Visits from the last 2 months.
Tuesday, February 3, 2009
Tuesday, January 20, 2009
Panama Vacation
I scribbled the following on the sick-bag in the plane ride back from Zurich:
(Yes, I went to Zurich)
(Yes, in Switzerland)
(Nuff said)
It was last summer when I decided to visit my parents' for the holidays in their new house in Boquete, in the Chiriqui Province in Panama. Now in order to guarantee sanity (or maybe insanity?) I also invited a few of my closest friends to come with me. It was particularly important to me that my friends met my parents, and that I got to share a bit of my culture with them. It is a side of me that doesn't show often but that I am very proud of. All in all, the house was beautiful, the food was superb and we have three really adorable neighbors that are 3, 5 and 7 years old and they say things like:
"My dog is a boy because he has a beard" and "No! you can tell he is a boy because his collar is blue"
I hope I speak for everyone when I say that we had a freaking blast. Panama is beautiful, there is lots of things to see and do. Overall my favorite was the unconditional hospitality and charm of Panamanian people. People that value and respect their land, their traditions. People that work hard and play hard. People that celebrate life for what it is and always carry a smile on their face.
To enumerate a few of the things we did in Boquete: swimming in waterfalls, relaxing in hot springs, dancing the old year off, rock climbing, hiking volcanoes, going to the beach, and there was a bit of drinking and dancing here and there to tie it all together. On the last day we also visited Panama City, the ruins of Panama Viejo, the Panama Canal and Las Bóvedas (el Casco Antiguo). Panama Viejo, a UNESCO World Heritage Site, consists of the ruins left of the original Panama City, which survived earthquakes and fires but was ultimately sacked in the year 1671 by the pirate Henry Morgan. The Panama Canal has some very interesting history and I must encourage you to read it, it is truly an amazing engineering feat. El Casco Antiguo is where Panamanians relocated the city after the pirate attack. It is also now a UNESCO World Heritage Site and all the buildings are undergoing major renovations. Unfortunately, the renovations have driven a lot of Panamanians to relocate to government housing, but it has also brought in a lot of foreign investment and stimulus to the tourism and service insdustry. All the buildings in el Casco Antiguo have a colonial feeling to them and inside there are apartments, shops, art galleries, hotels, cafes and restaurants.
Do check Steve's photostream for some fun trip documentation. Parisa stayed on her own through the last weekend and visisted Bocas del Toro, something I would love to do next time. She also took lots of great shots of the vacation, to be checked out here.
Sigh... Back in Boulder. Back to work. Dealines soon. I am feeling depressed.
(Yes, I went to Zurich)
(Yes, in Switzerland)
(Nuff said)
It was last summer when I decided to visit my parents' for the holidays in their new house in Boquete, in the Chiriqui Province in Panama. Now in order to guarantee sanity (or maybe insanity?) I also invited a few of my closest friends to come with me. It was particularly important to me that my friends met my parents, and that I got to share a bit of my culture with them. It is a side of me that doesn't show often but that I am very proud of. All in all, the house was beautiful, the food was superb and we have three really adorable neighbors that are 3, 5 and 7 years old and they say things like:
"My dog is a boy because he has a beard" and "No! you can tell he is a boy because his collar is blue"
I hope I speak for everyone when I say that we had a freaking blast. Panama is beautiful, there is lots of things to see and do. Overall my favorite was the unconditional hospitality and charm of Panamanian people. People that value and respect their land, their traditions. People that work hard and play hard. People that celebrate life for what it is and always carry a smile on their face.
To enumerate a few of the things we did in Boquete: swimming in waterfalls, relaxing in hot springs, dancing the old year off, rock climbing, hiking volcanoes, going to the beach, and there was a bit of drinking and dancing here and there to tie it all together. On the last day we also visited Panama City, the ruins of Panama Viejo, the Panama Canal and Las Bóvedas (el Casco Antiguo). Panama Viejo, a UNESCO World Heritage Site, consists of the ruins left of the original Panama City, which survived earthquakes and fires but was ultimately sacked in the year 1671 by the pirate Henry Morgan. The Panama Canal has some very interesting history and I must encourage you to read it, it is truly an amazing engineering feat. El Casco Antiguo is where Panamanians relocated the city after the pirate attack. It is also now a UNESCO World Heritage Site and all the buildings are undergoing major renovations. Unfortunately, the renovations have driven a lot of Panamanians to relocate to government housing, but it has also brought in a lot of foreign investment and stimulus to the tourism and service insdustry. All the buildings in el Casco Antiguo have a colonial feeling to them and inside there are apartments, shops, art galleries, hotels, cafes and restaurants.
