Archive for November, 2009

Interview with Dan the validation man

Wednesday, November 18th, 2009
Interview between Dan and Robert

Interview between Dan and Robert

Of course the antenna design algorithms have to be validated! That’s what you’d expect from any good software?

Isn’t antenna design routine validation and model validation the same thing??

After hearing these comments I decided to move the spotlight onto Dan your validation man to see what validation is all about. He is the person charged with the job of ensuring that the algorithms used for antenna designs and antenna models that are exported from Antenna Magus are validated and can be trusted.

My chat with Dan went something like this:

Me: Hello Dan, I heard a lot of positive feedback from our users that they love the fact that the exported simulation models are ready to run. Can you please explain how you do it?

Dan: It is always great when we get positive feedback, but I definitely can’t┬átake all the credit. It is a team effort between the engineers and myself.

Me: Some people think model validation and design routine validation is the same thing. Can you explain the differences?


Roasting coffee at the office.

Thursday, November 5th, 2009

If you do not like to drink coffee the reason is you haven?t tasted good coffee? well that?s what happened to me at least. I never liked coffee and now I love it! The secret can be summed up in two words: ?freshly roasted?.

A couple of us at Antenna Magus take coffee quite seriously and this number is growing. This week one of our antenna engineers brought his ?coffee roaster? to the office and we photographed the roasting process as seen in the picture below.

The coffee roasting process.jpg

The coffee roasting process

This was actually done using a hot-air popcorn popper ? like the one here (which costs +- R 150/ $20 US). If you like coffee and want to give this a try, you have to do the following:

  1. Buy green coffee beans. Don?t just settle for anything -the best coffee comes from Africa (specifically Ethiopia and Kenya). Hawaii also has good coffee but it is overpriced and some Mexican coffee is also very good. These are all Arabica coffees which we prefer, but you may disagree as taste is a matter of personal opinion.
  2. Take a handful of green beans and pour them into the roaster. You get different types of roasters (or poppers as non coffee roasters like to call them) so the best way to determine the amount of beans you can roast at a time is to switch on the popper and slowly add more beans till just before they stop moving or rotating. If there are too many beans in the popper, the beans at the bottom will be burnt before those on top have even started roasting ? and your coffee will be terrible!
  3. Watch the beans as they start changing colour from green to light brown. As the beans begin to roast, they expand and become lighter and will start spinning more vigorously until they start hopping and jumping and small pieces of husk (we like to call it chaff) will start blowing off. Some people use a coke can with open ends to extend the hole of the roaster ? this stops the beans from escaping when they expand and over-fill the popper bowl.
  4. By now you should hear a cracking sound ? the beans have reached ?first crack? stage and have expanded to 130% of their original size. This should happen after 3 ? 6 minutes depending on the roaster?s wattage, ambient temperature and type of bean.
  5. ?The next stage is ?second crack? which usually happens about 2 ? 3 minutes after ?first crack?. The cracking noises at this stage are slightly less pronounced than the ?first crack?, and this is where you have to be very careful not to burn the beans. Depending on how dark you prefer the roast you can stop roasting just before ?second crack? for a lighter roast up to about 30 seconds after ?second crack? has started for a very dark roast. I usually stop 10 seconds after the start on ?second crack?.
  6. The final step is to cool down the roasted beans as quick as you can. The interesting thing here is that from somewhere around the ?second crack? stage, the roasting becomes exothermic, and will keep going even after the heat is removed. If you don?t cool down the beans quick they might start to smoke and get burnt. The best way to do this is to put the beans into a big metal container that will disperse the heat, and fan them for a short while to cool them down – I use a big old cooking pot, but any metal bowl or pan should also work.?

I recommend roasting outside, where the chaff will not cause a mess and remember to make sure that there are not too many people close by as they WILL harass you for some of your coffee once they?ve smelled the aroma of the fresh roast filling the air.

Flavor peak is 12 ? 48 hours after roasting but it still tastes very good immediately after roast. We use a second hand Nouva Simonelli industrial espresso machine at work (purchased from an out-of business restaurant that regularly has to be repaired – but that?s a different story on its own!)

So what has this got to do with antenna design? Nothing! I guess fresh roasted coffee is great, just like Antenna Magus!

Author: Robert Kellerman

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