So, to model the movement of the water I mentioned a few posts ago, I am using a model called SI3D. This stands for semi-implicit three-dimensional. I won't go into what semi-implicit means. SI3D was created at UC Davis in 1997 by Pete Smith. Its creation earned Pete his PhD. Pete now works at the USGS (United States Geological Survey) in Sacramento. He mostly applies the model to the San Francisco Bay Delta.
After Pete graduated, Francisco Rueda came to UC Davis and further developed SI3D. In particular, he added water temperature as one of the state variables. Pete's model was mostly used for the movement of the water and was sufficient for most estuary applications. However, water temperature greatly affects how water moves, especially in large lakes, so by adding water temperature, the model could be applied to a greater number of systems. Francisco used the model on Lake Tahoe and Clear Lake. But, Pete continued to use his model, without temperature.
Francisco's addition of temperature to the model earned him a PhD. After he graduated, he did a post-doc at Cornell (he left Cornell a few months before I go there). After Cornell, he moved here to Granada to become a professor. So, SI3D has two different forms and is used in Sacramento, Ithaca, NY and Granada, Spain.
After Francisco graduated, SI3D was not used very much at Davis. Mostly because none of the funding agencies were willing to fund a three-dimensional model. Modeling in three-dimensions takes more computer time, so the entire project takes more time, making it more expensive. And in some cases, one or two dimensional models are sufficient. For example, a river is usually very well mixed, meaning that from the surface to the bottom, the water has the same properties. So, the up-down direction of the model is a waste of time.
I started at UC Davis in June 2004, 3 years after Francisco left.
Friday, October 26, 2007
Thursday, October 25, 2007
Nado Libre
I did it! I swam, in Spain! I brought my swim stuff with me, hoping I would find a pool. I found the pool, got a pamphlet, and had Josh and Gina help me translate. But then, for a few days I was still too chicken to head for a swim. As I've mentioned, the language barrier is difficult. I can only handle one daunting, new task per day. Tuesday was the grocery store, Wednesday was the computer store, so I guess today was the day for a swim. It was nice. The pool is 50m, and got pretty crowded, but I managed. It felt really good to feel comfortable someplace. I may not have mastered the language, but I was definitely one of the best swimmers at free swim. The swims cost 4 euros, kind of a lot. I might buy a pack of 10 for 29 euros and make a pledge to swim 10 more times while I am here. The crazy thing is thats only about every other day. . . 21 more days!
Time to walk to the bus station, I'm going to try and snap a few photos along the way.
Wish I could be at home begging my cat to sit with me while I settle in for another episode of Grey's Anatomy. . . oh well, conversations with Belgians and Germans will have to suffice for today.
Time to walk to the bus station, I'm going to try and snap a few photos along the way.
Wish I could be at home begging my cat to sit with me while I settle in for another episode of Grey's Anatomy. . . oh well, conversations with Belgians and Germans will have to suffice for today.
Churros y Chocolate
Today, we went to a different cafe for our morning coffee / breakfast. This place had churros and chocolate, a typical Spanish breakfast. The churros here a slighlty different than the churros we are accustomed to from Disneyland and ball games. They are friend dough, but are not covered in sugar and cinnamon. They did bring a sugar bowl to the table after we ordered the churros, and some of us dipped our churros in the sugar. Often, churros are served with chocolate, which I can best describe as warm chocolate pudding. The churros are dipped in the chocolate. I did not order the chocolate today, but I will go back with my camera for more churros and chocolate before I leave.
Now lets see if I can stay awake after that greasy treat.
Now lets see if I can stay awake after that greasy treat.
Wednesday, October 24, 2007
I forgot to tell you about the donkey!
On Saturday night, while bar hopping, I saw a donkey, not once, but twice, tied up to a door. The donkey was "dressed" very nicely. I neglected to take a picture because I didn't want to scare the poor thing. Anyway, eventually, I found out that this donkey was most likely the transportation for a guy at his bachelor party!
John, is there something you forget to tell me about Tahoe?
John, is there something you forget to tell me about Tahoe?
I had to buy a new flash drive. . .