Do check Steve's photostream for some fun trip documentation. Parisa stayed on her own through the last weekend and visisted Bocas del Toro, something I would love to do next time. She also took lots of great shots of the vacation, to be checked out here.
Sigh... Back in Boulder. Back to work. Dealines soon. I am feeling depressed.
Monday, December 1, 2008
22 days...
Now that the paper was submitted I can focus on really important things. Like my upcoming trip to Panama to spend Christmas with my parents and hang out with my favorite posse. I talked to my dad today for a while about things we could do while there and got really excited. So I spent most of the day researching Panama and Boquete, the town we'll be staying in.
I am a big dork (and maybe a bit of a control freak), and so I made up an itinerary. This is especially useful to me because everyone arrives and leaves at different times! So I wanted to make sure we all got to spend some quality time together, so this is my quirky (to put it gently) way of saying: I <3 you and can't wait to see you.
Note: Itinerary subject to change without notice
I am a big dork (and maybe a bit of a control freak), and so I made up an itinerary. This is especially useful to me because everyone arrives and leaves at different times! So I wanted to make sure we all got to spend some quality time together, so this is my quirky (to put it gently) way of saying: I <3 you and can't wait to see you.
Note: Itinerary subject to change without notice
Monday, November 17, 2008
Saving the world, one solar panel at a time
If you saw my previous post you probably thought "wtf is this?". I'm sorry that I did such a poor job of labeling anything on the graph, but I was really excited and it was sort of a rushed post.
Anyhow, as all of you know I've been stressing out over my research project because I still hadn't gotten any solid results worth publishing (deadline is less than 2 weeks). But now we did! and I want to share the loooooooooove :-) Get ready for me finally getting technical.
How solar panels work
Your typical photovoltaic (PV) cell is made out of silicon, though there are many different types and technologies that are quickly gaining better reputation. In lamest terms (and because I actually don't know much more detail about it) a photon is capable of kicking off an electron from the silicon valence band, effectively creating an electron-hole pair that flows creating electric current (and power!). Sounds very simple but not all photons are capable of creating the e-h pair. For this to occur the photon must have at least the same amount of energy as silicon's bandgap energy. If the photon is higher in energy the excess transforms into heat, same thing with low energy photons, they don't produce e-h pairs but they are still absorbed by the material. This is the reason why solar panels get hot, very very hot.
The solar resource
In case you did not now, solar panels are extremely sensitive to shading. Shading from clouds, neighboring building, trees, birds, etc. The relation between solar irradiance and output power is linear, however the relation between shading and output current/voltage is not. We only care about this if we put several solar panels in series or parallel to form a system, because then all the panels interact with each other and the operating point of Panel 1 will heavily depend on the operating points of Panels 2, 3, 4... n.
The series string problem
Solar panels produce direct current (dc) power, while pretty much every appliance in the world uses alternating current (ac) power. In order to interface the two you need an inverter. Types, sizes, cost, efficiency of inverters varies widely depending on the application, but one thing is known: the smaller the inverter the higher its efficiency is. Inverters tend to be big because more often than not they need a large transformer to convert the output voltage to 120V-ac, and transformers just like any type of magnetics tend to be lossy.
Typically, in a residential or commercial installation you would like to build up the dc voltage of your system and maintain it relatively constant in order to maximize the efficiency of your inverter. Hence everybody would like to put their solar panels in series, but this brings on another challenge as well. If the panels are in series they all share the string current, which means that the panel with the lowest output current will dictate where the rest of the system operates. You can bet all your money that the PV panels will operate far from its maximum rated power, and your entire system efficiency goes to hell. A single cell out of hundreds in the system can cause malfunction of the entire string.
