Monday, December 1, 2008
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
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*
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
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
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 :-(
Friday, August 1, 2008
Random thought: I just found out Amy Winehouse is 25 years old! I thought she was in her late thirties. Comparatively, I'm looking damn good.
I wanted to make a note of a recent conversation I had with one of my newest acquaintances, which for now must remain anonymous, but we'll call him (and yes it is a him) Timmy. Timmy, like so many of us, is looking for his better half. Now Timmy is a nice guy, he's really smart, making decent money, fun, his looks are not too shabby and more importantly, he is straight! And why am I not dating this guy?
Anyhow Timmy and I were talking about what we are looking for in our significant other. I didn't bring much to the table, nothing unexpected that is, I'd like to meet somebody smart, fun, interesting, not-too-shabby looking and somebody who has goals, I really admire people that continually challenge themselves in life. Timmy agreed with much of that but he told me about his "score sheet". Yes, my friend grades the women he meets. As the night progresses he keeps some sort of mental checklist that will lead him to decide whether this woman is worth his time. A few examples of the items on his score sheet follow (split into categories):
Can she handle multiple topics?
Are we equally involved/participating in the conversation?
Is the tone flirtatious?
Does she read?
Does she enjoy music/ movies/ theater/ art?
Does anything intellectual excite her?
Does she speak other languages?
What does she do?
Does she have goals?
Are the goals realistic?
Is she active or athletic?
Do I feel charmed?
Is she humble/ nice/ kind/ happy?
Why isn't this guy dating me? I totally ACED his test.
And that is all my memory serves me, but pretty fascinating no? It made me wonder if we all have a checklist like that, only we're not aware of it. Most of us certainly don't verbalize it the way Timmy did. I can't judge him for it, at least he knows exactly what he's looking for. But yeah, maybe you should start thinking about your own score sheet. As for me, I'm going out to the bar tonight, putting on my beer goggles, and looking for the love of my-next-10-minutes. Monogamy is so hard as it is, specially at my age! Wish me luck ;-)
Wednesday, July 16, 2008
P. S. Check out the line up for San Francisco's Outside Lands Music Festival. It is AWESOME. If you (or a friend) decide to buy a ticket, please buy it by clicking through my banner on the right, help a sister out!
Tuesday, June 17, 2008
Tuesday, June 3, 2008
So I was officially disabled both yesterday and today. I went to work but I left around noon because it was simply too uncomfortable. So I bought some Aloe Gelly and layed around naked in my room all afternoon watching movies and applying aloe every hour. I still sit down and stand up pretty awkwardly.... but we'll just have to give it a few days.
In any case, what I really wanted to share with you guys in this post was a recipe for Tequeños!!! Which are these really really tasty cheese sticks type thing wrapped in dough and fried. My friend Alvaro from high school gave me the recipe and they turned out WAAAAY better than I expected. So here it goes:
- 500 grams of all-purpose flour (about 4.5 cups)
- 250 grams of unsalted butter at room temperature (about 1 cup = 2 sticks)
- 1/2 Tablespoon of salt (this sounds like a lot, but it was ok)
- 1 egg
- Luke warm water
- Cotija or Oaxaca cheese cut into 1/2 inch strips (these are mexican cheeses that you can find at most grocerioes stores these days, they come in a block) you can also use Farmer's cheese
Ok, first of all you must be patient and do this slowly. Mix the butter and flower in a bowl and when it is all even, add the egg. At this point you got a pretty crumbly dough, and so you need to add water very slowly, maybe a few tablespoons at a time. The amount of water varies with the humidity of your location. Here in Boulder it is really dry, and I used about a cup of water. You will stop adding water as soon as the dough comes together and it is malleable and flexible.
Then I cut the entire thing in half and rolled it really thin (I'm talking 3 millimeters thin) with a rolling pin. The dough was more yellow than it looks in the picture above, I think it was just the lighting in my kitchen.
Then you cut into strips and wrap the cheese sticks in it! You have to make sure that everything is sealed pretty tightly, you don't want the cheese oozing out. So I also rolled it in my hands and used my fingers to make sure there were no gaps. Next you get some oil in a pan and make sure it is really hot before frying, but not quite smoking, that is too hot. Fry until golden brown and drain on a paper towel.
They are usually served as an appetizer. Serve hot with some ketchup or my personal favorite "pink sauce" (salsa rosada), on the side. Pink sauce is just a mix of ketchup, mayonnaise and ground pepper, in whatever proportions you prefer. You can also add Tabasco sauce, Worcestershire sauce, or whatever you please. If it looks pink in the end, you got pink sauce :-)
I didn't have any mayo, so I enjoyed them with a little ketchup. They turned out delicious! and now I know I can enjoy a little taste oh home anytime I want!!!
