0.001123;
 C1Mhz = 49.792437 * 10^-9;
 
 Zl = 100;
 Zs = Zl;
 
 Cf = C1Mhz * (f / 10^6)^-(2*delta/pi) * cos(delta);
 sf = (mu0 * 1i * f) / ((0.75^2) * R0);
 
 Zf = 1i * 2 * pi * f * Linf + R0 * ((1/4) + (3/4) * sqrt(1 + (a*sf*(sf+b))/(sf+c)));
 Yf = 2*pi*f*Cf*(1i+tan(delta));
 
 Z0 = sqrt(Zf/Yf);
 gamma = sqrt(Zf * Yf);
 
 A = cosh(gamma*d);
 B = Z0*sinh(gamma*d);
 C = (1/Z0) * sinh(gamma*d);
 D = cosh(gamma*d);
 
 ratio = Zl / (A*Zl + B + C * Zl * Zs + D * Zs);
 att=20*log10(abs(1/ratio));

If you put this in a nested loop that iterates over some distances and frequencies and plot it afterwards, you get a nice result such as this.

MAR1 Copper Line Attenuation

MAR1 Copper Line Attenuation

This shows you why ADSL is slower than for example internet access by cable. A reason why more recent versions of ADSL and VDSL are faster is because the line length is shortened and thus the frequency can be raised, and in turn so is the symbol rate.

Feb 05

Group T Studforum recap

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De examens op Groep T zitten er weer op, hoog tijd om opnieuw eens te kijken hoe deze examenperiode het studforum gebruikt werd.

Zoals onderstaande afbeeldingen tonen werd er dit jaar minder gebruik gemaakt van het Studforum. De trend om “Facebook groepen” te gebruiken is helaas niet gestopt maar juist toegenomen, zeker in de bachelor jaren.

Pageview vergelijking

Pageview vergelijking

Visits vergelijking

Visits vergelijking

De top 10 boards waren deze keer:

  1. 1eMAS – Engineering and Quality Management
  2. 3eBAC – EM – Machine-onderdelen en mechanisch ontwerp
  3. 2eBAC – Elektromagnetisme
  4. 1eBAC – Computersystemen en Databanken
  5. 1eBAC – Analyse
  6. 1eBAC – Lineaire Algebra en Analytische Meetkunde
  7. 3eBAC – EM – Elektrische machines en distributie
  8. 1eBAC – Chemie en Chemische Technologie
  9. 1eBAC – Mechanica (Dynamica & Statica)
  10. 2eBAC – Thermodynamica

Het is duidelijk dat de “oude garde” het meest trouw is aan het studforum, ook door het grote aantal EMers heb je in hun vakgebied nog populaire boards. Normaal gezien zou je dus enkel 1e Bachelor boards in de top 5 mogen zien staan, alleen al door het grote aantal studenten.

Jammer genoeg voor toekomstige studenten betekent dit slecht nieuws. De versnippering van examenvragen, de kwaliteit van de antwoorden en het feit dat posts op Facebook belachelijk veel moeilijker te vinden zijn zal hun examenperiodes er niet gemakkelijker op maken.

Ben je zelf een eerstejaarsstudent, probeer dan zeker je collega’s te overhalen om die Facebook groepen te mijden en examendiscussies op het StudForum te houden, je toekomstige schachten zullen je dankbaar zijn!