Module integrated converters (MIC)
To solve this problem many people have proposed inserting a high efficiency dc-dc converter at the output terminals of each solar panel before interfacing to the string. Each converter performs what is called Maximum Power Point Tracking (MPPT) to ensure that the panel is operating at the point of maximum rated power. This way each panel is effectively decoupled from the string and it is insensitive to any changes in the system. This solution has been proven many times before BY SIMULATION. So far there hasn't been any published research on a real system with actual hardware.... until now... And let me tell you why there isn't published research on real systems, BECAUSE BUILDING THIS STUFF IS HARD!@%#~!!!
Last Saturday Sara (from the building systems group in the Civil Engineering department), Scott (undergraduate EE working for my advisor) and I went outside for what I thought would be another failed experiment. But luckily I was wrong and the experiment went really, really well. What the graph from the previous post shows are performance results from the three cases we studied. The blue bars represent the series string without any converters, three solar panels in series, period. The green bars are the system with my converters and the red bars are the percentage power gained by integrating the converters in each case.
The first set of three bars is when all three panels were at full sun, you can see the gain is negative because there is a tiny bit of power used by my converters, but this is still a kick ass efficiency. The next set of bars are the system under "medium" shading conditions. I can't tell you what "medium" is because we haven't defined it yet, but it implies significantly lower solar iiradiance. The important thing is that output power was improved by nearly 20%. In the last case, the system was under "heavy" shading conditions, and the converters helped increased the output power by almost 40%!!!! These are really excellent numbers and I was very pleased with them.
It has been 6 long months since I first started building the circuit. Some days were longer than others, but I'm glad that now I get to relax a little bit more. Not just that but when good things happen I tend to feel more motivated to work. This research will be published next year in the Applied Power Electronics Conference 2009 happening in Washington D. C. next February where yours truly will be presenting this work.
The day after making history
As you expected I went out last night to celebrate this moment of history-in-the-making. I drank waaaay too much, and to make matters worse the bar we went to had karaoke. It was pure anarchy, by the end of the night I wasn't seeing double, but triple. I was hugging strangers and talking to them about solar power, it was ridiculous and wonderful. Most of today was spent in bed feeling sick, *sigh*. This is going to be a great week.
Anyhow, as all of you know I've been stressing out over my research project because I still hadn't gotten any solid results worth publishing (deadline is less than 2 weeks). But now we did! and I want to share the loooooooooove :-) Get ready for me finally getting technical.
How solar panels work
Your typical photovoltaic (PV) cell is made out of silicon, though there are many different types and technologies that are quickly gaining better reputation. In lamest terms (and because I actually don't know much more detail about it) a photon is capable of kicking off an electron from the silicon valence band, effectively creating an electron-hole pair that flows creating electric current (and power!). Sounds very simple but not all photons are capable of creating the e-h pair. For this to occur the photon must have at least the same amount of energy as silicon's bandgap energy. If the photon is higher in energy the excess transforms into heat, same thing with low energy photons, they don't produce e-h pairs but they are still absorbed by the material. This is the reason why solar panels get hot, very very hot.
The solar resource
In case you did not now, solar panels are extremely sensitive to shading. Shading from clouds, neighboring building, trees, birds, etc. The relation between solar irradiance and output power is linear, however the relation between shading and output current/voltage is not. We only care about this if we put several solar panels in series or parallel to form a system, because then all the panels interact with each other and the operating point of Panel 1 will heavily depend on the operating points of Panels 2, 3, 4... n.
The series string problem
Solar panels produce direct current (dc) power, while pretty much every appliance in the world uses alternating current (ac) power. In order to interface the two you need an inverter. Types, sizes, cost, efficiency of inverters varies widely depending on the application, but one thing is known: the smaller the inverter the higher its efficiency is. Inverters tend to be big because more often than not they need a large transformer to convert the output voltage to 120V-ac, and transformers just like any type of magnetics tend to be lossy.