I had 12 ounces of cotija cheese and about 30 tequeños turned out, but I only used half of the dough. I wrapped the rest in plastic stuck it in the fridge. I'm not sure how long it'll keep, so I plan on buying more cheese tomorrow. Yuuuummmmmm!
Thursday, May 29, 2008
Speaking of summer, I have set one single goal for myself and that is to get outside and enjoy Colorado. I spent so much time in the lab this semester that I feel like I need endless sun and fresh air to recover. I'm talking about doing something outdoorsy and healthy EVERY WEEKEND. That could be hiking, climbing, biking, backpacking, running, swimming, etc. I spent my first summery weekend working on my new old-bike, so let's not even go there. I do want to mention that the peeps at community cycles are extremely cool, and they know a lot about bikes and tools and maintenance. I plan on going back multiple times to take advantage of those very things in the future. I want to do a little more work on my bike and paint it, I'll post a picture of it when it's ready....
This last memorial day weekend I went hiking up to the first flat iron with Brendan. Twas not very hard and the views were supa-fantastik. I also enjoyed the hippies, music, free organic milk and nutrition bars at the Boulder Creek Festival on Sunday. I don't have words to describe how happy and healthy this town is, and how contagious it is!
On Monday I ran the famous BolderBOULDER 10K road race, which was my first ever. The race was beyond fun, way better than I could have ever envisioned. You get to run through the city and neighborhoods and people sit outside cheering you on. Also there were like four live bands/artists/performers per mile or so, so you never get bored! And it was just cool to run along the side of 50,000 other people. At the end of the race I got a goody bag with beer, water and some healthy snacks. For my $50 registration fee I also got to keep this sweeeeeet Adidas clima-cool fancy-techy-type running shirt, all and all a great time and I look forward to doing it again next year if I'm still around. Oh! the results:
Overall place: 25,416 out of 48,387
Women's place: 11,136 out of 26,287
They give you an RFID tag that you attach to your shoe in order to accurately measure your time every mile (how cool is that?!). My times:
- mile 1: 0:10:06.90
- mile 2: 0:09:49.82
- mile 3: 0:12:46.61 (I walked a little part of this one)
- mile 4: 0:10:05.74
- mile 5: 0:14:34.31 (and I walked most of this one)
- mile 6: 0:10:11.69
- net time: 1:09:51.40
- pace: 11:15 (based on net time)
Sunday, May 11, 2008
Things I have gotten stolen this year:
Winter coat ($200)
Winter hat ($25)
Cell phone ($100)
Blue Betty... sniff, sniff... ($650)
Tuesday, April 15, 2008
I spent spring break in Urbana,
I had a lot of fun.
Got to see all of my friends,
but one friend really shun.
Thanks Anthony for hosting me,
but now I gotta run.
by Amado Nervo
Tu cabellera es negra como el ala
del misterio; tan negra como un lóbrego
jamás, como un adiós, como un «¡quién sabe!»
Pero hay algo más negro aún: ¡tus ojos!
Tus ojos son dos magos pensativos,
dos esfinges que duermen en la sombra,
dos enigmas muy bellos... Pero hay algo,
pero hay algo más bello aún: tu boca.
Tu boca, ¡oh sí!; tu boca, hecha divinamente
para el amor, para la cálida
comunión del amor, tu boca joven;
pero hay algo mejor aún: ¡tu alma!
Tu alma recogida, silenciosa,
de piedades tan hondas como el piélago,
de ternuras tan hondas...
Pero hay algo,
pero hay algo más hondo aún: ¡tu ensueño!
A Mockingbird Remix
Sunday, March 23, 2008
The information on the Xcel Energy link above doesn't really get into the specifics. Here's a white paper, which also isn't very helpful. Mostly because Xcel probably isn't sure how they are going to do this, all they know is that they want to :-) and so do I. So yeah, sorry about that, I'll give you more information as it comes along, for now enjoy the wavering green bars in the video.
I'm on spring break right now, but I'll probably be going to the lab everyday this week. School has been keeping me really busy and I just had the week from hell. But being busy also comes with this notion that you are getting things done, and that is a wonderful feeling. My summer plans have finally concretized too (can I say that? is that grammatically correct?). I am going to stay in Boulder instead of going to California. I still plan on going to visit Salt & Pepper for a long weekend sometime in May though, so get ready for total anarchy. I am also planning on going home for a little while to attend a friend's wedding, and see the parents... the usual, I <3 going home.
The main reason I am staying here over the summer is because we want to build a small array of solar panels and use our converters. Then test the full system so that we can submit a paper for a conference next year *trumpets and horns*. I really am happy that I get to stay here, summers in Boulder simply can't go wrong. California would have been really awesome, mostly because I'd get to hang out with with all the people I know there, all my brilliant, successful, beautiful friends. But I am a bit relieved that I don't have to work with "real" engineers. Grown-ups intimidate me, specially the professional kind.