Francisco told me where to go, but it was nerve-wracking none-the-less. I brought the old one (which for some reason tells me it has no more space when I know there is nothing on it!) and said the following:
"Lo Siento, no hablo espanol. Necisitio un. . " and held up my old flash drive. She got the picture and let me pick from two, a 1gb and a 2 gb. I picked the 1 GB. She was also nice enough to turn the computer screen and show me the price rather than speak it. I have found being told a price very intimidating, and I often just hold out some money!
That was my brave move for the day, swimming will have to wait until tomorrow. . .
"Lo Siento, no hablo espanol. Necisitio un. . " and held up my old flash drive. She got the picture and let me pick from two, a 1gb and a 2 gb. I picked the 1 GB. She was also nice enough to turn the computer screen and show me the price rather than speak it. I have found being told a price very intimidating, and I often just hold out some money!
That was my brave move for the day, swimming will have to wait until tomorrow. . .
Question. . .
If I can't understand the nutrient content information, does that mean the calories don't count?
This "Chocolate Extrafino con Leche" is really good!
I broke all kinds of Spanish etiquette today, I think. I ate lunch at my desk. Except for this chocolate, I think I'm ready to come home.
This "Chocolate Extrafino con Leche" is really good!
I broke all kinds of Spanish etiquette today, I think. I ate lunch at my desk. Except for this chocolate, I think I'm ready to come home.
John is cured (why I'm here part 2)
The next step in modeling is to calibrate the model. This means that I tinker with variables to try and get my model to match my observations as best as I can. In the example from the other day, this would mean that I could try to change X, because perhaps John was going faster or slower than I thought.
The final step in modeling is to apply the model. This is usually the final goal. So, in our example, the question was, "where is John", and I can apply my calibrated model to guess where John is at any given time! Sweet!
However, the model I am developing, calibrating and applying is a bit more complicated than a man walking only from east to west.
Let's say suddenly John is cured from his crazy disorder! Ahhhh! Now he can walk west to east or east to west (which would be the negative of west to east) and north to south or south to north (negative of north to south). In fact, he can even walk at an angle, heading north-east or south-east. This makes my model a bit more complicated. Here's another figure for you to ponder:
So, now his velocity is a little bit more complicated because its not straight west to east. However, I can still try to guess his location, but my model gets a bit more complicated (now its two dimension!)
deltat = t/n
DO i = 1, n
D(i) = D_start + X_es*deltat + X_ns*deltat
END DO
So, this time I have two parameters (X_es anc X_ns) that I can tinker with to calibrate. Once its calibrated, again I can apply.
So, to understand what I am modeling, lets say there are 10,000 John's lining the street, they can go any direction, even jump up and down. And instead of John's on a street, its water molecules in a river. That's the initial part of my model, the movement of water. But, instead of trying to model individual molecules, I group them all together and model the mass movement of the water. In addition to modeling how the water moves, I model how certain chemical reactions occurs in the water and affect the quality.
The final step in modeling is to apply the model. This is usually the final goal. So, in our example, the question was, "where is John", and I can apply my calibrated model to guess where John is at any given time! Sweet!
However, the model I am developing, calibrating and applying is a bit more complicated than a man walking only from east to west.
Let's say suddenly John is cured from his crazy disorder! Ahhhh! Now he can walk west to east or east to west (which would be the negative of west to east) and north to south or south to north (negative of north to south). In fact, he can even walk at an angle, heading north-east or south-east. This makes my model a bit more complicated. Here's another figure for you to ponder:
So, now his velocity is a little bit more complicated because its not straight west to east. However, I can still try to guess his location, but my model gets a bit more complicated (now its two dimension!)
deltat = t/n
DO i = 1, n
D(i) = D_start + X_es*deltat + X_ns*deltat
END DO
So, this time I have two parameters (X_es anc X_ns) that I can tinker with to calibrate. Once its calibrated, again I can apply.
So, to understand what I am modeling, lets say there are 10,000 John's lining the street, they can go any direction, even jump up and down. And instead of John's on a street, its water molecules in a river. That's the initial part of my model, the movement of water. But, instead of trying to model individual molecules, I group them all together and model the mass movement of the water. In addition to modeling how the water moves, I model how certain chemical reactions occurs in the water and affect the quality.
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