Typically, in a residential or commercial installation you would like to build up the dc voltage of your system and maintain it relatively constant in order to maximize the efficiency of your inverter. Hence everybody would like to put their solar panels in series, but this brings on another challenge as well. If the panels are in series they all share the string current, which means that the panel with the lowest output current will dictate where the rest of the system operates. You can bet all your money that the PV panels will operate far from its maximum rated power, and your entire system efficiency goes to hell. A single cell out of hundreds in the system can cause malfunction of the entire string.
Module integrated converters (MIC)
To solve this problem many people have proposed inserting a high efficiency dc-dc converter at the output terminals of each solar panel before interfacing to the string. Each converter performs what is called Maximum Power Point Tracking (MPPT) to ensure that the panel is operating at the point of maximum rated power. This way each panel is effectively decoupled from the string and it is insensitive to any changes in the system. This solution has been proven many times before BY SIMULATION. So far there hasn't been any published research on a real system with actual hardware.... until now... And let me tell you why there isn't published research on real systems, BECAUSE BUILDING THIS STUFF IS HARD!@%#~!!!
Last Saturday Sara (from the building systems group in the Civil Engineering department), Scott (undergraduate EE working for my advisor) and I went outside for what I thought would be another failed experiment. But luckily I was wrong and the experiment went really, really well. What the graph from the previous post shows are performance results from the three cases we studied. The blue bars represent the series string without any converters, three solar panels in series, period. The green bars are the system with my converters and the red bars are the percentage power gained by integrating the converters in each case.
The first set of three bars is when all three panels were at full sun, you can see the gain is negative because there is a tiny bit of power used by my converters, but this is still a kick ass efficiency. The next set of bars are the system under "medium" shading conditions. I can't tell you what "medium" is because we haven't defined it yet, but it implies significantly lower solar iiradiance. The important thing is that output power was improved by nearly 20%. In the last case, the system was under "heavy" shading conditions, and the converters helped increased the output power by almost 40%!!!! These are really excellent numbers and I was very pleased with them.It has been 6 long months since I first started building the circuit. Some days were longer than others, but I'm glad that now I get to relax a little bit more. Not just that but when good things happen I tend to feel more motivated to work. This research will be published next year in the Applied Power Electronics Conference 2009 happening in Washington D. C. next February where yours truly will be presenting this work.
The day after making history
As you expected I went out last night to celebrate this moment of history-in-the-making. I drank waaaay too much, and to make matters worse the bar we went to had karaoke. It was pure anarchy, by the end of the night I wasn't seeing double, but triple. I was hugging strangers and talking to them about solar power, it was ridiculous and wonderful. Most of today was spent in bed feeling sick, *sigh*. This is going to be a great week.
Sunday, November 16, 2008
Thursday, November 6, 2008
A comparative study of two useful discrete-valued random fields for the statistical modeling of images*
*Is the title for a Computer Science paper from the late 80's. No I didn't read it, just borrowed the title.
I did this yesterday:
Which is a huge improvement from this:
When I am done with what I'm doing right now, I will share it with you.
Some free publicity:
My friend Dan Hill is a "modern day prophet denouncing the hypocrisies of our time". He is also a very talented artist, writer, filmmaker, historian, librarian, entomologist, space cowboy, time-traveler and connoisseur of all that is vice. He has a bi-monthly periodical that exposes, well... the hypocrisies of our time. Each issue is a journey through the deepest darkest secrets of human nature.
You can order it via his website "The Fifty Flip Experiment" for $2 an issue, or buy a 1-year subscription for $10 (includes shipping!).
Me and Dan once drew humanoid elephants together.
I hope he doesn't sue me for copyright infringement.
I did this yesterday:
Which is a huge improvement from this:
When I am done with what I'm doing right now, I will share it with you.
Some free publicity:
My friend Dan Hill is a "modern day prophet denouncing the hypocrisies of our time". He is also a very talented artist, writer, filmmaker, historian, librarian, entomologist, space cowboy, time-traveler and connoisseur of all that is vice. He has a bi-monthly periodical that exposes, well... the hypocrisies of our time. Each issue is a journey through the deepest darkest secrets of human nature.
You can order it via his website "The Fifty Flip Experiment" for $2 an issue, or buy a 1-year subscription for $10 (includes shipping!).