I'm going to leave you with some music from my friend Armando's band, Gaêlica, celtic music madness.
Sunday, February 24, 2008
Here's a blog entry comparing the bills the two senators have proposed, which ones have passed, etc. It seems more revealing than comparing their voting records, which are extremely similar.
Sunday, February 17, 2008
Spring semester started exactly a month ago. I am taking three classes and two of them are labs, which if you're an engineering student, know that they are 3x the workload compared to a lecture-based class. I hate being constantly busy and tired, did I say tired? I mean exhausted, drained and I'm barely getting any research done. But I am also really enjoying the classes, I swear, I am learning tons! but sometimes learning is a rocky road... you know?
When I came back from my California trip my advisor was rather unhappy with our industry sponsor, now they got some beef over IP. I really respect my advisor and definitely agree with him, but it makes me a little uncomfortable because I also like our industry sponsors and I am still interested in the project... One of the engineers from the company is coming down next week (or maybe the one after) so we'll see what goes down...
On a brigther note, I passed my prelim exam!!! this is the PhD qualifying exam, over which I suffered enormous amounts of stress. I am sooooo glad it's over now. I am not 100% sure that I want to get a PhD, but it is nice to know that the door remains open :-D And I have to thank my friends who were so supportive every step of the way, always asking me how it was going, how I was feeling, always making me feel like I was smarter than I really am, you guys are awesome! I passed!
A couple more updates: My advisor got me an undergrad assistant! I was like "huh?". I'm not sure what to make of it, maybe he thinks (or should I say "knows"?) that I'm not getting enough research done, or maybe he just wants to speed it up a little, I don't know. The point is, this guy, we'll call him "Scott" seems nice and smart and all that, but he shows up like EVERY FRIGGIN DAY asking me what he should do. Every day is the same answer, but he just doesn't get it. I tell him "Oh, I'm working on this Bill Of Materials, when it gets approved and sent out you can start doing schematic and layout, but I'll let you know when that happens". Does he think I will forget to let him know??? Anyways, this went on for 2 weeks and finally the BOM got approved and he can probably get started on Monday. I am going to have to coach him a little bit, which is a completely new feeling for me, I have never thought of myself as anybody's boss, or mentor, or teacher for that matter... I fear for that poor boy. Did I mention he got me a Valentine's day card that he made with the laser-cutter in the department? It has two lions and a big red-heart in the middle. Actually is a pretty sweet-looking laser-cut card, I can't deny it.
Sunday, January 20, 2008
Look at me. Now look at yourself. Look out the window. Aren’t we beautiful? Our youth, that is. Isn’t it blossoming just right? Aren’t our souls rich, ripe, sweet? Aren’t our eyes overwhelmingly deep?
I know how you think. You are sitting in front of a computer reading this, and you forget the world is at your fingertips. We own the world. We are the world. Can’t you tell people turning their heads every time you walk into a room? Can’t you feel the looks like freckles all over your skin?
My dad seems to think I should be cruising through school given all the amazing resources I have available in this “digital age” and all. What he doesn’t realize is that it takes that much more work to stay updated with current events, to read email, to check the news across the globe, the weather, to keep up with my friend’s blogs, to synchronize my phone with my pc, to remain an interesting well rounded human being, to discover new music, to make statements, to have opinions, to discern, to believe, to create, to be different, unique, original, to be the future.
Don’t you realize that when my parents, your parents, try to give you their opinion (and I mean “opinion” not “advice”) they are only trying to sabotage you? They are jealous, old, and don’t know the first thing about how hard it is to be you. What they do know, is how wonderful it is to be you. They want that, and since they can’t have it, they try to make you be like them. They want you to get a job, they want you to raise a family, they want you to find a pretty little house with a guest bedroom for when they come visit.**
Haven’t you noticed just how tight your skin is? How straight your back is? And with what ease you can walk up those stairs! Seriously, please take a minute to appreciate your own existence. We are conscious. We have it all. We deserve it. We give it back. That is how awesome we are.
Even though I can easily handle the wait, I am anxiously looking forward to the world you and I will build together. It will be fair, fun and new. It will be interesting, because that is what is owed to us. We are not here to take, we are here to make. We are social, smart, healthy, kind. We are young. We are imperfect, we are human.
Come with me. Let’s give ourselves. Let’s make an imperfect world together. Let there be light, dark. Let there be chaos.
*I don’t expect anyone to make any sense of this post. I’ve been reading too much of this and taking too many cold meds.
** Let it be noted I am not making any generalizations or assumptions about people’s (nor mine) actual parents. I use the term parents for all those generations that came before me who simple don’t get “it”.