Me and Dan once drew humanoid elephants together.
I hope he doesn't sue me for copyright infringement.
Tuesday, September 30, 2008
Thursday, September 25, 2008
Saturday, September 20, 2008
Minor milestone
Today I gave a short presentation to our research group about my work. I felt like it went relatively well, though I wasn't in the audience, so it may have been garbage. In my presentation I tried to make up for whatever lack of substance with entertainment, thus I used lots of clip-art. People welcomed it more warmly than I expected. Who doesn't love clip-art?
If you want to be in on it, my presentation is here.
Parisa, I really want to post my polaroids, but I have to find a scanner first. I'm on it! ok?
If you want to be in on it, my presentation is here.
Parisa, I really want to post my polaroids, but I have to find a scanner first. I'm on it! ok?
Monday, September 8, 2008
Reporting from the trenches
My little summer vacation was fabulous. I feel so motivated and full of energy to tackle a new semester full of research and control courses. Right after Caracas and before going back to Boulder I went to the Bay area and visited some of my favorite people. I am of course speaking of Andrew Bird, Rodrigo y Gabriela, Manu Chao, Radiohead, M. Ward, Los Amigos Invisibles, Wilco, Cold War Kids, Beck, Regina Spektor, Devendra Banhart, Cake, etc.
Oh! and I got to see Steve and Parisa too! San Francisco's Outside Lands Music Festival. it was by far the most significant musical experience of my life... yet. The line up was out of this world and it was really well organized. SF's Golden Gate Park is massive, it takes up about half of the city, no kidding. I wish I had written this post right after I got back, because then I would have been more inclined to comment. My favorite performances were:
So back in Boulder: I am taking two different control courses and I have started climbing. Finally bought some shoes and started going to the gym. It's something I've been meaning to do for the last year, and finally got around to it since I was able to save a little money over the summer. It's really fun though I feel like my arms are not strong enough yet (and I have realized I am a little scared of heights too), but I'll keep working on it. Everyone at the gym is cut as hell, so it is obvious it is great exercise. One of my favorite things about going to the climbing gym is watching all the pros strut their stuff and climb in unimaginable ways, it's a guilty pleasure I suppose.
Oh my! I almost forgot! In California I stayed most of the time with my friend Steve Hanna in Berkeley. Aside from his overall awesomeness he is also a really great (and overly modest) photographer. We had some good fun with his camera, him shooting, me posing and you should check out his gallery here.
Errr. I have to go do homework :-(
Oh! and I got to see Steve and Parisa too! San Francisco's Outside Lands Music Festival. it was by far the most significant musical experience of my life... yet. The line up was out of this world and it was really well organized. SF's Golden Gate Park is massive, it takes up about half of the city, no kidding. I wish I had written this post right after I got back, because then I would have been more inclined to comment. My favorite performances were:
- Andrew Bird: I am simply infatuated with this dude. I would have his babies any day.
- Rodrigo y Gabriela: I couldn't believe how much energy two guitars can bring.
- Sharon Jones and the Dap Kings: That woman has so much presence. She really owned the stage.
- Manu Chao: His beats make me jump, it's uncontrollable.
- Los Amigos Invisibles: I have to support the motherland, plus it's just really fun danceable music.
So back in Boulder: I am taking two different control courses and I have started climbing. Finally bought some shoes and started going to the gym. It's something I've been meaning to do for the last year, and finally got around to it since I was able to save a little money over the summer. It's really fun though I feel like my arms are not strong enough yet (and I have realized I am a little scared of heights too), but I'll keep working on it. Everyone at the gym is cut as hell, so it is obvious it is great exercise. One of my favorite things about going to the climbing gym is watching all the pros strut their stuff and climb in unimaginable ways, it's a guilty pleasure I suppose.
Oh my! I almost forgot! In California I stayed most of the time with my friend Steve Hanna in Berkeley. Aside from his overall awesomeness he is also a really great (and overly modest) photographer. We had some good fun with his camera, him shooting, me posing and you should check out his gallery here.
Errr. I have to go do homework :-(
Subscribe to:
Posts (Atom)